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861 lines
26 KiB
861 lines
26 KiB
/* SPDX-License-Identifier: GPL-2.0 */ |
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/* |
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* linux/cgroup-defs.h - basic definitions for cgroup |
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* |
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* This file provides basic type and interface. Include this file directly |
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* only if necessary to avoid cyclic dependencies. |
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*/ |
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#ifndef _LINUX_CGROUP_DEFS_H |
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#define _LINUX_CGROUP_DEFS_H |
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|
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#include <linux/limits.h> |
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#include <linux/list.h> |
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#include <linux/idr.h> |
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#include <linux/wait.h> |
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#include <linux/mutex.h> |
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#include <linux/rcupdate.h> |
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#include <linux/refcount.h> |
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#include <linux/percpu-refcount.h> |
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#include <linux/percpu-rwsem.h> |
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#include <linux/u64_stats_sync.h> |
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#include <linux/workqueue.h> |
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#include <linux/bpf-cgroup.h> |
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#include <linux/psi_types.h> |
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#ifdef CONFIG_CGROUPS |
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struct cgroup; |
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struct cgroup_root; |
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struct cgroup_subsys; |
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struct cgroup_taskset; |
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struct kernfs_node; |
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struct kernfs_ops; |
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struct kernfs_open_file; |
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struct seq_file; |
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struct poll_table_struct; |
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#define MAX_CGROUP_TYPE_NAMELEN 32 |
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#define MAX_CGROUP_ROOT_NAMELEN 64 |
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#define MAX_CFTYPE_NAME 64 |
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/* define the enumeration of all cgroup subsystems */ |
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#define SUBSYS(_x) _x ## _cgrp_id, |
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enum cgroup_subsys_id { |
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#include <linux/cgroup_subsys.h> |
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CGROUP_SUBSYS_COUNT, |
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}; |
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#undef SUBSYS |
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/* bits in struct cgroup_subsys_state flags field */ |
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enum { |
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CSS_NO_REF = (1 << 0), /* no reference counting for this css */ |
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CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */ |
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CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */ |
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CSS_VISIBLE = (1 << 3), /* css is visible to userland */ |
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CSS_DYING = (1 << 4), /* css is dying */ |
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}; |
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/* bits in struct cgroup flags field */ |
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enum { |
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/* Control Group requires release notifications to userspace */ |
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CGRP_NOTIFY_ON_RELEASE, |
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/* |
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* Clone the parent's configuration when creating a new child |
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* cpuset cgroup. For historical reasons, this option can be |
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* specified at mount time and thus is implemented here. |
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*/ |
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CGRP_CPUSET_CLONE_CHILDREN, |
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/* Control group has to be frozen. */ |
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CGRP_FREEZE, |
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/* Cgroup is frozen. */ |
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CGRP_FROZEN, |
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}; |
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/* cgroup_root->flags */ |
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enum { |
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CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */ |
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CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */ |
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/* |
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* Consider namespaces as delegation boundaries. If this flag is |
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* set, controller specific interface files in a namespace root |
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* aren't writeable from inside the namespace. |
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*/ |
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CGRP_ROOT_NS_DELEGATE = (1 << 3), |
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/* |
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* Enable cpuset controller in v1 cgroup to use v2 behavior. |
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*/ |
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CGRP_ROOT_CPUSET_V2_MODE = (1 << 4), |
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/* |
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* Enable legacy local memory.events. |
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*/ |
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CGRP_ROOT_MEMORY_LOCAL_EVENTS = (1 << 5), |
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/* |
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* Enable recursive subtree protection |
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*/ |
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CGRP_ROOT_MEMORY_RECURSIVE_PROT = (1 << 6), |
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}; |
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/* cftype->flags */ |
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enum { |
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CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */ |
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CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */ |
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CFTYPE_NS_DELEGATABLE = (1 << 2), /* writeable beyond delegation boundaries */ |
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CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */ |
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CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */ |
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CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */ |
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/* internal flags, do not use outside cgroup core proper */ |
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__CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */ |
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__CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */ |
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}; |
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/* |
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* cgroup_file is the handle for a file instance created in a cgroup which |
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* is used, for example, to generate file changed notifications. This can |
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* be obtained by setting cftype->file_offset. |
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*/ |
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struct cgroup_file { |
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/* do not access any fields from outside cgroup core */ |
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struct kernfs_node *kn; |
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unsigned long notified_at; |
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struct timer_list notify_timer; |
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}; |
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/* |
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* Per-subsystem/per-cgroup state maintained by the system. This is the |
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* fundamental structural building block that controllers deal with. |
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* |
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* Fields marked with "PI:" are public and immutable and may be accessed |
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* directly without synchronization. |
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*/ |
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struct cgroup_subsys_state { |
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/* PI: the cgroup that this css is attached to */ |
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struct cgroup *cgroup; |
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/* PI: the cgroup subsystem that this css is attached to */ |
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struct cgroup_subsys *ss; |
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/* reference count - access via css_[try]get() and css_put() */ |
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struct percpu_ref refcnt; |
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/* siblings list anchored at the parent's ->children */ |
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struct list_head sibling; |
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struct list_head children; |
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/* flush target list anchored at cgrp->rstat_css_list */ |
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struct list_head rstat_css_node; |
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/* |
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* PI: Subsys-unique ID. 0 is unused and root is always 1. The |
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* matching css can be looked up using css_from_id(). |
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*/ |
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int id; |
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unsigned int flags; |
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/* |
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* Monotonically increasing unique serial number which defines a |
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* uniform order among all csses. It's guaranteed that all |
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* ->children lists are in the ascending order of ->serial_nr and |
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* used to allow interrupting and resuming iterations. |
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*/ |
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u64 serial_nr; |
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/* |
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* Incremented by online self and children. Used to guarantee that |
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* parents are not offlined before their children. |
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*/ |
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atomic_t online_cnt; |
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/* percpu_ref killing and RCU release */ |
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struct work_struct destroy_work; |
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struct rcu_work destroy_rwork; |
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/* |
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* PI: the parent css. Placed here for cache proximity to following |
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* fields of the containing structure. |
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*/ |
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struct cgroup_subsys_state *parent; |
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}; |
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/* |
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* A css_set is a structure holding pointers to a set of |
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* cgroup_subsys_state objects. This saves space in the task struct |
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* object and speeds up fork()/exit(), since a single inc/dec and a |
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* list_add()/del() can bump the reference count on the entire cgroup |
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* set for a task. |
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*/ |
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struct css_set { |
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/* |
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* Set of subsystem states, one for each subsystem. This array is |
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* immutable after creation apart from the init_css_set during |
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* subsystem registration (at boot time). |
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*/ |
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struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
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/* reference count */ |
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refcount_t refcount; |
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/* |
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* For a domain cgroup, the following points to self. If threaded, |
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* to the matching cset of the nearest domain ancestor. The |
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* dom_cset provides access to the domain cgroup and its csses to |
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* which domain level resource consumptions should be charged. |
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*/ |
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struct css_set *dom_cset; |
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/* the default cgroup associated with this css_set */ |
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struct cgroup *dfl_cgrp; |
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/* internal task count, protected by css_set_lock */ |
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int nr_tasks; |
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/* |
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* Lists running through all tasks using this cgroup group. |
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* mg_tasks lists tasks which belong to this cset but are in the |
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* process of being migrated out or in. Protected by |
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* css_set_rwsem, but, during migration, once tasks are moved to |
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* mg_tasks, it can be read safely while holding cgroup_mutex. |
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*/ |
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struct list_head tasks; |
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struct list_head mg_tasks; |
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struct list_head dying_tasks; |
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/* all css_task_iters currently walking this cset */ |
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struct list_head task_iters; |
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/* |
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* On the default hierarhcy, ->subsys[ssid] may point to a css |
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* attached to an ancestor instead of the cgroup this css_set is |
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* associated with. The following node is anchored at |
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* ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to |
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* iterate through all css's attached to a given cgroup. |
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*/ |
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struct list_head e_cset_node[CGROUP_SUBSYS_COUNT]; |
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/* all threaded csets whose ->dom_cset points to this cset */ |
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struct list_head threaded_csets; |
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struct list_head threaded_csets_node; |
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/* |
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* List running through all cgroup groups in the same hash |
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* slot. Protected by css_set_lock |
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*/ |
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struct hlist_node hlist; |
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/* |
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* List of cgrp_cset_links pointing at cgroups referenced from this |
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* css_set. Protected by css_set_lock. |
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*/ |
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struct list_head cgrp_links; |
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/* |
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* List of csets participating in the on-going migration either as |
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* source or destination. Protected by cgroup_mutex. |
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*/ |
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struct list_head mg_preload_node; |
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struct list_head mg_node; |
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/* |
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* If this cset is acting as the source of migration the following |
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* two fields are set. mg_src_cgrp and mg_dst_cgrp are |
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* respectively the source and destination cgroups of the on-going |
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* migration. mg_dst_cset is the destination cset the target tasks |
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* on this cset should be migrated to. Protected by cgroup_mutex. |
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*/ |
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struct cgroup *mg_src_cgrp; |
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struct cgroup *mg_dst_cgrp; |
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struct css_set *mg_dst_cset; |
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/* dead and being drained, ignore for migration */ |
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bool dead; |
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/* For RCU-protected deletion */ |
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struct rcu_head rcu_head; |
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}; |
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struct cgroup_base_stat { |
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struct task_cputime cputime; |
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}; |
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/* |
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* rstat - cgroup scalable recursive statistics. Accounting is done |
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* per-cpu in cgroup_rstat_cpu which is then lazily propagated up the |
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* hierarchy on reads. |
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* |
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* When a stat gets updated, the cgroup_rstat_cpu and its ancestors are |
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* linked into the updated tree. On the following read, propagation only |
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* considers and consumes the updated tree. This makes reading O(the |
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* number of descendants which have been active since last read) instead of |
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* O(the total number of descendants). |
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* |
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* This is important because there can be a lot of (draining) cgroups which |
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* aren't active and stat may be read frequently. The combination can |
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* become very expensive. By propagating selectively, increasing reading |
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* frequency decreases the cost of each read. |
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* |
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* This struct hosts both the fields which implement the above - |
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* updated_children and updated_next - and the fields which track basic |
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* resource statistics on top of it - bsync, bstat and last_bstat. |
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*/ |
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struct cgroup_rstat_cpu { |
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/* |
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* ->bsync protects ->bstat. These are the only fields which get |
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* updated in the hot path. |
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*/ |
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struct u64_stats_sync bsync; |
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struct cgroup_base_stat bstat; |
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/* |
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* Snapshots at the last reading. These are used to calculate the |
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* deltas to propagate to the global counters. |
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*/ |
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struct cgroup_base_stat last_bstat; |
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/* |
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* Child cgroups with stat updates on this cpu since the last read |
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* are linked on the parent's ->updated_children through |
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* ->updated_next. |
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* |
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* In addition to being more compact, singly-linked list pointing |
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* to the cgroup makes it unnecessary for each per-cpu struct to |
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* point back to the associated cgroup. |
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* |
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* Protected by per-cpu cgroup_rstat_cpu_lock. |
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*/ |
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struct cgroup *updated_children; /* terminated by self cgroup */ |
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struct cgroup *updated_next; /* NULL iff not on the list */ |
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}; |
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struct cgroup_freezer_state { |
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/* Should the cgroup and its descendants be frozen. */ |
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bool freeze; |
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/* Should the cgroup actually be frozen? */ |
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int e_freeze; |
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/* Fields below are protected by css_set_lock */ |
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/* Number of frozen descendant cgroups */ |
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int nr_frozen_descendants; |
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/* |
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* Number of tasks, which are counted as frozen: |
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* frozen, SIGSTOPped, and PTRACEd. |
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*/ |
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int nr_frozen_tasks; |
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}; |
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struct cgroup { |
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/* self css with NULL ->ss, points back to this cgroup */ |
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struct cgroup_subsys_state self; |
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unsigned long flags; /* "unsigned long" so bitops work */ |
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/* |
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* The depth this cgroup is at. The root is at depth zero and each |
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* step down the hierarchy increments the level. This along with |
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* ancestor_ids[] can determine whether a given cgroup is a |
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* descendant of another without traversing the hierarchy. |
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*/ |
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int level; |
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/* Maximum allowed descent tree depth */ |
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int max_depth; |
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/* |
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* Keep track of total numbers of visible and dying descent cgroups. |
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* Dying cgroups are cgroups which were deleted by a user, |
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* but are still existing because someone else is holding a reference. |
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* max_descendants is a maximum allowed number of descent cgroups. |
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* |
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* nr_descendants and nr_dying_descendants are protected |
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* by cgroup_mutex and css_set_lock. It's fine to read them holding |
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* any of cgroup_mutex and css_set_lock; for writing both locks |
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* should be held. |
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*/ |
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int nr_descendants; |
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int nr_dying_descendants; |
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int max_descendants; |
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/* |
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* Each non-empty css_set associated with this cgroup contributes |
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* one to nr_populated_csets. The counter is zero iff this cgroup |
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* doesn't have any tasks. |
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* |
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* All children which have non-zero nr_populated_csets and/or |
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* nr_populated_children of their own contribute one to either |
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* nr_populated_domain_children or nr_populated_threaded_children |
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* depending on their type. Each counter is zero iff all cgroups |
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* of the type in the subtree proper don't have any tasks. |
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*/ |
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int nr_populated_csets; |
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int nr_populated_domain_children; |
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int nr_populated_threaded_children; |
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int nr_threaded_children; /* # of live threaded child cgroups */ |
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struct kernfs_node *kn; /* cgroup kernfs entry */ |
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struct cgroup_file procs_file; /* handle for "cgroup.procs" */ |
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struct cgroup_file events_file; /* handle for "cgroup.events" */ |
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/* |
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* The bitmask of subsystems enabled on the child cgroups. |
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* ->subtree_control is the one configured through |
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* "cgroup.subtree_control" while ->child_ss_mask is the effective |
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* one which may have more subsystems enabled. Controller knobs |
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* are made available iff it's enabled in ->subtree_control. |
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*/ |
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u16 subtree_control; |
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u16 subtree_ss_mask; |
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u16 old_subtree_control; |
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u16 old_subtree_ss_mask; |
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/* Private pointers for each registered subsystem */ |
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struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT]; |
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struct cgroup_root *root; |
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/* |
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* List of cgrp_cset_links pointing at css_sets with tasks in this |
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* cgroup. Protected by css_set_lock. |
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*/ |
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struct list_head cset_links; |
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/* |
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* On the default hierarchy, a css_set for a cgroup with some |
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* susbsys disabled will point to css's which are associated with |
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* the closest ancestor which has the subsys enabled. The |
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* following lists all css_sets which point to this cgroup's css |
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* for the given subsystem. |
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*/ |
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struct list_head e_csets[CGROUP_SUBSYS_COUNT]; |
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/* |
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* If !threaded, self. If threaded, it points to the nearest |
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* domain ancestor. Inside a threaded subtree, cgroups are exempt |
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* from process granularity and no-internal-task constraint. |
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* Domain level resource consumptions which aren't tied to a |
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* specific task are charged to the dom_cgrp. |
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*/ |
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struct cgroup *dom_cgrp; |
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struct cgroup *old_dom_cgrp; /* used while enabling threaded */ |
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/* per-cpu recursive resource statistics */ |
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struct cgroup_rstat_cpu __percpu *rstat_cpu; |
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struct list_head rstat_css_list; |
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/* cgroup basic resource statistics */ |
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struct cgroup_base_stat last_bstat; |
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struct cgroup_base_stat bstat; |
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struct prev_cputime prev_cputime; /* for printing out cputime */ |
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/* |
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* list of pidlists, up to two for each namespace (one for procs, one |
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* for tasks); created on demand. |
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*/ |
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struct list_head pidlists; |
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struct mutex pidlist_mutex; |
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/* used to wait for offlining of csses */ |
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wait_queue_head_t offline_waitq; |
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/* used to schedule release agent */ |
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struct work_struct release_agent_work; |
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/* used to track pressure stalls */ |
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struct psi_group psi; |
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/* used to store eBPF programs */ |
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struct cgroup_bpf bpf; |
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/* If there is block congestion on this cgroup. */ |
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atomic_t congestion_count; |
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/* Used to store internal freezer state */ |
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struct cgroup_freezer_state freezer; |
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/* ids of the ancestors at each level including self */ |
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u64 ancestor_ids[]; |
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}; |
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/* |
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* A cgroup_root represents the root of a cgroup hierarchy, and may be |
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* associated with a kernfs_root to form an active hierarchy. This is |
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* internal to cgroup core. Don't access directly from controllers. |
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*/ |
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struct cgroup_root { |
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struct kernfs_root *kf_root; |
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/* The bitmask of subsystems attached to this hierarchy */ |
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unsigned int subsys_mask; |
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/* Unique id for this hierarchy. */ |
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int hierarchy_id; |
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/* The root cgroup. Root is destroyed on its release. */ |
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struct cgroup cgrp; |
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/* for cgrp->ancestor_ids[0] */ |
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u64 cgrp_ancestor_id_storage; |
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/* Number of cgroups in the hierarchy, used only for /proc/cgroups */ |
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atomic_t nr_cgrps; |
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/* A list running through the active hierarchies */ |
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struct list_head root_list; |
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/* Hierarchy-specific flags */ |
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unsigned int flags; |
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/* The path to use for release notifications. */ |
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char release_agent_path[PATH_MAX]; |
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/* The name for this hierarchy - may be empty */ |
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char name[MAX_CGROUP_ROOT_NAMELEN]; |
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}; |
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/* |
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* struct cftype: handler definitions for cgroup control files |
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* |
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* When reading/writing to a file: |
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* - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata |
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* - the 'cftype' of the file is file->f_path.dentry->d_fsdata |
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*/ |
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struct cftype { |
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/* |
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* By convention, the name should begin with the name of the |
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* subsystem, followed by a period. Zero length string indicates |
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* end of cftype array. |
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*/ |
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char name[MAX_CFTYPE_NAME]; |
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unsigned long private; |
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/* |
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* The maximum length of string, excluding trailing nul, that can |
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* be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed. |
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*/ |
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size_t max_write_len; |
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|
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/* CFTYPE_* flags */ |
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unsigned int flags; |
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|
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/* |
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* If non-zero, should contain the offset from the start of css to |
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* a struct cgroup_file field. cgroup will record the handle of |
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* the created file into it. The recorded handle can be used as |
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* long as the containing css remains accessible. |
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*/ |
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unsigned int file_offset; |
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|
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/* |
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* Fields used for internal bookkeeping. Initialized automatically |
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* during registration. |
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*/ |
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struct cgroup_subsys *ss; /* NULL for cgroup core files */ |
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struct list_head node; /* anchored at ss->cfts */ |
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struct kernfs_ops *kf_ops; |
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int (*open)(struct kernfs_open_file *of); |
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void (*release)(struct kernfs_open_file *of); |
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|
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/* |
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* read_u64() is a shortcut for the common case of returning a |
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* single integer. Use it in place of read() |
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*/ |
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u64 (*read_u64)(struct cgroup_subsys_state *css, struct cftype *cft); |
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/* |
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* read_s64() is a signed version of read_u64() |
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*/ |
|
s64 (*read_s64)(struct cgroup_subsys_state *css, struct cftype *cft); |
|
|
|
/* generic seq_file read interface */ |
|
int (*seq_show)(struct seq_file *sf, void *v); |
|
|
|
/* optional ops, implement all or none */ |
|
void *(*seq_start)(struct seq_file *sf, loff_t *ppos); |
|
void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos); |
|
void (*seq_stop)(struct seq_file *sf, void *v); |
|
|
|
/* |
|
* write_u64() is a shortcut for the common case of accepting |
|
* a single integer (as parsed by simple_strtoull) from |
|
* userspace. Use in place of write(); return 0 or error. |
|
*/ |
|
int (*write_u64)(struct cgroup_subsys_state *css, struct cftype *cft, |
|
u64 val); |
|
/* |
|
* write_s64() is a signed version of write_u64() |
|
*/ |
|
int (*write_s64)(struct cgroup_subsys_state *css, struct cftype *cft, |
|
s64 val); |
|
|
|
/* |
|
* write() is the generic write callback which maps directly to |
|
* kernfs write operation and overrides all other operations. |
|
* Maximum write size is determined by ->max_write_len. Use |
|
* of_css/cft() to access the associated css and cft. |
|
*/ |
|
ssize_t (*write)(struct kernfs_open_file *of, |
|
char *buf, size_t nbytes, loff_t off); |
|
|
|
__poll_t (*poll)(struct kernfs_open_file *of, |
|
struct poll_table_struct *pt); |
|
|
|
#ifdef CONFIG_DEBUG_LOCK_ALLOC |
|
struct lock_class_key lockdep_key; |
|
#endif |
|
}; |
|
|
|
/* |
|
* Control Group subsystem type. |
|
* See Documentation/admin-guide/cgroup-v1/cgroups.rst for details |
|
*/ |
|
struct cgroup_subsys { |
|
struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css); |
|
int (*css_online)(struct cgroup_subsys_state *css); |
|
void (*css_offline)(struct cgroup_subsys_state *css); |
|
void (*css_released)(struct cgroup_subsys_state *css); |
|
void (*css_free)(struct cgroup_subsys_state *css); |
|
void (*css_reset)(struct cgroup_subsys_state *css); |
|
void (*css_rstat_flush)(struct cgroup_subsys_state *css, int cpu); |
|
int (*css_extra_stat_show)(struct seq_file *seq, |
|
struct cgroup_subsys_state *css); |
|
|
|
int (*can_attach)(struct cgroup_taskset *tset); |
|
void (*cancel_attach)(struct cgroup_taskset *tset); |
|
void (*attach)(struct cgroup_taskset *tset); |
|
void (*post_attach)(void); |
|
int (*can_fork)(struct task_struct *task, |
|
struct css_set *cset); |
|
void (*cancel_fork)(struct task_struct *task, struct css_set *cset); |
|
void (*fork)(struct task_struct *task); |
|
void (*exit)(struct task_struct *task); |
|
void (*release)(struct task_struct *task); |
|
void (*bind)(struct cgroup_subsys_state *root_css); |
|
|
|
bool early_init:1; |
|
|
|
/* |
|
* If %true, the controller, on the default hierarchy, doesn't show |
|
* up in "cgroup.controllers" or "cgroup.subtree_control", is |
|
* implicitly enabled on all cgroups on the default hierarchy, and |
|
* bypasses the "no internal process" constraint. This is for |
|
* utility type controllers which is transparent to userland. |
|
* |
|
* An implicit controller can be stolen from the default hierarchy |
|
* anytime and thus must be okay with offline csses from previous |
|
* hierarchies coexisting with csses for the current one. |
|
*/ |
|
bool implicit_on_dfl:1; |
|
|
|
/* |
|
* If %true, the controller, supports threaded mode on the default |
|
* hierarchy. In a threaded subtree, both process granularity and |
|
* no-internal-process constraint are ignored and a threaded |
|
* controllers should be able to handle that. |
|
* |
|
* Note that as an implicit controller is automatically enabled on |
|
* all cgroups on the default hierarchy, it should also be |
|
* threaded. implicit && !threaded is not supported. |
|
*/ |
|
bool threaded:1; |
|
|
|
/* the following two fields are initialized automtically during boot */ |
|
int id; |
|
const char *name; |
|
|
|
/* optional, initialized automatically during boot if not set */ |
|
const char *legacy_name; |
|
|
|
/* link to parent, protected by cgroup_lock() */ |
|
struct cgroup_root *root; |
|
|
|
/* idr for css->id */ |
|
struct idr css_idr; |
|
|
|
/* |
|
* List of cftypes. Each entry is the first entry of an array |
|
* terminated by zero length name. |
|
*/ |
|
struct list_head cfts; |
|
|
|
/* |
|
* Base cftypes which are automatically registered. The two can |
|
* point to the same array. |
|
*/ |
|
struct cftype *dfl_cftypes; /* for the default hierarchy */ |
|
struct cftype *legacy_cftypes; /* for the legacy hierarchies */ |
|
|
|
/* |
|
* A subsystem may depend on other subsystems. When such subsystem |
|
* is enabled on a cgroup, the depended-upon subsystems are enabled |
|
* together if available. Subsystems enabled due to dependency are |
|
* not visible to userland until explicitly enabled. The following |
|
* specifies the mask of subsystems that this one depends on. |
|
*/ |
|
unsigned int depends_on; |
|
}; |
|
|
|
extern struct percpu_rw_semaphore cgroup_threadgroup_rwsem; |
|
|
|
/** |
|
* cgroup_threadgroup_change_begin - threadgroup exclusion for cgroups |
|
* @tsk: target task |
|
* |
|
* Allows cgroup operations to synchronize against threadgroup changes |
|
* using a percpu_rw_semaphore. |
|
*/ |
|
static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) |
|
{ |
|
percpu_down_read(&cgroup_threadgroup_rwsem); |
|
} |
|
|
|
/** |
|
* cgroup_threadgroup_change_end - threadgroup exclusion for cgroups |
|
* @tsk: target task |
|
* |
|
* Counterpart of cgroup_threadcgroup_change_begin(). |
|
*/ |
|
static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) |
|
{ |
|
percpu_up_read(&cgroup_threadgroup_rwsem); |
|
} |
|
|
|
#else /* CONFIG_CGROUPS */ |
|
|
|
#define CGROUP_SUBSYS_COUNT 0 |
|
|
|
static inline void cgroup_threadgroup_change_begin(struct task_struct *tsk) |
|
{ |
|
might_sleep(); |
|
} |
|
|
|
static inline void cgroup_threadgroup_change_end(struct task_struct *tsk) {} |
|
|
|
#endif /* CONFIG_CGROUPS */ |
|
|
|
#ifdef CONFIG_SOCK_CGROUP_DATA |
|
|
|
/* |
|
* sock_cgroup_data is embedded at sock->sk_cgrp_data and contains |
|
* per-socket cgroup information except for memcg association. |
|
* |
|
* On legacy hierarchies, net_prio and net_cls controllers directly set |
|
* attributes on each sock which can then be tested by the network layer. |
|
* On the default hierarchy, each sock is associated with the cgroup it was |
|
* created in and the networking layer can match the cgroup directly. |
|
* |
|
* To avoid carrying all three cgroup related fields separately in sock, |
|
* sock_cgroup_data overloads (prioidx, classid) and the cgroup pointer. |
|
* On boot, sock_cgroup_data records the cgroup that the sock was created |
|
* in so that cgroup2 matches can be made; however, once either net_prio or |
|
* net_cls starts being used, the area is overriden to carry prioidx and/or |
|
* classid. The two modes are distinguished by whether the lowest bit is |
|
* set. Clear bit indicates cgroup pointer while set bit prioidx and |
|
* classid. |
|
* |
|
* While userland may start using net_prio or net_cls at any time, once |
|
* either is used, cgroup2 matching no longer works. There is no reason to |
|
* mix the two and this is in line with how legacy and v2 compatibility is |
|
* handled. On mode switch, cgroup references which are already being |
|
* pointed to by socks may be leaked. While this can be remedied by adding |
|
* synchronization around sock_cgroup_data, given that the number of leaked |
|
* cgroups is bound and highly unlikely to be high, this seems to be the |
|
* better trade-off. |
|
*/ |
|
struct sock_cgroup_data { |
|
union { |
|
#ifdef __LITTLE_ENDIAN |
|
struct { |
|
u8 is_data : 1; |
|
u8 no_refcnt : 1; |
|
u8 unused : 6; |
|
u8 padding; |
|
u16 prioidx; |
|
u32 classid; |
|
} __packed; |
|
#else |
|
struct { |
|
u32 classid; |
|
u16 prioidx; |
|
u8 padding; |
|
u8 unused : 6; |
|
u8 no_refcnt : 1; |
|
u8 is_data : 1; |
|
} __packed; |
|
#endif |
|
u64 val; |
|
}; |
|
}; |
|
|
|
/* |
|
* There's a theoretical window where the following accessors race with |
|
* updaters and return part of the previous pointer as the prioidx or |
|
* classid. Such races are short-lived and the result isn't critical. |
|
*/ |
|
static inline u16 sock_cgroup_prioidx(const struct sock_cgroup_data *skcd) |
|
{ |
|
/* fallback to 1 which is always the ID of the root cgroup */ |
|
return (skcd->is_data & 1) ? skcd->prioidx : 1; |
|
} |
|
|
|
static inline u32 sock_cgroup_classid(const struct sock_cgroup_data *skcd) |
|
{ |
|
/* fallback to 0 which is the unconfigured default classid */ |
|
return (skcd->is_data & 1) ? skcd->classid : 0; |
|
} |
|
|
|
/* |
|
* If invoked concurrently, the updaters may clobber each other. The |
|
* caller is responsible for synchronization. |
|
*/ |
|
static inline void sock_cgroup_set_prioidx(struct sock_cgroup_data *skcd, |
|
u16 prioidx) |
|
{ |
|
struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; |
|
|
|
if (sock_cgroup_prioidx(&skcd_buf) == prioidx) |
|
return; |
|
|
|
if (!(skcd_buf.is_data & 1)) { |
|
skcd_buf.val = 0; |
|
skcd_buf.is_data = 1; |
|
} |
|
|
|
skcd_buf.prioidx = prioidx; |
|
WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ |
|
} |
|
|
|
static inline void sock_cgroup_set_classid(struct sock_cgroup_data *skcd, |
|
u32 classid) |
|
{ |
|
struct sock_cgroup_data skcd_buf = {{ .val = READ_ONCE(skcd->val) }}; |
|
|
|
if (sock_cgroup_classid(&skcd_buf) == classid) |
|
return; |
|
|
|
if (!(skcd_buf.is_data & 1)) { |
|
skcd_buf.val = 0; |
|
skcd_buf.is_data = 1; |
|
} |
|
|
|
skcd_buf.classid = classid; |
|
WRITE_ONCE(skcd->val, skcd_buf.val); /* see sock_cgroup_ptr() */ |
|
} |
|
|
|
#else /* CONFIG_SOCK_CGROUP_DATA */ |
|
|
|
struct sock_cgroup_data { |
|
}; |
|
|
|
#endif /* CONFIG_SOCK_CGROUP_DATA */ |
|
|
|
#endif /* _LINUX_CGROUP_DEFS_H */
|
|
|