forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
6652 lines
177 KiB
6652 lines
177 KiB
/* |
|
* Generic process-grouping system. |
|
* |
|
* Based originally on the cpuset system, extracted by Paul Menage |
|
* Copyright (C) 2006 Google, Inc |
|
* |
|
* Notifications support |
|
* Copyright (C) 2009 Nokia Corporation |
|
* Author: Kirill A. Shutemov |
|
* |
|
* Copyright notices from the original cpuset code: |
|
* -------------------------------------------------- |
|
* Copyright (C) 2003 BULL SA. |
|
* Copyright (C) 2004-2006 Silicon Graphics, Inc. |
|
* |
|
* Portions derived from Patrick Mochel's sysfs code. |
|
* sysfs is Copyright (c) 2001-3 Patrick Mochel |
|
* |
|
* 2003-10-10 Written by Simon Derr. |
|
* 2003-10-22 Updates by Stephen Hemminger. |
|
* 2004 May-July Rework by Paul Jackson. |
|
* --------------------------------------------------- |
|
* |
|
* This file is subject to the terms and conditions of the GNU General Public |
|
* License. See the file COPYING in the main directory of the Linux |
|
* distribution for more details. |
|
*/ |
|
|
|
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
|
|
|
#include <linux/cgroup.h> |
|
#include <linux/cred.h> |
|
#include <linux/ctype.h> |
|
#include <linux/errno.h> |
|
#include <linux/init_task.h> |
|
#include <linux/kernel.h> |
|
#include <linux/list.h> |
|
#include <linux/magic.h> |
|
#include <linux/mm.h> |
|
#include <linux/mutex.h> |
|
#include <linux/mount.h> |
|
#include <linux/pagemap.h> |
|
#include <linux/proc_fs.h> |
|
#include <linux/rcupdate.h> |
|
#include <linux/sched.h> |
|
#include <linux/slab.h> |
|
#include <linux/spinlock.h> |
|
#include <linux/percpu-rwsem.h> |
|
#include <linux/string.h> |
|
#include <linux/sort.h> |
|
#include <linux/kmod.h> |
|
#include <linux/delayacct.h> |
|
#include <linux/cgroupstats.h> |
|
#include <linux/hashtable.h> |
|
#include <linux/pid_namespace.h> |
|
#include <linux/idr.h> |
|
#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */ |
|
#include <linux/kthread.h> |
|
#include <linux/delay.h> |
|
#include <linux/atomic.h> |
|
#include <linux/cpuset.h> |
|
#include <linux/proc_ns.h> |
|
#include <linux/nsproxy.h> |
|
#include <linux/file.h> |
|
#include <net/sock.h> |
|
|
|
#define CREATE_TRACE_POINTS |
|
#include <trace/events/cgroup.h> |
|
|
|
/* |
|
* pidlists linger the following amount before being destroyed. The goal |
|
* is avoiding frequent destruction in the middle of consecutive read calls |
|
* Expiring in the middle is a performance problem not a correctness one. |
|
* 1 sec should be enough. |
|
*/ |
|
#define CGROUP_PIDLIST_DESTROY_DELAY HZ |
|
|
|
#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \ |
|
MAX_CFTYPE_NAME + 2) |
|
|
|
/* |
|
* cgroup_mutex is the master lock. Any modification to cgroup or its |
|
* hierarchy must be performed while holding it. |
|
* |
|
* css_set_lock protects task->cgroups pointer, the list of css_set |
|
* objects, and the chain of tasks off each css_set. |
|
* |
|
* These locks are exported if CONFIG_PROVE_RCU so that accessors in |
|
* cgroup.h can use them for lockdep annotations. |
|
*/ |
|
#ifdef CONFIG_PROVE_RCU |
|
DEFINE_MUTEX(cgroup_mutex); |
|
DEFINE_SPINLOCK(css_set_lock); |
|
EXPORT_SYMBOL_GPL(cgroup_mutex); |
|
EXPORT_SYMBOL_GPL(css_set_lock); |
|
#else |
|
static DEFINE_MUTEX(cgroup_mutex); |
|
static DEFINE_SPINLOCK(css_set_lock); |
|
#endif |
|
|
|
/* |
|
* Protects cgroup_idr and css_idr so that IDs can be released without |
|
* grabbing cgroup_mutex. |
|
*/ |
|
static DEFINE_SPINLOCK(cgroup_idr_lock); |
|
|
|
/* |
|
* Protects cgroup_file->kn for !self csses. It synchronizes notifications |
|
* against file removal/re-creation across css hiding. |
|
*/ |
|
static DEFINE_SPINLOCK(cgroup_file_kn_lock); |
|
|
|
/* |
|
* Protects cgroup_subsys->release_agent_path. Modifying it also requires |
|
* cgroup_mutex. Reading requires either cgroup_mutex or this spinlock. |
|
*/ |
|
static DEFINE_SPINLOCK(release_agent_path_lock); |
|
|
|
struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
|
|
|
#define cgroup_assert_mutex_or_rcu_locked() \ |
|
RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \ |
|
!lockdep_is_held(&cgroup_mutex), \ |
|
"cgroup_mutex or RCU read lock required"); |
|
|
|
/* |
|
* cgroup destruction makes heavy use of work items and there can be a lot |
|
* of concurrent destructions. Use a separate workqueue so that cgroup |
|
* destruction work items don't end up filling up max_active of system_wq |
|
* which may lead to deadlock. |
|
*/ |
|
static struct workqueue_struct *cgroup_destroy_wq; |
|
|
|
/* |
|
* pidlist destructions need to be flushed on cgroup destruction. Use a |
|
* separate workqueue as flush domain. |
|
*/ |
|
static struct workqueue_struct *cgroup_pidlist_destroy_wq; |
|
|
|
/* generate an array of cgroup subsystem pointers */ |
|
#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys, |
|
static struct cgroup_subsys *cgroup_subsys[] = { |
|
#include <linux/cgroup_subsys.h> |
|
}; |
|
#undef SUBSYS |
|
|
|
/* array of cgroup subsystem names */ |
|
#define SUBSYS(_x) [_x ## _cgrp_id] = #_x, |
|
static const char *cgroup_subsys_name[] = { |
|
#include <linux/cgroup_subsys.h> |
|
}; |
|
#undef SUBSYS |
|
|
|
/* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */ |
|
#define SUBSYS(_x) \ |
|
DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \ |
|
DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \ |
|
EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \ |
|
EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key); |
|
#include <linux/cgroup_subsys.h> |
|
#undef SUBSYS |
|
|
|
#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key, |
|
static struct static_key_true *cgroup_subsys_enabled_key[] = { |
|
#include <linux/cgroup_subsys.h> |
|
}; |
|
#undef SUBSYS |
|
|
|
#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key, |
|
static struct static_key_true *cgroup_subsys_on_dfl_key[] = { |
|
#include <linux/cgroup_subsys.h> |
|
}; |
|
#undef SUBSYS |
|
|
|
/* |
|
* The default hierarchy, reserved for the subsystems that are otherwise |
|
* unattached - it never has more than a single cgroup, and all tasks are |
|
* part of that cgroup. |
|
*/ |
|
struct cgroup_root cgrp_dfl_root; |
|
EXPORT_SYMBOL_GPL(cgrp_dfl_root); |
|
|
|
/* |
|
* The default hierarchy always exists but is hidden until mounted for the |
|
* first time. This is for backward compatibility. |
|
*/ |
|
static bool cgrp_dfl_visible; |
|
|
|
/* Controllers blocked by the commandline in v1 */ |
|
static u16 cgroup_no_v1_mask; |
|
|
|
/* some controllers are not supported in the default hierarchy */ |
|
static u16 cgrp_dfl_inhibit_ss_mask; |
|
|
|
/* some controllers are implicitly enabled on the default hierarchy */ |
|
static unsigned long cgrp_dfl_implicit_ss_mask; |
|
|
|
/* The list of hierarchy roots */ |
|
|
|
static LIST_HEAD(cgroup_roots); |
|
static int cgroup_root_count; |
|
|
|
/* hierarchy ID allocation and mapping, protected by cgroup_mutex */ |
|
static DEFINE_IDR(cgroup_hierarchy_idr); |
|
|
|
/* |
|
* Assign a monotonically increasing serial number to csses. It guarantees |
|
* cgroups with bigger numbers are newer than those with smaller numbers. |
|
* Also, as csses are always appended to the parent's ->children list, it |
|
* guarantees that sibling csses are always sorted in the ascending serial |
|
* number order on the list. Protected by cgroup_mutex. |
|
*/ |
|
static u64 css_serial_nr_next = 1; |
|
|
|
/* |
|
* These bitmask flags indicate whether tasks in the fork and exit paths have |
|
* fork/exit handlers to call. This avoids us having to do extra work in the |
|
* fork/exit path to check which subsystems have fork/exit callbacks. |
|
*/ |
|
static u16 have_fork_callback __read_mostly; |
|
static u16 have_exit_callback __read_mostly; |
|
static u16 have_free_callback __read_mostly; |
|
|
|
/* cgroup namespace for init task */ |
|
struct cgroup_namespace init_cgroup_ns = { |
|
.count = { .counter = 2, }, |
|
.user_ns = &init_user_ns, |
|
.ns.ops = &cgroupns_operations, |
|
.ns.inum = PROC_CGROUP_INIT_INO, |
|
.root_cset = &init_css_set, |
|
}; |
|
|
|
/* Ditto for the can_fork callback. */ |
|
static u16 have_canfork_callback __read_mostly; |
|
|
|
static struct file_system_type cgroup2_fs_type; |
|
static struct cftype cgroup_dfl_base_files[]; |
|
static struct cftype cgroup_legacy_base_files[]; |
|
|
|
static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask); |
|
static void cgroup_lock_and_drain_offline(struct cgroup *cgrp); |
|
static int cgroup_apply_control(struct cgroup *cgrp); |
|
static void cgroup_finalize_control(struct cgroup *cgrp, int ret); |
|
static void css_task_iter_advance(struct css_task_iter *it); |
|
static int cgroup_destroy_locked(struct cgroup *cgrp); |
|
static struct cgroup_subsys_state *css_create(struct cgroup *cgrp, |
|
struct cgroup_subsys *ss); |
|
static void css_release(struct percpu_ref *ref); |
|
static void kill_css(struct cgroup_subsys_state *css); |
|
static int cgroup_addrm_files(struct cgroup_subsys_state *css, |
|
struct cgroup *cgrp, struct cftype cfts[], |
|
bool is_add); |
|
|
|
/** |
|
* cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID |
|
* @ssid: subsys ID of interest |
|
* |
|
* cgroup_subsys_enabled() can only be used with literal subsys names which |
|
* is fine for individual subsystems but unsuitable for cgroup core. This |
|
* is slower static_key_enabled() based test indexed by @ssid. |
|
*/ |
|
static bool cgroup_ssid_enabled(int ssid) |
|
{ |
|
if (CGROUP_SUBSYS_COUNT == 0) |
|
return false; |
|
|
|
return static_key_enabled(cgroup_subsys_enabled_key[ssid]); |
|
} |
|
|
|
static bool cgroup_ssid_no_v1(int ssid) |
|
{ |
|
return cgroup_no_v1_mask & (1 << ssid); |
|
} |
|
|
|
/** |
|
* cgroup_on_dfl - test whether a cgroup is on the default hierarchy |
|
* @cgrp: the cgroup of interest |
|
* |
|
* The default hierarchy is the v2 interface of cgroup and this function |
|
* can be used to test whether a cgroup is on the default hierarchy for |
|
* cases where a subsystem should behave differnetly depending on the |
|
* interface version. |
|
* |
|
* The set of behaviors which change on the default hierarchy are still |
|
* being determined and the mount option is prefixed with __DEVEL__. |
|
* |
|
* List of changed behaviors: |
|
* |
|
* - Mount options "noprefix", "xattr", "clone_children", "release_agent" |
|
* and "name" are disallowed. |
|
* |
|
* - When mounting an existing superblock, mount options should match. |
|
* |
|
* - Remount is disallowed. |
|
* |
|
* - rename(2) is disallowed. |
|
* |
|
* - "tasks" is removed. Everything should be at process granularity. Use |
|
* "cgroup.procs" instead. |
|
* |
|
* - "cgroup.procs" is not sorted. pids will be unique unless they got |
|
* recycled inbetween reads. |
|
* |
|
* - "release_agent" and "notify_on_release" are removed. Replacement |
|
* notification mechanism will be implemented. |
|
* |
|
* - "cgroup.clone_children" is removed. |
|
* |
|
* - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup |
|
* and its descendants contain no task; otherwise, 1. The file also |
|
* generates kernfs notification which can be monitored through poll and |
|
* [di]notify when the value of the file changes. |
|
* |
|
* - cpuset: tasks will be kept in empty cpusets when hotplug happens and |
|
* take masks of ancestors with non-empty cpus/mems, instead of being |
|
* moved to an ancestor. |
|
* |
|
* - cpuset: a task can be moved into an empty cpuset, and again it takes |
|
* masks of ancestors. |
|
* |
|
* - memcg: use_hierarchy is on by default and the cgroup file for the flag |
|
* is not created. |
|
* |
|
* - blkcg: blk-throttle becomes properly hierarchical. |
|
* |
|
* - debug: disallowed on the default hierarchy. |
|
*/ |
|
static bool cgroup_on_dfl(const struct cgroup *cgrp) |
|
{ |
|
return cgrp->root == &cgrp_dfl_root; |
|
} |
|
|
|
/* IDR wrappers which synchronize using cgroup_idr_lock */ |
|
static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end, |
|
gfp_t gfp_mask) |
|
{ |
|
int ret; |
|
|
|
idr_preload(gfp_mask); |
|
spin_lock_bh(&cgroup_idr_lock); |
|
ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM); |
|
spin_unlock_bh(&cgroup_idr_lock); |
|
idr_preload_end(); |
|
return ret; |
|
} |
|
|
|
static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id) |
|
{ |
|
void *ret; |
|
|
|
spin_lock_bh(&cgroup_idr_lock); |
|
ret = idr_replace(idr, ptr, id); |
|
spin_unlock_bh(&cgroup_idr_lock); |
|
return ret; |
|
} |
|
|
|
static void cgroup_idr_remove(struct idr *idr, int id) |
|
{ |
|
spin_lock_bh(&cgroup_idr_lock); |
|
idr_remove(idr, id); |
|
spin_unlock_bh(&cgroup_idr_lock); |
|
} |
|
|
|
static struct cgroup *cgroup_parent(struct cgroup *cgrp) |
|
{ |
|
struct cgroup_subsys_state *parent_css = cgrp->self.parent; |
|
|
|
if (parent_css) |
|
return container_of(parent_css, struct cgroup, self); |
|
return NULL; |
|
} |
|
|
|
/* subsystems visibly enabled on a cgroup */ |
|
static u16 cgroup_control(struct cgroup *cgrp) |
|
{ |
|
struct cgroup *parent = cgroup_parent(cgrp); |
|
u16 root_ss_mask = cgrp->root->subsys_mask; |
|
|
|
if (parent) |
|
return parent->subtree_control; |
|
|
|
if (cgroup_on_dfl(cgrp)) |
|
root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask | |
|
cgrp_dfl_implicit_ss_mask); |
|
return root_ss_mask; |
|
} |
|
|
|
/* subsystems enabled on a cgroup */ |
|
static u16 cgroup_ss_mask(struct cgroup *cgrp) |
|
{ |
|
struct cgroup *parent = cgroup_parent(cgrp); |
|
|
|
if (parent) |
|
return parent->subtree_ss_mask; |
|
|
|
return cgrp->root->subsys_mask; |
|
} |
|
|
|
/** |
|
* cgroup_css - obtain a cgroup's css for the specified subsystem |
|
* @cgrp: the cgroup of interest |
|
* @ss: the subsystem of interest (%NULL returns @cgrp->self) |
|
* |
|
* Return @cgrp's css (cgroup_subsys_state) associated with @ss. This |
|
* function must be called either under cgroup_mutex or rcu_read_lock() and |
|
* the caller is responsible for pinning the returned css if it wants to |
|
* keep accessing it outside the said locks. This function may return |
|
* %NULL if @cgrp doesn't have @subsys_id enabled. |
|
*/ |
|
static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, |
|
struct cgroup_subsys *ss) |
|
{ |
|
if (ss) |
|
return rcu_dereference_check(cgrp->subsys[ss->id], |
|
lockdep_is_held(&cgroup_mutex)); |
|
else |
|
return &cgrp->self; |
|
} |
|
|
|
/** |
|
* cgroup_e_css - obtain a cgroup's effective css for the specified subsystem |
|
* @cgrp: the cgroup of interest |
|
* @ss: the subsystem of interest (%NULL returns @cgrp->self) |
|
* |
|
* Similar to cgroup_css() but returns the effective css, which is defined |
|
* as the matching css of the nearest ancestor including self which has @ss |
|
* enabled. If @ss is associated with the hierarchy @cgrp is on, this |
|
* function is guaranteed to return non-NULL css. |
|
*/ |
|
static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp, |
|
struct cgroup_subsys *ss) |
|
{ |
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
if (!ss) |
|
return &cgrp->self; |
|
|
|
/* |
|
* This function is used while updating css associations and thus |
|
* can't test the csses directly. Test ss_mask. |
|
*/ |
|
while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) { |
|
cgrp = cgroup_parent(cgrp); |
|
if (!cgrp) |
|
return NULL; |
|
} |
|
|
|
return cgroup_css(cgrp, ss); |
|
} |
|
|
|
/** |
|
* 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; |
|
|
|
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; |
|
} |
|
|
|
/* convenient tests for these bits */ |
|
static inline bool cgroup_is_dead(const struct cgroup *cgrp) |
|
{ |
|
return !(cgrp->self.flags & CSS_ONLINE); |
|
} |
|
|
|
static void cgroup_get(struct cgroup *cgrp) |
|
{ |
|
WARN_ON_ONCE(cgroup_is_dead(cgrp)); |
|
css_get(&cgrp->self); |
|
} |
|
|
|
static bool cgroup_tryget(struct cgroup *cgrp) |
|
{ |
|
return css_tryget(&cgrp->self); |
|
} |
|
|
|
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 (cft->ss) |
|
return rcu_dereference_raw(cgrp->subsys[cft->ss->id]); |
|
else |
|
return &cgrp->self; |
|
} |
|
EXPORT_SYMBOL_GPL(of_css); |
|
|
|
static int notify_on_release(const struct cgroup *cgrp) |
|
{ |
|
return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags); |
|
} |
|
|
|
/** |
|
* 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(cgrp, cgroup_subsys[(ssid)]))) \ |
|
; \ |
|
else |
|
|
|
/** |
|
* for_each_subsys - iterate all enabled cgroup subsystems |
|
* @ss: the iteration cursor |
|
* @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end |
|
*/ |
|
#define for_each_subsys(ss, ssid) \ |
|
for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \ |
|
(((ss) = cgroup_subsys[ssid]) || true); (ssid)++) |
|
|
|
/** |
|
* 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_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \ |
|
(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 across the hierarchies */ |
|
#define for_each_root(root) \ |
|
list_for_each_entry((root), &cgroup_roots, root_list) |
|
|
|
/* 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 preorder */ |
|
#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 |
|
|
|
static void cgroup_release_agent(struct work_struct *work); |
|
static void check_for_release(struct cgroup *cgrp); |
|
|
|
/* |
|
* A cgroup can be associated with multiple css_sets as different tasks may |
|
* belong to different cgroups on different hierarchies. In the other |
|
* direction, a css_set is naturally associated with multiple cgroups. |
|
* This M:N relationship is represented by the following link structure |
|
* which exists for each association and allows traversing the associations |
|
* from both sides. |
|
*/ |
|
struct cgrp_cset_link { |
|
/* the cgroup and css_set this link associates */ |
|
struct cgroup *cgrp; |
|
struct css_set *cset; |
|
|
|
/* list of cgrp_cset_links anchored at cgrp->cset_links */ |
|
struct list_head cset_link; |
|
|
|
/* list of cgrp_cset_links anchored at css_set->cgrp_links */ |
|
struct list_head cgrp_link; |
|
}; |
|
|
|
/* |
|
* 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 = ATOMIC_INIT(1), |
|
.cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links), |
|
.tasks = LIST_HEAD_INIT(init_css_set.tasks), |
|
.mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), |
|
.mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node), |
|
.mg_node = LIST_HEAD_INIT(init_css_set.mg_node), |
|
.task_iters = LIST_HEAD_INIT(init_css_set.task_iters), |
|
}; |
|
|
|
static int css_set_count = 1; /* 1 for init_css_set */ |
|
|
|
/** |
|
* css_set_populated - does a css_set contain any tasks? |
|
* @cset: target css_set |
|
*/ |
|
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 - updated 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->populated_cnt accordingly. The |
|
* count is propagated towards root so that a given cgroup's populated_cnt |
|
* is zero iff the cgroup and all its descendants don't contain any tasks. |
|
* |
|
* @cgrp's interface file "cgroup.populated" is zero if |
|
* @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt |
|
* 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) |
|
{ |
|
lockdep_assert_held(&css_set_lock); |
|
|
|
do { |
|
bool trigger; |
|
|
|
if (populated) |
|
trigger = !cgrp->populated_cnt++; |
|
else |
|
trigger = !--cgrp->populated_cnt; |
|
|
|
if (!trigger) |
|
break; |
|
|
|
check_for_release(cgrp); |
|
cgroup_file_notify(&cgrp->events_file); |
|
|
|
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_cnt 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); |
|
} |
|
|
|
/** |
|
* 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_cnt 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) { |
|
struct css_task_iter *it, *pos; |
|
|
|
WARN_ON_ONCE(list_empty(&task->cg_list)); |
|
|
|
/* |
|
* @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_advance*() |
|
* for details. |
|
*/ |
|
list_for_each_entry_safe(it, pos, &from_cset->task_iters, |
|
iters_node) |
|
if (it->task_pos == &task->cg_list) |
|
css_task_iter_advance(it); |
|
|
|
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() changing the css_set to |
|
* init_css_set and dropping the old one. |
|
*/ |
|
WARN_ON_ONCE(task->flags & PF_EXITING); |
|
|
|
rcu_assign_pointer(task->cgroups, 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; |
|
} |
|
|
|
static 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 (!atomic_dec_and_test(&cset->refcount)) |
|
return; |
|
|
|
/* 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); |
|
} |
|
|
|
kfree_rcu(cset, rcu_head); |
|
} |
|
|
|
static void put_css_set(struct css_set *cset) |
|
{ |
|
unsigned long flags; |
|
|
|
/* |
|
* Ensure that the refcount doesn't hit zero while any readers |
|
* can see it. Similar to atomic_dec_and_lock(), but for an |
|
* rwlock |
|
*/ |
|
if (atomic_add_unless(&cset->refcount, -1, 1)) |
|
return; |
|
|
|
spin_lock_irqsave(&css_set_lock, flags); |
|
put_css_set_locked(cset); |
|
spin_unlock_irqrestore(&css_set_lock, flags); |
|
} |
|
|
|
/* |
|
* refcounted get/put for css_set objects |
|
*/ |
|
static inline void get_css_set(struct css_set *cset) |
|
{ |
|
atomic_inc(&cset->refcount); |
|
} |
|
|
|
/** |
|
* 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 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; |
|
|
|
/* |
|
* 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(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 choronological 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(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; |
|
} |
|
|
|
atomic_set(&cset->refcount, 1); |
|
INIT_LIST_HEAD(&cset->cgrp_links); |
|
INIT_LIST_HEAD(&cset->tasks); |
|
INIT_LIST_HEAD(&cset->mg_tasks); |
|
INIT_LIST_HEAD(&cset->mg_preload_node); |
|
INIT_LIST_HEAD(&cset->mg_node); |
|
INIT_LIST_HEAD(&cset->task_iters); |
|
INIT_HLIST_NODE(&cset->hlist); |
|
|
|
/* 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); |
|
|
|
return cset; |
|
} |
|
|
|
static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root) |
|
{ |
|
struct cgroup *root_cgrp = kf_root->kn->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); |
|
} |
|
|
|
static void cgroup_free_root(struct cgroup_root *root) |
|
{ |
|
if (root) { |
|
idr_destroy(&root->cgroup_idr); |
|
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); |
|
|
|
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 { |
|
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 { |
|
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. |
|
*/ |
|
static struct cgroup *task_cgroup_from_root(struct task_struct *task, |
|
struct cgroup_root *root) |
|
{ |
|
/* |
|
* No need to lock the task - since we hold cgroup_mutex the |
|
* task can't change groups, so the only thing that can happen |
|
* is that it exits and its css is set back to init_css_set. |
|
*/ |
|
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 const struct file_operations proc_cgroupstats_operations; |
|
|
|
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)) |
|
snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s", |
|
cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name, |
|
cft->name); |
|
else |
|
strncpy(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. |
|
*/ |
|
static 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. |
|
*/ |
|
static 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); |
|
} |
|
|
|
kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name)); |
|
} |
|
|
|
/** |
|
* css_clear_dir - remove subsys files in a cgroup directory |
|
* @css: taget 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; |
|
|
|
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_dfl_base_files; |
|
else |
|
cfts = cgroup_legacy_base_files; |
|
|
|
return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true); |
|
} |
|
|
|
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; |
|
} |
|
|
|
static 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; |
|
|
|
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; |
|
} while_each_subsys_mask(); |
|
|
|
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)); |
|
|
|
/* 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); |
|
|
|
/* 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; |
|
} |
|
|
|
static 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; |
|
} |
|
|
|
static int cgroup_show_options(struct seq_file *seq, |
|
struct kernfs_root *kf_root) |
|
{ |
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
if (root != &cgrp_dfl_root) |
|
for_each_subsys(ss, ssid) |
|
if (root->subsys_mask & (1 << ssid)) |
|
seq_show_option(seq, ss->legacy_name, NULL); |
|
if (root->flags & CGRP_ROOT_NOPREFIX) |
|
seq_puts(seq, ",noprefix"); |
|
if (root->flags & CGRP_ROOT_XATTR) |
|
seq_puts(seq, ",xattr"); |
|
|
|
spin_lock(&release_agent_path_lock); |
|
if (strlen(root->release_agent_path)) |
|
seq_show_option(seq, "release_agent", |
|
root->release_agent_path); |
|
spin_unlock(&release_agent_path_lock); |
|
|
|
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags)) |
|
seq_puts(seq, ",clone_children"); |
|
if (strlen(root->name)) |
|
seq_show_option(seq, "name", root->name); |
|
return 0; |
|
} |
|
|
|
struct cgroup_sb_opts { |
|
u16 subsys_mask; |
|
unsigned int flags; |
|
char *release_agent; |
|
bool cpuset_clone_children; |
|
char *name; |
|
/* User explicitly requested empty subsystem */ |
|
bool none; |
|
}; |
|
|
|
static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) |
|
{ |
|
char *token, *o = data; |
|
bool all_ss = false, one_ss = false; |
|
u16 mask = U16_MAX; |
|
struct cgroup_subsys *ss; |
|
int nr_opts = 0; |
|
int i; |
|
|
|
#ifdef CONFIG_CPUSETS |
|
mask = ~((u16)1 << cpuset_cgrp_id); |
|
#endif |
|
|
|
memset(opts, 0, sizeof(*opts)); |
|
|
|
while ((token = strsep(&o, ",")) != NULL) { |
|
nr_opts++; |
|
|
|
if (!*token) |
|
return -EINVAL; |
|
if (!strcmp(token, "none")) { |
|
/* Explicitly have no subsystems */ |
|
opts->none = true; |
|
continue; |
|
} |
|
if (!strcmp(token, "all")) { |
|
/* Mutually exclusive option 'all' + subsystem name */ |
|
if (one_ss) |
|
return -EINVAL; |
|
all_ss = true; |
|
continue; |
|
} |
|
if (!strcmp(token, "noprefix")) { |
|
opts->flags |= CGRP_ROOT_NOPREFIX; |
|
continue; |
|
} |
|
if (!strcmp(token, "clone_children")) { |
|
opts->cpuset_clone_children = true; |
|
continue; |
|
} |
|
if (!strcmp(token, "xattr")) { |
|
opts->flags |= CGRP_ROOT_XATTR; |
|
continue; |
|
} |
|
if (!strncmp(token, "release_agent=", 14)) { |
|
/* Specifying two release agents is forbidden */ |
|
if (opts->release_agent) |
|
return -EINVAL; |
|
opts->release_agent = |
|
kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL); |
|
if (!opts->release_agent) |
|
return -ENOMEM; |
|
continue; |
|
} |
|
if (!strncmp(token, "name=", 5)) { |
|
const char *name = token + 5; |
|
/* Can't specify an empty name */ |
|
if (!strlen(name)) |
|
return -EINVAL; |
|
/* Must match [\w.-]+ */ |
|
for (i = 0; i < strlen(name); i++) { |
|
char c = name[i]; |
|
if (isalnum(c)) |
|
continue; |
|
if ((c == '.') || (c == '-') || (c == '_')) |
|
continue; |
|
return -EINVAL; |
|
} |
|
/* Specifying two names is forbidden */ |
|
if (opts->name) |
|
return -EINVAL; |
|
opts->name = kstrndup(name, |
|
MAX_CGROUP_ROOT_NAMELEN - 1, |
|
GFP_KERNEL); |
|
if (!opts->name) |
|
return -ENOMEM; |
|
|
|
continue; |
|
} |
|
|
|
for_each_subsys(ss, i) { |
|
if (strcmp(token, ss->legacy_name)) |
|
continue; |
|
if (!cgroup_ssid_enabled(i)) |
|
continue; |
|
if (cgroup_ssid_no_v1(i)) |
|
continue; |
|
|
|
/* Mutually exclusive option 'all' + subsystem name */ |
|
if (all_ss) |
|
return -EINVAL; |
|
opts->subsys_mask |= (1 << i); |
|
one_ss = true; |
|
|
|
break; |
|
} |
|
if (i == CGROUP_SUBSYS_COUNT) |
|
return -ENOENT; |
|
} |
|
|
|
/* |
|
* If the 'all' option was specified select all the subsystems, |
|
* otherwise if 'none', 'name=' and a subsystem name options were |
|
* not specified, let's default to 'all' |
|
*/ |
|
if (all_ss || (!one_ss && !opts->none && !opts->name)) |
|
for_each_subsys(ss, i) |
|
if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i)) |
|
opts->subsys_mask |= (1 << i); |
|
|
|
/* |
|
* We either have to specify by name or by subsystems. (So all |
|
* empty hierarchies must have a name). |
|
*/ |
|
if (!opts->subsys_mask && !opts->name) |
|
return -EINVAL; |
|
|
|
/* |
|
* Option noprefix was introduced just for backward compatibility |
|
* with the old cpuset, so we allow noprefix only if mounting just |
|
* the cpuset subsystem. |
|
*/ |
|
if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask)) |
|
return -EINVAL; |
|
|
|
/* Can't specify "none" and some subsystems */ |
|
if (opts->subsys_mask && opts->none) |
|
return -EINVAL; |
|
|
|
return 0; |
|
} |
|
|
|
static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) |
|
{ |
|
int ret = 0; |
|
struct cgroup_root *root = cgroup_root_from_kf(kf_root); |
|
struct cgroup_sb_opts opts; |
|
u16 added_mask, removed_mask; |
|
|
|
if (root == &cgrp_dfl_root) { |
|
pr_err("remount is not allowed\n"); |
|
return -EINVAL; |
|
} |
|
|
|
cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
|
|
|
/* See what subsystems are wanted */ |
|
ret = parse_cgroupfs_options(data, &opts); |
|
if (ret) |
|
goto out_unlock; |
|
|
|
if (opts.subsys_mask != root->subsys_mask || opts.release_agent) |
|
pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", |
|
task_tgid_nr(current), current->comm); |
|
|
|
added_mask = opts.subsys_mask & ~root->subsys_mask; |
|
removed_mask = root->subsys_mask & ~opts.subsys_mask; |
|
|
|
/* Don't allow flags or name to change at remount */ |
|
if ((opts.flags ^ root->flags) || |
|
(opts.name && strcmp(opts.name, root->name))) { |
|
pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n", |
|
opts.flags, opts.name ?: "", root->flags, root->name); |
|
ret = -EINVAL; |
|
goto out_unlock; |
|
} |
|
|
|
/* remounting is not allowed for populated hierarchies */ |
|
if (!list_empty(&root->cgrp.self.children)) { |
|
ret = -EBUSY; |
|
goto out_unlock; |
|
} |
|
|
|
ret = rebind_subsystems(root, added_mask); |
|
if (ret) |
|
goto out_unlock; |
|
|
|
WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask)); |
|
|
|
if (opts.release_agent) { |
|
spin_lock(&release_agent_path_lock); |
|
strcpy(root->release_agent_path, opts.release_agent); |
|
spin_unlock(&release_agent_path_lock); |
|
} |
|
|
|
trace_cgroup_remount(root); |
|
|
|
out_unlock: |
|
kfree(opts.release_agent); |
|
kfree(opts.name); |
|
mutex_unlock(&cgroup_mutex); |
|
return ret; |
|
} |
|
|
|
/* |
|
* To reduce the fork() overhead for systems that are not actually using |
|
* their cgroups capability, we don't maintain the lists running through |
|
* each css_set to its tasks until we see the list actually used - in other |
|
* words after the first mount. |
|
*/ |
|
static bool use_task_css_set_links __read_mostly; |
|
|
|
static void cgroup_enable_task_cg_lists(void) |
|
{ |
|
struct task_struct *p, *g; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
|
|
if (use_task_css_set_links) |
|
goto out_unlock; |
|
|
|
use_task_css_set_links = true; |
|
|
|
/* |
|
* We need tasklist_lock because RCU is not safe against |
|
* while_each_thread(). Besides, a forking task that has passed |
|
* cgroup_post_fork() without seeing use_task_css_set_links = 1 |
|
* is not guaranteed to have its child immediately visible in the |
|
* tasklist if we walk through it with RCU. |
|
*/ |
|
read_lock(&tasklist_lock); |
|
do_each_thread(g, p) { |
|
WARN_ON_ONCE(!list_empty(&p->cg_list) || |
|
task_css_set(p) != &init_css_set); |
|
|
|
/* |
|
* We should check if the process is exiting, otherwise |
|
* it will race with cgroup_exit() in that the list |
|
* entry won't be deleted though the process has exited. |
|
* Do it while holding siglock so that we don't end up |
|
* racing against cgroup_exit(). |
|
* |
|
* Interrupts were already disabled while acquiring |
|
* the css_set_lock, so we do not need to disable it |
|
* again when acquiring the sighand->siglock here. |
|
*/ |
|
spin_lock(&p->sighand->siglock); |
|
if (!(p->flags & PF_EXITING)) { |
|
struct css_set *cset = task_css_set(p); |
|
|
|
if (!css_set_populated(cset)) |
|
css_set_update_populated(cset, true); |
|
list_add_tail(&p->cg_list, &cset->tasks); |
|
get_css_set(cset); |
|
} |
|
spin_unlock(&p->sighand->siglock); |
|
} while_each_thread(g, p); |
|
read_unlock(&tasklist_lock); |
|
out_unlock: |
|
spin_unlock_irq(&css_set_lock); |
|
} |
|
|
|
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; |
|
|
|
for_each_subsys(ss, ssid) |
|
INIT_LIST_HEAD(&cgrp->e_csets[ssid]); |
|
|
|
init_waitqueue_head(&cgrp->offline_waitq); |
|
INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent); |
|
} |
|
|
|
static void init_cgroup_root(struct cgroup_root *root, |
|
struct cgroup_sb_opts *opts) |
|
{ |
|
struct cgroup *cgrp = &root->cgrp; |
|
|
|
INIT_LIST_HEAD(&root->root_list); |
|
atomic_set(&root->nr_cgrps, 1); |
|
cgrp->root = root; |
|
init_cgroup_housekeeping(cgrp); |
|
idr_init(&root->cgroup_idr); |
|
|
|
root->flags = opts->flags; |
|
if (opts->release_agent) |
|
strcpy(root->release_agent_path, opts->release_agent); |
|
if (opts->name) |
|
strcpy(root->name, opts->name); |
|
if (opts->cpuset_clone_children) |
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags); |
|
} |
|
|
|
static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) |
|
{ |
|
LIST_HEAD(tmp_links); |
|
struct cgroup *root_cgrp = &root->cgrp; |
|
struct css_set *cset; |
|
int i, ret; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL); |
|
if (ret < 0) |
|
goto out; |
|
root_cgrp->id = ret; |
|
root_cgrp->ancestor_ids[0] = ret; |
|
|
|
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; |
|
|
|
root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops, |
|
KERNFS_ROOT_CREATE_DEACTIVATED, |
|
root_cgrp); |
|
if (IS_ERR(root->kf_root)) { |
|
ret = PTR_ERR(root->kf_root); |
|
goto exit_root_id; |
|
} |
|
root_cgrp->kn = root->kf_root->kn; |
|
|
|
ret = css_populate_dir(&root_cgrp->self); |
|
if (ret) |
|
goto destroy_root; |
|
|
|
ret = rebind_subsystems(root, ss_mask); |
|
if (ret) |
|
goto destroy_root; |
|
|
|
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); |
|
|
|
kernfs_activate(root_cgrp->kn); |
|
ret = 0; |
|
goto out; |
|
|
|
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; |
|
} |
|
|
|
static struct dentry *cgroup_mount(struct file_system_type *fs_type, |
|
int flags, const char *unused_dev_name, |
|
void *data) |
|
{ |
|
bool is_v2 = fs_type == &cgroup2_fs_type; |
|
struct super_block *pinned_sb = NULL; |
|
struct cgroup_namespace *ns = current->nsproxy->cgroup_ns; |
|
struct cgroup_subsys *ss; |
|
struct cgroup_root *root; |
|
struct cgroup_sb_opts opts; |
|
struct dentry *dentry; |
|
int ret; |
|
int i; |
|
bool new_sb; |
|
|
|
get_cgroup_ns(ns); |
|
|
|
/* Check if the caller has permission to mount. */ |
|
if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) { |
|
put_cgroup_ns(ns); |
|
return ERR_PTR(-EPERM); |
|
} |
|
|
|
/* |
|
* The first time anyone tries to mount a cgroup, enable the list |
|
* linking each css_set to its tasks and fix up all existing tasks. |
|
*/ |
|
if (!use_task_css_set_links) |
|
cgroup_enable_task_cg_lists(); |
|
|
|
if (is_v2) { |
|
if (data) { |
|
pr_err("cgroup2: unknown option \"%s\"\n", (char *)data); |
|
put_cgroup_ns(ns); |
|
return ERR_PTR(-EINVAL); |
|
} |
|
cgrp_dfl_visible = true; |
|
root = &cgrp_dfl_root; |
|
cgroup_get(&root->cgrp); |
|
goto out_mount; |
|
} |
|
|
|
cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp); |
|
|
|
/* First find the desired set of subsystems */ |
|
ret = parse_cgroupfs_options(data, &opts); |
|
if (ret) |
|
goto out_unlock; |
|
|
|
/* |
|
* Destruction of cgroup root is asynchronous, so subsystems may |
|
* still be dying after the previous unmount. Let's drain the |
|
* dying subsystems. We just need to ensure that the ones |
|
* unmounted previously finish dying and don't care about new ones |
|
* starting. Testing ref liveliness is good enough. |
|
*/ |
|
for_each_subsys(ss, i) { |
|
if (!(opts.subsys_mask & (1 << i)) || |
|
ss->root == &cgrp_dfl_root) |
|
continue; |
|
|
|
if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) { |
|
mutex_unlock(&cgroup_mutex); |
|
msleep(10); |
|
ret = restart_syscall(); |
|
goto out_free; |
|
} |
|
cgroup_put(&ss->root->cgrp); |
|
} |
|
|
|
for_each_root(root) { |
|
bool name_match = false; |
|
|
|
if (root == &cgrp_dfl_root) |
|
continue; |
|
|
|
/* |
|
* If we asked for a name then it must match. Also, if |
|
* name matches but sybsys_mask doesn't, we should fail. |
|
* Remember whether name matched. |
|
*/ |
|
if (opts.name) { |
|
if (strcmp(opts.name, root->name)) |
|
continue; |
|
name_match = true; |
|
} |
|
|
|
/* |
|
* If we asked for subsystems (or explicitly for no |
|
* subsystems) then they must match. |
|
*/ |
|
if ((opts.subsys_mask || opts.none) && |
|
(opts.subsys_mask != root->subsys_mask)) { |
|
if (!name_match) |
|
continue; |
|
ret = -EBUSY; |
|
goto out_unlock; |
|
} |
|
|
|
if (root->flags ^ opts.flags) |
|
pr_warn("new mount options do not match the existing superblock, will be ignored\n"); |
|
|
|
/* |
|
* We want to reuse @root whose lifetime is governed by its |
|
* ->cgrp. Let's check whether @root is alive and keep it |
|
* that way. As cgroup_kill_sb() can happen anytime, we |
|
* want to block it by pinning the sb so that @root doesn't |
|
* get killed before mount is complete. |
|
* |
|
* With the sb pinned, tryget_live can reliably indicate |
|
* whether @root can be reused. If it's being killed, |
|
* drain it. We can use wait_queue for the wait but this |
|
* path is super cold. Let's just sleep a bit and retry. |
|
*/ |
|
pinned_sb = kernfs_pin_sb(root->kf_root, NULL); |
|
if (IS_ERR(pinned_sb) || |
|
!percpu_ref_tryget_live(&root->cgrp.self.refcnt)) { |
|
mutex_unlock(&cgroup_mutex); |
|
if (!IS_ERR_OR_NULL(pinned_sb)) |
|
deactivate_super(pinned_sb); |
|
msleep(10); |
|
ret = restart_syscall(); |
|
goto out_free; |
|
} |
|
|
|
ret = 0; |
|
goto out_unlock; |
|
} |
|
|
|
/* |
|
* No such thing, create a new one. name= matching without subsys |
|
* specification is allowed for already existing hierarchies but we |
|
* can't create new one without subsys specification. |
|
*/ |
|
if (!opts.subsys_mask && !opts.none) { |
|
ret = -EINVAL; |
|
goto out_unlock; |
|
} |
|
|
|
/* Hierarchies may only be created in the initial cgroup namespace. */ |
|
if (ns != &init_cgroup_ns) { |
|
ret = -EPERM; |
|
goto out_unlock; |
|
} |
|
|
|
root = kzalloc(sizeof(*root), GFP_KERNEL); |
|
if (!root) { |
|
ret = -ENOMEM; |
|
goto out_unlock; |
|
} |
|
|
|
init_cgroup_root(root, &opts); |
|
|
|
ret = cgroup_setup_root(root, opts.subsys_mask); |
|
if (ret) |
|
cgroup_free_root(root); |
|
|
|
out_unlock: |
|
mutex_unlock(&cgroup_mutex); |
|
out_free: |
|
kfree(opts.release_agent); |
|
kfree(opts.name); |
|
|
|
if (ret) { |
|
put_cgroup_ns(ns); |
|
return ERR_PTR(ret); |
|
} |
|
out_mount: |
|
dentry = kernfs_mount(fs_type, flags, root->kf_root, |
|
is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC, |
|
&new_sb); |
|
|
|
/* |
|
* In non-init cgroup namespace, instead of root cgroup's |
|
* dentry, we return the dentry corresponding to the |
|
* cgroupns->root_cgrp. |
|
*/ |
|
if (!IS_ERR(dentry) && ns != &init_cgroup_ns) { |
|
struct dentry *nsdentry; |
|
struct cgroup *cgrp; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
spin_lock_irq(&css_set_lock); |
|
|
|
cgrp = cset_cgroup_from_root(ns->root_cset, root); |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
mutex_unlock(&cgroup_mutex); |
|
|
|
nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb); |
|
dput(dentry); |
|
dentry = nsdentry; |
|
} |
|
|
|
if (IS_ERR(dentry) || !new_sb) |
|
cgroup_put(&root->cgrp); |
|
|
|
/* |
|
* If @pinned_sb, we're reusing an existing root and holding an |
|
* extra ref on its sb. Mount is complete. Put the extra ref. |
|
*/ |
|
if (pinned_sb) { |
|
WARN_ON(new_sb); |
|
deactivate_super(pinned_sb); |
|
} |
|
|
|
put_cgroup_ns(ns); |
|
return dentry; |
|
} |
|
|
|
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 mounts or children, start killing it. |
|
* This prevents new mounts by disabling percpu_ref_tryget_live(). |
|
* cgroup_mount() may wait for @root's release. |
|
* |
|
* And don't kill the default root. |
|
*/ |
|
if (!list_empty(&root->cgrp.self.children) || |
|
root == &cgrp_dfl_root) |
|
cgroup_put(&root->cgrp); |
|
else |
|
percpu_ref_kill(&root->cgrp.self.refcnt); |
|
|
|
kernfs_kill_sb(sb); |
|
} |
|
|
|
static struct file_system_type cgroup_fs_type = { |
|
.name = "cgroup", |
|
.mount = cgroup_mount, |
|
.kill_sb = cgroup_kill_sb, |
|
.fs_flags = FS_USERNS_MOUNT, |
|
}; |
|
|
|
static struct file_system_type cgroup2_fs_type = { |
|
.name = "cgroup2", |
|
.mount = cgroup_mount, |
|
.kill_sb = cgroup_kill_sb, |
|
.fs_flags = FS_USERNS_MOUNT, |
|
}; |
|
|
|
static 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); |
|
|
|
/* used to track tasks and other necessary states during migration */ |
|
struct cgroup_taskset { |
|
/* the src and dst cset list running through cset->mg_node */ |
|
struct list_head src_csets; |
|
struct list_head dst_csets; |
|
|
|
/* the subsys currently being processed */ |
|
int ssid; |
|
|
|
/* |
|
* Fields for cgroup_taskset_*() iteration. |
|
* |
|
* Before migration is committed, the target migration tasks are on |
|
* ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of |
|
* the csets on ->dst_csets. ->csets point to either ->src_csets |
|
* or ->dst_csets depending on whether migration is committed. |
|
* |
|
* ->cur_csets and ->cur_task point to the current task position |
|
* during iteration. |
|
*/ |
|
struct list_head *csets; |
|
struct css_set *cur_cset; |
|
struct task_struct *cur_task; |
|
}; |
|
|
|
#define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \ |
|
.src_csets = LIST_HEAD_INIT(tset.src_csets), \ |
|
.dst_csets = LIST_HEAD_INIT(tset.dst_csets), \ |
|
.csets = &tset.src_csets, \ |
|
} |
|
|
|
/** |
|
* cgroup_taskset_add - try to add a migration target task to a taskset |
|
* @task: target task |
|
* @tset: target taskset |
|
* |
|
* Add @task, which is a migration target, to @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_taskset_add(struct task_struct *task, |
|
struct cgroup_taskset *tset) |
|
{ |
|
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; |
|
|
|
/* leave @task alone if post_fork() hasn't linked it yet */ |
|
if (list_empty(&task->cg_list)) |
|
return; |
|
|
|
cset = task_css_set(task); |
|
if (!cset->mg_src_cgrp) |
|
return; |
|
|
|
list_move_tail(&task->cg_list, &cset->mg_tasks); |
|
if (list_empty(&cset->mg_node)) |
|
list_add_tail(&cset->mg_node, &tset->src_csets); |
|
if (list_empty(&cset->mg_dst_cset->mg_node)) |
|
list_move_tail(&cset->mg_dst_cset->mg_node, |
|
&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 (&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_taskset_migrate - migrate a taskset |
|
* @tset: taget taskset |
|
* @root: cgroup root the migration is taking place on |
|
* |
|
* Migrate tasks in @tset 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 @tset are migrated. |
|
* @tset is consumed regardless of success. |
|
*/ |
|
static int cgroup_taskset_migrate(struct cgroup_taskset *tset, |
|
struct cgroup_root *root) |
|
{ |
|
struct cgroup_subsys *ss; |
|
struct task_struct *task, *tmp_task; |
|
struct css_set *cset, *tmp_cset; |
|
int ssid, failed_ssid, ret; |
|
|
|
/* methods shouldn't be called if no task is actually migrating */ |
|
if (list_empty(&tset->src_csets)) |
|
return 0; |
|
|
|
/* check that we can legitimately attach to the cgroup */ |
|
do_each_subsys_mask(ss, ssid, root->subsys_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); |
|
css_set_move_task(task, from_cset, to_cset, true); |
|
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; |
|
|
|
do_each_subsys_mask(ss, ssid, root->subsys_mask) { |
|
if (ss->attach) { |
|
tset->ssid = ssid; |
|
ss->attach(tset); |
|
} |
|
} while_each_subsys_mask(); |
|
|
|
ret = 0; |
|
goto out_release_tset; |
|
|
|
out_cancel_attach: |
|
do_each_subsys_mask(ss, ssid, root->subsys_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); |
|
return ret; |
|
} |
|
|
|
/** |
|
* cgroup_may_migrate_to - verify whether a cgroup can be migration destination |
|
* @dst_cgrp: destination cgroup to test |
|
* |
|
* On the default hierarchy, except for the root, subtree_control must be |
|
* zero for migration destination cgroups with tasks so that child cgroups |
|
* don't compete against tasks. |
|
*/ |
|
static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp) |
|
{ |
|
return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) || |
|
!dst_cgrp->subtree_control; |
|
} |
|
|
|
/** |
|
* cgroup_migrate_finish - cleanup after attach |
|
* @preloaded_csets: list of preloaded css_sets |
|
* |
|
* Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See |
|
* those functions for details. |
|
*/ |
|
static void cgroup_migrate_finish(struct list_head *preloaded_csets) |
|
{ |
|
struct css_set *cset, *tmp_cset; |
|
|
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, 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 |
|
* @preloaded_csets: list of preloaded css_sets |
|
* |
|
* Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin |
|
* @src_cset and add it to @preloaded_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. |
|
*/ |
|
static void cgroup_migrate_add_src(struct css_set *src_cset, |
|
struct cgroup *dst_cgrp, |
|
struct list_head *preloaded_csets) |
|
{ |
|
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; |
|
|
|
src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root); |
|
|
|
if (!list_empty(&src_cset->mg_preload_node)) |
|
return; |
|
|
|
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(&src_cset->mg_preload_node, preloaded_csets); |
|
} |
|
|
|
/** |
|
* cgroup_migrate_prepare_dst - prepare destination css_sets for migration |
|
* @preloaded_csets: list of preloaded source css_sets |
|
* |
|
* Tasks are about to be moved and all the source css_sets have been |
|
* preloaded to @preloaded_csets. This function looks up and pins all |
|
* destination css_sets, links each to its source, and append them to |
|
* @preloaded_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 |
|
* @preloaded_csets. |
|
*/ |
|
static int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets) |
|
{ |
|
LIST_HEAD(csets); |
|
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, preloaded_csets, mg_preload_node) { |
|
struct css_set *dst_cset; |
|
|
|
dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp); |
|
if (!dst_cset) |
|
goto err; |
|
|
|
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(&dst_cset->mg_preload_node, &csets); |
|
else |
|
put_css_set(dst_cset); |
|
} |
|
|
|
list_splice_tail(&csets, preloaded_csets); |
|
return 0; |
|
err: |
|
cgroup_migrate_finish(&csets); |
|
return -ENOMEM; |
|
} |
|
|
|
/** |
|
* 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 |
|
* @root: cgroup root migration is taking place on |
|
* |
|
* 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. |
|
*/ |
|
static int cgroup_migrate(struct task_struct *leader, bool threadgroup, |
|
struct cgroup_root *root) |
|
{ |
|
struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
|
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_taskset_add(task, &tset); |
|
if (!threadgroup) |
|
break; |
|
} while_each_thread(leader, task); |
|
rcu_read_unlock(); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
return cgroup_taskset_migrate(&tset, root); |
|
} |
|
|
|
/** |
|
* 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. |
|
*/ |
|
static int cgroup_attach_task(struct cgroup *dst_cgrp, |
|
struct task_struct *leader, bool threadgroup) |
|
{ |
|
LIST_HEAD(preloaded_csets); |
|
struct task_struct *task; |
|
int ret; |
|
|
|
if (!cgroup_may_migrate_to(dst_cgrp)) |
|
return -EBUSY; |
|
|
|
/* 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, |
|
&preloaded_csets); |
|
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(&preloaded_csets); |
|
if (!ret) |
|
ret = cgroup_migrate(leader, threadgroup, dst_cgrp->root); |
|
|
|
cgroup_migrate_finish(&preloaded_csets); |
|
|
|
if (!ret) |
|
trace_cgroup_attach_task(dst_cgrp, leader, threadgroup); |
|
|
|
return ret; |
|
} |
|
|
|
static int cgroup_procs_write_permission(struct task_struct *task, |
|
struct cgroup *dst_cgrp, |
|
struct kernfs_open_file *of) |
|
{ |
|
const struct cred *cred = current_cred(); |
|
const struct cred *tcred = get_task_cred(task); |
|
int ret = 0; |
|
|
|
/* |
|
* even if we're attaching all tasks in the thread group, we only |
|
* need to check permissions on one of them. |
|
*/ |
|
if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) && |
|
!uid_eq(cred->euid, tcred->uid) && |
|
!uid_eq(cred->euid, tcred->suid)) |
|
ret = -EACCES; |
|
|
|
if (!ret && cgroup_on_dfl(dst_cgrp)) { |
|
struct super_block *sb = of->file->f_path.dentry->d_sb; |
|
struct cgroup *cgrp; |
|
struct inode *inode; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
cgrp = task_cgroup_from_root(task, &cgrp_dfl_root); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
while (!cgroup_is_descendant(dst_cgrp, cgrp)) |
|
cgrp = cgroup_parent(cgrp); |
|
|
|
ret = -ENOMEM; |
|
inode = kernfs_get_inode(sb, cgrp->procs_file.kn); |
|
if (inode) { |
|
ret = inode_permission(inode, MAY_WRITE); |
|
iput(inode); |
|
} |
|
} |
|
|
|
put_cred(tcred); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Find the task_struct of the task to attach by vpid and pass it along to the |
|
* function to attach either it or all tasks in its threadgroup. Will lock |
|
* cgroup_mutex and threadgroup. |
|
*/ |
|
static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf, |
|
size_t nbytes, loff_t off, bool threadgroup) |
|
{ |
|
struct task_struct *tsk; |
|
struct cgroup_subsys *ss; |
|
struct cgroup *cgrp; |
|
pid_t pid; |
|
int ssid, ret; |
|
|
|
if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0) |
|
return -EINVAL; |
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, false); |
|
if (!cgrp) |
|
return -ENODEV; |
|
|
|
percpu_down_write(&cgroup_threadgroup_rwsem); |
|
rcu_read_lock(); |
|
if (pid) { |
|
tsk = find_task_by_vpid(pid); |
|
if (!tsk) { |
|
ret = -ESRCH; |
|
goto out_unlock_rcu; |
|
} |
|
} 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)) { |
|
ret = -EINVAL; |
|
goto out_unlock_rcu; |
|
} |
|
|
|
get_task_struct(tsk); |
|
rcu_read_unlock(); |
|
|
|
ret = cgroup_procs_write_permission(tsk, cgrp, of); |
|
if (!ret) |
|
ret = cgroup_attach_task(cgrp, tsk, threadgroup); |
|
|
|
put_task_struct(tsk); |
|
goto out_unlock_threadgroup; |
|
|
|
out_unlock_rcu: |
|
rcu_read_unlock(); |
|
out_unlock_threadgroup: |
|
percpu_up_write(&cgroup_threadgroup_rwsem); |
|
for_each_subsys(ss, ssid) |
|
if (ss->post_attach) |
|
ss->post_attach(); |
|
cgroup_kn_unlock(of->kn); |
|
return ret ?: nbytes; |
|
} |
|
|
|
/** |
|
* cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from' |
|
* @from: attach to all cgroups of a given task |
|
* @tsk: the task to be attached |
|
*/ |
|
int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk) |
|
{ |
|
struct cgroup_root *root; |
|
int retval = 0; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
percpu_down_write(&cgroup_threadgroup_rwsem); |
|
for_each_root(root) { |
|
struct cgroup *from_cgrp; |
|
|
|
if (root == &cgrp_dfl_root) |
|
continue; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
from_cgrp = task_cgroup_from_root(from, root); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
retval = cgroup_attach_task(from_cgrp, tsk, false); |
|
if (retval) |
|
break; |
|
} |
|
percpu_up_write(&cgroup_threadgroup_rwsem); |
|
mutex_unlock(&cgroup_mutex); |
|
|
|
return retval; |
|
} |
|
EXPORT_SYMBOL_GPL(cgroup_attach_task_all); |
|
|
|
static ssize_t cgroup_tasks_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, loff_t off) |
|
{ |
|
return __cgroup_procs_write(of, buf, nbytes, off, false); |
|
} |
|
|
|
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, nbytes, off, true); |
|
} |
|
|
|
static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, loff_t off) |
|
{ |
|
struct cgroup *cgrp; |
|
|
|
BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); |
|
|
|
cgrp = cgroup_kn_lock_live(of->kn, false); |
|
if (!cgrp) |
|
return -ENODEV; |
|
spin_lock(&release_agent_path_lock); |
|
strlcpy(cgrp->root->release_agent_path, strstrip(buf), |
|
sizeof(cgrp->root->release_agent_path)); |
|
spin_unlock(&release_agent_path_lock); |
|
cgroup_kn_unlock(of->kn); |
|
return nbytes; |
|
} |
|
|
|
static int cgroup_release_agent_show(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup *cgrp = seq_css(seq)->cgroup; |
|
|
|
spin_lock(&release_agent_path_lock); |
|
seq_puts(seq, cgrp->root->release_agent_path); |
|
spin_unlock(&release_agent_path_lock); |
|
seq_putc(seq, '\n'); |
|
return 0; |
|
} |
|
|
|
static int cgroup_sane_behavior_show(struct seq_file *seq, void *v) |
|
{ |
|
seq_puts(seq, "0\n"); |
|
return 0; |
|
} |
|
|
|
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_printf(seq, "%s", 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) |
|
{ |
|
LIST_HEAD(preloaded_csets); |
|
struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset); |
|
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, |
|
&preloaded_csets); |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
/* NULL dst indicates self on default hierarchy */ |
|
ret = cgroup_migrate_prepare_dst(&preloaded_csets); |
|
if (ret) |
|
goto out_finish; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) { |
|
struct task_struct *task, *ntask; |
|
|
|
/* src_csets precede dst_csets, break on the first dst_cset */ |
|
if (!src_cset->mg_src_cgrp) |
|
break; |
|
|
|
/* all tasks in src_csets need to be migrated */ |
|
list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list) |
|
cgroup_taskset_add(task, &tset); |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
ret = cgroup_taskset_migrate(&tset, cgrp->root); |
|
out_finish: |
|
cgroup_migrate_finish(&preloaded_csets); |
|
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. |
|
*/ |
|
static 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(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 of a subtree |
|
* @cgrp: root of the target subtree |
|
* |
|
* Save ->subtree_control and ->subtree_ss_mask 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; |
|
} |
|
} |
|
|
|
/** |
|
* 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 of a subtree |
|
* @cgrp: root of the target subtree |
|
* |
|
* Restore ->subtree_control and ->subtree_ss_mask 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; |
|
} |
|
} |
|
|
|
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_disble(). |
|
*/ |
|
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); |
|
|
|
WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt)); |
|
|
|
if (!(cgroup_ss_mask(dsct) & (1 << ss->id))) |
|
continue; |
|
|
|
if (!css) { |
|
css = css_create(dsct, ss); |
|
if (IS_ERR(css)) |
|
return PTR_ERR(css); |
|
} |
|
|
|
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); |
|
|
|
WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt)); |
|
|
|
if (!css) |
|
continue; |
|
|
|
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() 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); |
|
} |
|
|
|
/* 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; |
|
} |
|
|
|
/* |
|
* Except for the root, subtree_control must be zero for a cgroup |
|
* with tasks so that child cgroups don't compete against tasks. |
|
*/ |
|
if (enable && cgroup_parent(cgrp)) { |
|
struct cgrp_cset_link *link; |
|
|
|
/* |
|
* Because namespaces pin csets too, @cgrp->cset_links |
|
* might not be empty even when @cgrp is empty. Walk and |
|
* verify each cset. |
|
*/ |
|
spin_lock_irq(&css_set_lock); |
|
|
|
ret = 0; |
|
list_for_each_entry(link, &cgrp->cset_links, cset_link) { |
|
if (css_set_populated(link->cset)) { |
|
ret = -EBUSY; |
|
break; |
|
} |
|
} |
|
|
|
spin_unlock_irq(&css_set_lock); |
|
|
|
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); |
|
|
|
kernfs_activate(cgrp->kn); |
|
ret = 0; |
|
out_unlock: |
|
cgroup_kn_unlock(of->kn); |
|
return ret ?: nbytes; |
|
} |
|
|
|
static int cgroup_events_show(struct seq_file *seq, void *v) |
|
{ |
|
seq_printf(seq, "populated %d\n", |
|
cgroup_is_populated(seq_css(seq)->cgroup)); |
|
return 0; |
|
} |
|
|
|
static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf, |
|
size_t nbytes, loff_t off) |
|
{ |
|
struct cgroup *cgrp = of->kn->parent->priv; |
|
struct cftype *cft = of->kn->priv; |
|
struct cgroup_subsys_state *css; |
|
int ret; |
|
|
|
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 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) |
|
{ |
|
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, |
|
.write = cgroup_file_write, |
|
.seq_show = cgroup_seqfile_show, |
|
}; |
|
|
|
static struct kernfs_ops cgroup_kf_ops = { |
|
.atomic_write_len = PAGE_SIZE, |
|
.write = cgroup_file_write, |
|
.seq_start = cgroup_seqfile_start, |
|
.seq_next = cgroup_seqfile_next, |
|
.seq_stop = cgroup_seqfile_stop, |
|
.seq_show = cgroup_seqfile_show, |
|
}; |
|
|
|
/* |
|
* cgroup_rename - Only allow simple rename of directories in place. |
|
*/ |
|
static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent, |
|
const char *new_name_str) |
|
{ |
|
struct cgroup *cgrp = kn->priv; |
|
int ret; |
|
|
|
if (kernfs_type(kn) != KERNFS_DIR) |
|
return -ENOTDIR; |
|
if (kn->parent != new_parent) |
|
return -EIO; |
|
|
|
/* |
|
* This isn't a proper migration and its usefulness is very |
|
* limited. Disallow on the default hierarchy. |
|
*/ |
|
if (cgroup_on_dfl(cgrp)) |
|
return -EPERM; |
|
|
|
/* |
|
* We're gonna grab cgroup_mutex which nests outside kernfs |
|
* active_ref. kernfs_rename() doesn't require active_ref |
|
* protection. Break them before grabbing cgroup_mutex. |
|
*/ |
|
kernfs_break_active_protection(new_parent); |
|
kernfs_break_active_protection(kn); |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
ret = kernfs_rename(kn, new_parent, new_name_str); |
|
if (!ret) |
|
trace_cgroup_rename(cgrp); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
|
|
kernfs_unbreak_active_protection(kn); |
|
kernfs_unbreak_active_protection(new_parent); |
|
return ret; |
|
} |
|
|
|
/* 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 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), 0, cft->kf_ops, (void *)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; |
|
|
|
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_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 (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) |
|
{ |
|
LIST_HEAD(pending); |
|
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); |
|
|
|
pax_open_kernel(); |
|
const_cast(cft->kf_ops) = NULL; |
|
const_cast(cft->ss) = NULL; |
|
|
|
/* revert flags set by cgroup core while adding @cfts */ |
|
const_cast(cft->flags) &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL); |
|
pax_close_kernel(); |
|
} |
|
} |
|
|
|
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->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; |
|
} |
|
|
|
pax_open_kernel(); |
|
const_cast(cft->kf_ops) = kf_ops; |
|
const_cast(cft->ss) = ss; |
|
pax_close_kernel(); |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static int cgroup_rm_cftypes_locked(struct cftype *cfts) |
|
{ |
|
lockdep_assert_held(&cgroup_mutex); |
|
|
|
if (!cfts || !cfts[0].ss) |
|
return -ENOENT; |
|
|
|
pax_list_del((struct list_head *)&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); |
|
|
|
pax_list_add_tail((struct list_head *)&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; |
|
|
|
pax_open_kernel(); |
|
for (cft = cfts; cft && cft->name[0] != '\0'; cft++) |
|
const_cast(cft->flags) |= __CFTYPE_ONLY_ON_DFL; |
|
pax_close_kernel(); |
|
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; |
|
|
|
pax_open_kernel(); |
|
for (cft = cfts; cft && cft->name[0] != '\0'; cft++) |
|
const_cast(cft->flags) |= __CFTYPE_NOT_ON_DFL; |
|
pax_close_kernel(); |
|
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) |
|
kernfs_notify(cfile->kn); |
|
spin_unlock_irqrestore(&cgroup_file_kn_lock, flags); |
|
} |
|
|
|
/** |
|
* cgroup_task_count - count the number of tasks in a cgroup. |
|
* @cgrp: the cgroup in question |
|
* |
|
* Return the number of tasks in the cgroup. The returned number can be |
|
* higher than the actual number of tasks due to css_set references from |
|
* namespace roots and temporary usages. |
|
*/ |
|
static int cgroup_task_count(const struct cgroup *cgrp) |
|
{ |
|
int count = 0; |
|
struct cgrp_cset_link *link; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
list_for_each_entry(link, &cgrp->cset_links, cset_link) |
|
count += atomic_read(&link->cset->refcount); |
|
spin_unlock_irq(&css_set_lock); |
|
return count; |
|
} |
|
|
|
/** |
|
* 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() inbetween 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) |
|
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; |
|
} |
|
|
|
/** |
|
* 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; |
|
} |
|
|
|
/** |
|
* css_task_iter_advance_css_set - advance a task itererator 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 list_head *l = it->cset_pos; |
|
struct cgrp_cset_link *link; |
|
struct css_set *cset; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
|
|
/* Advance to the next non-empty css_set */ |
|
do { |
|
l = l->next; |
|
if (l == it->cset_head) { |
|
it->cset_pos = NULL; |
|
it->task_pos = NULL; |
|
return; |
|
} |
|
|
|
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; |
|
} |
|
} while (!css_set_populated(cset)); |
|
|
|
it->cset_pos = l; |
|
|
|
if (!list_empty(&cset->tasks)) |
|
it->task_pos = cset->tasks.next; |
|
else |
|
it->task_pos = cset->mg_tasks.next; |
|
|
|
it->tasks_head = &cset->tasks; |
|
it->mg_tasks_head = &cset->mg_tasks; |
|
|
|
/* |
|
* 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_advance(struct css_task_iter *it) |
|
{ |
|
struct list_head *l = it->task_pos; |
|
|
|
lockdep_assert_held(&css_set_lock); |
|
WARN_ON_ONCE(!l); |
|
|
|
/* |
|
* Advance iterator to find next entry. cset->tasks is consumed |
|
* first and then ->mg_tasks. After ->mg_tasks, we move onto the |
|
* next cset. |
|
*/ |
|
l = l->next; |
|
|
|
if (l == it->tasks_head) |
|
l = it->mg_tasks_head->next; |
|
|
|
if (l == it->mg_tasks_head) |
|
css_task_iter_advance_css_set(it); |
|
else |
|
it->task_pos = l; |
|
} |
|
|
|
/** |
|
* css_task_iter_start - initiate task iteration |
|
* @css: the css to walk tasks of |
|
* @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, |
|
struct css_task_iter *it) |
|
{ |
|
/* no one should try to iterate before mounting cgroups */ |
|
WARN_ON_ONCE(!use_task_css_set_links); |
|
|
|
memset(it, 0, sizeof(*it)); |
|
|
|
spin_lock_irq(&css_set_lock); |
|
|
|
it->ss = css->ss; |
|
|
|
if (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_css_set(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); |
|
|
|
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_task) |
|
put_task_struct(it->cur_task); |
|
} |
|
|
|
/** |
|
* cgroup_trasnsfer_tasks - move tasks from one cgroup to another |
|
* @to: cgroup to which the tasks will be moved |
|
* @from: cgroup in which the tasks currently reside |
|
* |
|
* Locking rules between cgroup_post_fork() and the migration path |
|
* guarantee that, if a task is forking while being migrated, the new child |
|
* is guaranteed to be either visible in the source cgroup after the |
|
* parent's migration is complete or put into the target cgroup. No task |
|
* can slip out of migration through forking. |
|
*/ |
|
int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from) |
|
{ |
|
LIST_HEAD(preloaded_csets); |
|
struct cgrp_cset_link *link; |
|
struct css_task_iter it; |
|
struct task_struct *task; |
|
int ret; |
|
|
|
if (!cgroup_may_migrate_to(to)) |
|
return -EBUSY; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
percpu_down_write(&cgroup_threadgroup_rwsem); |
|
|
|
/* all tasks in @from are being moved, all csets are source */ |
|
spin_lock_irq(&css_set_lock); |
|
list_for_each_entry(link, &from->cset_links, cset_link) |
|
cgroup_migrate_add_src(link->cset, to, &preloaded_csets); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
ret = cgroup_migrate_prepare_dst(&preloaded_csets); |
|
if (ret) |
|
goto out_err; |
|
|
|
/* |
|
* Migrate tasks one-by-one until @from is empty. This fails iff |
|
* ->can_attach() fails. |
|
*/ |
|
do { |
|
css_task_iter_start(&from->self, &it); |
|
task = css_task_iter_next(&it); |
|
if (task) |
|
get_task_struct(task); |
|
css_task_iter_end(&it); |
|
|
|
if (task) { |
|
ret = cgroup_migrate(task, false, to->root); |
|
if (!ret) |
|
trace_cgroup_transfer_tasks(to, task, false); |
|
put_task_struct(task); |
|
} |
|
} while (task && !ret); |
|
out_err: |
|
cgroup_migrate_finish(&preloaded_csets); |
|
percpu_up_write(&cgroup_threadgroup_rwsem); |
|
mutex_unlock(&cgroup_mutex); |
|
return ret; |
|
} |
|
|
|
/* |
|
* Stuff for reading the 'tasks'/'procs' files. |
|
* |
|
* Reading this file can return large amounts of data if a cgroup has |
|
* *lots* of attached tasks. So it may need several calls to read(), |
|
* but we cannot guarantee that the information we produce is correct |
|
* unless we produce it entirely atomically. |
|
* |
|
*/ |
|
|
|
/* which pidlist file are we talking about? */ |
|
enum cgroup_filetype { |
|
CGROUP_FILE_PROCS, |
|
CGROUP_FILE_TASKS, |
|
}; |
|
|
|
/* |
|
* A pidlist is a list of pids that virtually represents the contents of one |
|
* of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists, |
|
* a pair (one each for procs, tasks) for each pid namespace that's relevant |
|
* to the cgroup. |
|
*/ |
|
struct cgroup_pidlist { |
|
/* |
|
* used to find which pidlist is wanted. doesn't change as long as |
|
* this particular list stays in the list. |
|
*/ |
|
struct { enum cgroup_filetype type; struct pid_namespace *ns; } key; |
|
/* array of xids */ |
|
pid_t *list; |
|
/* how many elements the above list has */ |
|
int length; |
|
/* each of these stored in a list by its cgroup */ |
|
struct list_head links; |
|
/* pointer to the cgroup we belong to, for list removal purposes */ |
|
struct cgroup *owner; |
|
/* for delayed destruction */ |
|
struct delayed_work destroy_dwork; |
|
}; |
|
|
|
/* |
|
* The following two functions "fix" the issue where there are more pids |
|
* than kmalloc will give memory for; in such cases, we use vmalloc/vfree. |
|
* TODO: replace with a kernel-wide solution to this problem |
|
*/ |
|
#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2)) |
|
static void *pidlist_allocate(int count) |
|
{ |
|
if (PIDLIST_TOO_LARGE(count)) |
|
return vmalloc(count * sizeof(pid_t)); |
|
else |
|
return kmalloc(count * sizeof(pid_t), GFP_KERNEL); |
|
} |
|
|
|
static void pidlist_free(void *p) |
|
{ |
|
kvfree(p); |
|
} |
|
|
|
/* |
|
* Used to destroy all pidlists lingering waiting for destroy timer. None |
|
* should be left afterwards. |
|
*/ |
|
static void cgroup_pidlist_destroy_all(struct cgroup *cgrp) |
|
{ |
|
struct cgroup_pidlist *l, *tmp_l; |
|
|
|
mutex_lock(&cgrp->pidlist_mutex); |
|
list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links) |
|
mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0); |
|
mutex_unlock(&cgrp->pidlist_mutex); |
|
|
|
flush_workqueue(cgroup_pidlist_destroy_wq); |
|
BUG_ON(!list_empty(&cgrp->pidlists)); |
|
} |
|
|
|
static void cgroup_pidlist_destroy_work_fn(struct work_struct *work) |
|
{ |
|
struct delayed_work *dwork = to_delayed_work(work); |
|
struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist, |
|
destroy_dwork); |
|
struct cgroup_pidlist *tofree = NULL; |
|
|
|
mutex_lock(&l->owner->pidlist_mutex); |
|
|
|
/* |
|
* Destroy iff we didn't get queued again. The state won't change |
|
* as destroy_dwork can only be queued while locked. |
|
*/ |
|
if (!delayed_work_pending(dwork)) { |
|
list_del(&l->links); |
|
pidlist_free(l->list); |
|
put_pid_ns(l->key.ns); |
|
tofree = l; |
|
} |
|
|
|
mutex_unlock(&l->owner->pidlist_mutex); |
|
kfree(tofree); |
|
} |
|
|
|
/* |
|
* pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries |
|
* Returns the number of unique elements. |
|
*/ |
|
static int pidlist_uniq(pid_t *list, int length) |
|
{ |
|
int src, dest = 1; |
|
|
|
/* |
|
* we presume the 0th element is unique, so i starts at 1. trivial |
|
* edge cases first; no work needs to be done for either |
|
*/ |
|
if (length == 0 || length == 1) |
|
return length; |
|
/* src and dest walk down the list; dest counts unique elements */ |
|
for (src = 1; src < length; src++) { |
|
/* find next unique element */ |
|
while (list[src] == list[src-1]) { |
|
src++; |
|
if (src == length) |
|
goto after; |
|
} |
|
/* dest always points to where the next unique element goes */ |
|
list[dest] = list[src]; |
|
dest++; |
|
} |
|
after: |
|
return dest; |
|
} |
|
|
|
/* |
|
* The two pid files - task and cgroup.procs - guaranteed that the result |
|
* is sorted, which forced this whole pidlist fiasco. As pid order is |
|
* different per namespace, each namespace needs differently sorted list, |
|
* making it impossible to use, for example, single rbtree of member tasks |
|
* sorted by task pointer. As pidlists can be fairly large, allocating one |
|
* per open file is dangerous, so cgroup had to implement shared pool of |
|
* pidlists keyed by cgroup and namespace. |
|
* |
|
* All this extra complexity was caused by the original implementation |
|
* committing to an entirely unnecessary property. In the long term, we |
|
* want to do away with it. Explicitly scramble sort order if on the |
|
* default hierarchy so that no such expectation exists in the new |
|
* interface. |
|
* |
|
* Scrambling is done by swapping every two consecutive bits, which is |
|
* non-identity one-to-one mapping which disturbs sort order sufficiently. |
|
*/ |
|
static pid_t pid_fry(pid_t pid) |
|
{ |
|
unsigned a = pid & 0x55555555; |
|
unsigned b = pid & 0xAAAAAAAA; |
|
|
|
return (a << 1) | (b >> 1); |
|
} |
|
|
|
static pid_t cgroup_pid_fry(struct cgroup *cgrp, pid_t pid) |
|
{ |
|
if (cgroup_on_dfl(cgrp)) |
|
return pid_fry(pid); |
|
else |
|
return pid; |
|
} |
|
|
|
static int cmppid(const void *a, const void *b) |
|
{ |
|
return *(pid_t *)a - *(pid_t *)b; |
|
} |
|
|
|
static int fried_cmppid(const void *a, const void *b) |
|
{ |
|
return pid_fry(*(pid_t *)a) - pid_fry(*(pid_t *)b); |
|
} |
|
|
|
static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp, |
|
enum cgroup_filetype type) |
|
{ |
|
struct cgroup_pidlist *l; |
|
/* don't need task_nsproxy() if we're looking at ourself */ |
|
struct pid_namespace *ns = task_active_pid_ns(current); |
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex); |
|
|
|
list_for_each_entry(l, &cgrp->pidlists, links) |
|
if (l->key.type == type && l->key.ns == ns) |
|
return l; |
|
return NULL; |
|
} |
|
|
|
/* |
|
* find the appropriate pidlist for our purpose (given procs vs tasks) |
|
* returns with the lock on that pidlist already held, and takes care |
|
* of the use count, or returns NULL with no locks held if we're out of |
|
* memory. |
|
*/ |
|
static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp, |
|
enum cgroup_filetype type) |
|
{ |
|
struct cgroup_pidlist *l; |
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex); |
|
|
|
l = cgroup_pidlist_find(cgrp, type); |
|
if (l) |
|
return l; |
|
|
|
/* entry not found; create a new one */ |
|
l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL); |
|
if (!l) |
|
return l; |
|
|
|
INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn); |
|
l->key.type = type; |
|
/* don't need task_nsproxy() if we're looking at ourself */ |
|
l->key.ns = get_pid_ns(task_active_pid_ns(current)); |
|
l->owner = cgrp; |
|
list_add(&l->links, &cgrp->pidlists); |
|
return l; |
|
} |
|
|
|
/* |
|
* Load a cgroup's pidarray with either procs' tgids or tasks' pids |
|
*/ |
|
static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type, |
|
struct cgroup_pidlist **lp) |
|
{ |
|
pid_t *array; |
|
int length; |
|
int pid, n = 0; /* used for populating the array */ |
|
struct css_task_iter it; |
|
struct task_struct *tsk; |
|
struct cgroup_pidlist *l; |
|
|
|
lockdep_assert_held(&cgrp->pidlist_mutex); |
|
|
|
/* |
|
* If cgroup gets more users after we read count, we won't have |
|
* enough space - tough. This race is indistinguishable to the |
|
* caller from the case that the additional cgroup users didn't |
|
* show up until sometime later on. |
|
*/ |
|
length = cgroup_task_count(cgrp); |
|
array = pidlist_allocate(length); |
|
if (!array) |
|
return -ENOMEM; |
|
/* now, populate the array */ |
|
css_task_iter_start(&cgrp->self, &it); |
|
while ((tsk = css_task_iter_next(&it))) { |
|
if (unlikely(n == length)) |
|
break; |
|
/* get tgid or pid for procs or tasks file respectively */ |
|
if (type == CGROUP_FILE_PROCS) |
|
pid = task_tgid_vnr(tsk); |
|
else |
|
pid = task_pid_vnr(tsk); |
|
if (pid > 0) /* make sure to only use valid results */ |
|
array[n++] = pid; |
|
} |
|
css_task_iter_end(&it); |
|
length = n; |
|
/* now sort & (if procs) strip out duplicates */ |
|
if (cgroup_on_dfl(cgrp)) |
|
sort(array, length, sizeof(pid_t), fried_cmppid, NULL); |
|
else |
|
sort(array, length, sizeof(pid_t), cmppid, NULL); |
|
if (type == CGROUP_FILE_PROCS) |
|
length = pidlist_uniq(array, length); |
|
|
|
l = cgroup_pidlist_find_create(cgrp, type); |
|
if (!l) { |
|
pidlist_free(array); |
|
return -ENOMEM; |
|
} |
|
|
|
/* store array, freeing old if necessary */ |
|
pidlist_free(l->list); |
|
l->list = array; |
|
l->length = length; |
|
*lp = l; |
|
return 0; |
|
} |
|
|
|
/** |
|
* cgroupstats_build - build and fill cgroupstats |
|
* @stats: cgroupstats to fill information into |
|
* @dentry: A dentry entry belonging to the cgroup for which stats have |
|
* been requested. |
|
* |
|
* Build and fill cgroupstats so that taskstats can export it to user |
|
* space. |
|
*/ |
|
int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) |
|
{ |
|
struct kernfs_node *kn = kernfs_node_from_dentry(dentry); |
|
struct cgroup *cgrp; |
|
struct css_task_iter it; |
|
struct task_struct *tsk; |
|
|
|
/* it should be kernfs_node belonging to cgroupfs and is a directory */ |
|
if (dentry->d_sb->s_type != &cgroup_fs_type || !kn || |
|
kernfs_type(kn) != KERNFS_DIR) |
|
return -EINVAL; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
/* |
|
* We aren't being called from kernfs and there's no guarantee on |
|
* @kn->priv's validity. For this and css_tryget_online_from_dir(), |
|
* @kn->priv is RCU safe. Let's do the RCU dancing. |
|
*/ |
|
rcu_read_lock(); |
|
cgrp = rcu_dereference(kn->priv); |
|
if (!cgrp || cgroup_is_dead(cgrp)) { |
|
rcu_read_unlock(); |
|
mutex_unlock(&cgroup_mutex); |
|
return -ENOENT; |
|
} |
|
rcu_read_unlock(); |
|
|
|
css_task_iter_start(&cgrp->self, &it); |
|
while ((tsk = css_task_iter_next(&it))) { |
|
switch (tsk->state) { |
|
case TASK_RUNNING: |
|
stats->nr_running++; |
|
break; |
|
case TASK_INTERRUPTIBLE: |
|
stats->nr_sleeping++; |
|
break; |
|
case TASK_UNINTERRUPTIBLE: |
|
stats->nr_uninterruptible++; |
|
break; |
|
case TASK_STOPPED: |
|
stats->nr_stopped++; |
|
break; |
|
default: |
|
if (delayacct_is_task_waiting_on_io(tsk)) |
|
stats->nr_io_wait++; |
|
break; |
|
} |
|
} |
|
css_task_iter_end(&it); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
return 0; |
|
} |
|
|
|
|
|
/* |
|
* seq_file methods for the tasks/procs files. The seq_file position is the |
|
* next pid to display; the seq_file iterator is a pointer to the pid |
|
* in the cgroup->l->list array. |
|
*/ |
|
|
|
static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos) |
|
{ |
|
/* |
|
* Initially we receive a position value that corresponds to |
|
* one more than the last pid shown (or 0 on the first call or |
|
* after a seek to the start). Use a binary-search to find the |
|
* next pid to display, if any |
|
*/ |
|
struct kernfs_open_file *of = s->private; |
|
struct cgroup *cgrp = seq_css(s)->cgroup; |
|
struct cgroup_pidlist *l; |
|
enum cgroup_filetype type = seq_cft(s)->private; |
|
int index = 0, pid = *pos; |
|
int *iter, ret; |
|
|
|
mutex_lock(&cgrp->pidlist_mutex); |
|
|
|
/* |
|
* !NULL @of->priv indicates that this isn't the first start() |
|
* after open. If the matching pidlist is around, we can use that. |
|
* Look for it. Note that @of->priv can't be used directly. It |
|
* could already have been destroyed. |
|
*/ |
|
if (of->priv) |
|
of->priv = cgroup_pidlist_find(cgrp, type); |
|
|
|
/* |
|
* Either this is the first start() after open or the matching |
|
* pidlist has been destroyed inbetween. Create a new one. |
|
*/ |
|
if (!of->priv) { |
|
ret = pidlist_array_load(cgrp, type, |
|
(struct cgroup_pidlist **)&of->priv); |
|
if (ret) |
|
return ERR_PTR(ret); |
|
} |
|
l = of->priv; |
|
|
|
if (pid) { |
|
int end = l->length; |
|
|
|
while (index < end) { |
|
int mid = (index + end) / 2; |
|
if (cgroup_pid_fry(cgrp, l->list[mid]) == pid) { |
|
index = mid; |
|
break; |
|
} else if (cgroup_pid_fry(cgrp, l->list[mid]) <= pid) |
|
index = mid + 1; |
|
else |
|
end = mid; |
|
} |
|
} |
|
/* If we're off the end of the array, we're done */ |
|
if (index >= l->length) |
|
return NULL; |
|
/* Update the abstract position to be the actual pid that we found */ |
|
iter = l->list + index; |
|
*pos = cgroup_pid_fry(cgrp, *iter); |
|
return iter; |
|
} |
|
|
|
static void cgroup_pidlist_stop(struct seq_file *s, void *v) |
|
{ |
|
struct kernfs_open_file *of = s->private; |
|
struct cgroup_pidlist *l = of->priv; |
|
|
|
if (l) |
|
mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, |
|
CGROUP_PIDLIST_DESTROY_DELAY); |
|
mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex); |
|
} |
|
|
|
static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) |
|
{ |
|
struct kernfs_open_file *of = s->private; |
|
struct cgroup_pidlist *l = of->priv; |
|
pid_t *p = v; |
|
pid_t *end = l->list + l->length; |
|
/* |
|
* Advance to the next pid in the array. If this goes off the |
|
* end, we're done |
|
*/ |
|
p++; |
|
if (p >= end) { |
|
return NULL; |
|
} else { |
|
*pos = cgroup_pid_fry(seq_css(s)->cgroup, *p); |
|
return p; |
|
} |
|
} |
|
|
|
static int cgroup_pidlist_show(struct seq_file *s, void *v) |
|
{ |
|
seq_printf(s, "%d\n", *(int *)v); |
|
|
|
return 0; |
|
} |
|
|
|
static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css, |
|
struct cftype *cft) |
|
{ |
|
return notify_on_release(css->cgroup); |
|
} |
|
|
|
static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css, |
|
struct cftype *cft, u64 val) |
|
{ |
|
if (val) |
|
set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
|
else |
|
clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags); |
|
return 0; |
|
} |
|
|
|
static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css, |
|
struct cftype *cft) |
|
{ |
|
return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
|
} |
|
|
|
static int cgroup_clone_children_write(struct cgroup_subsys_state *css, |
|
struct cftype *cft, u64 val) |
|
{ |
|
if (val) |
|
set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
|
else |
|
clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags); |
|
return 0; |
|
} |
|
|
|
/* cgroup core interface files for the default hierarchy */ |
|
static struct cftype cgroup_dfl_base_files[] = { |
|
{ |
|
.name = "cgroup.procs", |
|
.file_offset = offsetof(struct cgroup, procs_file), |
|
.seq_start = cgroup_pidlist_start, |
|
.seq_next = cgroup_pidlist_next, |
|
.seq_stop = cgroup_pidlist_stop, |
|
.seq_show = cgroup_pidlist_show, |
|
.private = CGROUP_FILE_PROCS, |
|
.write = cgroup_procs_write, |
|
}, |
|
{ |
|
.name = "cgroup.controllers", |
|
.seq_show = cgroup_controllers_show, |
|
}, |
|
{ |
|
.name = "cgroup.subtree_control", |
|
.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, |
|
}, |
|
{ } /* terminate */ |
|
}; |
|
|
|
/* cgroup core interface files for the legacy hierarchies */ |
|
static struct cftype cgroup_legacy_base_files[] = { |
|
{ |
|
.name = "cgroup.procs", |
|
.seq_start = cgroup_pidlist_start, |
|
.seq_next = cgroup_pidlist_next, |
|
.seq_stop = cgroup_pidlist_stop, |
|
.seq_show = cgroup_pidlist_show, |
|
.private = CGROUP_FILE_PROCS, |
|
.write = cgroup_procs_write, |
|
}, |
|
{ |
|
.name = "cgroup.clone_children", |
|
.read_u64 = cgroup_clone_children_read, |
|
.write_u64 = cgroup_clone_children_write, |
|
}, |
|
{ |
|
.name = "cgroup.sane_behavior", |
|
.flags = CFTYPE_ONLY_ON_ROOT, |
|
.seq_show = cgroup_sane_behavior_show, |
|
}, |
|
{ |
|
.name = "tasks", |
|
.seq_start = cgroup_pidlist_start, |
|
.seq_next = cgroup_pidlist_next, |
|
.seq_stop = cgroup_pidlist_stop, |
|
.seq_show = cgroup_pidlist_show, |
|
.private = CGROUP_FILE_TASKS, |
|
.write = cgroup_tasks_write, |
|
}, |
|
{ |
|
.name = "notify_on_release", |
|
.read_u64 = cgroup_read_notify_on_release, |
|
.write_u64 = cgroup_write_notify_on_release, |
|
}, |
|
{ |
|
.name = "release_agent", |
|
.flags = CFTYPE_ONLY_ON_ROOT, |
|
.seq_show = cgroup_release_agent_show, |
|
.write = cgroup_release_agent_write, |
|
.max_write_len = PATH_MAX - 1, |
|
}, |
|
{ } /* 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_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; |
|
|
|
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); |
|
cgroup_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); |
|
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_free_rcu_fn(struct rcu_head *rcu_head) |
|
{ |
|
struct cgroup_subsys_state *css = |
|
container_of(rcu_head, struct cgroup_subsys_state, rcu_head); |
|
|
|
INIT_WORK(&css->destroy_work, css_free_work_fn); |
|
queue_work(cgroup_destroy_wq, &css->destroy_work); |
|
} |
|
|
|
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 */ |
|
cgroup_idr_replace(&ss->css_idr, NULL, css->id); |
|
if (ss->css_released) |
|
ss->css_released(css); |
|
} else { |
|
/* cgroup release path */ |
|
trace_cgroup_release(cgrp); |
|
|
|
cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id); |
|
cgrp->id = -1; |
|
|
|
/* |
|
* 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); |
|
|
|
call_rcu(&css->rcu_head, css_free_rcu_fn); |
|
} |
|
|
|
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(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); |
|
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); |
|
} |
|
|
|
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_reset) |
|
ss->css_reset(css); |
|
|
|
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; |
|
|
|
if (ss->broken_hierarchy && !ss->warned_broken_hierarchy && |
|
cgroup_parent(parent)) { |
|
pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n", |
|
current->comm, current->pid, ss->name); |
|
if (!strcmp(ss->name, "memory")) |
|
pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n"); |
|
ss->warned_broken_hierarchy = true; |
|
} |
|
|
|
return css; |
|
|
|
err_list_del: |
|
list_del_rcu(&css->sibling); |
|
err_free_css: |
|
call_rcu(&css->rcu_head, css_free_rcu_fn); |
|
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) |
|
{ |
|
struct cgroup_root *root = parent->root; |
|
struct cgroup *cgrp, *tcgrp; |
|
int level = parent->level + 1; |
|
int ret; |
|
|
|
/* allocate the cgroup and its ID, 0 is reserved for the root */ |
|
cgrp = kzalloc(sizeof(*cgrp) + |
|
sizeof(cgrp->ancestor_ids[0]) * (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; |
|
|
|
/* |
|
* Temporarily set the pointer to NULL, so idr_find() won't return |
|
* a half-baked cgroup. |
|
*/ |
|
cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL); |
|
if (cgrp->id < 0) { |
|
ret = -ENOMEM; |
|
goto out_cancel_ref; |
|
} |
|
|
|
init_cgroup_housekeeping(cgrp); |
|
|
|
cgrp->self.parent = &parent->self; |
|
cgrp->root = root; |
|
cgrp->level = level; |
|
|
|
for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp)) |
|
cgrp->ancestor_ids[tcgrp->level] = tcgrp->id; |
|
|
|
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(parent); |
|
|
|
/* |
|
* @cgrp is now fully operational. If something fails after this |
|
* point, it'll be released via the normal destruction path. |
|
*/ |
|
cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id); |
|
|
|
/* |
|
* 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_cancel_ref: |
|
percpu_ref_exit(&cgrp->self.refcnt); |
|
out_free_cgrp: |
|
kfree(cgrp); |
|
return ERR_PTR(ret); |
|
} |
|
|
|
static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name, |
|
umode_t mode) |
|
{ |
|
struct cgroup *parent, *cgrp; |
|
struct kernfs_node *kn; |
|
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; |
|
|
|
cgrp = cgroup_create(parent); |
|
if (IS_ERR(cgrp)) { |
|
ret = PTR_ERR(cgrp); |
|
goto out_unlock; |
|
} |
|
|
|
/* create the directory */ |
|
kn = kernfs_create_dir(parent->kn, name, mode, cgrp); |
|
if (IS_ERR(kn)) { |
|
ret = PTR_ERR(kn); |
|
goto out_destroy; |
|
} |
|
cgrp->kn = kn; |
|
|
|
/* |
|
* This extra ref will be put in cgroup_free_fn() and guarantees |
|
* that @cgrp->kn is always accessible. |
|
*/ |
|
kernfs_get(kn); |
|
|
|
ret = cgroup_kn_set_ugid(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_mkdir(cgrp); |
|
|
|
/* let's create and online css's */ |
|
kernfs_activate(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 |
|
* initate 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); |
|
|
|
/* |
|
* 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_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); |
|
|
|
/* |
|
* Remove @cgrp directory along with the base files. @cgrp has an |
|
* extra ref on its kn. |
|
*/ |
|
kernfs_remove(cgrp->kn); |
|
|
|
check_for_release(cgroup_parent(cgrp)); |
|
|
|
/* put the base reference */ |
|
percpu_ref_kill(&cgrp->self.refcnt); |
|
|
|
return 0; |
|
}; |
|
|
|
static 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_rmdir(cgrp); |
|
|
|
cgroup_kn_unlock(kn); |
|
return ret; |
|
} |
|
|
|
static struct kernfs_syscall_ops cgroup_kf_syscall_ops = { |
|
.remount_fs = cgroup_remount, |
|
.show_options = cgroup_show_options, |
|
.mkdir = cgroup_mkdir, |
|
.rmdir = cgroup_rmdir, |
|
.rename = cgroup_rename, |
|
.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(cgroup_css(&cgrp_dfl_root.cgrp, ss)); |
|
/* 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_free_callback |= (bool)ss->free << 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_sb_opts __initdata opts; |
|
struct cgroup_subsys *ss; |
|
int i; |
|
|
|
init_cgroup_root(&cgrp_dfl_root, &opts); |
|
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_disable_mask __initdata; |
|
|
|
/** |
|
* 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(percpu_init_rwsem(&cgroup_threadgroup_rwsem)); |
|
BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files)); |
|
BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files)); |
|
|
|
/* |
|
* The latency of the synchronize_sched() 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); |
|
|
|
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_disable_mask & (1 << ssid)) { |
|
static_branch_disable(cgroup_subsys_enabled_key[ssid]); |
|
printk(KERN_INFO "Disabling %s control group subsystem\n", |
|
ss->name); |
|
continue; |
|
} |
|
|
|
if (cgroup_ssid_no_v1(ssid)) |
|
printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n", |
|
ss->name); |
|
|
|
cgrp_dfl_root.subsys_mask |= 1 << ss->id; |
|
|
|
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->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]); |
|
} |
|
|
|
/* 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("cgroups", 0, NULL, &proc_cgroupstats_operations)); |
|
|
|
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); |
|
|
|
/* |
|
* Used to destroy pidlists and separate to serve as flush domain. |
|
* Cap @max_active to 1 too. |
|
*/ |
|
cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy", |
|
0, 1); |
|
BUG_ON(!cgroup_pidlist_destroy_wq); |
|
|
|
return 0; |
|
} |
|
core_initcall(cgroup_wq_init); |
|
|
|
/* |
|
* 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; |
|
} |
|
|
|
/* Display information about each subsystem and each hierarchy */ |
|
static int proc_cgroupstats_show(struct seq_file *m, void *v) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int i; |
|
|
|
seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n"); |
|
/* |
|
* ideally we don't want subsystems moving around while we do this. |
|
* cgroup_mutex is also necessary to guarantee an atomic snapshot of |
|
* subsys/hierarchy state. |
|
*/ |
|
mutex_lock(&cgroup_mutex); |
|
|
|
for_each_subsys(ss, i) |
|
seq_printf(m, "%s\t%d\t%d\t%d\n", |
|
ss->legacy_name, ss->root->hierarchy_id, |
|
atomic_read(&ss->root->nr_cgrps), |
|
cgroup_ssid_enabled(i)); |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
return 0; |
|
} |
|
|
|
static int cgroupstats_open(struct inode *inode, struct file *file) |
|
{ |
|
return single_open(file, proc_cgroupstats_show, NULL); |
|
} |
|
|
|
static const struct file_operations proc_cgroupstats_operations = { |
|
.open = cgroupstats_open, |
|
.read = seq_read, |
|
.llseek = seq_lseek, |
|
.release = single_release, |
|
}; |
|
|
|
/** |
|
* 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 parent's css_set. Empty cg_list indicates that |
|
* @child isn't holding reference to its css_set. |
|
*/ |
|
void cgroup_fork(struct task_struct *child) |
|
{ |
|
RCU_INIT_POINTER(child->cgroups, &init_css_set); |
|
INIT_LIST_HEAD(&child->cg_list); |
|
} |
|
|
|
/** |
|
* cgroup_can_fork - called on a new task before the process is exposed |
|
* @child: the task in question. |
|
* |
|
* This calls the subsystem can_fork() callbacks. If the 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 cgroup_subsys *ss; |
|
int i, j, ret; |
|
|
|
do_each_subsys_mask(ss, i, have_canfork_callback) { |
|
ret = ss->can_fork(child); |
|
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); |
|
} |
|
|
|
return ret; |
|
} |
|
|
|
/** |
|
* cgroup_cancel_fork - called if a fork failed after cgroup_can_fork() |
|
* @child: the task in question |
|
* |
|
* This calls the cancel_fork() callbacks if a fork failed *after* |
|
* cgroup_can_fork() succeded. |
|
*/ |
|
void cgroup_cancel_fork(struct task_struct *child) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int i; |
|
|
|
for_each_subsys(ss, i) |
|
if (ss->cancel_fork) |
|
ss->cancel_fork(child); |
|
} |
|
|
|
/** |
|
* cgroup_post_fork - called on a new task after adding it to the task list |
|
* @child: the task in question |
|
* |
|
* Adds the task to the list running through its css_set if necessary and |
|
* call the subsystem fork() callbacks. Has to be after the task is |
|
* visible on the task list in case we race with the first call to |
|
* cgroup_task_iter_start() - to guarantee that the new task ends up on its |
|
* list. |
|
*/ |
|
void cgroup_post_fork(struct task_struct *child) |
|
{ |
|
struct cgroup_subsys *ss; |
|
int i; |
|
|
|
/* |
|
* This may race against cgroup_enable_task_cg_lists(). As that |
|
* function sets use_task_css_set_links before grabbing |
|
* tasklist_lock and we just went through tasklist_lock to add |
|
* @child, it's guaranteed that either we see the set |
|
* use_task_css_set_links or cgroup_enable_task_cg_lists() sees |
|
* @child during its iteration. |
|
* |
|
* If we won the race, @child is associated with %current's |
|
* css_set. Grabbing css_set_lock guarantees both that the |
|
* association is stable, and, on completion of the parent's |
|
* migration, @child is visible in the source of migration or |
|
* already in the destination cgroup. This guarantee is necessary |
|
* when implementing operations which need to migrate all tasks of |
|
* a cgroup to another. |
|
* |
|
* Note that if we lose to cgroup_enable_task_cg_lists(), @child |
|
* will remain in init_css_set. This is safe because all tasks are |
|
* in the init_css_set before cg_links is enabled and there's no |
|
* operation which transfers all tasks out of init_css_set. |
|
*/ |
|
if (use_task_css_set_links) { |
|
struct css_set *cset; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
cset = task_css_set(current); |
|
if (list_empty(&child->cg_list)) { |
|
get_css_set(cset); |
|
css_set_move_task(child, NULL, cset, false); |
|
} |
|
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(); |
|
} |
|
|
|
/** |
|
* cgroup_exit - detach cgroup from exiting task |
|
* @tsk: pointer to task_struct of exiting process |
|
* |
|
* Description: Detach cgroup from @tsk and release it. |
|
* |
|
* Note that cgroups marked notify_on_release force every task in |
|
* them to take the global cgroup_mutex mutex when exiting. |
|
* This could impact scaling on very large systems. Be reluctant to |
|
* use notify_on_release cgroups where very high task exit scaling |
|
* is required on large systems. |
|
* |
|
* We set the exiting tasks cgroup to the root cgroup (top_cgroup). We |
|
* call cgroup_exit() while the task is still competent to handle |
|
* notify_on_release(), then leave the task attached to the root cgroup in |
|
* each hierarchy for the remainder of its exit. No need to bother with |
|
* init_css_set refcnting. init_css_set never goes away and we can't race |
|
* with migration path - PF_EXITING is visible to migration path. |
|
*/ |
|
void cgroup_exit(struct task_struct *tsk) |
|
{ |
|
struct cgroup_subsys *ss; |
|
struct css_set *cset; |
|
int i; |
|
|
|
/* |
|
* Unlink from @tsk from its css_set. As migration path can't race |
|
* with us, we can check css_set and cg_list without synchronization. |
|
*/ |
|
cset = task_css_set(tsk); |
|
|
|
if (!list_empty(&tsk->cg_list)) { |
|
spin_lock_irq(&css_set_lock); |
|
css_set_move_task(tsk, cset, NULL, false); |
|
spin_unlock_irq(&css_set_lock); |
|
} else { |
|
get_css_set(cset); |
|
} |
|
|
|
/* see cgroup_post_fork() for details */ |
|
do_each_subsys_mask(ss, i, have_exit_callback) { |
|
ss->exit(tsk); |
|
} while_each_subsys_mask(); |
|
} |
|
|
|
void cgroup_free(struct task_struct *task) |
|
{ |
|
struct css_set *cset = task_css_set(task); |
|
struct cgroup_subsys *ss; |
|
int ssid; |
|
|
|
do_each_subsys_mask(ss, ssid, have_free_callback) { |
|
ss->free(task); |
|
} while_each_subsys_mask(); |
|
|
|
put_css_set(cset); |
|
} |
|
|
|
static void check_for_release(struct cgroup *cgrp) |
|
{ |
|
if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) && |
|
!css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp)) |
|
schedule_work(&cgrp->release_agent_work); |
|
} |
|
|
|
/* |
|
* Notify userspace when a cgroup is released, by running the |
|
* configured release agent with the name of the cgroup (path |
|
* relative to the root of cgroup file system) as the argument. |
|
* |
|
* Most likely, this user command will try to rmdir this cgroup. |
|
* |
|
* This races with the possibility that some other task will be |
|
* attached to this cgroup before it is removed, or that some other |
|
* user task will 'mkdir' a child cgroup of this cgroup. That's ok. |
|
* The presumed 'rmdir' will fail quietly if this cgroup is no longer |
|
* unused, and this cgroup will be reprieved from its death sentence, |
|
* to continue to serve a useful existence. Next time it's released, |
|
* we will get notified again, if it still has 'notify_on_release' set. |
|
* |
|
* The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which |
|
* means only wait until the task is successfully execve()'d. The |
|
* separate release agent task is forked by call_usermodehelper(), |
|
* then control in this thread returns here, without waiting for the |
|
* release agent task. We don't bother to wait because the caller of |
|
* this routine has no use for the exit status of the release agent |
|
* task, so no sense holding our caller up for that. |
|
*/ |
|
static void cgroup_release_agent(struct work_struct *work) |
|
{ |
|
struct cgroup *cgrp = |
|
container_of(work, struct cgroup, release_agent_work); |
|
char *pathbuf = NULL, *agentbuf = NULL; |
|
char *argv[3], *envp[3]; |
|
int ret; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); |
|
agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); |
|
if (!pathbuf || !agentbuf) |
|
goto out; |
|
|
|
if (agentbuf[0] == '\0') |
|
goto out; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns); |
|
spin_unlock_irq(&css_set_lock); |
|
if (ret < 0 || ret >= PATH_MAX) |
|
goto out; |
|
|
|
argv[0] = agentbuf; |
|
argv[1] = pathbuf; |
|
argv[2] = NULL; |
|
|
|
/* minimal command environment */ |
|
envp[0] = "HOME=/"; |
|
envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin"; |
|
envp[2] = NULL; |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC); |
|
goto out_free; |
|
out: |
|
mutex_unlock(&cgroup_mutex); |
|
out_free: |
|
kfree(agentbuf); |
|
kfree(pathbuf); |
|
} |
|
|
|
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; |
|
cgroup_disable_mask |= 1 << i; |
|
} |
|
} |
|
return 1; |
|
} |
|
__setup("cgroup_disable=", cgroup_disable); |
|
|
|
static int __init cgroup_no_v1(char *str) |
|
{ |
|
struct cgroup_subsys *ss; |
|
char *token; |
|
int i; |
|
|
|
while ((token = strsep(&str, ",")) != NULL) { |
|
if (!*token) |
|
continue; |
|
|
|
if (!strcmp(token, "all")) { |
|
cgroup_no_v1_mask = U16_MAX; |
|
break; |
|
} |
|
|
|
for_each_subsys(ss, i) { |
|
if (strcmp(token, ss->name) && |
|
strcmp(token, ss->legacy_name)) |
|
continue; |
|
|
|
cgroup_no_v1_mask |= 1 << i; |
|
} |
|
} |
|
return 1; |
|
} |
|
__setup("cgroup_no_v1=", cgroup_no_v1); |
|
|
|
/** |
|
* 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(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 doens't exist 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; |
|
|
|
mutex_lock(&cgroup_mutex); |
|
|
|
kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path); |
|
if (kn) { |
|
if (kernfs_type(kn) == KERNFS_DIR) { |
|
cgrp = kn->priv; |
|
cgroup_get(cgrp); |
|
} else { |
|
cgrp = ERR_PTR(-ENOTDIR); |
|
} |
|
kernfs_put(kn); |
|
} else { |
|
cgrp = ERR_PTR(-ENOENT); |
|
} |
|
|
|
mutex_unlock(&cgroup_mutex); |
|
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_subsys_state *css; |
|
struct cgroup *cgrp; |
|
struct file *f; |
|
|
|
f = fget_raw(fd); |
|
if (!f) |
|
return ERR_PTR(-EBADF); |
|
|
|
css = css_tryget_online_from_dir(f->f_path.dentry, NULL); |
|
fput(f); |
|
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; |
|
} |
|
EXPORT_SYMBOL_GPL(cgroup_get_from_fd); |
|
|
|
/* |
|
* sock->sk_cgrp_data handling. For more info, see sock_cgroup_data |
|
* definition in cgroup-defs.h. |
|
*/ |
|
#ifdef CONFIG_SOCK_CGROUP_DATA |
|
|
|
#if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID) |
|
|
|
DEFINE_SPINLOCK(cgroup_sk_update_lock); |
|
static bool cgroup_sk_alloc_disabled __read_mostly; |
|
|
|
void cgroup_sk_alloc_disable(void) |
|
{ |
|
if (cgroup_sk_alloc_disabled) |
|
return; |
|
pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n"); |
|
cgroup_sk_alloc_disabled = true; |
|
} |
|
|
|
#else |
|
|
|
#define cgroup_sk_alloc_disabled false |
|
|
|
#endif |
|
|
|
void cgroup_sk_alloc(struct sock_cgroup_data *skcd) |
|
{ |
|
if (cgroup_sk_alloc_disabled) |
|
return; |
|
|
|
/* Socket clone path */ |
|
if (skcd->val) { |
|
cgroup_get(sock_cgroup_ptr(skcd)); |
|
return; |
|
} |
|
|
|
rcu_read_lock(); |
|
|
|
while (true) { |
|
struct css_set *cset; |
|
|
|
cset = task_css_set(current); |
|
if (likely(cgroup_tryget(cset->dfl_cgrp))) { |
|
skcd->val = (unsigned long)cset->dfl_cgrp; |
|
break; |
|
} |
|
cpu_relax(); |
|
} |
|
|
|
rcu_read_unlock(); |
|
} |
|
|
|
void cgroup_sk_free(struct sock_cgroup_data *skcd) |
|
{ |
|
cgroup_put(sock_cgroup_ptr(skcd)); |
|
} |
|
|
|
#endif /* CONFIG_SOCK_CGROUP_DATA */ |
|
|
|
/* cgroup namespaces */ |
|
|
|
static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns) |
|
{ |
|
return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES); |
|
} |
|
|
|
static void dec_cgroup_namespaces(struct ucounts *ucounts) |
|
{ |
|
dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES); |
|
} |
|
|
|
static struct cgroup_namespace *alloc_cgroup_ns(void) |
|
{ |
|
struct cgroup_namespace *new_ns; |
|
int ret; |
|
|
|
new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL); |
|
if (!new_ns) |
|
return ERR_PTR(-ENOMEM); |
|
ret = ns_alloc_inum(&new_ns->ns); |
|
if (ret) { |
|
kfree(new_ns); |
|
return ERR_PTR(ret); |
|
} |
|
atomic_set(&new_ns->count, 1); |
|
new_ns->ns.ops = &cgroupns_operations; |
|
return new_ns; |
|
} |
|
|
|
void free_cgroup_ns(struct cgroup_namespace *ns) |
|
{ |
|
put_css_set(ns->root_cset); |
|
dec_cgroup_namespaces(ns->ucounts); |
|
put_user_ns(ns->user_ns); |
|
ns_free_inum(&ns->ns); |
|
kfree(ns); |
|
} |
|
EXPORT_SYMBOL(free_cgroup_ns); |
|
|
|
struct cgroup_namespace *copy_cgroup_ns(unsigned long flags, |
|
struct user_namespace *user_ns, |
|
struct cgroup_namespace *old_ns) |
|
{ |
|
struct cgroup_namespace *new_ns; |
|
struct ucounts *ucounts; |
|
struct css_set *cset; |
|
|
|
BUG_ON(!old_ns); |
|
|
|
if (!(flags & CLONE_NEWCGROUP)) { |
|
get_cgroup_ns(old_ns); |
|
return old_ns; |
|
} |
|
|
|
/* Allow only sysadmin to create cgroup namespace. */ |
|
if (!ns_capable(user_ns, CAP_SYS_ADMIN)) |
|
return ERR_PTR(-EPERM); |
|
|
|
ucounts = inc_cgroup_namespaces(user_ns); |
|
if (!ucounts) |
|
return ERR_PTR(-ENOSPC); |
|
|
|
/* It is not safe to take cgroup_mutex here */ |
|
spin_lock_irq(&css_set_lock); |
|
cset = task_css_set(current); |
|
get_css_set(cset); |
|
spin_unlock_irq(&css_set_lock); |
|
|
|
new_ns = alloc_cgroup_ns(); |
|
if (IS_ERR(new_ns)) { |
|
put_css_set(cset); |
|
dec_cgroup_namespaces(ucounts); |
|
return new_ns; |
|
} |
|
|
|
new_ns->user_ns = get_user_ns(user_ns); |
|
new_ns->ucounts = ucounts; |
|
new_ns->root_cset = cset; |
|
|
|
return new_ns; |
|
} |
|
|
|
static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns) |
|
{ |
|
return container_of(ns, struct cgroup_namespace, ns); |
|
} |
|
|
|
static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns) |
|
{ |
|
struct cgroup_namespace *cgroup_ns = to_cg_ns(ns); |
|
|
|
if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) || |
|
!ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN)) |
|
return -EPERM; |
|
|
|
/* Don't need to do anything if we are attaching to our own cgroupns. */ |
|
if (cgroup_ns == nsproxy->cgroup_ns) |
|
return 0; |
|
|
|
get_cgroup_ns(cgroup_ns); |
|
put_cgroup_ns(nsproxy->cgroup_ns); |
|
nsproxy->cgroup_ns = cgroup_ns; |
|
|
|
return 0; |
|
} |
|
|
|
static struct ns_common *cgroupns_get(struct task_struct *task) |
|
{ |
|
struct cgroup_namespace *ns = NULL; |
|
struct nsproxy *nsproxy; |
|
|
|
task_lock(task); |
|
nsproxy = task->nsproxy; |
|
if (nsproxy) { |
|
ns = nsproxy->cgroup_ns; |
|
get_cgroup_ns(ns); |
|
} |
|
task_unlock(task); |
|
|
|
return ns ? &ns->ns : NULL; |
|
} |
|
|
|
static void cgroupns_put(struct ns_common *ns) |
|
{ |
|
put_cgroup_ns(to_cg_ns(ns)); |
|
} |
|
|
|
static struct user_namespace *cgroupns_owner(struct ns_common *ns) |
|
{ |
|
return to_cg_ns(ns)->user_ns; |
|
} |
|
|
|
const struct proc_ns_operations cgroupns_operations = { |
|
.name = "cgroup", |
|
.type = CLONE_NEWCGROUP, |
|
.get = cgroupns_get, |
|
.put = cgroupns_put, |
|
.install = cgroupns_install, |
|
.owner = cgroupns_owner, |
|
}; |
|
|
|
static __init int cgroup_namespaces_init(void) |
|
{ |
|
return 0; |
|
} |
|
subsys_initcall(cgroup_namespaces_init); |
|
|
|
#ifdef CONFIG_CGROUP_DEBUG |
|
static struct cgroup_subsys_state * |
|
debug_css_alloc(struct cgroup_subsys_state *parent_css) |
|
{ |
|
struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL); |
|
|
|
if (!css) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
return css; |
|
} |
|
|
|
static void debug_css_free(struct cgroup_subsys_state *css) |
|
{ |
|
kfree(css); |
|
} |
|
|
|
static u64 debug_taskcount_read(struct cgroup_subsys_state *css, |
|
struct cftype *cft) |
|
{ |
|
return cgroup_task_count(css->cgroup); |
|
} |
|
|
|
static u64 current_css_set_read(struct cgroup_subsys_state *css, |
|
struct cftype *cft) |
|
{ |
|
return (u64)(unsigned long)current->cgroups; |
|
} |
|
|
|
static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, |
|
struct cftype *cft) |
|
{ |
|
u64 count; |
|
|
|
rcu_read_lock(); |
|
count = atomic_read(&task_css_set(current)->refcount); |
|
rcu_read_unlock(); |
|
return count; |
|
} |
|
|
|
static int current_css_set_cg_links_read(struct seq_file *seq, void *v) |
|
{ |
|
struct cgrp_cset_link *link; |
|
struct css_set *cset; |
|
char *name_buf; |
|
|
|
name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL); |
|
if (!name_buf) |
|
return -ENOMEM; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
rcu_read_lock(); |
|
cset = rcu_dereference(current->cgroups); |
|
list_for_each_entry(link, &cset->cgrp_links, cgrp_link) { |
|
struct cgroup *c = link->cgrp; |
|
|
|
cgroup_name(c, name_buf, NAME_MAX + 1); |
|
seq_printf(seq, "Root %d group %s\n", |
|
c->root->hierarchy_id, name_buf); |
|
} |
|
rcu_read_unlock(); |
|
spin_unlock_irq(&css_set_lock); |
|
kfree(name_buf); |
|
return 0; |
|
} |
|
|
|
#define MAX_TASKS_SHOWN_PER_CSS 25 |
|
static int cgroup_css_links_read(struct seq_file *seq, void *v) |
|
{ |
|
struct cgroup_subsys_state *css = seq_css(seq); |
|
struct cgrp_cset_link *link; |
|
|
|
spin_lock_irq(&css_set_lock); |
|
list_for_each_entry(link, &css->cgroup->cset_links, cset_link) { |
|
struct css_set *cset = link->cset; |
|
struct task_struct *task; |
|
int count = 0; |
|
|
|
seq_printf(seq, "css_set %pK\n", cset); |
|
|
|
list_for_each_entry(task, &cset->tasks, cg_list) { |
|
if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
|
goto overflow; |
|
seq_printf(seq, " task %d\n", task_pid_vnr(task)); |
|
} |
|
|
|
list_for_each_entry(task, &cset->mg_tasks, cg_list) { |
|
if (count++ > MAX_TASKS_SHOWN_PER_CSS) |
|
goto overflow; |
|
seq_printf(seq, " task %d\n", task_pid_vnr(task)); |
|
} |
|
continue; |
|
overflow: |
|
seq_puts(seq, " ...\n"); |
|
} |
|
spin_unlock_irq(&css_set_lock); |
|
return 0; |
|
} |
|
|
|
static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft) |
|
{ |
|
return (!cgroup_is_populated(css->cgroup) && |
|
!css_has_online_children(&css->cgroup->self)); |
|
} |
|
|
|
static struct cftype debug_files[] = { |
|
{ |
|
.name = "taskcount", |
|
.read_u64 = debug_taskcount_read, |
|
}, |
|
|
|
{ |
|
.name = "current_css_set", |
|
.read_u64 = current_css_set_read, |
|
}, |
|
|
|
{ |
|
.name = "current_css_set_refcount", |
|
.read_u64 = current_css_set_refcount_read, |
|
}, |
|
|
|
{ |
|
.name = "current_css_set_cg_links", |
|
.seq_show = current_css_set_cg_links_read, |
|
}, |
|
|
|
{ |
|
.name = "cgroup_css_links", |
|
.seq_show = cgroup_css_links_read, |
|
}, |
|
|
|
{ |
|
.name = "releasable", |
|
.read_u64 = releasable_read, |
|
}, |
|
|
|
{ } /* terminate */ |
|
}; |
|
|
|
struct cgroup_subsys debug_cgrp_subsys = { |
|
.css_alloc = debug_css_alloc, |
|
.css_free = debug_css_free, |
|
.legacy_cftypes = debug_files, |
|
}; |
|
#endif /* CONFIG_CGROUP_DEBUG */
|
|
|