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6822 lines
177 KiB
6822 lines
177 KiB
/* |
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* Generic process-grouping system. |
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* |
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* Based originally on the cpuset system, extracted by Paul Menage |
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* Copyright (C) 2006 Google, Inc |
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* |
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* Notifications support |
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* Copyright (C) 2009 Nokia Corporation |
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* Author: Kirill A. Shutemov |
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* |
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* Copyright notices from the original cpuset code: |
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* -------------------------------------------------- |
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* Copyright (C) 2003 BULL SA. |
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* Copyright (C) 2004-2006 Silicon Graphics, Inc. |
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* |
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* Portions derived from Patrick Mochel's sysfs code. |
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* sysfs is Copyright (c) 2001-3 Patrick Mochel |
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* |
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* 2003-10-10 Written by Simon Derr. |
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* 2003-10-22 Updates by Stephen Hemminger. |
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* 2004 May-July Rework by Paul Jackson. |
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* --------------------------------------------------- |
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* |
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* This file is subject to the terms and conditions of the GNU General Public |
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* License. See the file COPYING in the main directory of the Linux |
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* distribution for more details. |
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*/ |
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|
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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|
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#include "cgroup-internal.h" |
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|
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#include <linux/bpf-cgroup.h> |
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#include <linux/cred.h> |
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#include <linux/errno.h> |
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#include <linux/init_task.h> |
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#include <linux/kernel.h> |
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#include <linux/magic.h> |
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#include <linux/mutex.h> |
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#include <linux/mount.h> |
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#include <linux/pagemap.h> |
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#include <linux/proc_fs.h> |
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#include <linux/rcupdate.h> |
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#include <linux/sched.h> |
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#include <linux/sched/task.h> |
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#include <linux/slab.h> |
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#include <linux/spinlock.h> |
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#include <linux/percpu-rwsem.h> |
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#include <linux/string.h> |
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#include <linux/hashtable.h> |
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#include <linux/idr.h> |
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#include <linux/kthread.h> |
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#include <linux/atomic.h> |
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#include <linux/cpuset.h> |
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#include <linux/proc_ns.h> |
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#include <linux/nsproxy.h> |
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#include <linux/file.h> |
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#include <linux/fs_parser.h> |
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#include <linux/sched/cputime.h> |
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#include <linux/psi.h> |
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#include <net/sock.h> |
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|
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#define CREATE_TRACE_POINTS |
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#include <trace/events/cgroup.h> |
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#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
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MAX_CFTYPE_NAME + 2) |
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/* let's not notify more than 100 times per second */ |
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#define CGROUP_FILE_NOTIFY_MIN_INTV DIV_ROUND_UP(HZ, 100) |
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/* |
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* To avoid confusing the compiler (and generating warnings) with code |
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* that attempts to access what would be a 0-element array (i.e. sized |
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* to a potentially empty array when CGROUP_SUBSYS_COUNT == 0), this |
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* constant expression can be added. |
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*/ |
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#define CGROUP_HAS_SUBSYS_CONFIG (CGROUP_SUBSYS_COUNT > 0) |
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|
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/* |
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* cgroup_mutex is the master lock. Any modification to cgroup or its |
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* hierarchy must be performed while holding it. |
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* |
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* css_set_lock protects task->cgroups pointer, the list of css_set |
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* objects, and the chain of tasks off each css_set. |
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* |
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* These locks are exported if CONFIG_PROVE_RCU so that accessors in |
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* cgroup.h can use them for lockdep annotations. |
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*/ |
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DEFINE_MUTEX(cgroup_mutex); |
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DEFINE_SPINLOCK(css_set_lock); |
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#ifdef CONFIG_PROVE_RCU |
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EXPORT_SYMBOL_GPL(cgroup_mutex); |
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EXPORT_SYMBOL_GPL(css_set_lock); |
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#endif |
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DEFINE_SPINLOCK(trace_cgroup_path_lock); |
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char trace_cgroup_path[TRACE_CGROUP_PATH_LEN]; |
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bool cgroup_debug __read_mostly; |
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|
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/* |
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* Protects cgroup_idr and css_idr so that IDs can be released without |
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* grabbing cgroup_mutex. |
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*/ |
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static DEFINE_SPINLOCK(cgroup_idr_lock); |
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|
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/* |
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* Protects cgroup_file->kn for !self csses. It synchronizes notifications |
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* against file removal/re-creation across css hiding. |
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*/ |
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static DEFINE_SPINLOCK(cgroup_file_kn_lock); |
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DEFINE_PERCPU_RWSEM(cgroup_threadgroup_rwsem); |
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#define cgroup_assert_mutex_or_rcu_locked() \ |
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RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
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!lockdep_is_held(&cgroup_mutex), \ |
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"cgroup_mutex or RCU read lock required"); |
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|
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/* |
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* cgroup destruction makes heavy use of work items and there can be a lot |
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* of concurrent destructions. Use a separate workqueue so that cgroup |
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* destruction work items don't end up filling up max_active of system_wq |
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* which may lead to deadlock. |
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*/ |
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static struct workqueue_struct *cgroup_destroy_wq; |
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|
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/* generate an array of cgroup subsystem pointers */ |
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#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
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struct cgroup_subsys *cgroup_subsys[] = { |
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#include <linux/cgroup_subsys.h> |
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}; |
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#undef SUBSYS |
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|
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/* array of cgroup subsystem names */ |
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#define SUBSYS(_x) [_x ## _cgrp_id] = #_x, |
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static const char *cgroup_subsys_name[] = { |
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#include <linux/cgroup_subsys.h> |
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}; |
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#undef SUBSYS |
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/* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
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#define SUBSYS(_x) \ |
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DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ |
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DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ |
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EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ |
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EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); |
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#include <linux/cgroup_subsys.h> |
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#undef SUBSYS |
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#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, |
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static struct static_key_true *cgroup_subsys_enabled_key[] = { |
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#include <linux/cgroup_subsys.h> |
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}; |
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#undef SUBSYS |
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#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, |
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static struct static_key_true *cgroup_subsys_on_dfl_key[] = { |
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#include <linux/cgroup_subsys.h> |
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}; |
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#undef SUBSYS |
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static DEFINE_PER_CPU(struct cgroup_rstat_cpu, cgrp_dfl_root_rstat_cpu); |
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|
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/* the default hierarchy */ |
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struct cgroup_root cgrp_dfl_root = { .cgrp.rstat_cpu = &cgrp_dfl_root_rstat_cpu }; |
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EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
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/* |
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* The default hierarchy always exists but is hidden until mounted for the |
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* first time. This is for backward compatibility. |
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*/ |
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static bool cgrp_dfl_visible; |
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|
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/* some controllers are not supported in the default hierarchy */ |
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static u16 cgrp_dfl_inhibit_ss_mask; |
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|
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/* some controllers are implicitly enabled on the default hierarchy */ |
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static u16 cgrp_dfl_implicit_ss_mask; |
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/* some controllers can be threaded on the default hierarchy */ |
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static u16 cgrp_dfl_threaded_ss_mask; |
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|
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/* The list of hierarchy roots */ |
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LIST_HEAD(cgroup_roots); |
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static int cgroup_root_count; |
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/* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
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static DEFINE_IDR(cgroup_hierarchy_idr); |
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/* |
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* Assign a monotonically increasing serial number to csses. It guarantees |
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* cgroups with bigger numbers are newer than those with smaller numbers. |
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* Also, as csses are always appended to the parent's ->children list, it |
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* guarantees that sibling csses are always sorted in the ascending serial |
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* number order on the list. Protected by cgroup_mutex. |
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*/ |
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static u64 css_serial_nr_next = 1; |
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/* |
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* These bitmasks identify subsystems with specific features to avoid |
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* having to do iterative checks repeatedly. |
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*/ |
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static u16 have_fork_callback __read_mostly; |
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static u16 have_exit_callback __read_mostly; |
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static u16 have_release_callback __read_mostly; |
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static u16 have_canfork_callback __read_mostly; |
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/* cgroup namespace for init task */ |
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struct cgroup_namespace init_cgroup_ns = { |
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.ns.count = REFCOUNT_INIT(2), |
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.user_ns = &init_user_ns, |
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.ns.ops = &cgroupns_operations, |
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.ns.inum = PROC_CGROUP_INIT_INO, |
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.root_cset = &init_css_set, |
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}; |
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static struct file_system_type cgroup2_fs_type; |
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static struct cftype cgroup_base_files[]; |
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|
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/* cgroup optional features */ |
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enum cgroup_opt_features { |
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#ifdef CONFIG_PSI |
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OPT_FEATURE_PRESSURE, |
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#endif |
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OPT_FEATURE_COUNT |
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}; |
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static const char *cgroup_opt_feature_names[OPT_FEATURE_COUNT] = { |
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#ifdef CONFIG_PSI |
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"pressure", |
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#endif |
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}; |
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static u16 cgroup_feature_disable_mask __read_mostly; |
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static int cgroup_apply_control(struct cgroup *cgrp); |
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static void cgroup_finalize_control(struct cgroup *cgrp, int ret); |
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static void css_task_iter_skip(struct css_task_iter *it, |
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struct task_struct *task); |
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static int cgroup_destroy_locked(struct cgroup *cgrp); |
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static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, |
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struct cgroup_subsys *ss); |
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static void css_release(struct percpu_ref *ref); |
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static void kill_css(struct cgroup_subsys_state *css); |
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static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
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struct cgroup *cgrp, struct cftype cfts[], |
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bool is_add); |
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/** |
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* cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID |
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* @ssid: subsys ID of interest |
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* |
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* cgroup_subsys_enabled() can only be used with literal subsys names which |
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* is fine for individual subsystems but unsuitable for cgroup core. This |
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* is slower static_key_enabled() based test indexed by @ssid. |
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*/ |
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bool cgroup_ssid_enabled(int ssid) |
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{ |
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if (!CGROUP_HAS_SUBSYS_CONFIG) |
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return false; |
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return static_key_enabled(cgroup_subsys_enabled_key[ssid]); |
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} |
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/** |
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* cgroup_on_dfl - test whether a cgroup is on the default hierarchy |
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* @cgrp: the cgroup of interest |
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* |
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* The default hierarchy is the v2 interface of cgroup and this function |
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* can be used to test whether a cgroup is on the default hierarchy for |
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* cases where a subsystem should behave differently depending on the |
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* interface version. |
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* |
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* List of changed behaviors: |
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* |
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* - Mount options "noprefix", "xattr", "clone_children", "release_agent" |
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* and "name" are disallowed. |
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* |
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* - When mounting an existing superblock, mount options should match. |
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* |
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* - Remount is disallowed. |
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* |
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* - rename(2) is disallowed. |
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* |
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* - "tasks" is removed. Everything should be at process granularity. Use |
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* "cgroup.procs" instead. |
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* |
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* - "cgroup.procs" is not sorted. pids will be unique unless they got |
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* recycled in-between reads. |
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* |
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* - "release_agent" and "notify_on_release" are removed. Replacement |
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* notification mechanism will be implemented. |
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* |
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* - "cgroup.clone_children" is removed. |
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* |
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* - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup |
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* and its descendants contain no task; otherwise, 1. The file also |
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* generates kernfs notification which can be monitored through poll and |
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* [di]notify when the value of the file changes. |
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* |
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* - cpuset: tasks will be kept in empty cpusets when hotplug happens and |
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* take masks of ancestors with non-empty cpus/mems, instead of being |
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* moved to an ancestor. |
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* |
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* - cpuset: a task can be moved into an empty cpuset, and again it takes |
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* masks of ancestors. |
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* |
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* - blkcg: blk-throttle becomes properly hierarchical. |
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* |
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* - debug: disallowed on the default hierarchy. |
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*/ |
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bool cgroup_on_dfl(const struct cgroup *cgrp) |
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{ |
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return cgrp->root == &cgrp_dfl_root; |
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} |
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/* IDR wrappers which synchronize using cgroup_idr_lock */ |
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static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, |
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gfp_t gfp_mask) |
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{ |
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int ret; |
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idr_preload(gfp_mask); |
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spin_lock_bh(&cgroup_idr_lock); |
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ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM); |
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spin_unlock_bh(&cgroup_idr_lock); |
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idr_preload_end(); |
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return ret; |
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} |
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static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) |
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{ |
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void *ret; |
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spin_lock_bh(&cgroup_idr_lock); |
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ret = idr_replace(idr, ptr, id); |
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spin_unlock_bh(&cgroup_idr_lock); |
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return ret; |
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} |
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static void cgroup_idr_remove(struct idr *idr, int id) |
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{ |
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spin_lock_bh(&cgroup_idr_lock); |
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idr_remove(idr, id); |
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spin_unlock_bh(&cgroup_idr_lock); |
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} |
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static bool cgroup_has_tasks(struct cgroup *cgrp) |
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{ |
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return cgrp->nr_populated_csets; |
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} |
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bool cgroup_is_threaded(struct cgroup *cgrp) |
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{ |
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return cgrp->dom_cgrp != cgrp; |
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} |
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/* can @cgrp host both domain and threaded children? */ |
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static bool cgroup_is_mixable(struct cgroup *cgrp) |
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{ |
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/* |
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* Root isn't under domain level resource control exempting it from |
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* the no-internal-process constraint, so it can serve as a thread |
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* root and a parent of resource domains at the same time. |
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*/ |
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return !cgroup_parent(cgrp); |
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} |
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/* can @cgrp become a thread root? Should always be true for a thread root */ |
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static bool cgroup_can_be_thread_root(struct cgroup *cgrp) |
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{ |
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/* mixables don't care */ |
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if (cgroup_is_mixable(cgrp)) |
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return true; |
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/* domain roots can't be nested under threaded */ |
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if (cgroup_is_threaded(cgrp)) |
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return false; |
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/* can only have either domain or threaded children */ |
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if (cgrp->nr_populated_domain_children) |
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return false; |
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|
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/* and no domain controllers can be enabled */ |
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if (cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask) |
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return false; |
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return true; |
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} |
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/* is @cgrp root of a threaded subtree? */ |
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bool cgroup_is_thread_root(struct cgroup *cgrp) |
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{ |
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/* thread root should be a domain */ |
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if (cgroup_is_threaded(cgrp)) |
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return false; |
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|
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/* a domain w/ threaded children is a thread root */ |
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if (cgrp->nr_threaded_children) |
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return true; |
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/* |
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* A domain which has tasks and explicit threaded controllers |
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* enabled is a thread root. |
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*/ |
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if (cgroup_has_tasks(cgrp) && |
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(cgrp->subtree_control & cgrp_dfl_threaded_ss_mask)) |
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return true; |
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return false; |
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} |
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/* a domain which isn't connected to the root w/o brekage can't be used */ |
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static bool cgroup_is_valid_domain(struct cgroup *cgrp) |
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{ |
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/* the cgroup itself can be a thread root */ |
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if (cgroup_is_threaded(cgrp)) |
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return false; |
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/* but the ancestors can't be unless mixable */ |
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while ((cgrp = cgroup_parent(cgrp))) { |
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if (!cgroup_is_mixable(cgrp) && cgroup_is_thread_root(cgrp)) |
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return false; |
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if (cgroup_is_threaded(cgrp)) |
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return false; |
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} |
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return true; |
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} |
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/* subsystems visibly enabled on a cgroup */ |
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static u16 cgroup_control(struct cgroup *cgrp) |
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{ |
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struct cgroup *parent = cgroup_parent(cgrp); |
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u16 root_ss_mask = cgrp->root->subsys_mask; |
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|
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if (parent) { |
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u16 ss_mask = parent->subtree_control; |
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|
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/* threaded cgroups can only have threaded controllers */ |
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if (cgroup_is_threaded(cgrp)) |
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ss_mask &= cgrp_dfl_threaded_ss_mask; |
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return ss_mask; |
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} |
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if (cgroup_on_dfl(cgrp)) |
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root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask | |
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cgrp_dfl_implicit_ss_mask); |
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return root_ss_mask; |
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} |
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|
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/* subsystems enabled on a cgroup */ |
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static u16 cgroup_ss_mask(struct cgroup *cgrp) |
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{ |
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struct cgroup *parent = cgroup_parent(cgrp); |
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|
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if (parent) { |
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u16 ss_mask = parent->subtree_ss_mask; |
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|
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/* threaded cgroups can only have threaded controllers */ |
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if (cgroup_is_threaded(cgrp)) |
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ss_mask &= cgrp_dfl_threaded_ss_mask; |
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return ss_mask; |
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} |
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|
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return cgrp->root->subsys_mask; |
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} |
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|
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/** |
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* cgroup_css - obtain a cgroup's css for the specified subsystem |
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* @cgrp: the cgroup of interest |
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* @ss: the subsystem of interest (%NULL returns @cgrp->self) |
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* |
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* Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
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* function must be called either under cgroup_mutex or rcu_read_lock() and |
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* the caller is responsible for pinning the returned css if it wants to |
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* keep accessing it outside the said locks. This function may return |
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* %NULL if @cgrp doesn't have @subsys_id enabled. |
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*/ |
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static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, |
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struct cgroup_subsys *ss) |
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{ |
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if (CGROUP_HAS_SUBSYS_CONFIG && ss) |
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return rcu_dereference_check(cgrp->subsys[ss->id], |
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lockdep_is_held(&cgroup_mutex)); |
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else |
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return &cgrp->self; |
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} |
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|
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/** |
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* cgroup_tryget_css - try to get a cgroup's css for the specified subsystem |
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* @cgrp: the cgroup of interest |
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* @ss: the subsystem of interest |
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* |
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* Find and get @cgrp's css associated with @ss. If the css doesn't exist |
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* or is offline, %NULL is returned. |
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*/ |
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static struct cgroup_subsys_state *cgroup_tryget_css(struct cgroup *cgrp, |
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struct cgroup_subsys *ss) |
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{ |
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struct cgroup_subsys_state *css; |
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|
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rcu_read_lock(); |
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css = cgroup_css(cgrp, ss); |
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if (css && !css_tryget_online(css)) |
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css = NULL; |
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rcu_read_unlock(); |
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|
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return css; |
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} |
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|
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/** |
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* cgroup_e_css_by_mask - obtain a cgroup's effective css for the specified ss |
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* @cgrp: the cgroup of interest |
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* @ss: the subsystem of interest (%NULL returns @cgrp->self) |
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* |
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* Similar to cgroup_css() but returns the effective css, which is defined |
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* as the matching css of the nearest ancestor including self which has @ss |
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* enabled. If @ss is associated with the hierarchy @cgrp is on, this |
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* function is guaranteed to return non-NULL css. |
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*/ |
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static struct cgroup_subsys_state *cgroup_e_css_by_mask(struct cgroup *cgrp, |
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struct cgroup_subsys *ss) |
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{ |
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lockdep_assert_held(&cgroup_mutex); |
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|
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if (!ss) |
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return &cgrp->self; |
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|
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/* |
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* This function is used while updating css associations and thus |
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* can't test the csses directly. Test ss_mask. |
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*/ |
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while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) { |
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cgrp = cgroup_parent(cgrp); |
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if (!cgrp) |
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return NULL; |
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} |
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|
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return cgroup_css(cgrp, ss); |
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} |
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|
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/** |
|
* cgroup_e_css - obtain a cgroup's effective css for the specified subsystem |
|
* @cgrp: the cgroup of interest |
|
* @ss: the subsystem of interest |
|
* |
|
* Find and get the effective css of @cgrp for @ss. The effective css is |
|
* defined as the matching css of the nearest ancestor including self which |
|
* has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, |
|
* the root css is returned, so this function always returns a valid css. |
|
* |
|
* The returned css is not guaranteed to be online, and therefore it is the |
|
* callers responsibility to try get a reference for it. |
|
*/ |
|
struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, |
|
struct cgroup_subsys *ss) |
|
{ |
|
struct cgroup_subsys_state *css; |
|
|
|
if (!CGROUP_HAS_SUBSYS_CONFIG) |
|
return NULL; |
|
|
|
do { |
|
css = cgroup_css(cgrp, ss); |
|
|
|
if (css) |
|
return css; |
|
cgrp = cgroup_parent(cgrp); |
|
} while (cgrp); |
|
|
|
return init_css_set.subsys[ss->id]; |
|
} |
|
|
|
/** |
|
* cgroup_get_e_css - get a cgroup's effective css for the specified subsystem |
|
* @cgrp: the cgroup of interest |
|
* @ss: the subsystem of interest |
|
* |
|
* Find and get the effective css of @cgrp for @ss. The effective css is |
|
* defined as the matching css of the nearest ancestor including self which |
|
* has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on, |
|
* the root css is returned, so this function always returns a valid css. |
|
* The returned css must be put using css_put(). |
|
*/ |
|
struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp, |
|
struct cgroup_subsys *ss) |
|
{ |
|
struct cgroup_subsys_state *css; |
|
|
|
if (!CGROUP_HAS_SUBSYS_CONFIG) |
|
return NULL; |
|
|
|
rcu_read_lock(); |
|
|
|
do { |
|
css = cgroup_css(cgrp, ss); |
|
|
|
if (css && css_tryget_online(css)) |
|
goto out_unlock; |
|
cgrp = cgroup_parent(cgrp); |
|
} while (cgrp); |
|
|
|
css = init_css_set.subsys[ss->id]; |
|
css_get(css); |
|
out_unlock: |
|
rcu_read_unlock(); |
|
return css; |
|
} |
|
EXPORT_SYMBOL_GPL(cgroup_get_e_css); |
|
|
|
static void cgroup_get_live(struct cgroup *cgrp) |
|
{ |
|
WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
|
css_get(&cgrp->self); |
|
} |
|
|
|
/** |
|
* __cgroup_task_count - count the number of tasks in a cgroup. The caller |
|
* is responsible for taking the css_set_lock. |
|
* @cgrp: the cgroup in question |
|
*/ |
|
int __cgroup_task_count(const struct cgroup *cgrp) |
|
{ |
|
int count = 0; |
|
struct cgrp_cset_link *link; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
list_for_each_entry(link, &cgrp->cset_links, cset_link) |
|
count += link->cset->nr_tasks; |
|
|
|
return count; |
|
} |
|
|
|
/** |
|
* cgroup_task_count - count the number of tasks in a cgroup. |
|
* @cgrp: the cgroup in question |
|
*/ |
|
int cgroup_task_count(const struct cgroup *cgrp) |
|
{ |
|
int count; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
count = __cgroup_task_count(cgrp); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
return count; |
|
} |
|
|
|
struct cgroup_subsys_state *of_css(struct kernfs_open_file *of) |
|
{ |
|
struct cgroup *cgrp = of->kn->parent->priv; |
|
struct cftype *cft = of_cft(of); |
|
|
|
/* |
|
* This is open and unprotected implementation of cgroup_css(). |
|
* seq_css() is only called from a kernfs file operation which has |
|
* an active reference on the file. Because all the subsystem |
|
* files are drained before a css is disassociated with a cgroup, |
|
* the matching css from the cgroup's subsys table is guaranteed to |
|
* be and stay valid until the enclosing operation is complete. |
|
*/ |
|
if (CGROUP_HAS_SUBSYS_CONFIG && cft->ss) |
|
return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); |
|
else |
|
return &cgrp->self; |
|
} |
|
EXPORT_SYMBOL_GPL(of_css); |
|
|
|
/** |
|
* for_each_css - iterate all css's of a cgroup |
|
* @css: the iteration cursor |
|
* @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end |
|
* @cgrp: the target cgroup to iterate css's of |
|
* |
|
* Should be called under cgroup_[tree_]mutex. |
|
*/ |
|
#define for_each_css(css, ssid, cgrp) \ |
|
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ |
|
if (!((css) = rcu_dereference_check( \ |
|
(cgrp)->subsys[(ssid)], \ |
|
lockdep_is_held(&cgroup_mutex)))) { } \ |
|
else |
|
|
|
/** |
|
* for_each_e_css - iterate all effective css's of a cgroup |
|
* @css: the iteration cursor |
|
* @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end |
|
* @cgrp: the target cgroup to iterate css's of |
|
* |
|
* Should be called under cgroup_[tree_]mutex. |
|
*/ |
|
#define for_each_e_css(css, ssid, cgrp) \ |
|
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \ |
|
if (!((css) = cgroup_e_css_by_mask(cgrp, \ |
|
cgroup_subsys[(ssid)]))) \ |
|
; \ |
|
else |
|
|
|
/** |
|
* do_each_subsys_mask - filter for_each_subsys with a bitmask |
|
* @ss: the iteration cursor |
|
* @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
|
* @ss_mask: the bitmask |
|
* |
|
* The block will only run for cases where the ssid-th bit (1 << ssid) of |
|
* @ss_mask is set. |
|
*/ |
|
#define do_each_subsys_mask(ss, ssid, ss_mask) do { \ |
|
unsigned long __ss_mask = (ss_mask); \ |
|
if (!CGROUP_HAS_SUBSYS_CONFIG) { \ |
|
(ssid) = 0; \ |
|
break; \ |
|
} \ |
|
for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \ |
|
(ss) = cgroup_subsys[ssid]; \ |
|
{ |
|
|
|
#define while_each_subsys_mask() \ |
|
} \ |
|
} \ |
|
} while (false) |
|
|
|
/* iterate over child cgrps, lock should be held throughout iteration */ |
|
#define cgroup_for_each_live_child(child, cgrp) \ |
|
list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ |
|
if (({ lockdep_assert_held(&cgroup_mutex); \ |
|
cgroup_is_dead(child); })) \ |
|
; \ |
|
else |
|
|
|
/* walk live descendants in pre order */ |
|
#define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \ |
|
css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \ |
|
if (({ lockdep_assert_held(&cgroup_mutex); \ |
|
(dsct) = (d_css)->cgroup; \ |
|
cgroup_is_dead(dsct); })) \ |
|
; \ |
|
else |
|
|
|
/* walk live descendants in postorder */ |
|
#define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \ |
|
css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \ |
|
if (({ lockdep_assert_held(&cgroup_mutex); \ |
|
(dsct) = (d_css)->cgroup; \ |
|
cgroup_is_dead(dsct); })) \ |
|
; \ |
|
else |
|
|
|
/* |
|
* The default css_set - used by init and its children prior to any |
|
* hierarchies being mounted. It contains a pointer to the root state |
|
* for each subsystem. Also used to anchor the list of css_sets. Not |
|
* reference-counted, to improve performance when child cgroups |
|
* haven't been created. |
|
*/ |
|
struct css_set init_css_set = { |
|
.refcount = REFCOUNT_INIT(1), |
|
.dom_cset = &init_css_set, |
|
.tasks = LIST_HEAD_INIT(init_css_set.tasks), |
|
.mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), |
|
.dying_tasks = LIST_HEAD_INIT(init_css_set.dying_tasks), |
|
.task_iters = LIST_HEAD_INIT(init_css_set.task_iters), |
|
.threaded_csets = LIST_HEAD_INIT(init_css_set.threaded_csets), |
|
.cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), |
|
.mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), |
|
.mg_node = LIST_HEAD_INIT(init_css_set.mg_node), |
|
|
|
/* |
|
* The following field is re-initialized when this cset gets linked |
|
* in cgroup_init(). However, let's initialize the field |
|
* statically too so that the default cgroup can be accessed safely |
|
* early during boot. |
|
*/ |
|
.dfl_cgrp = &cgrp_dfl_root.cgrp, |
|
}; |
|
|
|
static int css_set_count = 1; /* 1 for init_css_set */ |
|
|
|
static bool css_set_threaded(struct css_set *cset) |
|
{ |
|
return cset->dom_cset != cset; |
|
} |
|
|
|
/** |
|
* css_set_populated - does a css_set contain any tasks? |
|
* @cset: target css_set |
|
* |
|
* css_set_populated() should be the same as !!cset->nr_tasks at steady |
|
* state. However, css_set_populated() can be called while a task is being |
|
* added to or removed from the linked list before the nr_tasks is |
|
* properly updated. Hence, we can't just look at ->nr_tasks here. |
|
*/ |
|
static bool css_set_populated(struct css_set *cset) |
|
{ |
|
lockdep_assert_held(&css_set_lock); |
|
|
|
return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks); |
|
} |
|
|
|
/** |
|
* cgroup_update_populated - update the populated count of a cgroup |
|
* @cgrp: the target cgroup |
|
* @populated: inc or dec populated count |
|
* |
|
* One of the css_sets associated with @cgrp is either getting its first |
|
* task or losing the last. Update @cgrp->nr_populated_* accordingly. The |
|
* count is propagated towards root so that a given cgroup's |
|
* nr_populated_children is zero iff none of its descendants contain any |
|
* tasks. |
|
* |
|
* @cgrp's interface file "cgroup.populated" is zero if both |
|
* @cgrp->nr_populated_csets and @cgrp->nr_populated_children are zero and |
|
* 1 otherwise. When the sum changes from or to zero, userland is notified |
|
* that the content of the interface file has changed. This can be used to |
|
* detect when @cgrp and its descendants become populated or empty. |
|
*/ |
|
static void cgroup_update_populated(struct cgroup *cgrp, bool populated) |
|
{ |
|
struct cgroup *child = NULL; |
|
int adj = populated ? 1 : -1; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
do { |
|
bool was_populated = cgroup_is_populated(cgrp); |
|
|
|
if (!child) { |
|
cgrp->nr_populated_csets += adj; |
|
} else { |
|
if (cgroup_is_threaded(child)) |
|
cgrp->nr_populated_threaded_children += adj; |
|
else |
|
cgrp->nr_populated_domain_children += adj; |
|
} |
|
|
|
if (was_populated == cgroup_is_populated(cgrp)) |
|
break; |
|
|
|
cgroup1_check_for_release(cgrp); |
|
TRACE_CGROUP_PATH(notify_populated, cgrp, |
|
cgroup_is_populated(cgrp)); |
|
cgroup_file_notify(&cgrp->events_file); |
|
|
|
child = cgrp; |
|
cgrp = cgroup_parent(cgrp); |
|
} while (cgrp); |
|
} |
|
|
|
/** |
|
* css_set_update_populated - update populated state of a css_set |
|
* @cset: target css_set |
|
* @populated: whether @cset is populated or depopulated |
|
* |
|
* @cset is either getting the first task or losing the last. Update the |
|
* populated counters of all associated cgroups accordingly. |
|
*/ |
|
static void css_set_update_populated(struct css_set *cset, bool populated) |
|
{ |
|
struct cgrp_cset_link *link; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) |
|
cgroup_update_populated(link->cgrp, populated); |
|
} |
|
|
|
/* |
|
* @task is leaving, advance task iterators which are pointing to it so |
|
* that they can resume at the next position. Advancing an iterator might |
|
* remove it from the list, use safe walk. See css_task_iter_skip() for |
|
* details. |
|
*/ |
|
static void css_set_skip_task_iters(struct css_set *cset, |
|
struct task_struct *task) |
|
{ |
|
struct css_task_iter *it, *pos; |
|
|
|
list_for_each_entry_safe(it, pos, &cset->task_iters, iters_node) |
|
css_task_iter_skip(it, task); |
|
} |
|
|
|
/** |
|
* css_set_move_task - move a task from one css_set to another |
|
* @task: task being moved |
|
* @from_cset: css_set @task currently belongs to (may be NULL) |
|
* @to_cset: new css_set @task is being moved to (may be NULL) |
|
* @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks |
|
* |
|
* Move @task from @from_cset to @to_cset. If @task didn't belong to any |
|
* css_set, @from_cset can be NULL. If @task is being disassociated |
|
* instead of moved, @to_cset can be NULL. |
|
* |
|
* This function automatically handles populated counter updates and |
|
* css_task_iter adjustments but the caller is responsible for managing |
|
* @from_cset and @to_cset's reference counts. |
|
*/ |
|
static void css_set_move_task(struct task_struct *task, |
|
struct css_set *from_cset, struct css_set *to_cset, |
|
bool use_mg_tasks) |
|
{ |
|
lockdep_assert_held(&css_set_lock); |
|
|
|
if (to_cset && !css_set_populated(to_cset)) |
|
css_set_update_populated(to_cset, true); |
|
|
|
if (from_cset) { |
|
WARN_ON_ONCE(list_empty(&task->cg_list)); |
|
|
|
css_set_skip_task_iters(from_cset, task); |
|
list_del_init(&task->cg_list); |
|
if (!css_set_populated(from_cset)) |
|
css_set_update_populated(from_cset, false); |
|
} else { |
|
WARN_ON_ONCE(!list_empty(&task->cg_list)); |
|
} |
|
|
|
if (to_cset) { |
|
/* |
|
* We are synchronized through cgroup_threadgroup_rwsem |
|
* against PF_EXITING setting such that we can't race |
|
* against cgroup_exit()/cgroup_free() dropping the css_set. |
|
*/ |
|
WARN_ON_ONCE(task->flags & PF_EXITING); |
|
|
|
cgroup_move_task(task, to_cset); |
|
list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks : |
|
&to_cset->tasks); |
|
} |
|
} |
|
|
|
/* |
|
* hash table for cgroup groups. This improves the performance to find |
|
* an existing css_set. This hash doesn't (currently) take into |
|
* account cgroups in empty hierarchies. |
|
*/ |
|
#define CSS_SET_HASH_BITS 7 |
|
static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS); |
|
|
|
static unsigned long css_set_hash(struct cgroup_subsys_state *css[]) |
|
{ |
|
unsigned long key = 0UL; |
|
struct cgroup_subsys *ss; |
|
int i; |
|
|
|
for_each_subsys(ss, i) |
|
key += (unsigned long)css[i]; |
|
key = (key >> 16) ^ key; |
|
|
|
return key; |
|
} |
|
|
|
void put_css_set_locked(struct css_set *cset) |
|
{ |
|
struct cgrp_cset_link *link, *tmp_link; |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
if (!refcount_dec_and_test(&cset->refcount)) |
|
return; |
|
|
|
WARN_ON_ONCE(!list_empty(&cset->threaded_csets)); |
|
|
|
/* This css_set is dead. Unlink it and release cgroup and css refs */ |
|
for_each_subsys(ss, ssid) { |
|
list_del(&cset->e_cset_node[ssid]); |
|
css_put(cset->subsys[ssid]); |
|
} |
|
hash_del(&cset->hlist); |
|
css_set_count--; |
|
|
|
list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) { |
|
list_del(&link->cset_link); |
|
list_del(&link->cgrp_link); |
|
if (cgroup_parent(link->cgrp)) |
|
cgroup_put(link->cgrp); |
|
kfree(link); |
|
} |
|
|
|
if (css_set_threaded(cset)) { |
|
list_del(&cset->threaded_csets_node); |
|
put_css_set_locked(cset->dom_cset); |
|
} |
|
|
|
kfree_rcu(cset, rcu_head); |
|
} |
|
|
|
/** |
|
* compare_css_sets - helper function for find_existing_css_set(). |
|
* @cset: candidate css_set being tested |
|
* @old_cset: existing css_set for a task |
|
* @new_cgrp: cgroup that's being entered by the task |
|
* @template: desired set of css pointers in css_set (pre-calculated) |
|
* |
|
* Returns true if "cset" matches "old_cset" except for the hierarchy |
|
* which "new_cgrp" belongs to, for which it should match "new_cgrp". |
|
*/ |
|
static bool compare_css_sets(struct css_set *cset, |
|
struct css_set *old_cset, |
|
struct cgroup *new_cgrp, |
|
struct cgroup_subsys_state *template[]) |
|
{ |
|
struct cgroup *new_dfl_cgrp; |
|
struct list_head *l1, *l2; |
|
|
|
/* |
|
* On the default hierarchy, there can be csets which are |
|
* associated with the same set of cgroups but different csses. |
|
* Let's first ensure that csses match. |
|
*/ |
|
if (memcmp(template, cset->subsys, sizeof(cset->subsys))) |
|
return false; |
|
|
|
|
|
/* @cset's domain should match the default cgroup's */ |
|
if (cgroup_on_dfl(new_cgrp)) |
|
new_dfl_cgrp = new_cgrp; |
|
else |
|
new_dfl_cgrp = old_cset->dfl_cgrp; |
|
|
|
if (new_dfl_cgrp->dom_cgrp != cset->dom_cset->dfl_cgrp) |
|
return false; |
|
|
|
/* |
|
* Compare cgroup pointers in order to distinguish between |
|
* different cgroups in hierarchies. As different cgroups may |
|
* share the same effective css, this comparison is always |
|
* necessary. |
|
*/ |
|
l1 = &cset->cgrp_links; |
|
l2 = &old_cset->cgrp_links; |
|
while (1) { |
|
struct cgrp_cset_link *link1, *link2; |
|
struct cgroup *cgrp1, *cgrp2; |
|
|
|
l1 = l1->next; |
|
l2 = l2->next; |
|
/* See if we reached the end - both lists are equal length. */ |
|
if (l1 == &cset->cgrp_links) { |
|
BUG_ON(l2 != &old_cset->cgrp_links); |
|
break; |
|
} else { |
|
BUG_ON(l2 == &old_cset->cgrp_links); |
|
} |
|
/* Locate the cgroups associated with these links. */ |
|
link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link); |
|
link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link); |
|
cgrp1 = link1->cgrp; |
|
cgrp2 = link2->cgrp; |
|
/* Hierarchies should be linked in the same order. */ |
|
BUG_ON(cgrp1->root != cgrp2->root); |
|
|
|
/* |
|
* If this hierarchy is the hierarchy of the cgroup |
|
* that's changing, then we need to check that this |
|
* css_set points to the new cgroup; if it's any other |
|
* hierarchy, then this css_set should point to the |
|
* same cgroup as the old css_set. |
|
*/ |
|
if (cgrp1->root == new_cgrp->root) { |
|
if (cgrp1 != new_cgrp) |
|
return false; |
|
} else { |
|
if (cgrp1 != cgrp2) |
|
return false; |
|
} |
|
} |
|
return true; |
|
} |
|
|
|
/** |
|
* find_existing_css_set - init css array and find the matching css_set |
|
* @old_cset: the css_set that we're using before the cgroup transition |
|
* @cgrp: the cgroup that we're moving into |
|
* @template: out param for the new set of csses, should be clear on entry |
|
*/ |
|
static struct css_set *find_existing_css_set(struct css_set *old_cset, |
|
struct cgroup *cgrp, |
|
struct cgroup_subsys_state *template[]) |
|
{ |
|
struct cgroup_root *root = cgrp->root; |
|
struct cgroup_subsys *ss; |
|
struct css_set *cset; |
|
unsigned long key; |
|
int i; |
|
|
|
/* |
|
* Build the set of subsystem state objects that we want to see in the |
|
* new css_set. While subsystems can change globally, the entries here |
|
* won't change, so no need for locking. |
|
*/ |
|
for_each_subsys(ss, i) { |
|
if (root->subsys_mask & (1UL << i)) { |
|
/* |
|
* @ss is in this hierarchy, so we want the |
|
* effective css from @cgrp. |
|
*/ |
|
template[i] = cgroup_e_css_by_mask(cgrp, ss); |
|
} else { |
|
/* |
|
* @ss is not in this hierarchy, so we don't want |
|
* to change the css. |
|
*/ |
|
template[i] = old_cset->subsys[i]; |
|
} |
|
} |
|
|
|
key = css_set_hash(template); |
|
hash_for_each_possible(css_set_table, cset, hlist, key) { |
|
if (!compare_css_sets(cset, old_cset, cgrp, template)) |
|
continue; |
|
|
|
/* This css_set matches what we need */ |
|
return cset; |
|
} |
|
|
|
/* No existing cgroup group matched */ |
|
return NULL; |
|
} |
|
|
|
static void free_cgrp_cset_links(struct list_head *links_to_free) |
|
{ |
|
struct cgrp_cset_link *link, *tmp_link; |
|
|
|
list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) { |
|
list_del(&link->cset_link); |
|
kfree(link); |
|
} |
|
} |
|
|
|
/** |
|
* allocate_cgrp_cset_links - allocate cgrp_cset_links |
|
* @count: the number of links to allocate |
|
* @tmp_links: list_head the allocated links are put on |
|
* |
|
* Allocate @count cgrp_cset_link structures and chain them on @tmp_links |
|
* through ->cset_link. Returns 0 on success or -errno. |
|
*/ |
|
static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links) |
|
{ |
|
struct cgrp_cset_link *link; |
|
int i; |
|
|
|
INIT_LIST_HEAD(tmp_links); |
|
|
|
for (i = 0; i < count; i++) { |
|
link = kzalloc(sizeof(*link), GFP_KERNEL); |
|
if (!link) { |
|
free_cgrp_cset_links(tmp_links); |
|
return -ENOMEM; |
|
} |
|
list_add(&link->cset_link, tmp_links); |
|
} |
|
return 0; |
|
} |
|
|
|
/** |
|
* link_css_set - a helper function to link a css_set to a cgroup |
|
* @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links() |
|
* @cset: the css_set to be linked |
|
* @cgrp: the destination cgroup |
|
*/ |
|
static void link_css_set(struct list_head *tmp_links, struct css_set *cset, |
|
struct cgroup *cgrp) |
|
{ |
|
struct cgrp_cset_link *link; |
|
|
|
BUG_ON(list_empty(tmp_links)); |
|
|
|
if (cgroup_on_dfl(cgrp)) |
|
cset->dfl_cgrp = cgrp; |
|
|
|
link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link); |
|
link->cset = cset; |
|
link->cgrp = cgrp; |
|
|
|
/* |
|
* Always add links to the tail of the lists so that the lists are |
|
* in chronological order. |
|
*/ |
|
list_move_tail(&link->cset_link, &cgrp->cset_links); |
|
list_add_tail(&link->cgrp_link, &cset->cgrp_links); |
|
|
|
if (cgroup_parent(cgrp)) |
|
cgroup_get_live(cgrp); |
|
} |
|
|
|
/** |
|
* find_css_set - return a new css_set with one cgroup updated |
|
* @old_cset: the baseline css_set |
|
* @cgrp: the cgroup to be updated |
|
* |
|
* Return a new css_set that's equivalent to @old_cset, but with @cgrp |
|
* substituted into the appropriate hierarchy. |
|
*/ |
|
static struct css_set *find_css_set(struct css_set *old_cset, |
|
struct cgroup *cgrp) |
|
{ |
|
struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { }; |
|
struct css_set *cset; |
|
struct list_head tmp_links; |
|
struct cgrp_cset_link *link; |
|
struct cgroup_subsys *ss; |
|
unsigned long key; |
|
int ssid; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
/* First see if we already have a cgroup group that matches |
|
* the desired set */ |
|
spin_lock_irq(&css_set_lock); |
|
cset = find_existing_css_set(old_cset, cgrp, template); |
|
if (cset) |
|
get_css_set(cset); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
if (cset) |
|
return cset; |
|
|
|
cset = kzalloc(sizeof(*cset), GFP_KERNEL); |
|
if (!cset) |
|
return NULL; |
|
|
|
/* Allocate all the cgrp_cset_link objects that we'll need */ |
|
if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) { |
|
kfree(cset); |
|
return NULL; |
|
} |
|
|
|
refcount_set(&cset->refcount, 1); |
|
cset->dom_cset = cset; |
|
INIT_LIST_HEAD(&cset->tasks); |
|
INIT_LIST_HEAD(&cset->mg_tasks); |
|
INIT_LIST_HEAD(&cset->dying_tasks); |
|
INIT_LIST_HEAD(&cset->task_iters); |
|
INIT_LIST_HEAD(&cset->threaded_csets); |
|
INIT_HLIST_NODE(&cset->hlist); |
|
INIT_LIST_HEAD(&cset->cgrp_links); |
|
INIT_LIST_HEAD(&cset->mg_preload_node); |
|
INIT_LIST_HEAD(&cset->mg_node); |
|
|
|
/* Copy the set of subsystem state objects generated in |
|
* find_existing_css_set() */ |
|
memcpy(cset->subsys, template, sizeof(cset->subsys)); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
/* Add reference counts and links from the new css_set. */ |
|
list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) { |
|
struct cgroup *c = link->cgrp; |
|
|
|
if (c->root == cgrp->root) |
|
c = cgrp; |
|
link_css_set(&tmp_links, cset, c); |
|
} |
|
|
|
BUG_ON(!list_empty(&tmp_links)); |
|
|
|
css_set_count++; |
|
|
|
/* Add @cset to the hash table */ |
|
key = css_set_hash(cset->subsys); |
|
hash_add(css_set_table, &cset->hlist, key); |
|
|
|
for_each_subsys(ss, ssid) { |
|
struct cgroup_subsys_state *css = cset->subsys[ssid]; |
|
|
|
list_add_tail(&cset->e_cset_node[ssid], |
|
&css->cgroup->e_csets[ssid]); |
|
css_get(css); |
|
} |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* |
|
* If @cset should be threaded, look up the matching dom_cset and |
|
* link them up. We first fully initialize @cset then look for the |
|
* dom_cset. It's simpler this way and safe as @cset is guaranteed |
|
* to stay empty until we return. |
|
*/ |
|
if (cgroup_is_threaded(cset->dfl_cgrp)) { |
|
struct css_set *dcset; |
|
|
|
dcset = find_css_set(cset, cset->dfl_cgrp->dom_cgrp); |
|
if (!dcset) { |
|
put_css_set(cset); |
|
return NULL; |
|
} |
|
|
|
spin_lock_irq(&css_set_lock); |
|
cset->dom_cset = dcset; |
|
list_add_tail(&cset->threaded_csets_node, |
|
&dcset->threaded_csets); |
|
spin_unlock_irq(&css_set_lock); |
|
} |
|
|
|
return cset; |
|
} |
|
|
|
struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
|
{ |
|
struct cgroup *root_cgrp = kernfs_root_to_node(kf_root)->priv; |
|
|
|
return root_cgrp->root; |
|
} |
|
|
|
static int cgroup_init_root_id(struct cgroup_root *root) |
|
{ |
|
int id; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL); |
|
if (id < 0) |
|
return id; |
|
|
|
root->hierarchy_id = id; |
|
return 0; |
|
} |
|
|
|
static void cgroup_exit_root_id(struct cgroup_root *root) |
|
{ |
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id); |
|
} |
|
|
|
void cgroup_free_root(struct cgroup_root *root) |
|
{ |
|
kfree(root); |
|
} |
|
|
|
static void cgroup_destroy_root(struct cgroup_root *root) |
|
{ |
|
struct cgroup *cgrp = &root->cgrp; |
|
struct cgrp_cset_link *link, *tmp_link; |
|
|
|
trace_cgroup_destroy_root(root); |
|
|
|
cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
|
|
|
BUG_ON(atomic_read(&root->nr_cgrps)); |
|
BUG_ON(!list_empty(&cgrp->self.children)); |
|
|
|
/* Rebind all subsystems back to the default hierarchy */ |
|
WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask)); |
|
|
|
/* |
|
* Release all the links from cset_links to this hierarchy's |
|
* root cgroup |
|
*/ |
|
spin_lock_irq(&css_set_lock); |
|
|
|
list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) { |
|
list_del(&link->cset_link); |
|
list_del(&link->cgrp_link); |
|
kfree(link); |
|
} |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
|
|
if (!list_empty(&root->root_list)) { |
|
list_del(&root->root_list); |
|
cgroup_root_count--; |
|
} |
|
|
|
cgroup_exit_root_id(root); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
|
|
cgroup_rstat_exit(cgrp); |
|
kernfs_destroy_root(root->kf_root); |
|
cgroup_free_root(root); |
|
} |
|
|
|
/* |
|
* look up cgroup associated with current task's cgroup namespace on the |
|
* specified hierarchy |
|
*/ |
|
static struct cgroup * |
|
current_cgns_cgroup_from_root(struct cgroup_root *root) |
|
{ |
|
struct cgroup *res = NULL; |
|
struct css_set *cset; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
rcu_read_lock(); |
|
|
|
cset = current->nsproxy->cgroup_ns->root_cset; |
|
if (cset == &init_css_set) { |
|
res = &root->cgrp; |
|
} else if (root == &cgrp_dfl_root) { |
|
res = cset->dfl_cgrp; |
|
} else { |
|
struct cgrp_cset_link *link; |
|
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
|
struct cgroup *c = link->cgrp; |
|
|
|
if (c->root == root) { |
|
res = c; |
|
break; |
|
} |
|
} |
|
} |
|
rcu_read_unlock(); |
|
|
|
BUG_ON(!res); |
|
return res; |
|
} |
|
|
|
/* look up cgroup associated with given css_set on the specified hierarchy */ |
|
static struct cgroup *cset_cgroup_from_root(struct css_set *cset, |
|
struct cgroup_root *root) |
|
{ |
|
struct cgroup *res = NULL; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
lockdep_assert_held(&css_set_lock); |
|
|
|
if (cset == &init_css_set) { |
|
res = &root->cgrp; |
|
} else if (root == &cgrp_dfl_root) { |
|
res = cset->dfl_cgrp; |
|
} else { |
|
struct cgrp_cset_link *link; |
|
|
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
|
struct cgroup *c = link->cgrp; |
|
|
|
if (c->root == root) { |
|
res = c; |
|
break; |
|
} |
|
} |
|
} |
|
|
|
BUG_ON(!res); |
|
return res; |
|
} |
|
|
|
/* |
|
* Return the cgroup for "task" from the given hierarchy. Must be |
|
* called with cgroup_mutex and css_set_lock held. |
|
*/ |
|
struct cgroup *task_cgroup_from_root(struct task_struct *task, |
|
struct cgroup_root *root) |
|
{ |
|
/* |
|
* No need to lock the task - since we hold css_set_lock the |
|
* task can't change groups. |
|
*/ |
|
return cset_cgroup_from_root(task_css_set(task), root); |
|
} |
|
|
|
/* |
|
* A task must hold cgroup_mutex to modify cgroups. |
|
* |
|
* Any task can increment and decrement the count field without lock. |
|
* So in general, code holding cgroup_mutex can't rely on the count |
|
* field not changing. However, if the count goes to zero, then only |
|
* cgroup_attach_task() can increment it again. Because a count of zero |
|
* means that no tasks are currently attached, therefore there is no |
|
* way a task attached to that cgroup can fork (the other way to |
|
* increment the count). So code holding cgroup_mutex can safely |
|
* assume that if the count is zero, it will stay zero. Similarly, if |
|
* a task holds cgroup_mutex on a cgroup with zero count, it |
|
* knows that the cgroup won't be removed, as cgroup_rmdir() |
|
* needs that mutex. |
|
* |
|
* A cgroup can only be deleted if both its 'count' of using tasks |
|
* is zero, and its list of 'children' cgroups is empty. Since all |
|
* tasks in the system use _some_ cgroup, and since there is always at |
|
* least one task in the system (init, pid == 1), therefore, root cgroup |
|
* always has either children cgroups and/or using tasks. So we don't |
|
* need a special hack to ensure that root cgroup cannot be deleted. |
|
* |
|
* P.S. One more locking exception. RCU is used to guard the |
|
* update of a tasks cgroup pointer by cgroup_attach_task() |
|
*/ |
|
|
|
static struct kernfs_syscall_ops cgroup_kf_syscall_ops; |
|
|
|
static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft, |
|
char *buf) |
|
{ |
|
struct cgroup_subsys *ss = cft->ss; |
|
|
|
if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) && |
|
!(cgrp->root->flags & CGRP_ROOT_NOPREFIX)) { |
|
const char *dbg = (cft->flags & CFTYPE_DEBUG) ? ".__DEBUG__." : ""; |
|
|
|
snprintf(buf, CGROUP_FILE_NAME_MAX, "%s%s.%s", |
|
dbg, cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
|
cft->name); |
|
} else { |
|
strscpy(buf, cft->name, CGROUP_FILE_NAME_MAX); |
|
} |
|
return buf; |
|
} |
|
|
|
/** |
|
* cgroup_file_mode - deduce file mode of a control file |
|
* @cft: the control file in question |
|
* |
|
* S_IRUGO for read, S_IWUSR for write. |
|
*/ |
|
static umode_t cgroup_file_mode(const struct cftype *cft) |
|
{ |
|
umode_t mode = 0; |
|
|
|
if (cft->read_u64 || cft->read_s64 || cft->seq_show) |
|
mode |= S_IRUGO; |
|
|
|
if (cft->write_u64 || cft->write_s64 || cft->write) { |
|
if (cft->flags & CFTYPE_WORLD_WRITABLE) |
|
mode |= S_IWUGO; |
|
else |
|
mode |= S_IWUSR; |
|
} |
|
|
|
return mode; |
|
} |
|
|
|
/** |
|
* cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask |
|
* @subtree_control: the new subtree_control mask to consider |
|
* @this_ss_mask: available subsystems |
|
* |
|
* On the default hierarchy, a subsystem may request other subsystems to be |
|
* enabled together through its ->depends_on mask. In such cases, more |
|
* subsystems than specified in "cgroup.subtree_control" may be enabled. |
|
* |
|
* This function calculates which subsystems need to be enabled if |
|
* @subtree_control is to be applied while restricted to @this_ss_mask. |
|
*/ |
|
static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask) |
|
{ |
|
u16 cur_ss_mask = subtree_control; |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
cur_ss_mask |= cgrp_dfl_implicit_ss_mask; |
|
|
|
while (true) { |
|
u16 new_ss_mask = cur_ss_mask; |
|
|
|
do_each_subsys_mask(ss, ssid, cur_ss_mask) { |
|
new_ss_mask |= ss->depends_on; |
|
} while_each_subsys_mask(); |
|
|
|
/* |
|
* Mask out subsystems which aren't available. This can |
|
* happen only if some depended-upon subsystems were bound |
|
* to non-default hierarchies. |
|
*/ |
|
new_ss_mask &= this_ss_mask; |
|
|
|
if (new_ss_mask == cur_ss_mask) |
|
break; |
|
cur_ss_mask = new_ss_mask; |
|
} |
|
|
|
return cur_ss_mask; |
|
} |
|
|
|
/** |
|
* cgroup_kn_unlock - unlocking helper for cgroup kernfs methods |
|
* @kn: the kernfs_node being serviced |
|
* |
|
* This helper undoes cgroup_kn_lock_live() and should be invoked before |
|
* the method finishes if locking succeeded. Note that once this function |
|
* returns the cgroup returned by cgroup_kn_lock_live() may become |
|
* inaccessible any time. If the caller intends to continue to access the |
|
* cgroup, it should pin it before invoking this function. |
|
*/ |
|
void cgroup_kn_unlock(struct kernfs_node *kn) |
|
{ |
|
struct cgroup *cgrp; |
|
|
|
if (kernfs_type(kn) == KERNFS_DIR) |
|
cgrp = kn->priv; |
|
else |
|
cgrp = kn->parent->priv; |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
|
|
kernfs_unbreak_active_protection(kn); |
|
cgroup_put(cgrp); |
|
} |
|
|
|
/** |
|
* cgroup_kn_lock_live - locking helper for cgroup kernfs methods |
|
* @kn: the kernfs_node being serviced |
|
* @drain_offline: perform offline draining on the cgroup |
|
* |
|
* This helper is to be used by a cgroup kernfs method currently servicing |
|
* @kn. It breaks the active protection, performs cgroup locking and |
|
* verifies that the associated cgroup is alive. Returns the cgroup if |
|
* alive; otherwise, %NULL. A successful return should be undone by a |
|
* matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the |
|
* cgroup is drained of offlining csses before return. |
|
* |
|
* Any cgroup kernfs method implementation which requires locking the |
|
* associated cgroup should use this helper. It avoids nesting cgroup |
|
* locking under kernfs active protection and allows all kernfs operations |
|
* including self-removal. |
|
*/ |
|
struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn, bool drain_offline) |
|
{ |
|
struct cgroup *cgrp; |
|
|
|
if (kernfs_type(kn) == KERNFS_DIR) |
|
cgrp = kn->priv; |
|
else |
|
cgrp = kn->parent->priv; |
|
|
|
/* |
|
* We're gonna grab cgroup_mutex which nests outside kernfs |
|
* active_ref. cgroup liveliness check alone provides enough |
|
* protection against removal. Ensure @cgrp stays accessible and |
|
* break the active_ref protection. |
|
*/ |
|
if (!cgroup_tryget(cgrp)) |
|
return NULL; |
|
kernfs_break_active_protection(kn); |
|
|
|
if (drain_offline) |
|
cgroup_lock_and_drain_offline(cgrp); |
|
else |
|
mutex_lock(&cgroup_mutex); |
|
|
|
if (!cgroup_is_dead(cgrp)) |
|
return cgrp; |
|
|
|
cgroup_kn_unlock(kn); |
|
return NULL; |
|
} |
|
|
|
static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft) |
|
{ |
|
char name[CGROUP_FILE_NAME_MAX]; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
if (cft->file_offset) { |
|
struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss); |
|
struct cgroup_file *cfile = (void *)css + cft->file_offset; |
|
|
|
spin_lock_irq(&cgroup_file_kn_lock); |
|
cfile->kn = NULL; |
|
spin_unlock_irq(&cgroup_file_kn_lock); |
|
|
|
del_timer_sync(&cfile->notify_timer); |
|
} |
|
|
|
kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
|
} |
|
|
|
/** |
|
* css_clear_dir - remove subsys files in a cgroup directory |
|
* @css: target css |
|
*/ |
|
static void css_clear_dir(struct cgroup_subsys_state *css) |
|
{ |
|
struct cgroup *cgrp = css->cgroup; |
|
struct cftype *cfts; |
|
|
|
if (!(css->flags & CSS_VISIBLE)) |
|
return; |
|
|
|
css->flags &= ~CSS_VISIBLE; |
|
|
|
if (!css->ss) { |
|
if (cgroup_on_dfl(cgrp)) |
|
cfts = cgroup_base_files; |
|
else |
|
cfts = cgroup1_base_files; |
|
|
|
cgroup_addrm_files(css, cgrp, cfts, false); |
|
} else { |
|
list_for_each_entry(cfts, &css->ss->cfts, node) |
|
cgroup_addrm_files(css, cgrp, cfts, false); |
|
} |
|
} |
|
|
|
/** |
|
* css_populate_dir - create subsys files in a cgroup directory |
|
* @css: target css |
|
* |
|
* On failure, no file is added. |
|
*/ |
|
static int css_populate_dir(struct cgroup_subsys_state *css) |
|
{ |
|
struct cgroup *cgrp = css->cgroup; |
|
struct cftype *cfts, *failed_cfts; |
|
int ret; |
|
|
|
if ((css->flags & CSS_VISIBLE) || !cgrp->kn) |
|
return 0; |
|
|
|
if (!css->ss) { |
|
if (cgroup_on_dfl(cgrp)) |
|
cfts = cgroup_base_files; |
|
else |
|
cfts = cgroup1_base_files; |
|
|
|
ret = cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); |
|
if (ret < 0) |
|
return ret; |
|
} else { |
|
list_for_each_entry(cfts, &css->ss->cfts, node) { |
|
ret = cgroup_addrm_files(css, cgrp, cfts, true); |
|
if (ret < 0) { |
|
failed_cfts = cfts; |
|
goto err; |
|
} |
|
} |
|
} |
|
|
|
css->flags |= CSS_VISIBLE; |
|
|
|
return 0; |
|
err: |
|
list_for_each_entry(cfts, &css->ss->cfts, node) { |
|
if (cfts == failed_cfts) |
|
break; |
|
cgroup_addrm_files(css, cgrp, cfts, false); |
|
} |
|
return ret; |
|
} |
|
|
|
int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask) |
|
{ |
|
struct cgroup *dcgrp = &dst_root->cgrp; |
|
struct cgroup_subsys *ss; |
|
int ssid, i, ret; |
|
u16 dfl_disable_ss_mask = 0; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
do_each_subsys_mask(ss, ssid, ss_mask) { |
|
/* |
|
* If @ss has non-root csses attached to it, can't move. |
|
* If @ss is an implicit controller, it is exempt from this |
|
* rule and can be stolen. |
|
*/ |
|
if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)) && |
|
!ss->implicit_on_dfl) |
|
return -EBUSY; |
|
|
|
/* can't move between two non-dummy roots either */ |
|
if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root) |
|
return -EBUSY; |
|
|
|
/* |
|
* Collect ssid's that need to be disabled from default |
|
* hierarchy. |
|
*/ |
|
if (ss->root == &cgrp_dfl_root) |
|
dfl_disable_ss_mask |= 1 << ssid; |
|
|
|
} while_each_subsys_mask(); |
|
|
|
if (dfl_disable_ss_mask) { |
|
struct cgroup *scgrp = &cgrp_dfl_root.cgrp; |
|
|
|
/* |
|
* Controllers from default hierarchy that need to be rebound |
|
* are all disabled together in one go. |
|
*/ |
|
cgrp_dfl_root.subsys_mask &= ~dfl_disable_ss_mask; |
|
WARN_ON(cgroup_apply_control(scgrp)); |
|
cgroup_finalize_control(scgrp, 0); |
|
} |
|
|
|
do_each_subsys_mask(ss, ssid, ss_mask) { |
|
struct cgroup_root *src_root = ss->root; |
|
struct cgroup *scgrp = &src_root->cgrp; |
|
struct cgroup_subsys_state *css = cgroup_css(scgrp, ss); |
|
struct css_set *cset; |
|
|
|
WARN_ON(!css || cgroup_css(dcgrp, ss)); |
|
|
|
if (src_root != &cgrp_dfl_root) { |
|
/* disable from the source */ |
|
src_root->subsys_mask &= ~(1 << ssid); |
|
WARN_ON(cgroup_apply_control(scgrp)); |
|
cgroup_finalize_control(scgrp, 0); |
|
} |
|
|
|
/* rebind */ |
|
RCU_INIT_POINTER(scgrp->subsys[ssid], NULL); |
|
rcu_assign_pointer(dcgrp->subsys[ssid], css); |
|
ss->root = dst_root; |
|
css->cgroup = dcgrp; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
hash_for_each(css_set_table, i, cset, hlist) |
|
list_move_tail(&cset->e_cset_node[ss->id], |
|
&dcgrp->e_csets[ss->id]); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
if (ss->css_rstat_flush) { |
|
list_del_rcu(&css->rstat_css_node); |
|
list_add_rcu(&css->rstat_css_node, |
|
&dcgrp->rstat_css_list); |
|
} |
|
|
|
/* default hierarchy doesn't enable controllers by default */ |
|
dst_root->subsys_mask |= 1 << ssid; |
|
if (dst_root == &cgrp_dfl_root) { |
|
static_branch_enable(cgroup_subsys_on_dfl_key[ssid]); |
|
} else { |
|
dcgrp->subtree_control |= 1 << ssid; |
|
static_branch_disable(cgroup_subsys_on_dfl_key[ssid]); |
|
} |
|
|
|
ret = cgroup_apply_control(dcgrp); |
|
if (ret) |
|
pr_warn("partial failure to rebind %s controller (err=%d)\n", |
|
ss->name, ret); |
|
|
|
if (ss->bind) |
|
ss->bind(css); |
|
} while_each_subsys_mask(); |
|
|
|
kernfs_activate(dcgrp->kn); |
|
return 0; |
|
} |
|
|
|
int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node, |
|
struct kernfs_root *kf_root) |
|
{ |
|
int len = 0; |
|
char *buf = NULL; |
|
struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root); |
|
struct cgroup *ns_cgroup; |
|
|
|
buf = kmalloc(PATH_MAX, GFP_KERNEL); |
|
if (!buf) |
|
return -ENOMEM; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot); |
|
len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
if (len >= PATH_MAX) |
|
len = -ERANGE; |
|
else if (len > 0) { |
|
seq_escape(sf, buf, " \t\n\\"); |
|
len = 0; |
|
} |
|
kfree(buf); |
|
return len; |
|
} |
|
|
|
enum cgroup2_param { |
|
Opt_nsdelegate, |
|
Opt_memory_localevents, |
|
Opt_memory_recursiveprot, |
|
nr__cgroup2_params |
|
}; |
|
|
|
static const struct fs_parameter_spec cgroup2_fs_parameters[] = { |
|
fsparam_flag("nsdelegate", Opt_nsdelegate), |
|
fsparam_flag("memory_localevents", Opt_memory_localevents), |
|
fsparam_flag("memory_recursiveprot", Opt_memory_recursiveprot), |
|
{} |
|
}; |
|
|
|
static int cgroup2_parse_param(struct fs_context *fc, struct fs_parameter *param) |
|
{ |
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
|
struct fs_parse_result result; |
|
int opt; |
|
|
|
opt = fs_parse(fc, cgroup2_fs_parameters, param, &result); |
|
if (opt < 0) |
|
return opt; |
|
|
|
switch (opt) { |
|
case Opt_nsdelegate: |
|
ctx->flags |= CGRP_ROOT_NS_DELEGATE; |
|
return 0; |
|
case Opt_memory_localevents: |
|
ctx->flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS; |
|
return 0; |
|
case Opt_memory_recursiveprot: |
|
ctx->flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT; |
|
return 0; |
|
} |
|
return -EINVAL; |
|
} |
|
|
|
static void apply_cgroup_root_flags(unsigned int root_flags) |
|
{ |
|
if (current->nsproxy->cgroup_ns == &init_cgroup_ns) { |
|
if (root_flags & CGRP_ROOT_NS_DELEGATE) |
|
cgrp_dfl_root.flags |= CGRP_ROOT_NS_DELEGATE; |
|
else |
|
cgrp_dfl_root.flags &= ~CGRP_ROOT_NS_DELEGATE; |
|
|
|
if (root_flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS) |
|
cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_LOCAL_EVENTS; |
|
else |
|
cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_LOCAL_EVENTS; |
|
|
|
if (root_flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT) |
|
cgrp_dfl_root.flags |= CGRP_ROOT_MEMORY_RECURSIVE_PROT; |
|
else |
|
cgrp_dfl_root.flags &= ~CGRP_ROOT_MEMORY_RECURSIVE_PROT; |
|
} |
|
} |
|
|
|
static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root) |
|
{ |
|
if (cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) |
|
seq_puts(seq, ",nsdelegate"); |
|
if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_LOCAL_EVENTS) |
|
seq_puts(seq, ",memory_localevents"); |
|
if (cgrp_dfl_root.flags & CGRP_ROOT_MEMORY_RECURSIVE_PROT) |
|
seq_puts(seq, ",memory_recursiveprot"); |
|
return 0; |
|
} |
|
|
|
static int cgroup_reconfigure(struct fs_context *fc) |
|
{ |
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
|
|
|
apply_cgroup_root_flags(ctx->flags); |
|
return 0; |
|
} |
|
|
|
static void init_cgroup_housekeeping(struct cgroup *cgrp) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
INIT_LIST_HEAD(&cgrp->self.sibling); |
|
INIT_LIST_HEAD(&cgrp->self.children); |
|
INIT_LIST_HEAD(&cgrp->cset_links); |
|
INIT_LIST_HEAD(&cgrp->pidlists); |
|
mutex_init(&cgrp->pidlist_mutex); |
|
cgrp->self.cgroup = cgrp; |
|
cgrp->self.flags |= CSS_ONLINE; |
|
cgrp->dom_cgrp = cgrp; |
|
cgrp->max_descendants = INT_MAX; |
|
cgrp->max_depth = INT_MAX; |
|
INIT_LIST_HEAD(&cgrp->rstat_css_list); |
|
prev_cputime_init(&cgrp->prev_cputime); |
|
|
|
for_each_subsys(ss, ssid) |
|
INIT_LIST_HEAD(&cgrp->e_csets[ssid]); |
|
|
|
init_waitqueue_head(&cgrp->offline_waitq); |
|
INIT_WORK(&cgrp->release_agent_work, cgroup1_release_agent); |
|
} |
|
|
|
void init_cgroup_root(struct cgroup_fs_context *ctx) |
|
{ |
|
struct cgroup_root *root = ctx->root; |
|
struct cgroup *cgrp = &root->cgrp; |
|
|
|
INIT_LIST_HEAD(&root->root_list); |
|
atomic_set(&root->nr_cgrps, 1); |
|
cgrp->root = root; |
|
init_cgroup_housekeeping(cgrp); |
|
|
|
root->flags = ctx->flags; |
|
if (ctx->release_agent) |
|
strscpy(root->release_agent_path, ctx->release_agent, PATH_MAX); |
|
if (ctx->name) |
|
strscpy(root->name, ctx->name, MAX_CGROUP_ROOT_NAMELEN); |
|
if (ctx->cpuset_clone_children) |
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
|
} |
|
|
|
int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) |
|
{ |
|
LIST_HEAD(tmp_links); |
|
struct cgroup *root_cgrp = &root->cgrp; |
|
struct kernfs_syscall_ops *kf_sops; |
|
struct css_set *cset; |
|
int i, ret; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, |
|
0, GFP_KERNEL); |
|
if (ret) |
|
goto out; |
|
|
|
/* |
|
* We're accessing css_set_count without locking css_set_lock here, |
|
* but that's OK - it can only be increased by someone holding |
|
* cgroup_lock, and that's us. Later rebinding may disable |
|
* controllers on the default hierarchy and thus create new csets, |
|
* which can't be more than the existing ones. Allocate 2x. |
|
*/ |
|
ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links); |
|
if (ret) |
|
goto cancel_ref; |
|
|
|
ret = cgroup_init_root_id(root); |
|
if (ret) |
|
goto cancel_ref; |
|
|
|
kf_sops = root == &cgrp_dfl_root ? |
|
&cgroup_kf_syscall_ops : &cgroup1_kf_syscall_ops; |
|
|
|
root->kf_root = kernfs_create_root(kf_sops, |
|
KERNFS_ROOT_CREATE_DEACTIVATED | |
|
KERNFS_ROOT_SUPPORT_EXPORTOP | |
|
KERNFS_ROOT_SUPPORT_USER_XATTR, |
|
root_cgrp); |
|
if (IS_ERR(root->kf_root)) { |
|
ret = PTR_ERR(root->kf_root); |
|
goto exit_root_id; |
|
} |
|
root_cgrp->kn = kernfs_root_to_node(root->kf_root); |
|
WARN_ON_ONCE(cgroup_ino(root_cgrp) != 1); |
|
root_cgrp->ancestor_ids[0] = cgroup_id(root_cgrp); |
|
|
|
ret = css_populate_dir(&root_cgrp->self); |
|
if (ret) |
|
goto destroy_root; |
|
|
|
ret = cgroup_rstat_init(root_cgrp); |
|
if (ret) |
|
goto destroy_root; |
|
|
|
ret = rebind_subsystems(root, ss_mask); |
|
if (ret) |
|
goto exit_stats; |
|
|
|
ret = cgroup_bpf_inherit(root_cgrp); |
|
WARN_ON_ONCE(ret); |
|
|
|
trace_cgroup_setup_root(root); |
|
|
|
/* |
|
* There must be no failure case after here, since rebinding takes |
|
* care of subsystems' refcounts, which are explicitly dropped in |
|
* the failure exit path. |
|
*/ |
|
list_add(&root->root_list, &cgroup_roots); |
|
cgroup_root_count++; |
|
|
|
/* |
|
* Link the root cgroup in this hierarchy into all the css_set |
|
* objects. |
|
*/ |
|
spin_lock_irq(&css_set_lock); |
|
hash_for_each(css_set_table, i, cset, hlist) { |
|
link_css_set(&tmp_links, cset, root_cgrp); |
|
if (css_set_populated(cset)) |
|
cgroup_update_populated(root_cgrp, true); |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
BUG_ON(!list_empty(&root_cgrp->self.children)); |
|
BUG_ON(atomic_read(&root->nr_cgrps) != 1); |
|
|
|
ret = 0; |
|
goto out; |
|
|
|
exit_stats: |
|
cgroup_rstat_exit(root_cgrp); |
|
destroy_root: |
|
kernfs_destroy_root(root->kf_root); |
|
root->kf_root = NULL; |
|
exit_root_id: |
|
cgroup_exit_root_id(root); |
|
cancel_ref: |
|
percpu_ref_exit(&root_cgrp->self.refcnt); |
|
out: |
|
free_cgrp_cset_links(&tmp_links); |
|
return ret; |
|
} |
|
|
|
int cgroup_do_get_tree(struct fs_context *fc) |
|
{ |
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
|
int ret; |
|
|
|
ctx->kfc.root = ctx->root->kf_root; |
|
if (fc->fs_type == &cgroup2_fs_type) |
|
ctx->kfc.magic = CGROUP2_SUPER_MAGIC; |
|
else |
|
ctx->kfc.magic = CGROUP_SUPER_MAGIC; |
|
ret = kernfs_get_tree(fc); |
|
|
|
/* |
|
* In non-init cgroup namespace, instead of root cgroup's dentry, |
|
* we return the dentry corresponding to the cgroupns->root_cgrp. |
|
*/ |
|
if (!ret && ctx->ns != &init_cgroup_ns) { |
|
struct dentry *nsdentry; |
|
struct super_block *sb = fc->root->d_sb; |
|
struct cgroup *cgrp; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
spin_lock_irq(&css_set_lock); |
|
|
|
cgrp = cset_cgroup_from_root(ctx->ns->root_cset, ctx->root); |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
mutex_unlock(&cgroup_mutex); |
|
|
|
nsdentry = kernfs_node_dentry(cgrp->kn, sb); |
|
dput(fc->root); |
|
if (IS_ERR(nsdentry)) { |
|
deactivate_locked_super(sb); |
|
ret = PTR_ERR(nsdentry); |
|
nsdentry = NULL; |
|
} |
|
fc->root = nsdentry; |
|
} |
|
|
|
if (!ctx->kfc.new_sb_created) |
|
cgroup_put(&ctx->root->cgrp); |
|
|
|
return ret; |
|
} |
|
|
|
/* |
|
* Destroy a cgroup filesystem context. |
|
*/ |
|
static void cgroup_fs_context_free(struct fs_context *fc) |
|
{ |
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
|
|
|
kfree(ctx->name); |
|
kfree(ctx->release_agent); |
|
put_cgroup_ns(ctx->ns); |
|
kernfs_free_fs_context(fc); |
|
kfree(ctx); |
|
} |
|
|
|
static int cgroup_get_tree(struct fs_context *fc) |
|
{ |
|
struct cgroup_fs_context *ctx = cgroup_fc2context(fc); |
|
int ret; |
|
|
|
cgrp_dfl_visible = true; |
|
cgroup_get_live(&cgrp_dfl_root.cgrp); |
|
ctx->root = &cgrp_dfl_root; |
|
|
|
ret = cgroup_do_get_tree(fc); |
|
if (!ret) |
|
apply_cgroup_root_flags(ctx->flags); |
|
return ret; |
|
} |
|
|
|
static const struct fs_context_operations cgroup_fs_context_ops = { |
|
.free = cgroup_fs_context_free, |
|
.parse_param = cgroup2_parse_param, |
|
.get_tree = cgroup_get_tree, |
|
.reconfigure = cgroup_reconfigure, |
|
}; |
|
|
|
static const struct fs_context_operations cgroup1_fs_context_ops = { |
|
.free = cgroup_fs_context_free, |
|
.parse_param = cgroup1_parse_param, |
|
.get_tree = cgroup1_get_tree, |
|
.reconfigure = cgroup1_reconfigure, |
|
}; |
|
|
|
/* |
|
* Initialise the cgroup filesystem creation/reconfiguration context. Notably, |
|
* we select the namespace we're going to use. |
|
*/ |
|
static int cgroup_init_fs_context(struct fs_context *fc) |
|
{ |
|
struct cgroup_fs_context *ctx; |
|
|
|
ctx = kzalloc(sizeof(struct cgroup_fs_context), GFP_KERNEL); |
|
if (!ctx) |
|
return -ENOMEM; |
|
|
|
ctx->ns = current->nsproxy->cgroup_ns; |
|
get_cgroup_ns(ctx->ns); |
|
fc->fs_private = &ctx->kfc; |
|
if (fc->fs_type == &cgroup2_fs_type) |
|
fc->ops = &cgroup_fs_context_ops; |
|
else |
|
fc->ops = &cgroup1_fs_context_ops; |
|
put_user_ns(fc->user_ns); |
|
fc->user_ns = get_user_ns(ctx->ns->user_ns); |
|
fc->global = true; |
|
return 0; |
|
} |
|
|
|
static void cgroup_kill_sb(struct super_block *sb) |
|
{ |
|
struct kernfs_root *kf_root = kernfs_root_from_sb(sb); |
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
|
|
|
/* |
|
* If @root doesn't have any children, start killing it. |
|
* This prevents new mounts by disabling percpu_ref_tryget_live(). |
|
* |
|
* And don't kill the default root. |
|
*/ |
|
if (list_empty(&root->cgrp.self.children) && root != &cgrp_dfl_root && |
|
!percpu_ref_is_dying(&root->cgrp.self.refcnt)) { |
|
cgroup_bpf_offline(&root->cgrp); |
|
percpu_ref_kill(&root->cgrp.self.refcnt); |
|
} |
|
cgroup_put(&root->cgrp); |
|
kernfs_kill_sb(sb); |
|
} |
|
|
|
struct file_system_type cgroup_fs_type = { |
|
.name = "cgroup", |
|
.init_fs_context = cgroup_init_fs_context, |
|
.parameters = cgroup1_fs_parameters, |
|
.kill_sb = cgroup_kill_sb, |
|
.fs_flags = FS_USERNS_MOUNT, |
|
}; |
|
|
|
static struct file_system_type cgroup2_fs_type = { |
|
.name = "cgroup2", |
|
.init_fs_context = cgroup_init_fs_context, |
|
.parameters = cgroup2_fs_parameters, |
|
.kill_sb = cgroup_kill_sb, |
|
.fs_flags = FS_USERNS_MOUNT, |
|
}; |
|
|
|
#ifdef CONFIG_CPUSETS |
|
static const struct fs_context_operations cpuset_fs_context_ops = { |
|
.get_tree = cgroup1_get_tree, |
|
.free = cgroup_fs_context_free, |
|
}; |
|
|
|
/* |
|
* This is ugly, but preserves the userspace API for existing cpuset |
|
* users. If someone tries to mount the "cpuset" filesystem, we |
|
* silently switch it to mount "cgroup" instead |
|
*/ |
|
static int cpuset_init_fs_context(struct fs_context *fc) |
|
{ |
|
char *agent = kstrdup("/sbin/cpuset_release_agent", GFP_USER); |
|
struct cgroup_fs_context *ctx; |
|
int err; |
|
|
|
err = cgroup_init_fs_context(fc); |
|
if (err) { |
|
kfree(agent); |
|
return err; |
|
} |
|
|
|
fc->ops = &cpuset_fs_context_ops; |
|
|
|
ctx = cgroup_fc2context(fc); |
|
ctx->subsys_mask = 1 << cpuset_cgrp_id; |
|
ctx->flags |= CGRP_ROOT_NOPREFIX; |
|
ctx->release_agent = agent; |
|
|
|
get_filesystem(&cgroup_fs_type); |
|
put_filesystem(fc->fs_type); |
|
fc->fs_type = &cgroup_fs_type; |
|
|
|
return 0; |
|
} |
|
|
|
static struct file_system_type cpuset_fs_type = { |
|
.name = "cpuset", |
|
.init_fs_context = cpuset_init_fs_context, |
|
.fs_flags = FS_USERNS_MOUNT, |
|
}; |
|
#endif |
|
|
|
int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen, |
|
struct cgroup_namespace *ns) |
|
{ |
|
struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root); |
|
|
|
return kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen); |
|
} |
|
|
|
int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen, |
|
struct cgroup_namespace *ns) |
|
{ |
|
int ret; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
spin_lock_irq(&css_set_lock); |
|
|
|
ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns); |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
mutex_unlock(&cgroup_mutex); |
|
|
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(cgroup_path_ns); |
|
|
|
/** |
|
* task_cgroup_path - cgroup path of a task in the first cgroup hierarchy |
|
* @task: target task |
|
* @buf: the buffer to write the path into |
|
* @buflen: the length of the buffer |
|
* |
|
* Determine @task's cgroup on the first (the one with the lowest non-zero |
|
* hierarchy_id) cgroup hierarchy and copy its path into @buf. This |
|
* function grabs cgroup_mutex and shouldn't be used inside locks used by |
|
* cgroup controller callbacks. |
|
* |
|
* Return value is the same as kernfs_path(). |
|
*/ |
|
int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen) |
|
{ |
|
struct cgroup_root *root; |
|
struct cgroup *cgrp; |
|
int hierarchy_id = 1; |
|
int ret; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
spin_lock_irq(&css_set_lock); |
|
|
|
root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id); |
|
|
|
if (root) { |
|
cgrp = task_cgroup_from_root(task, root); |
|
ret = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns); |
|
} else { |
|
/* if no hierarchy exists, everyone is in "/" */ |
|
ret = strlcpy(buf, "/", buflen); |
|
} |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
mutex_unlock(&cgroup_mutex); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(task_cgroup_path); |
|
|
|
/** |
|
* cgroup_migrate_add_task - add a migration target task to a migration context |
|
* @task: target task |
|
* @mgctx: target migration context |
|
* |
|
* Add @task, which is a migration target, to @mgctx->tset. This function |
|
* becomes noop if @task doesn't need to be migrated. @task's css_set |
|
* should have been added as a migration source and @task->cg_list will be |
|
* moved from the css_set's tasks list to mg_tasks one. |
|
*/ |
|
static void cgroup_migrate_add_task(struct task_struct *task, |
|
struct cgroup_mgctx *mgctx) |
|
{ |
|
struct css_set *cset; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
/* @task either already exited or can't exit until the end */ |
|
if (task->flags & PF_EXITING) |
|
return; |
|
|
|
/* cgroup_threadgroup_rwsem protects racing against forks */ |
|
WARN_ON_ONCE(list_empty(&task->cg_list)); |
|
|
|
cset = task_css_set(task); |
|
if (!cset->mg_src_cgrp) |
|
return; |
|
|
|
mgctx->tset.nr_tasks++; |
|
|
|
list_move_tail(&task->cg_list, &cset->mg_tasks); |
|
if (list_empty(&cset->mg_node)) |
|
list_add_tail(&cset->mg_node, |
|
&mgctx->tset.src_csets); |
|
if (list_empty(&cset->mg_dst_cset->mg_node)) |
|
list_add_tail(&cset->mg_dst_cset->mg_node, |
|
&mgctx->tset.dst_csets); |
|
} |
|
|
|
/** |
|
* cgroup_taskset_first - reset taskset and return the first task |
|
* @tset: taskset of interest |
|
* @dst_cssp: output variable for the destination css |
|
* |
|
* @tset iteration is initialized and the first task is returned. |
|
*/ |
|
struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset, |
|
struct cgroup_subsys_state **dst_cssp) |
|
{ |
|
tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node); |
|
tset->cur_task = NULL; |
|
|
|
return cgroup_taskset_next(tset, dst_cssp); |
|
} |
|
|
|
/** |
|
* cgroup_taskset_next - iterate to the next task in taskset |
|
* @tset: taskset of interest |
|
* @dst_cssp: output variable for the destination css |
|
* |
|
* Return the next task in @tset. Iteration must have been initialized |
|
* with cgroup_taskset_first(). |
|
*/ |
|
struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset, |
|
struct cgroup_subsys_state **dst_cssp) |
|
{ |
|
struct css_set *cset = tset->cur_cset; |
|
struct task_struct *task = tset->cur_task; |
|
|
|
while (CGROUP_HAS_SUBSYS_CONFIG && &cset->mg_node != tset->csets) { |
|
if (!task) |
|
task = list_first_entry(&cset->mg_tasks, |
|
struct task_struct, cg_list); |
|
else |
|
task = list_next_entry(task, cg_list); |
|
|
|
if (&task->cg_list != &cset->mg_tasks) { |
|
tset->cur_cset = cset; |
|
tset->cur_task = task; |
|
|
|
/* |
|
* This function may be called both before and |
|
* after cgroup_taskset_migrate(). The two cases |
|
* can be distinguished by looking at whether @cset |
|
* has its ->mg_dst_cset set. |
|
*/ |
|
if (cset->mg_dst_cset) |
|
*dst_cssp = cset->mg_dst_cset->subsys[tset->ssid]; |
|
else |
|
*dst_cssp = cset->subsys[tset->ssid]; |
|
|
|
return task; |
|
} |
|
|
|
cset = list_next_entry(cset, mg_node); |
|
task = NULL; |
|
} |
|
|
|
return NULL; |
|
} |
|
|
|
/** |
|
* cgroup_migrate_execute - migrate a taskset |
|
* @mgctx: migration context |
|
* |
|
* Migrate tasks in @mgctx as setup by migration preparation functions. |
|
* This function fails iff one of the ->can_attach callbacks fails and |
|
* guarantees that either all or none of the tasks in @mgctx are migrated. |
|
* @mgctx is consumed regardless of success. |
|
*/ |
|
static int cgroup_migrate_execute(struct cgroup_mgctx *mgctx) |
|
{ |
|
struct cgroup_taskset *tset = &mgctx->tset; |
|
struct cgroup_subsys *ss; |
|
struct task_struct *task, *tmp_task; |
|
struct css_set *cset, *tmp_cset; |
|
int ssid, failed_ssid, ret; |
|
|
|
/* check that we can legitimately attach to the cgroup */ |
|
if (tset->nr_tasks) { |
|
do_each_subsys_mask(ss, ssid, mgctx->ss_mask) { |
|
if (ss->can_attach) { |
|
tset->ssid = ssid; |
|
ret = ss->can_attach(tset); |
|
if (ret) { |
|
failed_ssid = ssid; |
|
goto out_cancel_attach; |
|
} |
|
} |
|
} while_each_subsys_mask(); |
|
} |
|
|
|
/* |
|
* Now that we're guaranteed success, proceed to move all tasks to |
|
* the new cgroup. There are no failure cases after here, so this |
|
* is the commit point. |
|
*/ |
|
spin_lock_irq(&css_set_lock); |
|
list_for_each_entry(cset, &tset->src_csets, mg_node) { |
|
list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) { |
|
struct css_set *from_cset = task_css_set(task); |
|
struct css_set *to_cset = cset->mg_dst_cset; |
|
|
|
get_css_set(to_cset); |
|
to_cset->nr_tasks++; |
|
css_set_move_task(task, from_cset, to_cset, true); |
|
from_cset->nr_tasks--; |
|
/* |
|
* If the source or destination cgroup is frozen, |
|
* the task might require to change its state. |
|
*/ |
|
cgroup_freezer_migrate_task(task, from_cset->dfl_cgrp, |
|
to_cset->dfl_cgrp); |
|
put_css_set_locked(from_cset); |
|
|
|
} |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* |
|
* Migration is committed, all target tasks are now on dst_csets. |
|
* Nothing is sensitive to fork() after this point. Notify |
|
* controllers that migration is complete. |
|
*/ |
|
tset->csets = &tset->dst_csets; |
|
|
|
if (tset->nr_tasks) { |
|
do_each_subsys_mask(ss, ssid, mgctx->ss_mask) { |
|
if (ss->attach) { |
|
tset->ssid = ssid; |
|
ss->attach(tset); |
|
} |
|
} while_each_subsys_mask(); |
|
} |
|
|
|
ret = 0; |
|
goto out_release_tset; |
|
|
|
out_cancel_attach: |
|
if (tset->nr_tasks) { |
|
do_each_subsys_mask(ss, ssid, mgctx->ss_mask) { |
|
if (ssid == failed_ssid) |
|
break; |
|
if (ss->cancel_attach) { |
|
tset->ssid = ssid; |
|
ss->cancel_attach(tset); |
|
} |
|
} while_each_subsys_mask(); |
|
} |
|
out_release_tset: |
|
spin_lock_irq(&css_set_lock); |
|
list_splice_init(&tset->dst_csets, &tset->src_csets); |
|
list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) { |
|
list_splice_tail_init(&cset->mg_tasks, &cset->tasks); |
|
list_del_init(&cset->mg_node); |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* |
|
* Re-initialize the cgroup_taskset structure in case it is reused |
|
* again in another cgroup_migrate_add_task()/cgroup_migrate_execute() |
|
* iteration. |
|
*/ |
|
tset->nr_tasks = 0; |
|
tset->csets = &tset->src_csets; |
|
return ret; |
|
} |
|
|
|
/** |
|
* cgroup_migrate_vet_dst - verify whether a cgroup can be migration destination |
|
* @dst_cgrp: destination cgroup to test |
|
* |
|
* On the default hierarchy, except for the mixable, (possible) thread root |
|
* and threaded cgroups, subtree_control must be zero for migration |
|
* destination cgroups with tasks so that child cgroups don't compete |
|
* against tasks. |
|
*/ |
|
int cgroup_migrate_vet_dst(struct cgroup *dst_cgrp) |
|
{ |
|
/* v1 doesn't have any restriction */ |
|
if (!cgroup_on_dfl(dst_cgrp)) |
|
return 0; |
|
|
|
/* verify @dst_cgrp can host resources */ |
|
if (!cgroup_is_valid_domain(dst_cgrp->dom_cgrp)) |
|
return -EOPNOTSUPP; |
|
|
|
/* mixables don't care */ |
|
if (cgroup_is_mixable(dst_cgrp)) |
|
return 0; |
|
|
|
/* |
|
* If @dst_cgrp is already or can become a thread root or is |
|
* threaded, it doesn't matter. |
|
*/ |
|
if (cgroup_can_be_thread_root(dst_cgrp) || cgroup_is_threaded(dst_cgrp)) |
|
return 0; |
|
|
|
/* apply no-internal-process constraint */ |
|
if (dst_cgrp->subtree_control) |
|
return -EBUSY; |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* cgroup_migrate_finish - cleanup after attach |
|
* @mgctx: migration context |
|
* |
|
* Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
|
* those functions for details. |
|
*/ |
|
void cgroup_migrate_finish(struct cgroup_mgctx *mgctx) |
|
{ |
|
LIST_HEAD(preloaded); |
|
struct css_set *cset, *tmp_cset; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
|
|
list_splice_tail_init(&mgctx->preloaded_src_csets, &preloaded); |
|
list_splice_tail_init(&mgctx->preloaded_dst_csets, &preloaded); |
|
|
|
list_for_each_entry_safe(cset, tmp_cset, &preloaded, mg_preload_node) { |
|
cset->mg_src_cgrp = NULL; |
|
cset->mg_dst_cgrp = NULL; |
|
cset->mg_dst_cset = NULL; |
|
list_del_init(&cset->mg_preload_node); |
|
put_css_set_locked(cset); |
|
} |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
} |
|
|
|
/** |
|
* cgroup_migrate_add_src - add a migration source css_set |
|
* @src_cset: the source css_set to add |
|
* @dst_cgrp: the destination cgroup |
|
* @mgctx: migration context |
|
* |
|
* Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin |
|
* @src_cset and add it to @mgctx->src_csets, which should later be cleaned |
|
* up by cgroup_migrate_finish(). |
|
* |
|
* This function may be called without holding cgroup_threadgroup_rwsem |
|
* even if the target is a process. Threads may be created and destroyed |
|
* but as long as cgroup_mutex is not dropped, no new css_set can be put |
|
* into play and the preloaded css_sets are guaranteed to cover all |
|
* migrations. |
|
*/ |
|
void cgroup_migrate_add_src(struct css_set *src_cset, |
|
struct cgroup *dst_cgrp, |
|
struct cgroup_mgctx *mgctx) |
|
{ |
|
struct cgroup *src_cgrp; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
lockdep_assert_held(&css_set_lock); |
|
|
|
/* |
|
* If ->dead, @src_set is associated with one or more dead cgroups |
|
* and doesn't contain any migratable tasks. Ignore it early so |
|
* that the rest of migration path doesn't get confused by it. |
|
*/ |
|
if (src_cset->dead) |
|
return; |
|
|
|
if (!list_empty(&src_cset->mg_preload_node)) |
|
return; |
|
|
|
src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); |
|
|
|
WARN_ON(src_cset->mg_src_cgrp); |
|
WARN_ON(src_cset->mg_dst_cgrp); |
|
WARN_ON(!list_empty(&src_cset->mg_tasks)); |
|
WARN_ON(!list_empty(&src_cset->mg_node)); |
|
|
|
src_cset->mg_src_cgrp = src_cgrp; |
|
src_cset->mg_dst_cgrp = dst_cgrp; |
|
get_css_set(src_cset); |
|
list_add_tail(&src_cset->mg_preload_node, &mgctx->preloaded_src_csets); |
|
} |
|
|
|
/** |
|
* cgroup_migrate_prepare_dst - prepare destination css_sets for migration |
|
* @mgctx: migration context |
|
* |
|
* Tasks are about to be moved and all the source css_sets have been |
|
* preloaded to @mgctx->preloaded_src_csets. This function looks up and |
|
* pins all destination css_sets, links each to its source, and append them |
|
* to @mgctx->preloaded_dst_csets. |
|
* |
|
* This function must be called after cgroup_migrate_add_src() has been |
|
* called on each migration source css_set. After migration is performed |
|
* using cgroup_migrate(), cgroup_migrate_finish() must be called on |
|
* @mgctx. |
|
*/ |
|
int cgroup_migrate_prepare_dst(struct cgroup_mgctx *mgctx) |
|
{ |
|
struct css_set *src_cset, *tmp_cset; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
/* look up the dst cset for each src cset and link it to src */ |
|
list_for_each_entry_safe(src_cset, tmp_cset, &mgctx->preloaded_src_csets, |
|
mg_preload_node) { |
|
struct css_set *dst_cset; |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp); |
|
if (!dst_cset) |
|
return -ENOMEM; |
|
|
|
WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset); |
|
|
|
/* |
|
* If src cset equals dst, it's noop. Drop the src. |
|
* cgroup_migrate() will skip the cset too. Note that we |
|
* can't handle src == dst as some nodes are used by both. |
|
*/ |
|
if (src_cset == dst_cset) { |
|
src_cset->mg_src_cgrp = NULL; |
|
src_cset->mg_dst_cgrp = NULL; |
|
list_del_init(&src_cset->mg_preload_node); |
|
put_css_set(src_cset); |
|
put_css_set(dst_cset); |
|
continue; |
|
} |
|
|
|
src_cset->mg_dst_cset = dst_cset; |
|
|
|
if (list_empty(&dst_cset->mg_preload_node)) |
|
list_add_tail(&dst_cset->mg_preload_node, |
|
&mgctx->preloaded_dst_csets); |
|
else |
|
put_css_set(dst_cset); |
|
|
|
for_each_subsys(ss, ssid) |
|
if (src_cset->subsys[ssid] != dst_cset->subsys[ssid]) |
|
mgctx->ss_mask |= 1 << ssid; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* cgroup_migrate - migrate a process or task to a cgroup |
|
* @leader: the leader of the process or the task to migrate |
|
* @threadgroup: whether @leader points to the whole process or a single task |
|
* @mgctx: migration context |
|
* |
|
* Migrate a process or task denoted by @leader. If migrating a process, |
|
* the caller must be holding cgroup_threadgroup_rwsem. The caller is also |
|
* responsible for invoking cgroup_migrate_add_src() and |
|
* cgroup_migrate_prepare_dst() on the targets before invoking this |
|
* function and following up with cgroup_migrate_finish(). |
|
* |
|
* As long as a controller's ->can_attach() doesn't fail, this function is |
|
* guaranteed to succeed. This means that, excluding ->can_attach() |
|
* failure, when migrating multiple targets, the success or failure can be |
|
* decided for all targets by invoking group_migrate_prepare_dst() before |
|
* actually starting migrating. |
|
*/ |
|
int cgroup_migrate(struct task_struct *leader, bool threadgroup, |
|
struct cgroup_mgctx *mgctx) |
|
{ |
|
struct task_struct *task; |
|
|
|
/* |
|
* Prevent freeing of tasks while we take a snapshot. Tasks that are |
|
* already PF_EXITING could be freed from underneath us unless we |
|
* take an rcu_read_lock. |
|
*/ |
|
spin_lock_irq(&css_set_lock); |
|
rcu_read_lock(); |
|
task = leader; |
|
do { |
|
cgroup_migrate_add_task(task, mgctx); |
|
if (!threadgroup) |
|
break; |
|
} while_each_thread(leader, task); |
|
rcu_read_unlock(); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
return cgroup_migrate_execute(mgctx); |
|
} |
|
|
|
/** |
|
* cgroup_attach_task - attach a task or a whole threadgroup to a cgroup |
|
* @dst_cgrp: the cgroup to attach to |
|
* @leader: the task or the leader of the threadgroup to be attached |
|
* @threadgroup: attach the whole threadgroup? |
|
* |
|
* Call holding cgroup_mutex and cgroup_threadgroup_rwsem. |
|
*/ |
|
int cgroup_attach_task(struct cgroup *dst_cgrp, struct task_struct *leader, |
|
bool threadgroup) |
|
{ |
|
DEFINE_CGROUP_MGCTX(mgctx); |
|
struct task_struct *task; |
|
int ret = 0; |
|
|
|
/* look up all src csets */ |
|
spin_lock_irq(&css_set_lock); |
|
rcu_read_lock(); |
|
task = leader; |
|
do { |
|
cgroup_migrate_add_src(task_css_set(task), dst_cgrp, &mgctx); |
|
if (!threadgroup) |
|
break; |
|
} while_each_thread(leader, task); |
|
rcu_read_unlock(); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* prepare dst csets and commit */ |
|
ret = cgroup_migrate_prepare_dst(&mgctx); |
|
if (!ret) |
|
ret = cgroup_migrate(leader, threadgroup, &mgctx); |
|
|
|
cgroup_migrate_finish(&mgctx); |
|
|
|
if (!ret) |
|
TRACE_CGROUP_PATH(attach_task, dst_cgrp, leader, threadgroup); |
|
|
|
return ret; |
|
} |
|
|
|
struct task_struct *cgroup_procs_write_start(char *buf, bool threadgroup, |
|
bool *locked) |
|
__acquires(&cgroup_threadgroup_rwsem) |
|
{ |
|
struct task_struct *tsk; |
|
pid_t pid; |
|
|
|
if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
|
return ERR_PTR(-EINVAL); |
|
|
|
/* |
|
* If we migrate a single thread, we don't care about threadgroup |
|
* stability. If the thread is `current`, it won't exit(2) under our |
|
* hands or change PID through exec(2). We exclude |
|
* cgroup_update_dfl_csses and other cgroup_{proc,thread}s_write |
|
* callers by cgroup_mutex. |
|
* Therefore, we can skip the global lock. |
|
*/ |
|
lockdep_assert_held(&cgroup_mutex); |
|
if (pid || threadgroup) { |
|
percpu_down_write(&cgroup_threadgroup_rwsem); |
|
*locked = true; |
|
} else { |
|
*locked = false; |
|
} |
|
|
|
rcu_read_lock(); |
|
if (pid) { |
|
tsk = find_task_by_vpid(pid); |
|
if (!tsk) { |
|
tsk = ERR_PTR(-ESRCH); |
|
goto out_unlock_threadgroup; |
|
} |
|
} else { |
|
tsk = current; |
|
} |
|
|
|
if (threadgroup) |
|
tsk = tsk->group_leader; |
|
|
|
/* |
|
* kthreads may acquire PF_NO_SETAFFINITY during initialization. |
|
* If userland migrates such a kthread to a non-root cgroup, it can |
|
* become trapped in a cpuset, or RT kthread may be born in a |
|
* cgroup with no rt_runtime allocated. Just say no. |
|
*/ |
|
if (tsk->no_cgroup_migration || (tsk->flags & PF_NO_SETAFFINITY)) { |
|
tsk = ERR_PTR(-EINVAL); |
|
goto out_unlock_threadgroup; |
|
} |
|
|
|
get_task_struct(tsk); |
|
goto out_unlock_rcu; |
|
|
|
out_unlock_threadgroup: |
|
if (*locked) { |
|
percpu_up_write(&cgroup_threadgroup_rwsem); |
|
*locked = false; |
|
} |
|
out_unlock_rcu: |
|
rcu_read_unlock(); |
|
return tsk; |
|
} |
|
|
|
void cgroup_procs_write_finish(struct task_struct *task, bool locked) |
|
__releases(&cgroup_threadgroup_rwsem) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
/* release reference from cgroup_procs_write_start() */ |
|
put_task_struct(task); |
|
|
|
if (locked) |
|
percpu_up_write(&cgroup_threadgroup_rwsem); |
|
for_each_subsys(ss, ssid) |
|
if (ss->post_attach) |
|
ss->post_attach(); |
|
} |
|
|
|
static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask) |
|
{ |
|
struct cgroup_subsys *ss; |
|
bool printed = false; |
|
int ssid; |
|
|
|
do_each_subsys_mask(ss, ssid, ss_mask) { |
|
if (printed) |
|
seq_putc(seq, ' '); |
|
seq_puts(seq, ss->name); |
|
printed = true; |
|
} while_each_subsys_mask(); |
|
if (printed) |
|
seq_putc(seq, '\n'); |
|
} |
|
|
|
/* show controllers which are enabled from the parent */ |
|
static int cgroup_controllers_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
|
|
cgroup_print_ss_mask(seq, cgroup_control(cgrp)); |
|
return 0; |
|
} |
|
|
|
/* show controllers which are enabled for a given cgroup's children */ |
|
static int cgroup_subtree_control_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
|
|
cgroup_print_ss_mask(seq, cgrp->subtree_control); |
|
return 0; |
|
} |
|
|
|
/** |
|
* cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy |
|
* @cgrp: root of the subtree to update csses for |
|
* |
|
* @cgrp's control masks have changed and its subtree's css associations |
|
* need to be updated accordingly. This function looks up all css_sets |
|
* which are attached to the subtree, creates the matching updated css_sets |
|
* and migrates the tasks to the new ones. |
|
*/ |
|
static int cgroup_update_dfl_csses(struct cgroup *cgrp) |
|
{ |
|
DEFINE_CGROUP_MGCTX(mgctx); |
|
struct cgroup_subsys_state *d_css; |
|
struct cgroup *dsct; |
|
struct css_set *src_cset; |
|
int ret; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
percpu_down_write(&cgroup_threadgroup_rwsem); |
|
|
|
/* look up all csses currently attached to @cgrp's subtree */ |
|
spin_lock_irq(&css_set_lock); |
|
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
|
struct cgrp_cset_link *link; |
|
|
|
list_for_each_entry(link, &dsct->cset_links, cset_link) |
|
cgroup_migrate_add_src(link->cset, dsct, &mgctx); |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* NULL dst indicates self on default hierarchy */ |
|
ret = cgroup_migrate_prepare_dst(&mgctx); |
|
if (ret) |
|
goto out_finish; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
list_for_each_entry(src_cset, &mgctx.preloaded_src_csets, mg_preload_node) { |
|
struct task_struct *task, *ntask; |
|
|
|
/* all tasks in src_csets need to be migrated */ |
|
list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) |
|
cgroup_migrate_add_task(task, &mgctx); |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
ret = cgroup_migrate_execute(&mgctx); |
|
out_finish: |
|
cgroup_migrate_finish(&mgctx); |
|
percpu_up_write(&cgroup_threadgroup_rwsem); |
|
return ret; |
|
} |
|
|
|
/** |
|
* cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses |
|
* @cgrp: root of the target subtree |
|
* |
|
* Because css offlining is asynchronous, userland may try to re-enable a |
|
* controller while the previous css is still around. This function grabs |
|
* cgroup_mutex and drains the previous css instances of @cgrp's subtree. |
|
*/ |
|
void cgroup_lock_and_drain_offline(struct cgroup *cgrp) |
|
__acquires(&cgroup_mutex) |
|
{ |
|
struct cgroup *dsct; |
|
struct cgroup_subsys_state *d_css; |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
restart: |
|
mutex_lock(&cgroup_mutex); |
|
|
|
cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
|
for_each_subsys(ss, ssid) { |
|
struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
|
DEFINE_WAIT(wait); |
|
|
|
if (!css || !percpu_ref_is_dying(&css->refcnt)) |
|
continue; |
|
|
|
cgroup_get_live(dsct); |
|
prepare_to_wait(&dsct->offline_waitq, &wait, |
|
TASK_UNINTERRUPTIBLE); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
schedule(); |
|
finish_wait(&dsct->offline_waitq, &wait); |
|
|
|
cgroup_put(dsct); |
|
goto restart; |
|
} |
|
} |
|
} |
|
|
|
/** |
|
* cgroup_save_control - save control masks and dom_cgrp of a subtree |
|
* @cgrp: root of the target subtree |
|
* |
|
* Save ->subtree_control, ->subtree_ss_mask and ->dom_cgrp to the |
|
* respective old_ prefixed fields for @cgrp's subtree including @cgrp |
|
* itself. |
|
*/ |
|
static void cgroup_save_control(struct cgroup *cgrp) |
|
{ |
|
struct cgroup *dsct; |
|
struct cgroup_subsys_state *d_css; |
|
|
|
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
|
dsct->old_subtree_control = dsct->subtree_control; |
|
dsct->old_subtree_ss_mask = dsct->subtree_ss_mask; |
|
dsct->old_dom_cgrp = dsct->dom_cgrp; |
|
} |
|
} |
|
|
|
/** |
|
* cgroup_propagate_control - refresh control masks of a subtree |
|
* @cgrp: root of the target subtree |
|
* |
|
* For @cgrp and its subtree, ensure ->subtree_ss_mask matches |
|
* ->subtree_control and propagate controller availability through the |
|
* subtree so that descendants don't have unavailable controllers enabled. |
|
*/ |
|
static void cgroup_propagate_control(struct cgroup *cgrp) |
|
{ |
|
struct cgroup *dsct; |
|
struct cgroup_subsys_state *d_css; |
|
|
|
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
|
dsct->subtree_control &= cgroup_control(dsct); |
|
dsct->subtree_ss_mask = |
|
cgroup_calc_subtree_ss_mask(dsct->subtree_control, |
|
cgroup_ss_mask(dsct)); |
|
} |
|
} |
|
|
|
/** |
|
* cgroup_restore_control - restore control masks and dom_cgrp of a subtree |
|
* @cgrp: root of the target subtree |
|
* |
|
* Restore ->subtree_control, ->subtree_ss_mask and ->dom_cgrp from the |
|
* respective old_ prefixed fields for @cgrp's subtree including @cgrp |
|
* itself. |
|
*/ |
|
static void cgroup_restore_control(struct cgroup *cgrp) |
|
{ |
|
struct cgroup *dsct; |
|
struct cgroup_subsys_state *d_css; |
|
|
|
cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
|
dsct->subtree_control = dsct->old_subtree_control; |
|
dsct->subtree_ss_mask = dsct->old_subtree_ss_mask; |
|
dsct->dom_cgrp = dsct->old_dom_cgrp; |
|
} |
|
} |
|
|
|
static bool css_visible(struct cgroup_subsys_state *css) |
|
{ |
|
struct cgroup_subsys *ss = css->ss; |
|
struct cgroup *cgrp = css->cgroup; |
|
|
|
if (cgroup_control(cgrp) & (1 << ss->id)) |
|
return true; |
|
if (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) |
|
return false; |
|
return cgroup_on_dfl(cgrp) && ss->implicit_on_dfl; |
|
} |
|
|
|
/** |
|
* cgroup_apply_control_enable - enable or show csses according to control |
|
* @cgrp: root of the target subtree |
|
* |
|
* Walk @cgrp's subtree and create new csses or make the existing ones |
|
* visible. A css is created invisible if it's being implicitly enabled |
|
* through dependency. An invisible css is made visible when the userland |
|
* explicitly enables it. |
|
* |
|
* Returns 0 on success, -errno on failure. On failure, csses which have |
|
* been processed already aren't cleaned up. The caller is responsible for |
|
* cleaning up with cgroup_apply_control_disable(). |
|
*/ |
|
static int cgroup_apply_control_enable(struct cgroup *cgrp) |
|
{ |
|
struct cgroup *dsct; |
|
struct cgroup_subsys_state *d_css; |
|
struct cgroup_subsys *ss; |
|
int ssid, ret; |
|
|
|
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) { |
|
for_each_subsys(ss, ssid) { |
|
struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
|
|
|
if (!(cgroup_ss_mask(dsct) & (1 << ss->id))) |
|
continue; |
|
|
|
if (!css) { |
|
css = css_create(dsct, ss); |
|
if (IS_ERR(css)) |
|
return PTR_ERR(css); |
|
} |
|
|
|
WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt)); |
|
|
|
if (css_visible(css)) { |
|
ret = css_populate_dir(css); |
|
if (ret) |
|
return ret; |
|
} |
|
} |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* cgroup_apply_control_disable - kill or hide csses according to control |
|
* @cgrp: root of the target subtree |
|
* |
|
* Walk @cgrp's subtree and kill and hide csses so that they match |
|
* cgroup_ss_mask() and cgroup_visible_mask(). |
|
* |
|
* A css is hidden when the userland requests it to be disabled while other |
|
* subsystems are still depending on it. The css must not actively control |
|
* resources and be in the vanilla state if it's made visible again later. |
|
* Controllers which may be depended upon should provide ->css_reset() for |
|
* this purpose. |
|
*/ |
|
static void cgroup_apply_control_disable(struct cgroup *cgrp) |
|
{ |
|
struct cgroup *dsct; |
|
struct cgroup_subsys_state *d_css; |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) { |
|
for_each_subsys(ss, ssid) { |
|
struct cgroup_subsys_state *css = cgroup_css(dsct, ss); |
|
|
|
if (!css) |
|
continue; |
|
|
|
WARN_ON_ONCE(percpu_ref_is_dying(&css->refcnt)); |
|
|
|
if (css->parent && |
|
!(cgroup_ss_mask(dsct) & (1 << ss->id))) { |
|
kill_css(css); |
|
} else if (!css_visible(css)) { |
|
css_clear_dir(css); |
|
if (ss->css_reset) |
|
ss->css_reset(css); |
|
} |
|
} |
|
} |
|
} |
|
|
|
/** |
|
* cgroup_apply_control - apply control mask updates to the subtree |
|
* @cgrp: root of the target subtree |
|
* |
|
* subsystems can be enabled and disabled in a subtree using the following |
|
* steps. |
|
* |
|
* 1. Call cgroup_save_control() to stash the current state. |
|
* 2. Update ->subtree_control masks in the subtree as desired. |
|
* 3. Call cgroup_apply_control() to apply the changes. |
|
* 4. Optionally perform other related operations. |
|
* 5. Call cgroup_finalize_control() to finish up. |
|
* |
|
* This function implements step 3 and propagates the mask changes |
|
* throughout @cgrp's subtree, updates csses accordingly and perform |
|
* process migrations. |
|
*/ |
|
static int cgroup_apply_control(struct cgroup *cgrp) |
|
{ |
|
int ret; |
|
|
|
cgroup_propagate_control(cgrp); |
|
|
|
ret = cgroup_apply_control_enable(cgrp); |
|
if (ret) |
|
return ret; |
|
|
|
/* |
|
* At this point, cgroup_e_css_by_mask() results reflect the new csses |
|
* making the following cgroup_update_dfl_csses() properly update |
|
* css associations of all tasks in the subtree. |
|
*/ |
|
ret = cgroup_update_dfl_csses(cgrp); |
|
if (ret) |
|
return ret; |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* cgroup_finalize_control - finalize control mask update |
|
* @cgrp: root of the target subtree |
|
* @ret: the result of the update |
|
* |
|
* Finalize control mask update. See cgroup_apply_control() for more info. |
|
*/ |
|
static void cgroup_finalize_control(struct cgroup *cgrp, int ret) |
|
{ |
|
if (ret) { |
|
cgroup_restore_control(cgrp); |
|
cgroup_propagate_control(cgrp); |
|
} |
|
|
|
cgroup_apply_control_disable(cgrp); |
|
} |
|
|
|
static int cgroup_vet_subtree_control_enable(struct cgroup *cgrp, u16 enable) |
|
{ |
|
u16 domain_enable = enable & ~cgrp_dfl_threaded_ss_mask; |
|
|
|
/* if nothing is getting enabled, nothing to worry about */ |
|
if (!enable) |
|
return 0; |
|
|
|
/* can @cgrp host any resources? */ |
|
if (!cgroup_is_valid_domain(cgrp->dom_cgrp)) |
|
return -EOPNOTSUPP; |
|
|
|
/* mixables don't care */ |
|
if (cgroup_is_mixable(cgrp)) |
|
return 0; |
|
|
|
if (domain_enable) { |
|
/* can't enable domain controllers inside a thread subtree */ |
|
if (cgroup_is_thread_root(cgrp) || cgroup_is_threaded(cgrp)) |
|
return -EOPNOTSUPP; |
|
} else { |
|
/* |
|
* Threaded controllers can handle internal competitions |
|
* and are always allowed inside a (prospective) thread |
|
* subtree. |
|
*/ |
|
if (cgroup_can_be_thread_root(cgrp) || cgroup_is_threaded(cgrp)) |
|
return 0; |
|
} |
|
|
|
/* |
|
* Controllers can't be enabled for a cgroup with tasks to avoid |
|
* child cgroups competing against tasks. |
|
*/ |
|
if (cgroup_has_tasks(cgrp)) |
|
return -EBUSY; |
|
|
|
return 0; |
|
} |
|
|
|
/* change the enabled child controllers for a cgroup in the default hierarchy */ |
|
static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, |
|
loff_t off) |
|
{ |
|
u16 enable = 0, disable = 0; |
|
struct cgroup *cgrp, *child; |
|
struct cgroup_subsys *ss; |
|
char *tok; |
|
int ssid, ret; |
|
|
|
/* |
|
* Parse input - space separated list of subsystem names prefixed |
|
* with either + or -. |
|
*/ |
|
buf = strstrip(buf); |
|
while ((tok = strsep(&buf, " "))) { |
|
if (tok[0] == '\0') |
|
continue; |
|
do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) { |
|
if (!cgroup_ssid_enabled(ssid) || |
|
strcmp(tok + 1, ss->name)) |
|
continue; |
|
|
|
if (*tok == '+') { |
|
enable |= 1 << ssid; |
|
disable &= ~(1 << ssid); |
|
} else if (*tok == '-') { |
|
disable |= 1 << ssid; |
|
enable &= ~(1 << ssid); |
|
} else { |
|
return -EINVAL; |
|
} |
|
break; |
|
} while_each_subsys_mask(); |
|
if (ssid == CGROUP_SUBSYS_COUNT) |
|
return -EINVAL; |
|
} |
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, true); |
|
if (!cgrp) |
|
return -ENODEV; |
|
|
|
for_each_subsys(ss, ssid) { |
|
if (enable & (1 << ssid)) { |
|
if (cgrp->subtree_control & (1 << ssid)) { |
|
enable &= ~(1 << ssid); |
|
continue; |
|
} |
|
|
|
if (!(cgroup_control(cgrp) & (1 << ssid))) { |
|
ret = -ENOENT; |
|
goto out_unlock; |
|
} |
|
} else if (disable & (1 << ssid)) { |
|
if (!(cgrp->subtree_control & (1 << ssid))) { |
|
disable &= ~(1 << ssid); |
|
continue; |
|
} |
|
|
|
/* a child has it enabled? */ |
|
cgroup_for_each_live_child(child, cgrp) { |
|
if (child->subtree_control & (1 << ssid)) { |
|
ret = -EBUSY; |
|
goto out_unlock; |
|
} |
|
} |
|
} |
|
} |
|
|
|
if (!enable && !disable) { |
|
ret = 0; |
|
goto out_unlock; |
|
} |
|
|
|
ret = cgroup_vet_subtree_control_enable(cgrp, enable); |
|
if (ret) |
|
goto out_unlock; |
|
|
|
/* save and update control masks and prepare csses */ |
|
cgroup_save_control(cgrp); |
|
|
|
cgrp->subtree_control |= enable; |
|
cgrp->subtree_control &= ~disable; |
|
|
|
ret = cgroup_apply_control(cgrp); |
|
cgroup_finalize_control(cgrp, ret); |
|
if (ret) |
|
goto out_unlock; |
|
|
|
kernfs_activate(cgrp->kn); |
|
out_unlock: |
|
cgroup_kn_unlock(of->kn); |
|
return ret ?: nbytes; |
|
} |
|
|
|
/** |
|
* cgroup_enable_threaded - make @cgrp threaded |
|
* @cgrp: the target cgroup |
|
* |
|
* Called when "threaded" is written to the cgroup.type interface file and |
|
* tries to make @cgrp threaded and join the parent's resource domain. |
|
* This function is never called on the root cgroup as cgroup.type doesn't |
|
* exist on it. |
|
*/ |
|
static int cgroup_enable_threaded(struct cgroup *cgrp) |
|
{ |
|
struct cgroup *parent = cgroup_parent(cgrp); |
|
struct cgroup *dom_cgrp = parent->dom_cgrp; |
|
struct cgroup *dsct; |
|
struct cgroup_subsys_state *d_css; |
|
int ret; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
/* noop if already threaded */ |
|
if (cgroup_is_threaded(cgrp)) |
|
return 0; |
|
|
|
/* |
|
* If @cgroup is populated or has domain controllers enabled, it |
|
* can't be switched. While the below cgroup_can_be_thread_root() |
|
* test can catch the same conditions, that's only when @parent is |
|
* not mixable, so let's check it explicitly. |
|
*/ |
|
if (cgroup_is_populated(cgrp) || |
|
cgrp->subtree_control & ~cgrp_dfl_threaded_ss_mask) |
|
return -EOPNOTSUPP; |
|
|
|
/* we're joining the parent's domain, ensure its validity */ |
|
if (!cgroup_is_valid_domain(dom_cgrp) || |
|
!cgroup_can_be_thread_root(dom_cgrp)) |
|
return -EOPNOTSUPP; |
|
|
|
/* |
|
* The following shouldn't cause actual migrations and should |
|
* always succeed. |
|
*/ |
|
cgroup_save_control(cgrp); |
|
|
|
cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) |
|
if (dsct == cgrp || cgroup_is_threaded(dsct)) |
|
dsct->dom_cgrp = dom_cgrp; |
|
|
|
ret = cgroup_apply_control(cgrp); |
|
if (!ret) |
|
parent->nr_threaded_children++; |
|
|
|
cgroup_finalize_control(cgrp, ret); |
|
return ret; |
|
} |
|
|
|
static int cgroup_type_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
|
|
if (cgroup_is_threaded(cgrp)) |
|
seq_puts(seq, "threaded\n"); |
|
else if (!cgroup_is_valid_domain(cgrp)) |
|
seq_puts(seq, "domain invalid\n"); |
|
else if (cgroup_is_thread_root(cgrp)) |
|
seq_puts(seq, "domain threaded\n"); |
|
else |
|
seq_puts(seq, "domain\n"); |
|
|
|
return 0; |
|
} |
|
|
|
static ssize_t cgroup_type_write(struct kernfs_open_file *of, char *buf, |
|
size_t nbytes, loff_t off) |
|
{ |
|
struct cgroup *cgrp; |
|
int ret; |
|
|
|
/* only switching to threaded mode is supported */ |
|
if (strcmp(strstrip(buf), "threaded")) |
|
return -EINVAL; |
|
|
|
/* drain dying csses before we re-apply (threaded) subtree control */ |
|
cgrp = cgroup_kn_lock_live(of->kn, true); |
|
if (!cgrp) |
|
return -ENOENT; |
|
|
|
/* threaded can only be enabled */ |
|
ret = cgroup_enable_threaded(cgrp); |
|
|
|
cgroup_kn_unlock(of->kn); |
|
return ret ?: nbytes; |
|
} |
|
|
|
static int cgroup_max_descendants_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
int descendants = READ_ONCE(cgrp->max_descendants); |
|
|
|
if (descendants == INT_MAX) |
|
seq_puts(seq, "max\n"); |
|
else |
|
seq_printf(seq, "%d\n", descendants); |
|
|
|
return 0; |
|
} |
|
|
|
static ssize_t cgroup_max_descendants_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, loff_t off) |
|
{ |
|
struct cgroup *cgrp; |
|
int descendants; |
|
ssize_t ret; |
|
|
|
buf = strstrip(buf); |
|
if (!strcmp(buf, "max")) { |
|
descendants = INT_MAX; |
|
} else { |
|
ret = kstrtoint(buf, 0, &descendants); |
|
if (ret) |
|
return ret; |
|
} |
|
|
|
if (descendants < 0) |
|
return -ERANGE; |
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, false); |
|
if (!cgrp) |
|
return -ENOENT; |
|
|
|
cgrp->max_descendants = descendants; |
|
|
|
cgroup_kn_unlock(of->kn); |
|
|
|
return nbytes; |
|
} |
|
|
|
static int cgroup_max_depth_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
int depth = READ_ONCE(cgrp->max_depth); |
|
|
|
if (depth == INT_MAX) |
|
seq_puts(seq, "max\n"); |
|
else |
|
seq_printf(seq, "%d\n", depth); |
|
|
|
return 0; |
|
} |
|
|
|
static ssize_t cgroup_max_depth_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, loff_t off) |
|
{ |
|
struct cgroup *cgrp; |
|
ssize_t ret; |
|
int depth; |
|
|
|
buf = strstrip(buf); |
|
if (!strcmp(buf, "max")) { |
|
depth = INT_MAX; |
|
} else { |
|
ret = kstrtoint(buf, 0, &depth); |
|
if (ret) |
|
return ret; |
|
} |
|
|
|
if (depth < 0) |
|
return -ERANGE; |
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, false); |
|
if (!cgrp) |
|
return -ENOENT; |
|
|
|
cgrp->max_depth = depth; |
|
|
|
cgroup_kn_unlock(of->kn); |
|
|
|
return nbytes; |
|
} |
|
|
|
static int cgroup_events_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
|
|
seq_printf(seq, "populated %d\n", cgroup_is_populated(cgrp)); |
|
seq_printf(seq, "frozen %d\n", test_bit(CGRP_FROZEN, &cgrp->flags)); |
|
|
|
return 0; |
|
} |
|
|
|
static int cgroup_stat_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgroup = seq_css(seq)->cgroup; |
|
|
|
seq_printf(seq, "nr_descendants %d\n", |
|
cgroup->nr_descendants); |
|
seq_printf(seq, "nr_dying_descendants %d\n", |
|
cgroup->nr_dying_descendants); |
|
|
|
return 0; |
|
} |
|
|
|
static int __maybe_unused cgroup_extra_stat_show(struct seq_file *seq, |
|
struct cgroup *cgrp, int ssid) |
|
{ |
|
struct cgroup_subsys *ss = cgroup_subsys[ssid]; |
|
struct cgroup_subsys_state *css; |
|
int ret; |
|
|
|
if (!ss->css_extra_stat_show) |
|
return 0; |
|
|
|
css = cgroup_tryget_css(cgrp, ss); |
|
if (!css) |
|
return 0; |
|
|
|
ret = ss->css_extra_stat_show(seq, css); |
|
css_put(css); |
|
return ret; |
|
} |
|
|
|
static int cpu_stat_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup __maybe_unused *cgrp = seq_css(seq)->cgroup; |
|
int ret = 0; |
|
|
|
cgroup_base_stat_cputime_show(seq); |
|
#ifdef CONFIG_CGROUP_SCHED |
|
ret = cgroup_extra_stat_show(seq, cgrp, cpu_cgrp_id); |
|
#endif |
|
return ret; |
|
} |
|
|
|
#ifdef CONFIG_PSI |
|
static int cgroup_io_pressure_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi; |
|
|
|
return psi_show(seq, psi, PSI_IO); |
|
} |
|
static int cgroup_memory_pressure_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi; |
|
|
|
return psi_show(seq, psi, PSI_MEM); |
|
} |
|
static int cgroup_cpu_pressure_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
struct psi_group *psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi; |
|
|
|
return psi_show(seq, psi, PSI_CPU); |
|
} |
|
|
|
static ssize_t cgroup_pressure_write(struct kernfs_open_file *of, char *buf, |
|
size_t nbytes, enum psi_res res) |
|
{ |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
struct psi_trigger *new; |
|
struct cgroup *cgrp; |
|
struct psi_group *psi; |
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, false); |
|
if (!cgrp) |
|
return -ENODEV; |
|
|
|
cgroup_get(cgrp); |
|
cgroup_kn_unlock(of->kn); |
|
|
|
/* Allow only one trigger per file descriptor */ |
|
if (ctx->psi.trigger) { |
|
cgroup_put(cgrp); |
|
return -EBUSY; |
|
} |
|
|
|
psi = cgroup_ino(cgrp) == 1 ? &psi_system : &cgrp->psi; |
|
new = psi_trigger_create(psi, buf, nbytes, res); |
|
if (IS_ERR(new)) { |
|
cgroup_put(cgrp); |
|
return PTR_ERR(new); |
|
} |
|
|
|
smp_store_release(&ctx->psi.trigger, new); |
|
cgroup_put(cgrp); |
|
|
|
return nbytes; |
|
} |
|
|
|
static ssize_t cgroup_io_pressure_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, |
|
loff_t off) |
|
{ |
|
return cgroup_pressure_write(of, buf, nbytes, PSI_IO); |
|
} |
|
|
|
static ssize_t cgroup_memory_pressure_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, |
|
loff_t off) |
|
{ |
|
return cgroup_pressure_write(of, buf, nbytes, PSI_MEM); |
|
} |
|
|
|
static ssize_t cgroup_cpu_pressure_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, |
|
loff_t off) |
|
{ |
|
return cgroup_pressure_write(of, buf, nbytes, PSI_CPU); |
|
} |
|
|
|
static __poll_t cgroup_pressure_poll(struct kernfs_open_file *of, |
|
poll_table *pt) |
|
{ |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
|
|
return psi_trigger_poll(&ctx->psi.trigger, of->file, pt); |
|
} |
|
|
|
static void cgroup_pressure_release(struct kernfs_open_file *of) |
|
{ |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
|
|
psi_trigger_destroy(ctx->psi.trigger); |
|
} |
|
|
|
bool cgroup_psi_enabled(void) |
|
{ |
|
return (cgroup_feature_disable_mask & (1 << OPT_FEATURE_PRESSURE)) == 0; |
|
} |
|
|
|
#else /* CONFIG_PSI */ |
|
bool cgroup_psi_enabled(void) |
|
{ |
|
return false; |
|
} |
|
|
|
#endif /* CONFIG_PSI */ |
|
|
|
static int cgroup_freeze_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
|
|
seq_printf(seq, "%d\n", cgrp->freezer.freeze); |
|
|
|
return 0; |
|
} |
|
|
|
static ssize_t cgroup_freeze_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, loff_t off) |
|
{ |
|
struct cgroup *cgrp; |
|
ssize_t ret; |
|
int freeze; |
|
|
|
ret = kstrtoint(strstrip(buf), 0, &freeze); |
|
if (ret) |
|
return ret; |
|
|
|
if (freeze < 0 || freeze > 1) |
|
return -ERANGE; |
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, false); |
|
if (!cgrp) |
|
return -ENOENT; |
|
|
|
cgroup_freeze(cgrp, freeze); |
|
|
|
cgroup_kn_unlock(of->kn); |
|
|
|
return nbytes; |
|
} |
|
|
|
static void __cgroup_kill(struct cgroup *cgrp) |
|
{ |
|
struct css_task_iter it; |
|
struct task_struct *task; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
set_bit(CGRP_KILL, &cgrp->flags); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
css_task_iter_start(&cgrp->self, CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED, &it); |
|
while ((task = css_task_iter_next(&it))) { |
|
/* Ignore kernel threads here. */ |
|
if (task->flags & PF_KTHREAD) |
|
continue; |
|
|
|
/* Skip tasks that are already dying. */ |
|
if (__fatal_signal_pending(task)) |
|
continue; |
|
|
|
send_sig(SIGKILL, task, 0); |
|
} |
|
css_task_iter_end(&it); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
clear_bit(CGRP_KILL, &cgrp->flags); |
|
spin_unlock_irq(&css_set_lock); |
|
} |
|
|
|
static void cgroup_kill(struct cgroup *cgrp) |
|
{ |
|
struct cgroup_subsys_state *css; |
|
struct cgroup *dsct; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
cgroup_for_each_live_descendant_pre(dsct, css, cgrp) |
|
__cgroup_kill(dsct); |
|
} |
|
|
|
static ssize_t cgroup_kill_write(struct kernfs_open_file *of, char *buf, |
|
size_t nbytes, loff_t off) |
|
{ |
|
ssize_t ret = 0; |
|
int kill; |
|
struct cgroup *cgrp; |
|
|
|
ret = kstrtoint(strstrip(buf), 0, &kill); |
|
if (ret) |
|
return ret; |
|
|
|
if (kill != 1) |
|
return -ERANGE; |
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, false); |
|
if (!cgrp) |
|
return -ENOENT; |
|
|
|
/* |
|
* Killing is a process directed operation, i.e. the whole thread-group |
|
* is taken down so act like we do for cgroup.procs and only make this |
|
* writable in non-threaded cgroups. |
|
*/ |
|
if (cgroup_is_threaded(cgrp)) |
|
ret = -EOPNOTSUPP; |
|
else |
|
cgroup_kill(cgrp); |
|
|
|
cgroup_kn_unlock(of->kn); |
|
|
|
return ret ?: nbytes; |
|
} |
|
|
|
static int cgroup_file_open(struct kernfs_open_file *of) |
|
{ |
|
struct cftype *cft = of_cft(of); |
|
struct cgroup_file_ctx *ctx; |
|
int ret; |
|
|
|
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); |
|
if (!ctx) |
|
return -ENOMEM; |
|
|
|
ctx->ns = current->nsproxy->cgroup_ns; |
|
get_cgroup_ns(ctx->ns); |
|
of->priv = ctx; |
|
|
|
if (!cft->open) |
|
return 0; |
|
|
|
ret = cft->open(of); |
|
if (ret) { |
|
put_cgroup_ns(ctx->ns); |
|
kfree(ctx); |
|
} |
|
return ret; |
|
} |
|
|
|
static void cgroup_file_release(struct kernfs_open_file *of) |
|
{ |
|
struct cftype *cft = of_cft(of); |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
|
|
if (cft->release) |
|
cft->release(of); |
|
put_cgroup_ns(ctx->ns); |
|
kfree(ctx); |
|
} |
|
|
|
static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
|
size_t nbytes, loff_t off) |
|
{ |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
struct cgroup *cgrp = of->kn->parent->priv; |
|
struct cftype *cft = of_cft(of); |
|
struct cgroup_subsys_state *css; |
|
int ret; |
|
|
|
if (!nbytes) |
|
return 0; |
|
|
|
/* |
|
* If namespaces are delegation boundaries, disallow writes to |
|
* files in an non-init namespace root from inside the namespace |
|
* except for the files explicitly marked delegatable - |
|
* cgroup.procs and cgroup.subtree_control. |
|
*/ |
|
if ((cgrp->root->flags & CGRP_ROOT_NS_DELEGATE) && |
|
!(cft->flags & CFTYPE_NS_DELEGATABLE) && |
|
ctx->ns != &init_cgroup_ns && ctx->ns->root_cset->dfl_cgrp == cgrp) |
|
return -EPERM; |
|
|
|
if (cft->write) |
|
return cft->write(of, buf, nbytes, off); |
|
|
|
/* |
|
* kernfs guarantees that a file isn't deleted with operations in |
|
* flight, which means that the matching css is and stays alive and |
|
* doesn't need to be pinned. The RCU locking is not necessary |
|
* either. It's just for the convenience of using cgroup_css(). |
|
*/ |
|
rcu_read_lock(); |
|
css = cgroup_css(cgrp, cft->ss); |
|
rcu_read_unlock(); |
|
|
|
if (cft->write_u64) { |
|
unsigned long long v; |
|
ret = kstrtoull(buf, 0, &v); |
|
if (!ret) |
|
ret = cft->write_u64(css, cft, v); |
|
} else if (cft->write_s64) { |
|
long long v; |
|
ret = kstrtoll(buf, 0, &v); |
|
if (!ret) |
|
ret = cft->write_s64(css, cft, v); |
|
} else { |
|
ret = -EINVAL; |
|
} |
|
|
|
return ret ?: nbytes; |
|
} |
|
|
|
static __poll_t cgroup_file_poll(struct kernfs_open_file *of, poll_table *pt) |
|
{ |
|
struct cftype *cft = of_cft(of); |
|
|
|
if (cft->poll) |
|
return cft->poll(of, pt); |
|
|
|
return kernfs_generic_poll(of, pt); |
|
} |
|
|
|
static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos) |
|
{ |
|
return seq_cft(seq)->seq_start(seq, ppos); |
|
} |
|
|
|
static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos) |
|
{ |
|
return seq_cft(seq)->seq_next(seq, v, ppos); |
|
} |
|
|
|
static void cgroup_seqfile_stop(struct seq_file *seq, void *v) |
|
{ |
|
if (seq_cft(seq)->seq_stop) |
|
seq_cft(seq)->seq_stop(seq, v); |
|
} |
|
|
|
static int cgroup_seqfile_show(struct seq_file *m, void *arg) |
|
{ |
|
struct cftype *cft = seq_cft(m); |
|
struct cgroup_subsys_state *css = seq_css(m); |
|
|
|
if (cft->seq_show) |
|
return cft->seq_show(m, arg); |
|
|
|
if (cft->read_u64) |
|
seq_printf(m, "%llu\n", cft->read_u64(css, cft)); |
|
else if (cft->read_s64) |
|
seq_printf(m, "%lld\n", cft->read_s64(css, cft)); |
|
else |
|
return -EINVAL; |
|
return 0; |
|
} |
|
|
|
static struct kernfs_ops cgroup_kf_single_ops = { |
|
.atomic_write_len = PAGE_SIZE, |
|
.open = cgroup_file_open, |
|
.release = cgroup_file_release, |
|
.write = cgroup_file_write, |
|
.poll = cgroup_file_poll, |
|
.seq_show = cgroup_seqfile_show, |
|
}; |
|
|
|
static struct kernfs_ops cgroup_kf_ops = { |
|
.atomic_write_len = PAGE_SIZE, |
|
.open = cgroup_file_open, |
|
.release = cgroup_file_release, |
|
.write = cgroup_file_write, |
|
.poll = cgroup_file_poll, |
|
.seq_start = cgroup_seqfile_start, |
|
.seq_next = cgroup_seqfile_next, |
|
.seq_stop = cgroup_seqfile_stop, |
|
.seq_show = cgroup_seqfile_show, |
|
}; |
|
|
|
/* set uid and gid of cgroup dirs and files to that of the creator */ |
|
static int cgroup_kn_set_ugid(struct kernfs_node *kn) |
|
{ |
|
struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID, |
|
.ia_uid = current_fsuid(), |
|
.ia_gid = current_fsgid(), }; |
|
|
|
if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) && |
|
gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID)) |
|
return 0; |
|
|
|
return kernfs_setattr(kn, &iattr); |
|
} |
|
|
|
static void cgroup_file_notify_timer(struct timer_list *timer) |
|
{ |
|
cgroup_file_notify(container_of(timer, struct cgroup_file, |
|
notify_timer)); |
|
} |
|
|
|
static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp, |
|
struct cftype *cft) |
|
{ |
|
char name[CGROUP_FILE_NAME_MAX]; |
|
struct kernfs_node *kn; |
|
struct lock_class_key *key = NULL; |
|
int ret; |
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC |
|
key = &cft->lockdep_key; |
|
#endif |
|
kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name), |
|
cgroup_file_mode(cft), |
|
GLOBAL_ROOT_UID, GLOBAL_ROOT_GID, |
|
0, cft->kf_ops, cft, |
|
NULL, key); |
|
if (IS_ERR(kn)) |
|
return PTR_ERR(kn); |
|
|
|
ret = cgroup_kn_set_ugid(kn); |
|
if (ret) { |
|
kernfs_remove(kn); |
|
return ret; |
|
} |
|
|
|
if (cft->file_offset) { |
|
struct cgroup_file *cfile = (void *)css + cft->file_offset; |
|
|
|
timer_setup(&cfile->notify_timer, cgroup_file_notify_timer, 0); |
|
|
|
spin_lock_irq(&cgroup_file_kn_lock); |
|
cfile->kn = kn; |
|
spin_unlock_irq(&cgroup_file_kn_lock); |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* cgroup_addrm_files - add or remove files to a cgroup directory |
|
* @css: the target css |
|
* @cgrp: the target cgroup (usually css->cgroup) |
|
* @cfts: array of cftypes to be added |
|
* @is_add: whether to add or remove |
|
* |
|
* Depending on @is_add, add or remove files defined by @cfts on @cgrp. |
|
* For removals, this function never fails. |
|
*/ |
|
static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
|
struct cgroup *cgrp, struct cftype cfts[], |
|
bool is_add) |
|
{ |
|
struct cftype *cft, *cft_end = NULL; |
|
int ret = 0; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
restart: |
|
for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) { |
|
/* does cft->flags tell us to skip this file on @cgrp? */ |
|
if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled()) |
|
continue; |
|
if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp)) |
|
continue; |
|
if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp)) |
|
continue; |
|
if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp)) |
|
continue; |
|
if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp)) |
|
continue; |
|
if ((cft->flags & CFTYPE_DEBUG) && !cgroup_debug) |
|
continue; |
|
if (is_add) { |
|
ret = cgroup_add_file(css, cgrp, cft); |
|
if (ret) { |
|
pr_warn("%s: failed to add %s, err=%d\n", |
|
__func__, cft->name, ret); |
|
cft_end = cft; |
|
is_add = false; |
|
goto restart; |
|
} |
|
} else { |
|
cgroup_rm_file(cgrp, cft); |
|
} |
|
} |
|
return ret; |
|
} |
|
|
|
static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add) |
|
{ |
|
struct cgroup_subsys *ss = cfts[0].ss; |
|
struct cgroup *root = &ss->root->cgrp; |
|
struct cgroup_subsys_state *css; |
|
int ret = 0; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
/* add/rm files for all cgroups created before */ |
|
css_for_each_descendant_pre(css, cgroup_css(root, ss)) { |
|
struct cgroup *cgrp = css->cgroup; |
|
|
|
if (!(css->flags & CSS_VISIBLE)) |
|
continue; |
|
|
|
ret = cgroup_addrm_files(css, cgrp, cfts, is_add); |
|
if (ret) |
|
break; |
|
} |
|
|
|
if (is_add && !ret) |
|
kernfs_activate(root->kn); |
|
return ret; |
|
} |
|
|
|
static void cgroup_exit_cftypes(struct cftype *cfts) |
|
{ |
|
struct cftype *cft; |
|
|
|
for (cft = cfts; cft->name[0] != '\0'; cft++) { |
|
/* free copy for custom atomic_write_len, see init_cftypes() */ |
|
if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) |
|
kfree(cft->kf_ops); |
|
cft->kf_ops = NULL; |
|
cft->ss = NULL; |
|
|
|
/* revert flags set by cgroup core while adding @cfts */ |
|
cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL); |
|
} |
|
} |
|
|
|
static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
|
{ |
|
struct cftype *cft; |
|
|
|
for (cft = cfts; cft->name[0] != '\0'; cft++) { |
|
struct kernfs_ops *kf_ops; |
|
|
|
WARN_ON(cft->ss || cft->kf_ops); |
|
|
|
if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled()) |
|
continue; |
|
|
|
if (cft->seq_start) |
|
kf_ops = &cgroup_kf_ops; |
|
else |
|
kf_ops = &cgroup_kf_single_ops; |
|
|
|
/* |
|
* Ugh... if @cft wants a custom max_write_len, we need to |
|
* make a copy of kf_ops to set its atomic_write_len. |
|
*/ |
|
if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) { |
|
kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL); |
|
if (!kf_ops) { |
|
cgroup_exit_cftypes(cfts); |
|
return -ENOMEM; |
|
} |
|
kf_ops->atomic_write_len = cft->max_write_len; |
|
} |
|
|
|
cft->kf_ops = kf_ops; |
|
cft->ss = ss; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
|
{ |
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
if (!cfts || !cfts[0].ss) |
|
return -ENOENT; |
|
|
|
list_del(&cfts->node); |
|
cgroup_apply_cftypes(cfts, false); |
|
cgroup_exit_cftypes(cfts); |
|
return 0; |
|
} |
|
|
|
/** |
|
* cgroup_rm_cftypes - remove an array of cftypes from a subsystem |
|
* @cfts: zero-length name terminated array of cftypes |
|
* |
|
* Unregister @cfts. Files described by @cfts are removed from all |
|
* existing cgroups and all future cgroups won't have them either. This |
|
* function can be called anytime whether @cfts' subsys is attached or not. |
|
* |
|
* Returns 0 on successful unregistration, -ENOENT if @cfts is not |
|
* registered. |
|
*/ |
|
int cgroup_rm_cftypes(struct cftype *cfts) |
|
{ |
|
int ret; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
ret = cgroup_rm_cftypes_locked(cfts); |
|
mutex_unlock(&cgroup_mutex); |
|
return ret; |
|
} |
|
|
|
/** |
|
* cgroup_add_cftypes - add an array of cftypes to a subsystem |
|
* @ss: target cgroup subsystem |
|
* @cfts: zero-length name terminated array of cftypes |
|
* |
|
* Register @cfts to @ss. Files described by @cfts are created for all |
|
* existing cgroups to which @ss is attached and all future cgroups will |
|
* have them too. This function can be called anytime whether @ss is |
|
* attached or not. |
|
* |
|
* Returns 0 on successful registration, -errno on failure. Note that this |
|
* function currently returns 0 as long as @cfts registration is successful |
|
* even if some file creation attempts on existing cgroups fail. |
|
*/ |
|
static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
|
{ |
|
int ret; |
|
|
|
if (!cgroup_ssid_enabled(ss->id)) |
|
return 0; |
|
|
|
if (!cfts || cfts[0].name[0] == '\0') |
|
return 0; |
|
|
|
ret = cgroup_init_cftypes(ss, cfts); |
|
if (ret) |
|
return ret; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
list_add_tail(&cfts->node, &ss->cfts); |
|
ret = cgroup_apply_cftypes(cfts, true); |
|
if (ret) |
|
cgroup_rm_cftypes_locked(cfts); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
return ret; |
|
} |
|
|
|
/** |
|
* cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy |
|
* @ss: target cgroup subsystem |
|
* @cfts: zero-length name terminated array of cftypes |
|
* |
|
* Similar to cgroup_add_cftypes() but the added files are only used for |
|
* the default hierarchy. |
|
*/ |
|
int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
|
{ |
|
struct cftype *cft; |
|
|
|
for (cft = cfts; cft && cft->name[0] != '\0'; cft++) |
|
cft->flags |= __CFTYPE_ONLY_ON_DFL; |
|
return cgroup_add_cftypes(ss, cfts); |
|
} |
|
|
|
/** |
|
* cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies |
|
* @ss: target cgroup subsystem |
|
* @cfts: zero-length name terminated array of cftypes |
|
* |
|
* Similar to cgroup_add_cftypes() but the added files are only used for |
|
* the legacy hierarchies. |
|
*/ |
|
int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts) |
|
{ |
|
struct cftype *cft; |
|
|
|
for (cft = cfts; cft && cft->name[0] != '\0'; cft++) |
|
cft->flags |= __CFTYPE_NOT_ON_DFL; |
|
return cgroup_add_cftypes(ss, cfts); |
|
} |
|
|
|
/** |
|
* cgroup_file_notify - generate a file modified event for a cgroup_file |
|
* @cfile: target cgroup_file |
|
* |
|
* @cfile must have been obtained by setting cftype->file_offset. |
|
*/ |
|
void cgroup_file_notify(struct cgroup_file *cfile) |
|
{ |
|
unsigned long flags; |
|
|
|
spin_lock_irqsave(&cgroup_file_kn_lock, flags); |
|
if (cfile->kn) { |
|
unsigned long last = cfile->notified_at; |
|
unsigned long next = last + CGROUP_FILE_NOTIFY_MIN_INTV; |
|
|
|
if (time_in_range(jiffies, last, next)) { |
|
timer_reduce(&cfile->notify_timer, next); |
|
} else { |
|
kernfs_notify(cfile->kn); |
|
cfile->notified_at = jiffies; |
|
} |
|
} |
|
spin_unlock_irqrestore(&cgroup_file_kn_lock, flags); |
|
} |
|
|
|
/** |
|
* css_next_child - find the next child of a given css |
|
* @pos: the current position (%NULL to initiate traversal) |
|
* @parent: css whose children to walk |
|
* |
|
* This function returns the next child of @parent and should be called |
|
* under either cgroup_mutex or RCU read lock. The only requirement is |
|
* that @parent and @pos are accessible. The next sibling is guaranteed to |
|
* be returned regardless of their states. |
|
* |
|
* If a subsystem synchronizes ->css_online() and the start of iteration, a |
|
* css which finished ->css_online() is guaranteed to be visible in the |
|
* future iterations and will stay visible until the last reference is put. |
|
* A css which hasn't finished ->css_online() or already finished |
|
* ->css_offline() may show up during traversal. It's each subsystem's |
|
* responsibility to synchronize against on/offlining. |
|
*/ |
|
struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
|
struct cgroup_subsys_state *parent) |
|
{ |
|
struct cgroup_subsys_state *next; |
|
|
|
cgroup_assert_mutex_or_rcu_locked(); |
|
|
|
/* |
|
* @pos could already have been unlinked from the sibling list. |
|
* Once a cgroup is removed, its ->sibling.next is no longer |
|
* updated when its next sibling changes. CSS_RELEASED is set when |
|
* @pos is taken off list, at which time its next pointer is valid, |
|
* and, as releases are serialized, the one pointed to by the next |
|
* pointer is guaranteed to not have started release yet. This |
|
* implies that if we observe !CSS_RELEASED on @pos in this RCU |
|
* critical section, the one pointed to by its next pointer is |
|
* guaranteed to not have finished its RCU grace period even if we |
|
* have dropped rcu_read_lock() in-between iterations. |
|
* |
|
* If @pos has CSS_RELEASED set, its next pointer can't be |
|
* dereferenced; however, as each css is given a monotonically |
|
* increasing unique serial number and always appended to the |
|
* sibling list, the next one can be found by walking the parent's |
|
* children until the first css with higher serial number than |
|
* @pos's. While this path can be slower, it happens iff iteration |
|
* races against release and the race window is very small. |
|
*/ |
|
if (!pos) { |
|
next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling); |
|
} else if (likely(!(pos->flags & CSS_RELEASED))) { |
|
next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling); |
|
} else { |
|
list_for_each_entry_rcu(next, &parent->children, sibling, |
|
lockdep_is_held(&cgroup_mutex)) |
|
if (next->serial_nr > pos->serial_nr) |
|
break; |
|
} |
|
|
|
/* |
|
* @next, if not pointing to the head, can be dereferenced and is |
|
* the next sibling. |
|
*/ |
|
if (&next->sibling != &parent->children) |
|
return next; |
|
return NULL; |
|
} |
|
|
|
/** |
|
* css_next_descendant_pre - find the next descendant for pre-order walk |
|
* @pos: the current position (%NULL to initiate traversal) |
|
* @root: css whose descendants to walk |
|
* |
|
* To be used by css_for_each_descendant_pre(). Find the next descendant |
|
* to visit for pre-order traversal of @root's descendants. @root is |
|
* included in the iteration and the first node to be visited. |
|
* |
|
* While this function requires cgroup_mutex or RCU read locking, it |
|
* doesn't require the whole traversal to be contained in a single critical |
|
* section. This function will return the correct next descendant as long |
|
* as both @pos and @root are accessible and @pos is a descendant of @root. |
|
* |
|
* If a subsystem synchronizes ->css_online() and the start of iteration, a |
|
* css which finished ->css_online() is guaranteed to be visible in the |
|
* future iterations and will stay visible until the last reference is put. |
|
* A css which hasn't finished ->css_online() or already finished |
|
* ->css_offline() may show up during traversal. It's each subsystem's |
|
* responsibility to synchronize against on/offlining. |
|
*/ |
|
struct cgroup_subsys_state * |
|
css_next_descendant_pre(struct cgroup_subsys_state *pos, |
|
struct cgroup_subsys_state *root) |
|
{ |
|
struct cgroup_subsys_state *next; |
|
|
|
cgroup_assert_mutex_or_rcu_locked(); |
|
|
|
/* if first iteration, visit @root */ |
|
if (!pos) |
|
return root; |
|
|
|
/* visit the first child if exists */ |
|
next = css_next_child(NULL, pos); |
|
if (next) |
|
return next; |
|
|
|
/* no child, visit my or the closest ancestor's next sibling */ |
|
while (pos != root) { |
|
next = css_next_child(pos, pos->parent); |
|
if (next) |
|
return next; |
|
pos = pos->parent; |
|
} |
|
|
|
return NULL; |
|
} |
|
EXPORT_SYMBOL_GPL(css_next_descendant_pre); |
|
|
|
/** |
|
* css_rightmost_descendant - return the rightmost descendant of a css |
|
* @pos: css of interest |
|
* |
|
* Return the rightmost descendant of @pos. If there's no descendant, @pos |
|
* is returned. This can be used during pre-order traversal to skip |
|
* subtree of @pos. |
|
* |
|
* While this function requires cgroup_mutex or RCU read locking, it |
|
* doesn't require the whole traversal to be contained in a single critical |
|
* section. This function will return the correct rightmost descendant as |
|
* long as @pos is accessible. |
|
*/ |
|
struct cgroup_subsys_state * |
|
css_rightmost_descendant(struct cgroup_subsys_state *pos) |
|
{ |
|
struct cgroup_subsys_state *last, *tmp; |
|
|
|
cgroup_assert_mutex_or_rcu_locked(); |
|
|
|
do { |
|
last = pos; |
|
/* ->prev isn't RCU safe, walk ->next till the end */ |
|
pos = NULL; |
|
css_for_each_child(tmp, last) |
|
pos = tmp; |
|
} while (pos); |
|
|
|
return last; |
|
} |
|
|
|
static struct cgroup_subsys_state * |
|
css_leftmost_descendant(struct cgroup_subsys_state *pos) |
|
{ |
|
struct cgroup_subsys_state *last; |
|
|
|
do { |
|
last = pos; |
|
pos = css_next_child(NULL, pos); |
|
} while (pos); |
|
|
|
return last; |
|
} |
|
|
|
/** |
|
* css_next_descendant_post - find the next descendant for post-order walk |
|
* @pos: the current position (%NULL to initiate traversal) |
|
* @root: css whose descendants to walk |
|
* |
|
* To be used by css_for_each_descendant_post(). Find the next descendant |
|
* to visit for post-order traversal of @root's descendants. @root is |
|
* included in the iteration and the last node to be visited. |
|
* |
|
* While this function requires cgroup_mutex or RCU read locking, it |
|
* doesn't require the whole traversal to be contained in a single critical |
|
* section. This function will return the correct next descendant as long |
|
* as both @pos and @cgroup are accessible and @pos is a descendant of |
|
* @cgroup. |
|
* |
|
* If a subsystem synchronizes ->css_online() and the start of iteration, a |
|
* css which finished ->css_online() is guaranteed to be visible in the |
|
* future iterations and will stay visible until the last reference is put. |
|
* A css which hasn't finished ->css_online() or already finished |
|
* ->css_offline() may show up during traversal. It's each subsystem's |
|
* responsibility to synchronize against on/offlining. |
|
*/ |
|
struct cgroup_subsys_state * |
|
css_next_descendant_post(struct cgroup_subsys_state *pos, |
|
struct cgroup_subsys_state *root) |
|
{ |
|
struct cgroup_subsys_state *next; |
|
|
|
cgroup_assert_mutex_or_rcu_locked(); |
|
|
|
/* if first iteration, visit leftmost descendant which may be @root */ |
|
if (!pos) |
|
return css_leftmost_descendant(root); |
|
|
|
/* if we visited @root, we're done */ |
|
if (pos == root) |
|
return NULL; |
|
|
|
/* if there's an unvisited sibling, visit its leftmost descendant */ |
|
next = css_next_child(pos, pos->parent); |
|
if (next) |
|
return css_leftmost_descendant(next); |
|
|
|
/* no sibling left, visit parent */ |
|
return pos->parent; |
|
} |
|
|
|
/** |
|
* css_has_online_children - does a css have online children |
|
* @css: the target css |
|
* |
|
* Returns %true if @css has any online children; otherwise, %false. This |
|
* function can be called from any context but the caller is responsible |
|
* for synchronizing against on/offlining as necessary. |
|
*/ |
|
bool css_has_online_children(struct cgroup_subsys_state *css) |
|
{ |
|
struct cgroup_subsys_state *child; |
|
bool ret = false; |
|
|
|
rcu_read_lock(); |
|
css_for_each_child(child, css) { |
|
if (child->flags & CSS_ONLINE) { |
|
ret = true; |
|
break; |
|
} |
|
} |
|
rcu_read_unlock(); |
|
return ret; |
|
} |
|
|
|
static struct css_set *css_task_iter_next_css_set(struct css_task_iter *it) |
|
{ |
|
struct list_head *l; |
|
struct cgrp_cset_link *link; |
|
struct css_set *cset; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
/* find the next threaded cset */ |
|
if (it->tcset_pos) { |
|
l = it->tcset_pos->next; |
|
|
|
if (l != it->tcset_head) { |
|
it->tcset_pos = l; |
|
return container_of(l, struct css_set, |
|
threaded_csets_node); |
|
} |
|
|
|
it->tcset_pos = NULL; |
|
} |
|
|
|
/* find the next cset */ |
|
l = it->cset_pos; |
|
l = l->next; |
|
if (l == it->cset_head) { |
|
it->cset_pos = NULL; |
|
return NULL; |
|
} |
|
|
|
if (it->ss) { |
|
cset = container_of(l, struct css_set, e_cset_node[it->ss->id]); |
|
} else { |
|
link = list_entry(l, struct cgrp_cset_link, cset_link); |
|
cset = link->cset; |
|
} |
|
|
|
it->cset_pos = l; |
|
|
|
/* initialize threaded css_set walking */ |
|
if (it->flags & CSS_TASK_ITER_THREADED) { |
|
if (it->cur_dcset) |
|
put_css_set_locked(it->cur_dcset); |
|
it->cur_dcset = cset; |
|
get_css_set(cset); |
|
|
|
it->tcset_head = &cset->threaded_csets; |
|
it->tcset_pos = &cset->threaded_csets; |
|
} |
|
|
|
return cset; |
|
} |
|
|
|
/** |
|
* css_task_iter_advance_css_set - advance a task iterator to the next css_set |
|
* @it: the iterator to advance |
|
* |
|
* Advance @it to the next css_set to walk. |
|
*/ |
|
static void css_task_iter_advance_css_set(struct css_task_iter *it) |
|
{ |
|
struct css_set *cset; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
/* Advance to the next non-empty css_set and find first non-empty tasks list*/ |
|
while ((cset = css_task_iter_next_css_set(it))) { |
|
if (!list_empty(&cset->tasks)) { |
|
it->cur_tasks_head = &cset->tasks; |
|
break; |
|
} else if (!list_empty(&cset->mg_tasks)) { |
|
it->cur_tasks_head = &cset->mg_tasks; |
|
break; |
|
} else if (!list_empty(&cset->dying_tasks)) { |
|
it->cur_tasks_head = &cset->dying_tasks; |
|
break; |
|
} |
|
} |
|
if (!cset) { |
|
it->task_pos = NULL; |
|
return; |
|
} |
|
it->task_pos = it->cur_tasks_head->next; |
|
|
|
/* |
|
* We don't keep css_sets locked across iteration steps and thus |
|
* need to take steps to ensure that iteration can be resumed after |
|
* the lock is re-acquired. Iteration is performed at two levels - |
|
* css_sets and tasks in them. |
|
* |
|
* Once created, a css_set never leaves its cgroup lists, so a |
|
* pinned css_set is guaranteed to stay put and we can resume |
|
* iteration afterwards. |
|
* |
|
* Tasks may leave @cset across iteration steps. This is resolved |
|
* by registering each iterator with the css_set currently being |
|
* walked and making css_set_move_task() advance iterators whose |
|
* next task is leaving. |
|
*/ |
|
if (it->cur_cset) { |
|
list_del(&it->iters_node); |
|
put_css_set_locked(it->cur_cset); |
|
} |
|
get_css_set(cset); |
|
it->cur_cset = cset; |
|
list_add(&it->iters_node, &cset->task_iters); |
|
} |
|
|
|
static void css_task_iter_skip(struct css_task_iter *it, |
|
struct task_struct *task) |
|
{ |
|
lockdep_assert_held(&css_set_lock); |
|
|
|
if (it->task_pos == &task->cg_list) { |
|
it->task_pos = it->task_pos->next; |
|
it->flags |= CSS_TASK_ITER_SKIPPED; |
|
} |
|
} |
|
|
|
static void css_task_iter_advance(struct css_task_iter *it) |
|
{ |
|
struct task_struct *task; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
repeat: |
|
if (it->task_pos) { |
|
/* |
|
* Advance iterator to find next entry. We go through cset |
|
* tasks, mg_tasks and dying_tasks, when consumed we move onto |
|
* the next cset. |
|
*/ |
|
if (it->flags & CSS_TASK_ITER_SKIPPED) |
|
it->flags &= ~CSS_TASK_ITER_SKIPPED; |
|
else |
|
it->task_pos = it->task_pos->next; |
|
|
|
if (it->task_pos == &it->cur_cset->tasks) { |
|
it->cur_tasks_head = &it->cur_cset->mg_tasks; |
|
it->task_pos = it->cur_tasks_head->next; |
|
} |
|
if (it->task_pos == &it->cur_cset->mg_tasks) { |
|
it->cur_tasks_head = &it->cur_cset->dying_tasks; |
|
it->task_pos = it->cur_tasks_head->next; |
|
} |
|
if (it->task_pos == &it->cur_cset->dying_tasks) |
|
css_task_iter_advance_css_set(it); |
|
} else { |
|
/* called from start, proceed to the first cset */ |
|
css_task_iter_advance_css_set(it); |
|
} |
|
|
|
if (!it->task_pos) |
|
return; |
|
|
|
task = list_entry(it->task_pos, struct task_struct, cg_list); |
|
|
|
if (it->flags & CSS_TASK_ITER_PROCS) { |
|
/* if PROCS, skip over tasks which aren't group leaders */ |
|
if (!thread_group_leader(task)) |
|
goto repeat; |
|
|
|
/* and dying leaders w/o live member threads */ |
|
if (it->cur_tasks_head == &it->cur_cset->dying_tasks && |
|
!atomic_read(&task->signal->live)) |
|
goto repeat; |
|
} else { |
|
/* skip all dying ones */ |
|
if (it->cur_tasks_head == &it->cur_cset->dying_tasks) |
|
goto repeat; |
|
} |
|
} |
|
|
|
/** |
|
* css_task_iter_start - initiate task iteration |
|
* @css: the css to walk tasks of |
|
* @flags: CSS_TASK_ITER_* flags |
|
* @it: the task iterator to use |
|
* |
|
* Initiate iteration through the tasks of @css. The caller can call |
|
* css_task_iter_next() to walk through the tasks until the function |
|
* returns NULL. On completion of iteration, css_task_iter_end() must be |
|
* called. |
|
*/ |
|
void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags, |
|
struct css_task_iter *it) |
|
{ |
|
memset(it, 0, sizeof(*it)); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
|
|
it->ss = css->ss; |
|
it->flags = flags; |
|
|
|
if (CGROUP_HAS_SUBSYS_CONFIG && it->ss) |
|
it->cset_pos = &css->cgroup->e_csets[css->ss->id]; |
|
else |
|
it->cset_pos = &css->cgroup->cset_links; |
|
|
|
it->cset_head = it->cset_pos; |
|
|
|
css_task_iter_advance(it); |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
} |
|
|
|
/** |
|
* css_task_iter_next - return the next task for the iterator |
|
* @it: the task iterator being iterated |
|
* |
|
* The "next" function for task iteration. @it should have been |
|
* initialized via css_task_iter_start(). Returns NULL when the iteration |
|
* reaches the end. |
|
*/ |
|
struct task_struct *css_task_iter_next(struct css_task_iter *it) |
|
{ |
|
if (it->cur_task) { |
|
put_task_struct(it->cur_task); |
|
it->cur_task = NULL; |
|
} |
|
|
|
spin_lock_irq(&css_set_lock); |
|
|
|
/* @it may be half-advanced by skips, finish advancing */ |
|
if (it->flags & CSS_TASK_ITER_SKIPPED) |
|
css_task_iter_advance(it); |
|
|
|
if (it->task_pos) { |
|
it->cur_task = list_entry(it->task_pos, struct task_struct, |
|
cg_list); |
|
get_task_struct(it->cur_task); |
|
css_task_iter_advance(it); |
|
} |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
|
|
return it->cur_task; |
|
} |
|
|
|
/** |
|
* css_task_iter_end - finish task iteration |
|
* @it: the task iterator to finish |
|
* |
|
* Finish task iteration started by css_task_iter_start(). |
|
*/ |
|
void css_task_iter_end(struct css_task_iter *it) |
|
{ |
|
if (it->cur_cset) { |
|
spin_lock_irq(&css_set_lock); |
|
list_del(&it->iters_node); |
|
put_css_set_locked(it->cur_cset); |
|
spin_unlock_irq(&css_set_lock); |
|
} |
|
|
|
if (it->cur_dcset) |
|
put_css_set(it->cur_dcset); |
|
|
|
if (it->cur_task) |
|
put_task_struct(it->cur_task); |
|
} |
|
|
|
static void cgroup_procs_release(struct kernfs_open_file *of) |
|
{ |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
|
|
if (ctx->procs.started) |
|
css_task_iter_end(&ctx->procs.iter); |
|
} |
|
|
|
static void *cgroup_procs_next(struct seq_file *s, void *v, loff_t *pos) |
|
{ |
|
struct kernfs_open_file *of = s->private; |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
|
|
if (pos) |
|
(*pos)++; |
|
|
|
return css_task_iter_next(&ctx->procs.iter); |
|
} |
|
|
|
static void *__cgroup_procs_start(struct seq_file *s, loff_t *pos, |
|
unsigned int iter_flags) |
|
{ |
|
struct kernfs_open_file *of = s->private; |
|
struct cgroup *cgrp = seq_css(s)->cgroup; |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
struct css_task_iter *it = &ctx->procs.iter; |
|
|
|
/* |
|
* When a seq_file is seeked, it's always traversed sequentially |
|
* from position 0, so we can simply keep iterating on !0 *pos. |
|
*/ |
|
if (!ctx->procs.started) { |
|
if (WARN_ON_ONCE((*pos))) |
|
return ERR_PTR(-EINVAL); |
|
css_task_iter_start(&cgrp->self, iter_flags, it); |
|
ctx->procs.started = true; |
|
} else if (!(*pos)) { |
|
css_task_iter_end(it); |
|
css_task_iter_start(&cgrp->self, iter_flags, it); |
|
} else |
|
return it->cur_task; |
|
|
|
return cgroup_procs_next(s, NULL, NULL); |
|
} |
|
|
|
static void *cgroup_procs_start(struct seq_file *s, loff_t *pos) |
|
{ |
|
struct cgroup *cgrp = seq_css(s)->cgroup; |
|
|
|
/* |
|
* All processes of a threaded subtree belong to the domain cgroup |
|
* of the subtree. Only threads can be distributed across the |
|
* subtree. Reject reads on cgroup.procs in the subtree proper. |
|
* They're always empty anyway. |
|
*/ |
|
if (cgroup_is_threaded(cgrp)) |
|
return ERR_PTR(-EOPNOTSUPP); |
|
|
|
return __cgroup_procs_start(s, pos, CSS_TASK_ITER_PROCS | |
|
CSS_TASK_ITER_THREADED); |
|
} |
|
|
|
static int cgroup_procs_show(struct seq_file *s, void *v) |
|
{ |
|
seq_printf(s, "%d\n", task_pid_vnr(v)); |
|
return 0; |
|
} |
|
|
|
static int cgroup_may_write(const struct cgroup *cgrp, struct super_block *sb) |
|
{ |
|
int ret; |
|
struct inode *inode; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
inode = kernfs_get_inode(sb, cgrp->procs_file.kn); |
|
if (!inode) |
|
return -ENOMEM; |
|
|
|
ret = inode_permission(&init_user_ns, inode, MAY_WRITE); |
|
iput(inode); |
|
return ret; |
|
} |
|
|
|
static int cgroup_procs_write_permission(struct cgroup *src_cgrp, |
|
struct cgroup *dst_cgrp, |
|
struct super_block *sb, |
|
struct cgroup_namespace *ns) |
|
{ |
|
struct cgroup *com_cgrp = src_cgrp; |
|
int ret; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
/* find the common ancestor */ |
|
while (!cgroup_is_descendant(dst_cgrp, com_cgrp)) |
|
com_cgrp = cgroup_parent(com_cgrp); |
|
|
|
/* %current should be authorized to migrate to the common ancestor */ |
|
ret = cgroup_may_write(com_cgrp, sb); |
|
if (ret) |
|
return ret; |
|
|
|
/* |
|
* If namespaces are delegation boundaries, %current must be able |
|
* to see both source and destination cgroups from its namespace. |
|
*/ |
|
if ((cgrp_dfl_root.flags & CGRP_ROOT_NS_DELEGATE) && |
|
(!cgroup_is_descendant(src_cgrp, ns->root_cset->dfl_cgrp) || |
|
!cgroup_is_descendant(dst_cgrp, ns->root_cset->dfl_cgrp))) |
|
return -ENOENT; |
|
|
|
return 0; |
|
} |
|
|
|
static int cgroup_attach_permissions(struct cgroup *src_cgrp, |
|
struct cgroup *dst_cgrp, |
|
struct super_block *sb, bool threadgroup, |
|
struct cgroup_namespace *ns) |
|
{ |
|
int ret = 0; |
|
|
|
ret = cgroup_procs_write_permission(src_cgrp, dst_cgrp, sb, ns); |
|
if (ret) |
|
return ret; |
|
|
|
ret = cgroup_migrate_vet_dst(dst_cgrp); |
|
if (ret) |
|
return ret; |
|
|
|
if (!threadgroup && (src_cgrp->dom_cgrp != dst_cgrp->dom_cgrp)) |
|
ret = -EOPNOTSUPP; |
|
|
|
return ret; |
|
} |
|
|
|
static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, |
|
bool threadgroup) |
|
{ |
|
struct cgroup_file_ctx *ctx = of->priv; |
|
struct cgroup *src_cgrp, *dst_cgrp; |
|
struct task_struct *task; |
|
const struct cred *saved_cred; |
|
ssize_t ret; |
|
bool locked; |
|
|
|
dst_cgrp = cgroup_kn_lock_live(of->kn, false); |
|
if (!dst_cgrp) |
|
return -ENODEV; |
|
|
|
task = cgroup_procs_write_start(buf, threadgroup, &locked); |
|
ret = PTR_ERR_OR_ZERO(task); |
|
if (ret) |
|
goto out_unlock; |
|
|
|
/* find the source cgroup */ |
|
spin_lock_irq(&css_set_lock); |
|
src_cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* |
|
* Process and thread migrations follow same delegation rule. Check |
|
* permissions using the credentials from file open to protect against |
|
* inherited fd attacks. |
|
*/ |
|
saved_cred = override_creds(of->file->f_cred); |
|
ret = cgroup_attach_permissions(src_cgrp, dst_cgrp, |
|
of->file->f_path.dentry->d_sb, |
|
threadgroup, ctx->ns); |
|
revert_creds(saved_cred); |
|
if (ret) |
|
goto out_finish; |
|
|
|
ret = cgroup_attach_task(dst_cgrp, task, threadgroup); |
|
|
|
out_finish: |
|
cgroup_procs_write_finish(task, locked); |
|
out_unlock: |
|
cgroup_kn_unlock(of->kn); |
|
|
|
return ret; |
|
} |
|
|
|
static ssize_t cgroup_procs_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, loff_t off) |
|
{ |
|
return __cgroup_procs_write(of, buf, true) ?: nbytes; |
|
} |
|
|
|
static void *cgroup_threads_start(struct seq_file *s, loff_t *pos) |
|
{ |
|
return __cgroup_procs_start(s, pos, 0); |
|
} |
|
|
|
static ssize_t cgroup_threads_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, loff_t off) |
|
{ |
|
return __cgroup_procs_write(of, buf, false) ?: nbytes; |
|
} |
|
|
|
/* cgroup core interface files for the default hierarchy */ |
|
static struct cftype cgroup_base_files[] = { |
|
{ |
|
.name = "cgroup.type", |
|
.flags = CFTYPE_NOT_ON_ROOT, |
|
.seq_show = cgroup_type_show, |
|
.write = cgroup_type_write, |
|
}, |
|
{ |
|
.name = "cgroup.procs", |
|
.flags = CFTYPE_NS_DELEGATABLE, |
|
.file_offset = offsetof(struct cgroup, procs_file), |
|
.release = cgroup_procs_release, |
|
.seq_start = cgroup_procs_start, |
|
.seq_next = cgroup_procs_next, |
|
.seq_show = cgroup_procs_show, |
|
.write = cgroup_procs_write, |
|
}, |
|
{ |
|
.name = "cgroup.threads", |
|
.flags = CFTYPE_NS_DELEGATABLE, |
|
.release = cgroup_procs_release, |
|
.seq_start = cgroup_threads_start, |
|
.seq_next = cgroup_procs_next, |
|
.seq_show = cgroup_procs_show, |
|
.write = cgroup_threads_write, |
|
}, |
|
{ |
|
.name = "cgroup.controllers", |
|
.seq_show = cgroup_controllers_show, |
|
}, |
|
{ |
|
.name = "cgroup.subtree_control", |
|
.flags = CFTYPE_NS_DELEGATABLE, |
|
.seq_show = cgroup_subtree_control_show, |
|
.write = cgroup_subtree_control_write, |
|
}, |
|
{ |
|
.name = "cgroup.events", |
|
.flags = CFTYPE_NOT_ON_ROOT, |
|
.file_offset = offsetof(struct cgroup, events_file), |
|
.seq_show = cgroup_events_show, |
|
}, |
|
{ |
|
.name = "cgroup.max.descendants", |
|
.seq_show = cgroup_max_descendants_show, |
|
.write = cgroup_max_descendants_write, |
|
}, |
|
{ |
|
.name = "cgroup.max.depth", |
|
.seq_show = cgroup_max_depth_show, |
|
.write = cgroup_max_depth_write, |
|
}, |
|
{ |
|
.name = "cgroup.stat", |
|
.seq_show = cgroup_stat_show, |
|
}, |
|
{ |
|
.name = "cgroup.freeze", |
|
.flags = CFTYPE_NOT_ON_ROOT, |
|
.seq_show = cgroup_freeze_show, |
|
.write = cgroup_freeze_write, |
|
}, |
|
{ |
|
.name = "cgroup.kill", |
|
.flags = CFTYPE_NOT_ON_ROOT, |
|
.write = cgroup_kill_write, |
|
}, |
|
{ |
|
.name = "cpu.stat", |
|
.seq_show = cpu_stat_show, |
|
}, |
|
#ifdef CONFIG_PSI |
|
{ |
|
.name = "io.pressure", |
|
.flags = CFTYPE_PRESSURE, |
|
.seq_show = cgroup_io_pressure_show, |
|
.write = cgroup_io_pressure_write, |
|
.poll = cgroup_pressure_poll, |
|
.release = cgroup_pressure_release, |
|
}, |
|
{ |
|
.name = "memory.pressure", |
|
.flags = CFTYPE_PRESSURE, |
|
.seq_show = cgroup_memory_pressure_show, |
|
.write = cgroup_memory_pressure_write, |
|
.poll = cgroup_pressure_poll, |
|
.release = cgroup_pressure_release, |
|
}, |
|
{ |
|
.name = "cpu.pressure", |
|
.flags = CFTYPE_PRESSURE, |
|
.seq_show = cgroup_cpu_pressure_show, |
|
.write = cgroup_cpu_pressure_write, |
|
.poll = cgroup_pressure_poll, |
|
.release = cgroup_pressure_release, |
|
}, |
|
#endif /* CONFIG_PSI */ |
|
{ } /* terminate */ |
|
}; |
|
|
|
/* |
|
* css destruction is four-stage process. |
|
* |
|
* 1. Destruction starts. Killing of the percpu_ref is initiated. |
|
* Implemented in kill_css(). |
|
* |
|
* 2. When the percpu_ref is confirmed to be visible as killed on all CPUs |
|
* and thus css_tryget_online() is guaranteed to fail, the css can be |
|
* offlined by invoking offline_css(). After offlining, the base ref is |
|
* put. Implemented in css_killed_work_fn(). |
|
* |
|
* 3. When the percpu_ref reaches zero, the only possible remaining |
|
* accessors are inside RCU read sections. css_release() schedules the |
|
* RCU callback. |
|
* |
|
* 4. After the grace period, the css can be freed. Implemented in |
|
* css_free_work_fn(). |
|
* |
|
* It is actually hairier because both step 2 and 4 require process context |
|
* and thus involve punting to css->destroy_work adding two additional |
|
* steps to the already complex sequence. |
|
*/ |
|
static void css_free_rwork_fn(struct work_struct *work) |
|
{ |
|
struct cgroup_subsys_state *css = container_of(to_rcu_work(work), |
|
struct cgroup_subsys_state, destroy_rwork); |
|
struct cgroup_subsys *ss = css->ss; |
|
struct cgroup *cgrp = css->cgroup; |
|
|
|
percpu_ref_exit(&css->refcnt); |
|
|
|
if (ss) { |
|
/* css free path */ |
|
struct cgroup_subsys_state *parent = css->parent; |
|
int id = css->id; |
|
|
|
ss->css_free(css); |
|
cgroup_idr_remove(&ss->css_idr, id); |
|
cgroup_put(cgrp); |
|
|
|
if (parent) |
|
css_put(parent); |
|
} else { |
|
/* cgroup free path */ |
|
atomic_dec(&cgrp->root->nr_cgrps); |
|
cgroup1_pidlist_destroy_all(cgrp); |
|
cancel_work_sync(&cgrp->release_agent_work); |
|
|
|
if (cgroup_parent(cgrp)) { |
|
/* |
|
* We get a ref to the parent, and put the ref when |
|
* this cgroup is being freed, so it's guaranteed |
|
* that the parent won't be destroyed before its |
|
* children. |
|
*/ |
|
cgroup_put(cgroup_parent(cgrp)); |
|
kernfs_put(cgrp->kn); |
|
psi_cgroup_free(cgrp); |
|
cgroup_rstat_exit(cgrp); |
|
kfree(cgrp); |
|
} else { |
|
/* |
|
* This is root cgroup's refcnt reaching zero, |
|
* which indicates that the root should be |
|
* released. |
|
*/ |
|
cgroup_destroy_root(cgrp->root); |
|
} |
|
} |
|
} |
|
|
|
static void css_release_work_fn(struct work_struct *work) |
|
{ |
|
struct cgroup_subsys_state *css = |
|
container_of(work, struct cgroup_subsys_state, destroy_work); |
|
struct cgroup_subsys *ss = css->ss; |
|
struct cgroup *cgrp = css->cgroup; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
css->flags |= CSS_RELEASED; |
|
list_del_rcu(&css->sibling); |
|
|
|
if (ss) { |
|
/* css release path */ |
|
if (!list_empty(&css->rstat_css_node)) { |
|
cgroup_rstat_flush(cgrp); |
|
list_del_rcu(&css->rstat_css_node); |
|
} |
|
|
|
cgroup_idr_replace(&ss->css_idr, NULL, css->id); |
|
if (ss->css_released) |
|
ss->css_released(css); |
|
} else { |
|
struct cgroup *tcgrp; |
|
|
|
/* cgroup release path */ |
|
TRACE_CGROUP_PATH(release, cgrp); |
|
|
|
cgroup_rstat_flush(cgrp); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
for (tcgrp = cgroup_parent(cgrp); tcgrp; |
|
tcgrp = cgroup_parent(tcgrp)) |
|
tcgrp->nr_dying_descendants--; |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* |
|
* There are two control paths which try to determine |
|
* cgroup from dentry without going through kernfs - |
|
* cgroupstats_build() and css_tryget_online_from_dir(). |
|
* Those are supported by RCU protecting clearing of |
|
* cgrp->kn->priv backpointer. |
|
*/ |
|
if (cgrp->kn) |
|
RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv, |
|
NULL); |
|
} |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
|
|
INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn); |
|
queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork); |
|
} |
|
|
|
static void css_release(struct percpu_ref *ref) |
|
{ |
|
struct cgroup_subsys_state *css = |
|
container_of(ref, struct cgroup_subsys_state, refcnt); |
|
|
|
INIT_WORK(&css->destroy_work, css_release_work_fn); |
|
queue_work(cgroup_destroy_wq, &css->destroy_work); |
|
} |
|
|
|
static void init_and_link_css(struct cgroup_subsys_state *css, |
|
struct cgroup_subsys *ss, struct cgroup *cgrp) |
|
{ |
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
cgroup_get_live(cgrp); |
|
|
|
memset(css, 0, sizeof(*css)); |
|
css->cgroup = cgrp; |
|
css->ss = ss; |
|
css->id = -1; |
|
INIT_LIST_HEAD(&css->sibling); |
|
INIT_LIST_HEAD(&css->children); |
|
INIT_LIST_HEAD(&css->rstat_css_node); |
|
css->serial_nr = css_serial_nr_next++; |
|
atomic_set(&css->online_cnt, 0); |
|
|
|
if (cgroup_parent(cgrp)) { |
|
css->parent = cgroup_css(cgroup_parent(cgrp), ss); |
|
css_get(css->parent); |
|
} |
|
|
|
if (ss->css_rstat_flush) |
|
list_add_rcu(&css->rstat_css_node, &cgrp->rstat_css_list); |
|
|
|
BUG_ON(cgroup_css(cgrp, ss)); |
|
} |
|
|
|
/* invoke ->css_online() on a new CSS and mark it online if successful */ |
|
static int online_css(struct cgroup_subsys_state *css) |
|
{ |
|
struct cgroup_subsys *ss = css->ss; |
|
int ret = 0; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
if (ss->css_online) |
|
ret = ss->css_online(css); |
|
if (!ret) { |
|
css->flags |= CSS_ONLINE; |
|
rcu_assign_pointer(css->cgroup->subsys[ss->id], css); |
|
|
|
atomic_inc(&css->online_cnt); |
|
if (css->parent) |
|
atomic_inc(&css->parent->online_cnt); |
|
} |
|
return ret; |
|
} |
|
|
|
/* if the CSS is online, invoke ->css_offline() on it and mark it offline */ |
|
static void offline_css(struct cgroup_subsys_state *css) |
|
{ |
|
struct cgroup_subsys *ss = css->ss; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
if (!(css->flags & CSS_ONLINE)) |
|
return; |
|
|
|
if (ss->css_offline) |
|
ss->css_offline(css); |
|
|
|
css->flags &= ~CSS_ONLINE; |
|
RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL); |
|
|
|
wake_up_all(&css->cgroup->offline_waitq); |
|
} |
|
|
|
/** |
|
* css_create - create a cgroup_subsys_state |
|
* @cgrp: the cgroup new css will be associated with |
|
* @ss: the subsys of new css |
|
* |
|
* Create a new css associated with @cgrp - @ss pair. On success, the new |
|
* css is online and installed in @cgrp. This function doesn't create the |
|
* interface files. Returns 0 on success, -errno on failure. |
|
*/ |
|
static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, |
|
struct cgroup_subsys *ss) |
|
{ |
|
struct cgroup *parent = cgroup_parent(cgrp); |
|
struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss); |
|
struct cgroup_subsys_state *css; |
|
int err; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
css = ss->css_alloc(parent_css); |
|
if (!css) |
|
css = ERR_PTR(-ENOMEM); |
|
if (IS_ERR(css)) |
|
return css; |
|
|
|
init_and_link_css(css, ss, cgrp); |
|
|
|
err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL); |
|
if (err) |
|
goto err_free_css; |
|
|
|
err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL); |
|
if (err < 0) |
|
goto err_free_css; |
|
css->id = err; |
|
|
|
/* @css is ready to be brought online now, make it visible */ |
|
list_add_tail_rcu(&css->sibling, &parent_css->children); |
|
cgroup_idr_replace(&ss->css_idr, css, css->id); |
|
|
|
err = online_css(css); |
|
if (err) |
|
goto err_list_del; |
|
|
|
return css; |
|
|
|
err_list_del: |
|
list_del_rcu(&css->sibling); |
|
err_free_css: |
|
list_del_rcu(&css->rstat_css_node); |
|
INIT_RCU_WORK(&css->destroy_rwork, css_free_rwork_fn); |
|
queue_rcu_work(cgroup_destroy_wq, &css->destroy_rwork); |
|
return ERR_PTR(err); |
|
} |
|
|
|
/* |
|
* The returned cgroup is fully initialized including its control mask, but |
|
* it isn't associated with its kernfs_node and doesn't have the control |
|
* mask applied. |
|
*/ |
|
static struct cgroup *cgroup_create(struct cgroup *parent, const char *name, |
|
umode_t mode) |
|
{ |
|
struct cgroup_root *root = parent->root; |
|
struct cgroup *cgrp, *tcgrp; |
|
struct kernfs_node *kn; |
|
int level = parent->level + 1; |
|
int ret; |
|
|
|
/* allocate the cgroup and its ID, 0 is reserved for the root */ |
|
cgrp = kzalloc(struct_size(cgrp, ancestor_ids, (level + 1)), |
|
GFP_KERNEL); |
|
if (!cgrp) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL); |
|
if (ret) |
|
goto out_free_cgrp; |
|
|
|
ret = cgroup_rstat_init(cgrp); |
|
if (ret) |
|
goto out_cancel_ref; |
|
|
|
/* create the directory */ |
|
kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
|
if (IS_ERR(kn)) { |
|
ret = PTR_ERR(kn); |
|
goto out_stat_exit; |
|
} |
|
cgrp->kn = kn; |
|
|
|
init_cgroup_housekeeping(cgrp); |
|
|
|
cgrp->self.parent = &parent->self; |
|
cgrp->root = root; |
|
cgrp->level = level; |
|
|
|
ret = psi_cgroup_alloc(cgrp); |
|
if (ret) |
|
goto out_kernfs_remove; |
|
|
|
ret = cgroup_bpf_inherit(cgrp); |
|
if (ret) |
|
goto out_psi_free; |
|
|
|
/* |
|
* New cgroup inherits effective freeze counter, and |
|
* if the parent has to be frozen, the child has too. |
|
*/ |
|
cgrp->freezer.e_freeze = parent->freezer.e_freeze; |
|
if (cgrp->freezer.e_freeze) { |
|
/* |
|
* Set the CGRP_FREEZE flag, so when a process will be |
|
* attached to the child cgroup, it will become frozen. |
|
* At this point the new cgroup is unpopulated, so we can |
|
* consider it frozen immediately. |
|
*/ |
|
set_bit(CGRP_FREEZE, &cgrp->flags); |
|
set_bit(CGRP_FROZEN, &cgrp->flags); |
|
} |
|
|
|
spin_lock_irq(&css_set_lock); |
|
for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) { |
|
cgrp->ancestor_ids[tcgrp->level] = cgroup_id(tcgrp); |
|
|
|
if (tcgrp != cgrp) { |
|
tcgrp->nr_descendants++; |
|
|
|
/* |
|
* If the new cgroup is frozen, all ancestor cgroups |
|
* get a new frozen descendant, but their state can't |
|
* change because of this. |
|
*/ |
|
if (cgrp->freezer.e_freeze) |
|
tcgrp->freezer.nr_frozen_descendants++; |
|
} |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
if (notify_on_release(parent)) |
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
|
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags)) |
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags); |
|
|
|
cgrp->self.serial_nr = css_serial_nr_next++; |
|
|
|
/* allocation complete, commit to creation */ |
|
list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children); |
|
atomic_inc(&root->nr_cgrps); |
|
cgroup_get_live(parent); |
|
|
|
/* |
|
* On the default hierarchy, a child doesn't automatically inherit |
|
* subtree_control from the parent. Each is configured manually. |
|
*/ |
|
if (!cgroup_on_dfl(cgrp)) |
|
cgrp->subtree_control = cgroup_control(cgrp); |
|
|
|
cgroup_propagate_control(cgrp); |
|
|
|
return cgrp; |
|
|
|
out_psi_free: |
|
psi_cgroup_free(cgrp); |
|
out_kernfs_remove: |
|
kernfs_remove(cgrp->kn); |
|
out_stat_exit: |
|
cgroup_rstat_exit(cgrp); |
|
out_cancel_ref: |
|
percpu_ref_exit(&cgrp->self.refcnt); |
|
out_free_cgrp: |
|
kfree(cgrp); |
|
return ERR_PTR(ret); |
|
} |
|
|
|
static bool cgroup_check_hierarchy_limits(struct cgroup *parent) |
|
{ |
|
struct cgroup *cgroup; |
|
int ret = false; |
|
int level = 1; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
for (cgroup = parent; cgroup; cgroup = cgroup_parent(cgroup)) { |
|
if (cgroup->nr_descendants >= cgroup->max_descendants) |
|
goto fail; |
|
|
|
if (level > cgroup->max_depth) |
|
goto fail; |
|
|
|
level++; |
|
} |
|
|
|
ret = true; |
|
fail: |
|
return ret; |
|
} |
|
|
|
int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, umode_t mode) |
|
{ |
|
struct cgroup *parent, *cgrp; |
|
int ret; |
|
|
|
/* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */ |
|
if (strchr(name, '\n')) |
|
return -EINVAL; |
|
|
|
parent = cgroup_kn_lock_live(parent_kn, false); |
|
if (!parent) |
|
return -ENODEV; |
|
|
|
if (!cgroup_check_hierarchy_limits(parent)) { |
|
ret = -EAGAIN; |
|
goto out_unlock; |
|
} |
|
|
|
cgrp = cgroup_create(parent, name, mode); |
|
if (IS_ERR(cgrp)) { |
|
ret = PTR_ERR(cgrp); |
|
goto out_unlock; |
|
} |
|
|
|
/* |
|
* This extra ref will be put in cgroup_free_fn() and guarantees |
|
* that @cgrp->kn is always accessible. |
|
*/ |
|
kernfs_get(cgrp->kn); |
|
|
|
ret = cgroup_kn_set_ugid(cgrp->kn); |
|
if (ret) |
|
goto out_destroy; |
|
|
|
ret = css_populate_dir(&cgrp->self); |
|
if (ret) |
|
goto out_destroy; |
|
|
|
ret = cgroup_apply_control_enable(cgrp); |
|
if (ret) |
|
goto out_destroy; |
|
|
|
TRACE_CGROUP_PATH(mkdir, cgrp); |
|
|
|
/* let's create and online css's */ |
|
kernfs_activate(cgrp->kn); |
|
|
|
ret = 0; |
|
goto out_unlock; |
|
|
|
out_destroy: |
|
cgroup_destroy_locked(cgrp); |
|
out_unlock: |
|
cgroup_kn_unlock(parent_kn); |
|
return ret; |
|
} |
|
|
|
/* |
|
* This is called when the refcnt of a css is confirmed to be killed. |
|
* css_tryget_online() is now guaranteed to fail. Tell the subsystem to |
|
* initiate destruction and put the css ref from kill_css(). |
|
*/ |
|
static void css_killed_work_fn(struct work_struct *work) |
|
{ |
|
struct cgroup_subsys_state *css = |
|
container_of(work, struct cgroup_subsys_state, destroy_work); |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
do { |
|
offline_css(css); |
|
css_put(css); |
|
/* @css can't go away while we're holding cgroup_mutex */ |
|
css = css->parent; |
|
} while (css && atomic_dec_and_test(&css->online_cnt)); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
} |
|
|
|
/* css kill confirmation processing requires process context, bounce */ |
|
static void css_killed_ref_fn(struct percpu_ref *ref) |
|
{ |
|
struct cgroup_subsys_state *css = |
|
container_of(ref, struct cgroup_subsys_state, refcnt); |
|
|
|
if (atomic_dec_and_test(&css->online_cnt)) { |
|
INIT_WORK(&css->destroy_work, css_killed_work_fn); |
|
queue_work(cgroup_destroy_wq, &css->destroy_work); |
|
} |
|
} |
|
|
|
/** |
|
* kill_css - destroy a css |
|
* @css: css to destroy |
|
* |
|
* This function initiates destruction of @css by removing cgroup interface |
|
* files and putting its base reference. ->css_offline() will be invoked |
|
* asynchronously once css_tryget_online() is guaranteed to fail and when |
|
* the reference count reaches zero, @css will be released. |
|
*/ |
|
static void kill_css(struct cgroup_subsys_state *css) |
|
{ |
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
if (css->flags & CSS_DYING) |
|
return; |
|
|
|
css->flags |= CSS_DYING; |
|
|
|
/* |
|
* This must happen before css is disassociated with its cgroup. |
|
* See seq_css() for details. |
|
*/ |
|
css_clear_dir(css); |
|
|
|
/* |
|
* Killing would put the base ref, but we need to keep it alive |
|
* until after ->css_offline(). |
|
*/ |
|
css_get(css); |
|
|
|
/* |
|
* cgroup core guarantees that, by the time ->css_offline() is |
|
* invoked, no new css reference will be given out via |
|
* css_tryget_online(). We can't simply call percpu_ref_kill() and |
|
* proceed to offlining css's because percpu_ref_kill() doesn't |
|
* guarantee that the ref is seen as killed on all CPUs on return. |
|
* |
|
* Use percpu_ref_kill_and_confirm() to get notifications as each |
|
* css is confirmed to be seen as killed on all CPUs. |
|
*/ |
|
percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn); |
|
} |
|
|
|
/** |
|
* cgroup_destroy_locked - the first stage of cgroup destruction |
|
* @cgrp: cgroup to be destroyed |
|
* |
|
* css's make use of percpu refcnts whose killing latency shouldn't be |
|
* exposed to userland and are RCU protected. Also, cgroup core needs to |
|
* guarantee that css_tryget_online() won't succeed by the time |
|
* ->css_offline() is invoked. To satisfy all the requirements, |
|
* destruction is implemented in the following two steps. |
|
* |
|
* s1. Verify @cgrp can be destroyed and mark it dying. Remove all |
|
* userland visible parts and start killing the percpu refcnts of |
|
* css's. Set up so that the next stage will be kicked off once all |
|
* the percpu refcnts are confirmed to be killed. |
|
* |
|
* s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the |
|
* rest of destruction. Once all cgroup references are gone, the |
|
* cgroup is RCU-freed. |
|
* |
|
* This function implements s1. After this step, @cgrp is gone as far as |
|
* the userland is concerned and a new cgroup with the same name may be |
|
* created. As cgroup doesn't care about the names internally, this |
|
* doesn't cause any problem. |
|
*/ |
|
static int cgroup_destroy_locked(struct cgroup *cgrp) |
|
__releases(&cgroup_mutex) __acquires(&cgroup_mutex) |
|
{ |
|
struct cgroup *tcgrp, *parent = cgroup_parent(cgrp); |
|
struct cgroup_subsys_state *css; |
|
struct cgrp_cset_link *link; |
|
int ssid; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
/* |
|
* Only migration can raise populated from zero and we're already |
|
* holding cgroup_mutex. |
|
*/ |
|
if (cgroup_is_populated(cgrp)) |
|
return -EBUSY; |
|
|
|
/* |
|
* Make sure there's no live children. We can't test emptiness of |
|
* ->self.children as dead children linger on it while being |
|
* drained; otherwise, "rmdir parent/child parent" may fail. |
|
*/ |
|
if (css_has_online_children(&cgrp->self)) |
|
return -EBUSY; |
|
|
|
/* |
|
* Mark @cgrp and the associated csets dead. The former prevents |
|
* further task migration and child creation by disabling |
|
* cgroup_lock_live_group(). The latter makes the csets ignored by |
|
* the migration path. |
|
*/ |
|
cgrp->self.flags &= ~CSS_ONLINE; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
list_for_each_entry(link, &cgrp->cset_links, cset_link) |
|
link->cset->dead = true; |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* initiate massacre of all css's */ |
|
for_each_css(css, ssid, cgrp) |
|
kill_css(css); |
|
|
|
/* clear and remove @cgrp dir, @cgrp has an extra ref on its kn */ |
|
css_clear_dir(&cgrp->self); |
|
kernfs_remove(cgrp->kn); |
|
|
|
if (parent && cgroup_is_threaded(cgrp)) |
|
parent->nr_threaded_children--; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
for (tcgrp = cgroup_parent(cgrp); tcgrp; tcgrp = cgroup_parent(tcgrp)) { |
|
tcgrp->nr_descendants--; |
|
tcgrp->nr_dying_descendants++; |
|
/* |
|
* If the dying cgroup is frozen, decrease frozen descendants |
|
* counters of ancestor cgroups. |
|
*/ |
|
if (test_bit(CGRP_FROZEN, &cgrp->flags)) |
|
tcgrp->freezer.nr_frozen_descendants--; |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
cgroup1_check_for_release(parent); |
|
|
|
cgroup_bpf_offline(cgrp); |
|
|
|
/* put the base reference */ |
|
percpu_ref_kill(&cgrp->self.refcnt); |
|
|
|
return 0; |
|
}; |
|
|
|
int cgroup_rmdir(struct kernfs_node *kn) |
|
{ |
|
struct cgroup *cgrp; |
|
int ret = 0; |
|
|
|
cgrp = cgroup_kn_lock_live(kn, false); |
|
if (!cgrp) |
|
return 0; |
|
|
|
ret = cgroup_destroy_locked(cgrp); |
|
if (!ret) |
|
TRACE_CGROUP_PATH(rmdir, cgrp); |
|
|
|
cgroup_kn_unlock(kn); |
|
return ret; |
|
} |
|
|
|
static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
|
.show_options = cgroup_show_options, |
|
.mkdir = cgroup_mkdir, |
|
.rmdir = cgroup_rmdir, |
|
.show_path = cgroup_show_path, |
|
}; |
|
|
|
static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) |
|
{ |
|
struct cgroup_subsys_state *css; |
|
|
|
pr_debug("Initializing cgroup subsys %s\n", ss->name); |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
idr_init(&ss->css_idr); |
|
INIT_LIST_HEAD(&ss->cfts); |
|
|
|
/* Create the root cgroup state for this subsystem */ |
|
ss->root = &cgrp_dfl_root; |
|
css = ss->css_alloc(NULL); |
|
/* We don't handle early failures gracefully */ |
|
BUG_ON(IS_ERR(css)); |
|
init_and_link_css(css, ss, &cgrp_dfl_root.cgrp); |
|
|
|
/* |
|
* Root csses are never destroyed and we can't initialize |
|
* percpu_ref during early init. Disable refcnting. |
|
*/ |
|
css->flags |= CSS_NO_REF; |
|
|
|
if (early) { |
|
/* allocation can't be done safely during early init */ |
|
css->id = 1; |
|
} else { |
|
css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL); |
|
BUG_ON(css->id < 0); |
|
} |
|
|
|
/* Update the init_css_set to contain a subsys |
|
* pointer to this state - since the subsystem is |
|
* newly registered, all tasks and hence the |
|
* init_css_set is in the subsystem's root cgroup. */ |
|
init_css_set.subsys[ss->id] = css; |
|
|
|
have_fork_callback |= (bool)ss->fork << ss->id; |
|
have_exit_callback |= (bool)ss->exit << ss->id; |
|
have_release_callback |= (bool)ss->release << ss->id; |
|
have_canfork_callback |= (bool)ss->can_fork << ss->id; |
|
|
|
/* At system boot, before all subsystems have been |
|
* registered, no tasks have been forked, so we don't |
|
* need to invoke fork callbacks here. */ |
|
BUG_ON(!list_empty(&init_task.tasks)); |
|
|
|
BUG_ON(online_css(css)); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
} |
|
|
|
/** |
|
* cgroup_init_early - cgroup initialization at system boot |
|
* |
|
* Initialize cgroups at system boot, and initialize any |
|
* subsystems that request early init. |
|
*/ |
|
int __init cgroup_init_early(void) |
|
{ |
|
static struct cgroup_fs_context __initdata ctx; |
|
struct cgroup_subsys *ss; |
|
int i; |
|
|
|
ctx.root = &cgrp_dfl_root; |
|
init_cgroup_root(&ctx); |
|
cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF; |
|
|
|
RCU_INIT_POINTER(init_task.cgroups, &init_css_set); |
|
|
|
for_each_subsys(ss, i) { |
|
WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id, |
|
"invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n", |
|
i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free, |
|
ss->id, ss->name); |
|
WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN, |
|
"cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]); |
|
|
|
ss->id = i; |
|
ss->name = cgroup_subsys_name[i]; |
|
if (!ss->legacy_name) |
|
ss->legacy_name = cgroup_subsys_name[i]; |
|
|
|
if (ss->early_init) |
|
cgroup_init_subsys(ss, true); |
|
} |
|
return 0; |
|
} |
|
|
|
static u16 cgroup_enable_mask __initdata; |
|
static int __init cgroup_disable(char *str); |
|
|
|
/** |
|
* cgroup_init - cgroup initialization |
|
* |
|
* Register cgroup filesystem and /proc file, and initialize |
|
* any subsystems that didn't request early init. |
|
*/ |
|
int __init cgroup_init(void) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16); |
|
BUG_ON(cgroup_init_cftypes(NULL, cgroup_base_files)); |
|
BUG_ON(cgroup_init_cftypes(NULL, cgroup1_base_files)); |
|
|
|
cgroup_rstat_boot(); |
|
|
|
/* |
|
* The latency of the synchronize_rcu() is too high for cgroups, |
|
* avoid it at the cost of forcing all readers into the slow path. |
|
*/ |
|
rcu_sync_enter_start(&cgroup_threadgroup_rwsem.rss); |
|
|
|
get_user_ns(init_cgroup_ns.user_ns); |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
/* |
|
* Add init_css_set to the hash table so that dfl_root can link to |
|
* it during init. |
|
*/ |
|
hash_add(css_set_table, &init_css_set.hlist, |
|
css_set_hash(init_css_set.subsys)); |
|
|
|
BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0)); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
|
|
/* |
|
* Apply an implicit disable, knowing that an explicit enable will |
|
* prevent if from doing anything. |
|
*/ |
|
cgroup_disable("memory"); |
|
|
|
for_each_subsys(ss, ssid) { |
|
if (ss->early_init) { |
|
struct cgroup_subsys_state *css = |
|
init_css_set.subsys[ss->id]; |
|
|
|
css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, |
|
GFP_KERNEL); |
|
BUG_ON(css->id < 0); |
|
} else { |
|
cgroup_init_subsys(ss, false); |
|
} |
|
|
|
list_add_tail(&init_css_set.e_cset_node[ssid], |
|
&cgrp_dfl_root.cgrp.e_csets[ssid]); |
|
|
|
/* |
|
* Setting dfl_root subsys_mask needs to consider the |
|
* disabled flag and cftype registration needs kmalloc, |
|
* both of which aren't available during early_init. |
|
*/ |
|
if (!cgroup_ssid_enabled(ssid)) |
|
continue; |
|
|
|
if (cgroup1_ssid_disabled(ssid)) |
|
printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n", |
|
ss->name); |
|
|
|
cgrp_dfl_root.subsys_mask |= 1 << ss->id; |
|
|
|
/* implicit controllers must be threaded too */ |
|
WARN_ON(ss->implicit_on_dfl && !ss->threaded); |
|
|
|
if (ss->implicit_on_dfl) |
|
cgrp_dfl_implicit_ss_mask |= 1 << ss->id; |
|
else if (!ss->dfl_cftypes) |
|
cgrp_dfl_inhibit_ss_mask |= 1 << ss->id; |
|
|
|
if (ss->threaded) |
|
cgrp_dfl_threaded_ss_mask |= 1 << ss->id; |
|
|
|
if (ss->dfl_cftypes == ss->legacy_cftypes) { |
|
WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes)); |
|
} else { |
|
WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes)); |
|
WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes)); |
|
} |
|
|
|
if (ss->bind) |
|
ss->bind(init_css_set.subsys[ssid]); |
|
|
|
mutex_lock(&cgroup_mutex); |
|
css_populate_dir(init_css_set.subsys[ssid]); |
|
mutex_unlock(&cgroup_mutex); |
|
} |
|
|
|
/* init_css_set.subsys[] has been updated, re-hash */ |
|
hash_del(&init_css_set.hlist); |
|
hash_add(css_set_table, &init_css_set.hlist, |
|
css_set_hash(init_css_set.subsys)); |
|
|
|
WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup")); |
|
WARN_ON(register_filesystem(&cgroup_fs_type)); |
|
WARN_ON(register_filesystem(&cgroup2_fs_type)); |
|
WARN_ON(!proc_create_single("cgroups", 0, NULL, proc_cgroupstats_show)); |
|
#ifdef CONFIG_CPUSETS |
|
WARN_ON(register_filesystem(&cpuset_fs_type)); |
|
#endif |
|
|
|
return 0; |
|
} |
|
|
|
static int __init cgroup_wq_init(void) |
|
{ |
|
/* |
|
* There isn't much point in executing destruction path in |
|
* parallel. Good chunk is serialized with cgroup_mutex anyway. |
|
* Use 1 for @max_active. |
|
* |
|
* We would prefer to do this in cgroup_init() above, but that |
|
* is called before init_workqueues(): so leave this until after. |
|
*/ |
|
cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1); |
|
BUG_ON(!cgroup_destroy_wq); |
|
return 0; |
|
} |
|
core_initcall(cgroup_wq_init); |
|
|
|
void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen) |
|
{ |
|
struct kernfs_node *kn; |
|
|
|
kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id); |
|
if (!kn) |
|
return; |
|
kernfs_path(kn, buf, buflen); |
|
kernfs_put(kn); |
|
} |
|
|
|
/* |
|
* cgroup_get_from_id : get the cgroup associated with cgroup id |
|
* @id: cgroup id |
|
* On success return the cgrp, on failure return NULL |
|
*/ |
|
struct cgroup *cgroup_get_from_id(u64 id) |
|
{ |
|
struct kernfs_node *kn; |
|
struct cgroup *cgrp = NULL; |
|
|
|
kn = kernfs_find_and_get_node_by_id(cgrp_dfl_root.kf_root, id); |
|
if (!kn) |
|
goto out; |
|
|
|
rcu_read_lock(); |
|
|
|
cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv); |
|
if (cgrp && !cgroup_tryget(cgrp)) |
|
cgrp = NULL; |
|
|
|
rcu_read_unlock(); |
|
|
|
kernfs_put(kn); |
|
out: |
|
return cgrp; |
|
} |
|
EXPORT_SYMBOL_GPL(cgroup_get_from_id); |
|
|
|
/* |
|
* proc_cgroup_show() |
|
* - Print task's cgroup paths into seq_file, one line for each hierarchy |
|
* - Used for /proc/<pid>/cgroup. |
|
*/ |
|
int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, |
|
struct pid *pid, struct task_struct *tsk) |
|
{ |
|
char *buf; |
|
int retval; |
|
struct cgroup_root *root; |
|
|
|
retval = -ENOMEM; |
|
buf = kmalloc(PATH_MAX, GFP_KERNEL); |
|
if (!buf) |
|
goto out; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
spin_lock_irq(&css_set_lock); |
|
|
|
for_each_root(root) { |
|
struct cgroup_subsys *ss; |
|
struct cgroup *cgrp; |
|
int ssid, count = 0; |
|
|
|
if (root == &cgrp_dfl_root && !cgrp_dfl_visible) |
|
continue; |
|
|
|
seq_printf(m, "%d:", root->hierarchy_id); |
|
if (root != &cgrp_dfl_root) |
|
for_each_subsys(ss, ssid) |
|
if (root->subsys_mask & (1 << ssid)) |
|
seq_printf(m, "%s%s", count++ ? "," : "", |
|
ss->legacy_name); |
|
if (strlen(root->name)) |
|
seq_printf(m, "%sname=%s", count ? "," : "", |
|
root->name); |
|
seq_putc(m, ':'); |
|
|
|
cgrp = task_cgroup_from_root(tsk, root); |
|
|
|
/* |
|
* On traditional hierarchies, all zombie tasks show up as |
|
* belonging to the root cgroup. On the default hierarchy, |
|
* while a zombie doesn't show up in "cgroup.procs" and |
|
* thus can't be migrated, its /proc/PID/cgroup keeps |
|
* reporting the cgroup it belonged to before exiting. If |
|
* the cgroup is removed before the zombie is reaped, |
|
* " (deleted)" is appended to the cgroup path. |
|
*/ |
|
if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) { |
|
retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX, |
|
current->nsproxy->cgroup_ns); |
|
if (retval >= PATH_MAX) |
|
retval = -ENAMETOOLONG; |
|
if (retval < 0) |
|
goto out_unlock; |
|
|
|
seq_puts(m, buf); |
|
} else { |
|
seq_puts(m, "/"); |
|
} |
|
|
|
if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp)) |
|
seq_puts(m, " (deleted)\n"); |
|
else |
|
seq_putc(m, '\n'); |
|
} |
|
|
|
retval = 0; |
|
out_unlock: |
|
spin_unlock_irq(&css_set_lock); |
|
mutex_unlock(&cgroup_mutex); |
|
kfree(buf); |
|
out: |
|
return retval; |
|
} |
|
|
|
/** |
|
* cgroup_fork - initialize cgroup related fields during copy_process() |
|
* @child: pointer to task_struct of forking parent process. |
|
* |
|
* A task is associated with the init_css_set until cgroup_post_fork() |
|
* attaches it to the target css_set. |
|
*/ |
|
void cgroup_fork(struct task_struct *child) |
|
{ |
|
RCU_INIT_POINTER(child->cgroups, &init_css_set); |
|
INIT_LIST_HEAD(&child->cg_list); |
|
} |
|
|
|
static struct cgroup *cgroup_get_from_file(struct file *f) |
|
{ |
|
struct cgroup_subsys_state *css; |
|
struct cgroup *cgrp; |
|
|
|
css = css_tryget_online_from_dir(f->f_path.dentry, NULL); |
|
if (IS_ERR(css)) |
|
return ERR_CAST(css); |
|
|
|
cgrp = css->cgroup; |
|
if (!cgroup_on_dfl(cgrp)) { |
|
cgroup_put(cgrp); |
|
return ERR_PTR(-EBADF); |
|
} |
|
|
|
return cgrp; |
|
} |
|
|
|
/** |
|
* cgroup_css_set_fork - find or create a css_set for a child process |
|
* @kargs: the arguments passed to create the child process |
|
* |
|
* This functions finds or creates a new css_set which the child |
|
* process will be attached to in cgroup_post_fork(). By default, |
|
* the child process will be given the same css_set as its parent. |
|
* |
|
* If CLONE_INTO_CGROUP is specified this function will try to find an |
|
* existing css_set which includes the requested cgroup and if not create |
|
* a new css_set that the child will be attached to later. If this function |
|
* succeeds it will hold cgroup_threadgroup_rwsem on return. If |
|
* CLONE_INTO_CGROUP is requested this function will grab cgroup mutex |
|
* before grabbing cgroup_threadgroup_rwsem and will hold a reference |
|
* to the target cgroup. |
|
*/ |
|
static int cgroup_css_set_fork(struct kernel_clone_args *kargs) |
|
__acquires(&cgroup_mutex) __acquires(&cgroup_threadgroup_rwsem) |
|
{ |
|
int ret; |
|
struct cgroup *dst_cgrp = NULL; |
|
struct css_set *cset; |
|
struct super_block *sb; |
|
struct file *f; |
|
|
|
if (kargs->flags & CLONE_INTO_CGROUP) |
|
mutex_lock(&cgroup_mutex); |
|
|
|
cgroup_threadgroup_change_begin(current); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
cset = task_css_set(current); |
|
get_css_set(cset); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
if (!(kargs->flags & CLONE_INTO_CGROUP)) { |
|
kargs->cset = cset; |
|
return 0; |
|
} |
|
|
|
f = fget_raw(kargs->cgroup); |
|
if (!f) { |
|
ret = -EBADF; |
|
goto err; |
|
} |
|
sb = f->f_path.dentry->d_sb; |
|
|
|
dst_cgrp = cgroup_get_from_file(f); |
|
if (IS_ERR(dst_cgrp)) { |
|
ret = PTR_ERR(dst_cgrp); |
|
dst_cgrp = NULL; |
|
goto err; |
|
} |
|
|
|
if (cgroup_is_dead(dst_cgrp)) { |
|
ret = -ENODEV; |
|
goto err; |
|
} |
|
|
|
/* |
|
* Verify that we the target cgroup is writable for us. This is |
|
* usually done by the vfs layer but since we're not going through |
|
* the vfs layer here we need to do it "manually". |
|
*/ |
|
ret = cgroup_may_write(dst_cgrp, sb); |
|
if (ret) |
|
goto err; |
|
|
|
/* |
|
* Spawning a task directly into a cgroup works by passing a file |
|
* descriptor to the target cgroup directory. This can even be an O_PATH |
|
* file descriptor. But it can never be a cgroup.procs file descriptor. |
|
* This was done on purpose so spawning into a cgroup could be |
|
* conceptualized as an atomic |
|
* |
|
* fd = openat(dfd_cgroup, "cgroup.procs", ...); |
|
* write(fd, <child-pid>, ...); |
|
* |
|
* sequence, i.e. it's a shorthand for the caller opening and writing |
|
* cgroup.procs of the cgroup indicated by @dfd_cgroup. This allows us |
|
* to always use the caller's credentials. |
|
*/ |
|
ret = cgroup_attach_permissions(cset->dfl_cgrp, dst_cgrp, sb, |
|
!(kargs->flags & CLONE_THREAD), |
|
current->nsproxy->cgroup_ns); |
|
if (ret) |
|
goto err; |
|
|
|
kargs->cset = find_css_set(cset, dst_cgrp); |
|
if (!kargs->cset) { |
|
ret = -ENOMEM; |
|
goto err; |
|
} |
|
|
|
put_css_set(cset); |
|
fput(f); |
|
kargs->cgrp = dst_cgrp; |
|
return ret; |
|
|
|
err: |
|
cgroup_threadgroup_change_end(current); |
|
mutex_unlock(&cgroup_mutex); |
|
if (f) |
|
fput(f); |
|
if (dst_cgrp) |
|
cgroup_put(dst_cgrp); |
|
put_css_set(cset); |
|
if (kargs->cset) |
|
put_css_set(kargs->cset); |
|
return ret; |
|
} |
|
|
|
/** |
|
* cgroup_css_set_put_fork - drop references we took during fork |
|
* @kargs: the arguments passed to create the child process |
|
* |
|
* Drop references to the prepared css_set and target cgroup if |
|
* CLONE_INTO_CGROUP was requested. |
|
*/ |
|
static void cgroup_css_set_put_fork(struct kernel_clone_args *kargs) |
|
__releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex) |
|
{ |
|
cgroup_threadgroup_change_end(current); |
|
|
|
if (kargs->flags & CLONE_INTO_CGROUP) { |
|
struct cgroup *cgrp = kargs->cgrp; |
|
struct css_set *cset = kargs->cset; |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
|
|
if (cset) { |
|
put_css_set(cset); |
|
kargs->cset = NULL; |
|
} |
|
|
|
if (cgrp) { |
|
cgroup_put(cgrp); |
|
kargs->cgrp = NULL; |
|
} |
|
} |
|
} |
|
|
|
/** |
|
* cgroup_can_fork - called on a new task before the process is exposed |
|
* @child: the child process |
|
* @kargs: the arguments passed to create the child process |
|
* |
|
* This prepares a new css_set for the child process which the child will |
|
* be attached to in cgroup_post_fork(). |
|
* This calls the subsystem can_fork() callbacks. If the cgroup_can_fork() |
|
* callback returns an error, the fork aborts with that error code. This |
|
* allows for a cgroup subsystem to conditionally allow or deny new forks. |
|
*/ |
|
int cgroup_can_fork(struct task_struct *child, struct kernel_clone_args *kargs) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int i, j, ret; |
|
|
|
ret = cgroup_css_set_fork(kargs); |
|
if (ret) |
|
return ret; |
|
|
|
do_each_subsys_mask(ss, i, have_canfork_callback) { |
|
ret = ss->can_fork(child, kargs->cset); |
|
if (ret) |
|
goto out_revert; |
|
} while_each_subsys_mask(); |
|
|
|
return 0; |
|
|
|
out_revert: |
|
for_each_subsys(ss, j) { |
|
if (j >= i) |
|
break; |
|
if (ss->cancel_fork) |
|
ss->cancel_fork(child, kargs->cset); |
|
} |
|
|
|
cgroup_css_set_put_fork(kargs); |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() |
|
* @child: the child process |
|
* @kargs: the arguments passed to create the child process |
|
* |
|
* This calls the cancel_fork() callbacks if a fork failed *after* |
|
* cgroup_can_fork() succeeded and cleans up references we took to |
|
* prepare a new css_set for the child process in cgroup_can_fork(). |
|
*/ |
|
void cgroup_cancel_fork(struct task_struct *child, |
|
struct kernel_clone_args *kargs) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int i; |
|
|
|
for_each_subsys(ss, i) |
|
if (ss->cancel_fork) |
|
ss->cancel_fork(child, kargs->cset); |
|
|
|
cgroup_css_set_put_fork(kargs); |
|
} |
|
|
|
/** |
|
* cgroup_post_fork - finalize cgroup setup for the child process |
|
* @child: the child process |
|
* @kargs: the arguments passed to create the child process |
|
* |
|
* Attach the child process to its css_set calling the subsystem fork() |
|
* callbacks. |
|
*/ |
|
void cgroup_post_fork(struct task_struct *child, |
|
struct kernel_clone_args *kargs) |
|
__releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex) |
|
{ |
|
unsigned long cgrp_flags = 0; |
|
bool kill = false; |
|
struct cgroup_subsys *ss; |
|
struct css_set *cset; |
|
int i; |
|
|
|
cset = kargs->cset; |
|
kargs->cset = NULL; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
|
|
/* init tasks are special, only link regular threads */ |
|
if (likely(child->pid)) { |
|
if (kargs->cgrp) |
|
cgrp_flags = kargs->cgrp->flags; |
|
else |
|
cgrp_flags = cset->dfl_cgrp->flags; |
|
|
|
WARN_ON_ONCE(!list_empty(&child->cg_list)); |
|
cset->nr_tasks++; |
|
css_set_move_task(child, NULL, cset, false); |
|
} else { |
|
put_css_set(cset); |
|
cset = NULL; |
|
} |
|
|
|
if (!(child->flags & PF_KTHREAD)) { |
|
if (unlikely(test_bit(CGRP_FREEZE, &cgrp_flags))) { |
|
/* |
|
* If the cgroup has to be frozen, the new task has |
|
* too. Let's set the JOBCTL_TRAP_FREEZE jobctl bit to |
|
* get the task into the frozen state. |
|
*/ |
|
spin_lock(&child->sighand->siglock); |
|
WARN_ON_ONCE(child->frozen); |
|
child->jobctl |= JOBCTL_TRAP_FREEZE; |
|
spin_unlock(&child->sighand->siglock); |
|
|
|
/* |
|
* Calling cgroup_update_frozen() isn't required here, |
|
* because it will be called anyway a bit later from |
|
* do_freezer_trap(). So we avoid cgroup's transient |
|
* switch from the frozen state and back. |
|
*/ |
|
} |
|
|
|
/* |
|
* If the cgroup is to be killed notice it now and take the |
|
* child down right after we finished preparing it for |
|
* userspace. |
|
*/ |
|
kill = test_bit(CGRP_KILL, &cgrp_flags); |
|
} |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* |
|
* Call ss->fork(). This must happen after @child is linked on |
|
* css_set; otherwise, @child might change state between ->fork() |
|
* and addition to css_set. |
|
*/ |
|
do_each_subsys_mask(ss, i, have_fork_callback) { |
|
ss->fork(child); |
|
} while_each_subsys_mask(); |
|
|
|
/* Make the new cset the root_cset of the new cgroup namespace. */ |
|
if (kargs->flags & CLONE_NEWCGROUP) { |
|
struct css_set *rcset = child->nsproxy->cgroup_ns->root_cset; |
|
|
|
get_css_set(cset); |
|
child->nsproxy->cgroup_ns->root_cset = cset; |
|
put_css_set(rcset); |
|
} |
|
|
|
/* Cgroup has to be killed so take down child immediately. */ |
|
if (unlikely(kill)) |
|
do_send_sig_info(SIGKILL, SEND_SIG_NOINFO, child, PIDTYPE_TGID); |
|
|
|
cgroup_css_set_put_fork(kargs); |
|
} |
|
|
|
/** |
|
* cgroup_exit - detach cgroup from exiting task |
|
* @tsk: pointer to task_struct of exiting process |
|
* |
|
* Description: Detach cgroup from @tsk. |
|
* |
|
*/ |
|
void cgroup_exit(struct task_struct *tsk) |
|
{ |
|
struct cgroup_subsys *ss; |
|
struct css_set *cset; |
|
int i; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
|
|
WARN_ON_ONCE(list_empty(&tsk->cg_list)); |
|
cset = task_css_set(tsk); |
|
css_set_move_task(tsk, cset, NULL, false); |
|
list_add_tail(&tsk->cg_list, &cset->dying_tasks); |
|
cset->nr_tasks--; |
|
|
|
WARN_ON_ONCE(cgroup_task_frozen(tsk)); |
|
if (unlikely(!(tsk->flags & PF_KTHREAD) && |
|
test_bit(CGRP_FREEZE, &task_dfl_cgroup(tsk)->flags))) |
|
cgroup_update_frozen(task_dfl_cgroup(tsk)); |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* see cgroup_post_fork() for details */ |
|
do_each_subsys_mask(ss, i, have_exit_callback) { |
|
ss->exit(tsk); |
|
} while_each_subsys_mask(); |
|
} |
|
|
|
void cgroup_release(struct task_struct *task) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
do_each_subsys_mask(ss, ssid, have_release_callback) { |
|
ss->release(task); |
|
} while_each_subsys_mask(); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
css_set_skip_task_iters(task_css_set(task), task); |
|
list_del_init(&task->cg_list); |
|
spin_unlock_irq(&css_set_lock); |
|
} |
|
|
|
void cgroup_free(struct task_struct *task) |
|
{ |
|
struct css_set *cset = task_css_set(task); |
|
put_css_set(cset); |
|
} |
|
|
|
static int __init cgroup_disable(char *str) |
|
{ |
|
struct cgroup_subsys *ss; |
|
char *token; |
|
int i; |
|
|
|
while ((token = strsep(&str, ",")) != NULL) { |
|
if (!*token) |
|
continue; |
|
|
|
for_each_subsys(ss, i) { |
|
if (strcmp(token, ss->name) && |
|
strcmp(token, ss->legacy_name)) |
|
continue; |
|
|
|
/* An explicit cgroup_enable overrides a disable */ |
|
if (cgroup_enable_mask & (1 << i)) |
|
continue; |
|
|
|
static_branch_disable(cgroup_subsys_enabled_key[i]); |
|
pr_info("Disabling %s control group subsystem\n", |
|
ss->name); |
|
} |
|
|
|
for (i = 0; i < OPT_FEATURE_COUNT; i++) { |
|
if (strcmp(token, cgroup_opt_feature_names[i])) |
|
continue; |
|
cgroup_feature_disable_mask |= 1 << i; |
|
pr_info("Disabling %s control group feature\n", |
|
cgroup_opt_feature_names[i]); |
|
break; |
|
} |
|
} |
|
return 1; |
|
} |
|
__setup("cgroup_disable=", cgroup_disable); |
|
|
|
static int __init cgroup_enable(char *str) |
|
{ |
|
struct cgroup_subsys *ss; |
|
char *token; |
|
int i; |
|
|
|
while ((token = strsep(&str, ",")) != NULL) { |
|
if (!*token) |
|
continue; |
|
|
|
for_each_subsys(ss, i) { |
|
if (strcmp(token, ss->name) && |
|
strcmp(token, ss->legacy_name)) |
|
continue; |
|
|
|
cgroup_enable_mask |= 1 << i; |
|
static_branch_enable(cgroup_subsys_enabled_key[i]); |
|
pr_info("Enabling %s control group subsystem\n", |
|
ss->name); |
|
} |
|
} |
|
return 1; |
|
} |
|
__setup("cgroup_enable=", cgroup_enable); |
|
|
|
void __init __weak enable_debug_cgroup(void) { } |
|
|
|
static int __init enable_cgroup_debug(char *str) |
|
{ |
|
cgroup_debug = true; |
|
enable_debug_cgroup(); |
|
return 1; |
|
} |
|
__setup("cgroup_debug", enable_cgroup_debug); |
|
|
|
/** |
|
* css_tryget_online_from_dir - get corresponding css from a cgroup dentry |
|
* @dentry: directory dentry of interest |
|
* @ss: subsystem of interest |
|
* |
|
* If @dentry is a directory for a cgroup which has @ss enabled on it, try |
|
* to get the corresponding css and return it. If such css doesn't exist |
|
* or can't be pinned, an ERR_PTR value is returned. |
|
*/ |
|
struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, |
|
struct cgroup_subsys *ss) |
|
{ |
|
struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
|
struct file_system_type *s_type = dentry->d_sb->s_type; |
|
struct cgroup_subsys_state *css = NULL; |
|
struct cgroup *cgrp; |
|
|
|
/* is @dentry a cgroup dir? */ |
|
if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) || |
|
!kn || kernfs_type(kn) != KERNFS_DIR) |
|
return ERR_PTR(-EBADF); |
|
|
|
rcu_read_lock(); |
|
|
|
/* |
|
* This path doesn't originate from kernfs and @kn could already |
|
* have been or be removed at any point. @kn->priv is RCU |
|
* protected for this access. See css_release_work_fn() for details. |
|
*/ |
|
cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv); |
|
if (cgrp) |
|
css = cgroup_css(cgrp, ss); |
|
|
|
if (!css || !css_tryget_online(css)) |
|
css = ERR_PTR(-ENOENT); |
|
|
|
rcu_read_unlock(); |
|
return css; |
|
} |
|
|
|
/** |
|
* css_from_id - lookup css by id |
|
* @id: the cgroup id |
|
* @ss: cgroup subsys to be looked into |
|
* |
|
* Returns the css if there's valid one with @id, otherwise returns NULL. |
|
* Should be called under rcu_read_lock(). |
|
*/ |
|
struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss) |
|
{ |
|
WARN_ON_ONCE(!rcu_read_lock_held()); |
|
return idr_find(&ss->css_idr, id); |
|
} |
|
|
|
/** |
|
* cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path |
|
* @path: path on the default hierarchy |
|
* |
|
* Find the cgroup at @path on the default hierarchy, increment its |
|
* reference count and return it. Returns pointer to the found cgroup on |
|
* success, ERR_PTR(-ENOENT) if @path doesn't exist or if the cgroup has already |
|
* been released and ERR_PTR(-ENOTDIR) if @path points to a non-directory. |
|
*/ |
|
struct cgroup *cgroup_get_from_path(const char *path) |
|
{ |
|
struct kernfs_node *kn; |
|
struct cgroup *cgrp = ERR_PTR(-ENOENT); |
|
|
|
kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path); |
|
if (!kn) |
|
goto out; |
|
|
|
if (kernfs_type(kn) != KERNFS_DIR) { |
|
cgrp = ERR_PTR(-ENOTDIR); |
|
goto out_kernfs; |
|
} |
|
|
|
rcu_read_lock(); |
|
|
|
cgrp = rcu_dereference(*(void __rcu __force **)&kn->priv); |
|
if (!cgrp || !cgroup_tryget(cgrp)) |
|
cgrp = ERR_PTR(-ENOENT); |
|
|
|
rcu_read_unlock(); |
|
|
|
out_kernfs: |
|
kernfs_put(kn); |
|
out: |
|
return cgrp; |
|
} |
|
EXPORT_SYMBOL_GPL(cgroup_get_from_path); |
|
|
|
/** |
|
* cgroup_get_from_fd - get a cgroup pointer from a fd |
|
* @fd: fd obtained by open(cgroup2_dir) |
|
* |
|
* Find the cgroup from a fd which should be obtained |
|
* by opening a cgroup directory. Returns a pointer to the |
|
* cgroup on success. ERR_PTR is returned if the cgroup |
|
* cannot be found. |
|
*/ |
|
struct cgroup *cgroup_get_from_fd(int fd) |
|
{ |
|
struct cgroup *cgrp; |
|
struct file *f; |
|
|
|
f = fget_raw(fd); |
|
if (!f) |
|
return ERR_PTR(-EBADF); |
|
|
|
cgrp = cgroup_get_from_file(f); |
|
fput(f); |
|
return cgrp; |
|
} |
|
EXPORT_SYMBOL_GPL(cgroup_get_from_fd); |
|
|
|
static u64 power_of_ten(int power) |
|
{ |
|
u64 v = 1; |
|
while (power--) |
|
v *= 10; |
|
return v; |
|
} |
|
|
|
/** |
|
* cgroup_parse_float - parse a floating number |
|
* @input: input string |
|
* @dec_shift: number of decimal digits to shift |
|
* @v: output |
|
* |
|
* Parse a decimal floating point number in @input and store the result in |
|
* @v with decimal point right shifted @dec_shift times. For example, if |
|
* @input is "12.3456" and @dec_shift is 3, *@v will be set to 12345. |
|
* Returns 0 on success, -errno otherwise. |
|
* |
|
* There's nothing cgroup specific about this function except that it's |
|
* currently the only user. |
|
*/ |
|
int cgroup_parse_float(const char *input, unsigned dec_shift, s64 *v) |
|
{ |
|
s64 whole, frac = 0; |
|
int fstart = 0, fend = 0, flen; |
|
|
|
if (!sscanf(input, "%lld.%n%lld%n", &whole, &fstart, &frac, &fend)) |
|
return -EINVAL; |
|
if (frac < 0) |
|
return -EINVAL; |
|
|
|
flen = fend > fstart ? fend - fstart : 0; |
|
if (flen < dec_shift) |
|
frac *= power_of_ten(dec_shift - flen); |
|
else |
|
frac = DIV_ROUND_CLOSEST_ULL(frac, power_of_ten(flen - dec_shift)); |
|
|
|
*v = whole * power_of_ten(dec_shift) + frac; |
|
return 0; |
|
} |
|
|
|
/* |
|
* sock->sk_cgrp_data handling. For more info, see sock_cgroup_data |
|
* definition in cgroup-defs.h. |
|
*/ |
|
#ifdef CONFIG_SOCK_CGROUP_DATA |
|
|
|
void cgroup_sk_alloc(struct sock_cgroup_data *skcd) |
|
{ |
|
struct cgroup *cgroup; |
|
|
|
rcu_read_lock(); |
|
/* Don't associate the sock with unrelated interrupted task's cgroup. */ |
|
if (in_interrupt()) { |
|
cgroup = &cgrp_dfl_root.cgrp; |
|
cgroup_get(cgroup); |
|
goto out; |
|
} |
|
|
|
while (true) { |
|
struct css_set *cset; |
|
|
|
cset = task_css_set(current); |
|
if (likely(cgroup_tryget(cset->dfl_cgrp))) { |
|
cgroup = cset->dfl_cgrp; |
|
break; |
|
} |
|
cpu_relax(); |
|
} |
|
out: |
|
skcd->cgroup = cgroup; |
|
cgroup_bpf_get(cgroup); |
|
rcu_read_unlock(); |
|
} |
|
|
|
void cgroup_sk_clone(struct sock_cgroup_data *skcd) |
|
{ |
|
struct cgroup *cgrp = sock_cgroup_ptr(skcd); |
|
|
|
/* |
|
* We might be cloning a socket which is left in an empty |
|
* cgroup and the cgroup might have already been rmdir'd. |
|
* Don't use cgroup_get_live(). |
|
*/ |
|
cgroup_get(cgrp); |
|
cgroup_bpf_get(cgrp); |
|
} |
|
|
|
void cgroup_sk_free(struct sock_cgroup_data *skcd) |
|
{ |
|
struct cgroup *cgrp = sock_cgroup_ptr(skcd); |
|
|
|
cgroup_bpf_put(cgrp); |
|
cgroup_put(cgrp); |
|
} |
|
|
|
#endif /* CONFIG_SOCK_CGROUP_DATA */ |
|
|
|
#ifdef CONFIG_SYSFS |
|
static ssize_t show_delegatable_files(struct cftype *files, char *buf, |
|
ssize_t size, const char *prefix) |
|
{ |
|
struct cftype *cft; |
|
ssize_t ret = 0; |
|
|
|
for (cft = files; cft && cft->name[0] != '\0'; cft++) { |
|
if (!(cft->flags & CFTYPE_NS_DELEGATABLE)) |
|
continue; |
|
|
|
if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled()) |
|
continue; |
|
|
|
if (prefix) |
|
ret += snprintf(buf + ret, size - ret, "%s.", prefix); |
|
|
|
ret += snprintf(buf + ret, size - ret, "%s\n", cft->name); |
|
|
|
if (WARN_ON(ret >= size)) |
|
break; |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
static ssize_t delegate_show(struct kobject *kobj, struct kobj_attribute *attr, |
|
char *buf) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
ssize_t ret = 0; |
|
|
|
ret = show_delegatable_files(cgroup_base_files, buf, PAGE_SIZE - ret, |
|
NULL); |
|
|
|
for_each_subsys(ss, ssid) |
|
ret += show_delegatable_files(ss->dfl_cftypes, buf + ret, |
|
PAGE_SIZE - ret, |
|
cgroup_subsys_name[ssid]); |
|
|
|
return ret; |
|
} |
|
static struct kobj_attribute cgroup_delegate_attr = __ATTR_RO(delegate); |
|
|
|
static ssize_t features_show(struct kobject *kobj, struct kobj_attribute *attr, |
|
char *buf) |
|
{ |
|
return snprintf(buf, PAGE_SIZE, |
|
"nsdelegate\n" |
|
"memory_localevents\n" |
|
"memory_recursiveprot\n"); |
|
} |
|
static struct kobj_attribute cgroup_features_attr = __ATTR_RO(features); |
|
|
|
static struct attribute *cgroup_sysfs_attrs[] = { |
|
&cgroup_delegate_attr.attr, |
|
&cgroup_features_attr.attr, |
|
NULL, |
|
}; |
|
|
|
static const struct attribute_group cgroup_sysfs_attr_group = { |
|
.attrs = cgroup_sysfs_attrs, |
|
.name = "cgroup", |
|
}; |
|
|
|
static int __init cgroup_sysfs_init(void) |
|
{ |
|
return sysfs_create_group(kernel_kobj, &cgroup_sysfs_attr_group); |
|
} |
|
subsys_initcall(cgroup_sysfs_init); |
|
|
|
#endif /* CONFIG_SYSFS */
|
|
|