diff options
Diffstat (limited to 'include/linux/cgroup.h')
| -rw-r--r-- | include/linux/cgroup.h | 973 |
1 files changed, 973 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h new file mode 100644 index 000000000..5dfa915a6 --- /dev/null +++ b/include/linux/cgroup.h @@ -0,0 +1,973 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_CGROUP_H +#define _LINUX_CGROUP_H +/* + * cgroup interface + * + * Copyright (C) 2003 BULL SA + * Copyright (C) 2004-2006 Silicon Graphics, Inc. + * + */ + +#include <linux/sched.h> +#include <linux/nodemask.h> +#include <linux/list.h> +#include <linux/rculist.h> +#include <linux/cgroupstats.h> +#include <linux/fs.h> +#include <linux/seq_file.h> +#include <linux/kernfs.h> +#include <linux/jump_label.h> +#include <linux/types.h> +#include <linux/notifier.h> +#include <linux/ns_common.h> +#include <linux/nsproxy.h> +#include <linux/user_namespace.h> +#include <linux/refcount.h> +#include <linux/kernel_stat.h> + +#include <linux/cgroup-defs.h> +#include <linux/cgroup_namespace.h> + +struct kernel_clone_args; + +/* + * All weight knobs on the default hierarchy should use the following min, + * default and max values. The default value is the logarithmic center of + * MIN and MAX and allows 100x to be expressed in both directions. + */ +#define CGROUP_WEIGHT_MIN 1 +#define CGROUP_WEIGHT_DFL 100 +#define CGROUP_WEIGHT_MAX 10000 + +#ifdef CONFIG_CGROUPS + +/* + * To avoid confusing the compiler (and generating warnings) with code + * that attempts to access what would be a 0-element array (i.e. sized + * to a potentially empty array when CGROUP_SUBSYS_COUNT == 0), this + * constant expression can be added. + */ +#define CGROUP_HAS_SUBSYS_CONFIG (CGROUP_SUBSYS_COUNT > 0) + +enum css_task_iter_flags { + CSS_TASK_ITER_PROCS = (1U << 0), /* walk only threadgroup leaders */ + CSS_TASK_ITER_THREADED = (1U << 1), /* walk all threaded css_sets in the domain */ + CSS_TASK_ITER_WITH_DEAD = (1U << 2), /* include exiting tasks */ + CSS_TASK_ITER_SKIPPED = (1U << 16), /* internal flags */ +}; + +/* a css_task_iter should be treated as an opaque object */ +struct css_task_iter { + struct cgroup_subsys *ss; + unsigned int flags; + + struct list_head *cset_pos; + struct list_head *cset_head; + + struct list_head *tcset_pos; + struct list_head *tcset_head; + + struct list_head *task_pos; + + struct list_head *cur_tasks_head; + struct css_set *cur_cset; + struct css_set *cur_dcset; + struct task_struct *cur_task; + struct list_head iters_node; /* css_set->task_iters */ +}; + +enum cgroup_lifetime_events { + CGROUP_LIFETIME_ONLINE, + CGROUP_LIFETIME_OFFLINE, +}; + +/* + * Events on cgroup_task_notifier, data is struct cgroup_task_migrate_ctx. + * MIGRATING fires per task before the migration commits and an error return + * from the chain fails the migration, in which case tasks that were already + * notified receive MIGRATE_CANCELED. MIGRATED fires per task after the + * migration is committed and can't fail. Only migrations that change a task's + * dfl cgroup are reported. + */ +enum cgroup_task_events { + CGROUP_TASK_MIGRATING, + CGROUP_TASK_MIGRATED, + CGROUP_TASK_MIGRATE_CANCELED, +}; + +/* + * @src_dcgrp and @dst_dcgrp are @task's dfl cgroups before and after the + * migration. @src_dcgrp is NULL for CGROUP_TASK_MIGRATED as per-task sources + * are not tracked past the commit point. + */ +struct cgroup_task_migrate_ctx { + struct task_struct *task; + struct cgroup *src_dcgrp; + struct cgroup *dst_dcgrp; +}; + +extern struct file_system_type cgroup_fs_type; +extern struct cgroup_root cgrp_dfl_root; +extern struct css_set init_css_set; +extern struct mutex cgroup_mutex; +extern spinlock_t css_set_lock; +extern struct blocking_notifier_head cgroup_lifetime_notifier; +extern struct blocking_notifier_head cgroup_task_notifier; + +#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys; +#include <linux/cgroup_subsys.h> +#undef SUBSYS + +#define SUBSYS(_x) \ + extern struct static_key_true _x ## _cgrp_subsys_enabled_key; \ + extern struct static_key_true _x ## _cgrp_subsys_on_dfl_key; +#include <linux/cgroup_subsys.h> +#undef SUBSYS + +/** + * cgroup_subsys_enabled - fast test on whether a subsys is enabled + * @ss: subsystem in question + */ +#define cgroup_subsys_enabled(ss) \ + static_branch_likely(&ss ## _enabled_key) + +/** + * cgroup_subsys_on_dfl - fast test on whether a subsys is on default hierarchy + * @ss: subsystem in question + */ +#define cgroup_subsys_on_dfl(ss) \ + static_branch_likely(&ss ## _on_dfl_key) + +bool cgroup_on_dfl(const struct cgroup *cgrp); + +bool css_has_online_children(struct cgroup_subsys_state *css); +struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss); +struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgroup, + struct cgroup_subsys *ss); +struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgroup, + struct cgroup_subsys *ss); +struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry, + struct cgroup_subsys *ss); + +struct cgroup *cgroup_get_from_path(const char *path); +struct cgroup *cgroup_get_from_fd(int fd); +struct cgroup *cgroup_v1v2_get_from_fd(int fd); + +int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); +int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); + +int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); +int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); +int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); +int cgroup_rm_cftypes(struct cftype *cfts); +void cgroup_file_notify(struct cgroup_file *cfile); +void cgroup_file_show(struct cgroup_file *cfile, bool show); + +int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry); +int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns, + struct pid *pid, struct task_struct *tsk); + +void cgroup_fork(struct task_struct *p); +extern int cgroup_can_fork(struct task_struct *p, + struct kernel_clone_args *kargs); +extern void cgroup_cancel_fork(struct task_struct *p, + struct kernel_clone_args *kargs); +extern void cgroup_post_fork(struct task_struct *p, + struct kernel_clone_args *kargs); +void cgroup_task_exit(struct task_struct *p); +void cgroup_task_dead(struct task_struct *p); +void cgroup_task_release(struct task_struct *p); +void cgroup_task_free(struct task_struct *p); + +int cgroup_init_early(void); +int cgroup_init(void); + +int cgroup_parse_float(const char *input, unsigned dec_shift, s64 *v); + +/* + * Iteration helpers and macros. + */ + +struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, + struct cgroup_subsys_state *parent); +struct cgroup_subsys_state *css_next_descendant_pre(struct cgroup_subsys_state *pos, + struct cgroup_subsys_state *css); +struct cgroup_subsys_state *css_rightmost_descendant(struct cgroup_subsys_state *pos); +struct cgroup_subsys_state *css_next_descendant_post(struct cgroup_subsys_state *pos, + struct cgroup_subsys_state *css); + +struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset, + struct cgroup_subsys_state **dst_cssp); +struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset, + struct cgroup_subsys_state **dst_cssp); + +void css_task_iter_start(struct cgroup_subsys_state *css, unsigned int flags, + struct css_task_iter *it); +struct task_struct *css_task_iter_next(struct css_task_iter *it); +void css_task_iter_end(struct css_task_iter *it); + +/** + * css_for_each_child - iterate through children of a css + * @pos: the css * to use as the loop cursor + * @parent: css whose children to walk + * + * Walk @parent's children. Must be called under rcu_read_lock(). + * + * 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. + * + * It is allowed to temporarily drop RCU read lock during iteration. The + * caller is responsible for ensuring that @pos remains accessible until + * the start of the next iteration by, for example, bumping the css refcnt. + */ +#define css_for_each_child(pos, parent) \ + for ((pos) = css_next_child(NULL, (parent)); (pos); \ + (pos) = css_next_child((pos), (parent))) + +/** + * css_for_each_descendant_pre - pre-order walk of a css's descendants + * @pos: the css * to use as the loop cursor + * @root: css whose descendants to walk + * + * Walk @root's descendants. @root is included in the iteration and the + * first node to be visited. Must be called under rcu_read_lock(). + * + * 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. + * + * For example, the following guarantees that a descendant can't escape + * state updates of its ancestors. + * + * my_online(@css) + * { + * Lock @css's parent and @css; + * Inherit state from the parent; + * Unlock both. + * } + * + * my_update_state(@css) + * { + * css_for_each_descendant_pre(@pos, @css) { + * Lock @pos; + * if (@pos == @css) + * Update @css's state; + * else + * Verify @pos is alive and inherit state from its parent; + * Unlock @pos; + * } + * } + * + * As long as the inheriting step, including checking the parent state, is + * enclosed inside @pos locking, double-locking the parent isn't necessary + * while inheriting. The state update to the parent is guaranteed to be + * visible by walking order and, as long as inheriting operations to the + * same @pos are atomic to each other, multiple updates racing each other + * still result in the correct state. It's guaranateed that at least one + * inheritance happens for any css after the latest update to its parent. + * + * If checking parent's state requires locking the parent, each inheriting + * iteration should lock and unlock both @pos->parent and @pos. + * + * Alternatively, a subsystem may choose to use a single global lock to + * synchronize ->css_online() and ->css_offline() against tree-walking + * operations. + * + * It is allowed to temporarily drop RCU read lock during iteration. The + * caller is responsible for ensuring that @pos remains accessible until + * the start of the next iteration by, for example, bumping the css refcnt. + */ +#define css_for_each_descendant_pre(pos, css) \ + for ((pos) = css_next_descendant_pre(NULL, (css)); (pos); \ + (pos) = css_next_descendant_pre((pos), (css))) + +/** + * css_for_each_descendant_post - post-order walk of a css's descendants + * @pos: the css * to use as the loop cursor + * @css: css whose descendants to walk + * + * Similar to css_for_each_descendant_pre() but performs post-order + * traversal instead. @root is included in the iteration and the last + * node to be visited. + * + * 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. + * + * Note that the walk visibility guarantee example described in pre-order + * walk doesn't apply the same to post-order walks. + */ +#define css_for_each_descendant_post(pos, css) \ + for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \ + (pos) = css_next_descendant_post((pos), (css))) + +/* iterate over child cgrps, lock should be held throughout iteration */ +#define cgroup_for_each_live_child(child, cgrp) \ + list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \ + if (({ lockdep_assert_held(&cgroup_mutex); \ + cgroup_is_dead(child); })) \ + ; \ + else + +/* walk live descendants in pre order */ +#define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \ + css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \ + if (({ lockdep_assert_held(&cgroup_mutex); \ + (dsct) = (d_css)->cgroup; \ + cgroup_is_dead(dsct); })) \ + ; \ + else + +/* walk live descendants in postorder */ +#define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \ + css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \ + if (({ lockdep_assert_held(&cgroup_mutex); \ + (dsct) = (d_css)->cgroup; \ + cgroup_is_dead(dsct); })) \ + ; \ + else + +/** + * cgroup_taskset_for_each - iterate cgroup_taskset + * @task: the loop cursor + * @dst_css: the destination css + * @tset: taskset to iterate + * + * @tset may contain multiple tasks and they may belong to multiple + * processes. + * + * On the v2 hierarchy, there may be tasks from multiple processes and they + * may not share the source or destination csses. + * + * On traditional hierarchies, when there are multiple tasks in @tset, if a + * task of a process is in @tset, all tasks of the process are in @tset. + * Also, all are guaranteed to share the same source and destination csses. + * + * Iteration is not in any specific order. + */ +#define cgroup_taskset_for_each(task, dst_css, tset) \ + for ((task) = cgroup_taskset_first((tset), &(dst_css)); \ + (task); \ + (task) = cgroup_taskset_next((tset), &(dst_css))) + +/** + * cgroup_taskset_for_each_leader - iterate group leaders in a cgroup_taskset + * @leader: the loop cursor + * @dst_css: the destination css + * @tset: taskset to iterate + * + * Iterate threadgroup leaders of @tset. For single-task migrations, @tset + * may not contain any. + */ +#define cgroup_taskset_for_each_leader(leader, dst_css, tset) \ + for ((leader) = cgroup_taskset_first((tset), &(dst_css)); \ + (leader); \ + (leader) = cgroup_taskset_next((tset), &(dst_css))) \ + if ((leader) != (leader)->group_leader) \ + ; \ + else + +/* + * Inline functions. + */ + +#ifdef CONFIG_DEBUG_CGROUP_REF +void css_get(struct cgroup_subsys_state *css); +void css_get_many(struct cgroup_subsys_state *css, unsigned int n); +bool css_tryget(struct cgroup_subsys_state *css); +bool css_tryget_online(struct cgroup_subsys_state *css); +void css_put(struct cgroup_subsys_state *css); +void css_put_many(struct cgroup_subsys_state *css, unsigned int n); +#else +#define CGROUP_REF_FN_ATTRS static inline +#define CGROUP_REF_EXPORT(fn) +#include <linux/cgroup_refcnt.h> +#endif + +static inline u64 cgroup_id(const struct cgroup *cgrp) +{ + return cgrp->kn->id; +} + +/** + * 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 inline struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp, + struct cgroup_subsys *ss) +{ + if (CGROUP_HAS_SUBSYS_CONFIG && ss) + return rcu_dereference_check(cgrp->subsys[ss->id], + lockdep_is_held(&cgroup_mutex)); + else + return &cgrp->self; +} + +/** + * css_is_dying - test whether the specified css is dying + * @css: target css + * + * Test whether @css is in the process of offlining or already offline. In + * most cases, ->css_online() and ->css_offline() callbacks should be + * enough; however, the actual offline operations are RCU delayed and this + * test returns %true also when @css is scheduled to be offlined. + * + * This is useful, for example, when the use case requires synchronous + * behavior with respect to cgroup removal. cgroup removal schedules css + * offlining but the css can seem alive while the operation is being + * delayed. If the delay affects user visible semantics, this test can be + * used to resolve the situation. + */ +static inline bool css_is_dying(struct cgroup_subsys_state *css) +{ + return css->flags & CSS_DYING; +} + +static inline bool css_is_online(struct cgroup_subsys_state *css) +{ + return css->flags & CSS_ONLINE; +} + +static inline bool css_is_self(struct cgroup_subsys_state *css) +{ + if (css == &css->cgroup->self) { + /* cgroup::self should not have subsystem association */ + WARN_ON(css->ss != NULL); + return true; + } + + return false; +} + +static inline bool cgroup_is_dead(const struct cgroup *cgrp) +{ + return !(cgrp->self.flags & CSS_ONLINE); +} + +static inline void cgroup_get(struct cgroup *cgrp) +{ + css_get(&cgrp->self); +} + +static inline bool cgroup_tryget(struct cgroup *cgrp) +{ + return css_tryget(&cgrp->self); +} + +static inline void cgroup_put(struct cgroup *cgrp) +{ + css_put(&cgrp->self); +} + +static inline void cgroup_lock(void) +{ + mutex_lock(&cgroup_mutex); +} + +static inline void cgroup_unlock(void) +{ + mutex_unlock(&cgroup_mutex); +} + +/** + * task_css_set_check - obtain a task's css_set with extra access conditions + * @task: the task to obtain css_set for + * @__c: extra condition expression to be passed to rcu_dereference_check() + * + * A task's css_set is RCU protected, initialized and exited while holding + * task_lock(), and can only be modified while holding both cgroup_mutex + * and task_lock() while the task is alive. This macro verifies that the + * caller is inside proper critical section and returns @task's css_set. + * + * The caller can also specify additional allowed conditions via @__c, such + * as locks used during the cgroup_subsys::attach() methods. + */ +#ifdef CONFIG_PROVE_RCU +#define task_css_set_check(task, __c) \ + rcu_dereference_check((task)->cgroups, \ + rcu_read_lock_sched_held() || \ + lockdep_is_held(&cgroup_mutex) || \ + lockdep_is_held(&css_set_lock) || \ + (data_race((task)->flags) & PF_EXITING) || (__c)) +#else +#define task_css_set_check(task, __c) \ + rcu_dereference((task)->cgroups) +#endif + +/** + * task_css_check - obtain css for (task, subsys) w/ extra access conds + * @task: the target task + * @subsys_id: the target subsystem ID + * @__c: extra condition expression to be passed to rcu_dereference_check() + * + * Return the cgroup_subsys_state for the (@task, @subsys_id) pair. The + * synchronization rules are the same as task_css_set_check(). + */ +#define task_css_check(task, subsys_id, __c) \ + task_css_set_check((task), (__c))->subsys[(subsys_id)] + +/** + * task_css_set - obtain a task's css_set + * @task: the task to obtain css_set for + * + * See task_css_set_check(). + */ +static inline struct css_set *task_css_set(struct task_struct *task) +{ + return task_css_set_check(task, false); +} + +/** + * task_css - obtain css for (task, subsys) + * @task: the target task + * @subsys_id: the target subsystem ID + * + * See task_css_check(). + */ +static inline struct cgroup_subsys_state *task_css(struct task_struct *task, + int subsys_id) +{ + return task_css_check(task, subsys_id, false); +} + +/** + * task_get_css - find and get the css for (task, subsys) + * @task: the target task + * @subsys_id: the target subsystem ID + * + * Find the css for the (@task, @subsys_id) combination, increment a + * reference on and return it. This function is guaranteed to return a + * valid css. The returned css may already have been offlined. + */ +static inline struct cgroup_subsys_state * +task_get_css(struct task_struct *task, int subsys_id) +{ + struct cgroup_subsys_state *css; + + rcu_read_lock(); + while (true) { + css = task_css(task, subsys_id); + /* + * Can't use css_tryget_online() here. A task which has + * PF_EXITING set may stay associated with an offline css. + * If such task calls this function, css_tryget_online() + * will keep failing. + */ + if (likely(css_tryget(css))) + break; + cpu_relax(); + } + rcu_read_unlock(); + return css; +} + +/** + * task_css_is_root - test whether a task belongs to the root css + * @task: the target task + * @subsys_id: the target subsystem ID + * + * Test whether @task belongs to the root css on the specified subsystem. + * May be invoked in any context. + */ +static inline bool task_css_is_root(struct task_struct *task, int subsys_id) +{ + return task_css_check(task, subsys_id, true) == + init_css_set.subsys[subsys_id]; +} + +static inline struct cgroup *task_cgroup(struct task_struct *task, + int subsys_id) +{ + return task_css(task, subsys_id)->cgroup; +} + +static inline struct cgroup *task_dfl_cgroup(struct task_struct *task) +{ + return task_css_set(task)->dfl_cgrp; +} + +static inline 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; +} + +/** + * cgroup_is_descendant - test ancestry + * @cgrp: the cgroup to be tested + * @ancestor: possible ancestor of @cgrp + * + * Test whether @cgrp is a descendant of @ancestor. It also returns %true + * if @cgrp == @ancestor. This function is safe to call as long as @cgrp + * and @ancestor are accessible. + */ +static inline bool cgroup_is_descendant(struct cgroup *cgrp, + struct cgroup *ancestor) +{ + if (cgrp->root != ancestor->root || cgrp->level < ancestor->level) + return false; + return cgrp->ancestors[ancestor->level] == ancestor; +} + +/** + * cgroup_ancestor - find ancestor of cgroup + * @cgrp: cgroup to find ancestor of + * @ancestor_level: level of ancestor to find starting from root + * + * Find ancestor of cgroup at specified level starting from root if it exists + * and return pointer to it. Return NULL if @cgrp doesn't have ancestor at + * @ancestor_level. + * + * This function is safe to call as long as @cgrp is accessible. + */ +static inline struct cgroup *cgroup_ancestor(struct cgroup *cgrp, + int ancestor_level) +{ + if (ancestor_level < 0 || ancestor_level > cgrp->level) + return NULL; + return cgrp->ancestors[ancestor_level]; +} + +/** + * cgroup_common_ancestor - find common ancestor of two cgroups + * @a: first cgroup to find common ancestor of + * @b: second cgroup to find common ancestor of + * + * Find the first cgroup that is an ancestor of both @a and @b, if it exists + * and return a pointer to it. If such a cgroup doesn't exist, return NULL. + * + * This function is safe to call as long as both @a and @b are accessible. + */ +static inline struct cgroup *cgroup_common_ancestor(struct cgroup *a, + struct cgroup *b) +{ + int level; + + for (level = min(a->level, b->level); level >= 0; level--) + if (a->ancestors[level] == b->ancestors[level]) + return a->ancestors[level]; + return NULL; +} + +/** + * task_under_cgroup_hierarchy - test task's membership of cgroup ancestry + * @task: the task to be tested + * @ancestor: possible ancestor of @task's cgroup + * + * Tests whether @task's default cgroup hierarchy is a descendant of @ancestor. + * It follows all the same rules as cgroup_is_descendant, and only applies + * to the default hierarchy. + */ +static inline bool task_under_cgroup_hierarchy(struct task_struct *task, + struct cgroup *ancestor) +{ + struct css_set *cset = task_css_set(task); + + return cgroup_is_descendant(cset->dfl_cgrp, ancestor); +} + +/* + * Populated counters: writes happen under css_set_lock. The accessors below + * may read unlocked. What an unpopulated result means depends on context: + * + * - No lock held. Just a snapshot. May race with concurrent updates and is + * useful only as a hint. + * + * - cgroup_mutex held. Migration into the cgroup is blocked, so an observed + * !populated stays !populated until cgroup_mutex is dropped. + * + * - CSS_DYING set. The css can no longer be repopulated, so !populated is + * sticky once observed. + */ +static inline bool cgroup_has_tasks(struct cgroup *cgrp) +{ + return READ_ONCE(cgrp->self.nr_populated_csets); +} + +static inline bool css_is_populated(struct cgroup_subsys_state *css) +{ + return READ_ONCE(css->nr_populated_csets) || READ_ONCE(css->nr_populated_children); +} + +static inline bool cgroup_is_populated(struct cgroup *cgrp) +{ + return css_is_populated(&cgrp->self); +} + +/* returns ino associated with a cgroup */ +static inline ino_t cgroup_ino(struct cgroup *cgrp) +{ + return kernfs_ino(cgrp->kn); +} + +/* cft/css accessors for cftype->write() operation */ +static inline struct cftype *of_cft(struct kernfs_open_file *of) +{ + return of->kn->priv; +} + +struct cgroup_subsys_state *of_css(struct kernfs_open_file *of); + +/* cft/css accessors for cftype->seq_*() operations */ +static inline struct cftype *seq_cft(struct seq_file *seq) +{ + return of_cft(seq->private); +} + +static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq) +{ + return of_css(seq->private); +} + +/* + * Name / path handling functions. All are thin wrappers around the kernfs + * counterparts and can be called under any context. + */ + +static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen) +{ + return kernfs_name(cgrp->kn, buf, buflen); +} + +static inline int cgroup_path(struct cgroup *cgrp, char *buf, size_t buflen) +{ + return kernfs_path(cgrp->kn, buf, buflen); +} + +static inline void pr_cont_cgroup_name(struct cgroup *cgrp) +{ + pr_cont_kernfs_name(cgrp->kn); +} + +static inline void pr_cont_cgroup_path(struct cgroup *cgrp) +{ + pr_cont_kernfs_path(cgrp->kn); +} + +bool cgroup_psi_enabled(void); + +static inline void cgroup_init_kthreadd(void) +{ + /* + * kthreadd is inherited by all kthreads, keep it in the root so + * that the new kthreads are guaranteed to stay in the root until + * initialization is finished. + */ + current->no_cgroup_migration = 1; +} + +static inline void cgroup_kthread_ready(void) +{ + /* + * This kthread finished initialization. The creator should have + * set PF_NO_SETAFFINITY if this kthread should stay in the root. + */ + current->no_cgroup_migration = 0; +} + +void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen); +struct cgroup *__cgroup_get_from_id(u64 id); +struct cgroup *cgroup_get_from_id(u64 id); +#else /* !CONFIG_CGROUPS */ + +struct cgroup_subsys_state; +struct cgroup; + +static inline u64 cgroup_id(const struct cgroup *cgrp) { return 1; } +static inline void css_get(struct cgroup_subsys_state *css) {} +static inline void css_put(struct cgroup_subsys_state *css) {} +static inline void cgroup_lock(void) {} +static inline void cgroup_unlock(void) {} +static inline int cgroup_attach_task_all(struct task_struct *from, + struct task_struct *t) { return 0; } +static inline int cgroupstats_build(struct cgroupstats *stats, + struct dentry *dentry) { return -EINVAL; } + +static inline void cgroup_fork(struct task_struct *p) {} +static inline int cgroup_can_fork(struct task_struct *p, + struct kernel_clone_args *kargs) { return 0; } +static inline void cgroup_cancel_fork(struct task_struct *p, + struct kernel_clone_args *kargs) {} +static inline void cgroup_post_fork(struct task_struct *p, + struct kernel_clone_args *kargs) {} +static inline void cgroup_task_exit(struct task_struct *p) {} +static inline void cgroup_task_dead(struct task_struct *p) {} +static inline void cgroup_task_release(struct task_struct *p) {} +static inline void cgroup_task_free(struct task_struct *p) {} + +static inline int cgroup_init_early(void) { return 0; } +static inline int cgroup_init(void) { return 0; } +static inline void cgroup_init_kthreadd(void) {} +static inline void cgroup_kthread_ready(void) {} + +static inline struct cgroup *cgroup_parent(struct cgroup *cgrp) +{ + return NULL; +} + +static inline bool cgroup_psi_enabled(void) +{ + return false; +} + +static inline bool task_under_cgroup_hierarchy(struct task_struct *task, + struct cgroup *ancestor) +{ + return true; +} + +static inline void cgroup_path_from_kernfs_id(u64 id, char *buf, size_t buflen) +{} +#endif /* !CONFIG_CGROUPS */ + +#ifdef CONFIG_CGROUPS +/* + * cgroup scalable recursive statistics. + */ +void __css_rstat_updated(struct cgroup_subsys_state *css, int cpu); +void css_rstat_updated(struct cgroup_subsys_state *css, int cpu); +void css_rstat_flush(struct cgroup_subsys_state *css); + +/* + * Basic resource stats. + */ +#ifdef CONFIG_CGROUP_CPUACCT +void cpuacct_charge(struct task_struct *tsk, u64 cputime); +void cpuacct_account_field(struct task_struct *tsk, int index, u64 val); +#else +static inline void cpuacct_charge(struct task_struct *tsk, u64 cputime) {} +static inline void cpuacct_account_field(struct task_struct *tsk, int index, + u64 val) {} +#endif + +void __cgroup_account_cputime(struct cgroup *cgrp, u64 delta_exec); +void __cgroup_account_cputime_field(struct cgroup *cgrp, + enum cpu_usage_stat index, u64 delta_exec); + +static inline void cgroup_account_cputime(struct task_struct *task, + u64 delta_exec) +{ + struct cgroup *cgrp; + + cpuacct_charge(task, delta_exec); + + cgrp = task_dfl_cgroup(task); + if (cgroup_parent(cgrp)) + __cgroup_account_cputime(cgrp, delta_exec); +} + +static inline void cgroup_account_cputime_field(struct task_struct *task, + enum cpu_usage_stat index, + u64 delta_exec) +{ + struct cgroup *cgrp; + + cpuacct_account_field(task, index, delta_exec); + + cgrp = task_dfl_cgroup(task); + if (cgroup_parent(cgrp)) + __cgroup_account_cputime_field(cgrp, index, delta_exec); +} + +#else /* CONFIG_CGROUPS */ + +static inline void cgroup_account_cputime(struct task_struct *task, + u64 delta_exec) {} +static inline void cgroup_account_cputime_field(struct task_struct *task, + enum cpu_usage_stat index, + u64 delta_exec) {} + +#endif /* CONFIG_CGROUPS */ + +/* + * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data + * definition in cgroup-defs.h. + */ +#ifdef CONFIG_SOCK_CGROUP_DATA + +void cgroup_sk_alloc(struct sock_cgroup_data *skcd); +void cgroup_sk_clone(struct sock_cgroup_data *skcd); +void cgroup_sk_free(struct sock_cgroup_data *skcd); + +static inline struct cgroup *sock_cgroup_ptr(struct sock_cgroup_data *skcd) +{ + return skcd->cgroup; +} + +#else /* CONFIG_CGROUP_DATA */ + +static inline void cgroup_sk_alloc(struct sock_cgroup_data *skcd) {} +static inline void cgroup_sk_clone(struct sock_cgroup_data *skcd) {} +static inline void cgroup_sk_free(struct sock_cgroup_data *skcd) {} + +#endif /* CONFIG_CGROUP_DATA */ + +#ifdef CONFIG_CGROUPS + +void cgroup_enter_frozen(void); +void cgroup_leave_frozen(bool always_leave); +void cgroup_update_frozen(struct cgroup *cgrp); +void cgroup_freeze(struct cgroup *cgrp, bool freeze); +void cgroup_freezer_migrate_task(struct task_struct *task, struct cgroup *src, + struct cgroup *dst); + +static inline bool cgroup_task_frozen(struct task_struct *task) +{ + return task->frozen; +} + +#else /* !CONFIG_CGROUPS */ + +static inline void cgroup_enter_frozen(void) { } +static inline void cgroup_leave_frozen(bool always_leave) { } +static inline bool cgroup_task_frozen(struct task_struct *task) +{ + return false; +} + +#endif /* !CONFIG_CGROUPS */ + +#ifdef CONFIG_CGROUP_BPF +static inline void cgroup_bpf_get(struct cgroup *cgrp) +{ + percpu_ref_get(&cgrp->bpf.refcnt); +} + +static inline void cgroup_bpf_put(struct cgroup *cgrp) +{ + percpu_ref_put(&cgrp->bpf.refcnt); +} + +#else /* CONFIG_CGROUP_BPF */ + +static inline void cgroup_bpf_get(struct cgroup *cgrp) {} +static inline void cgroup_bpf_put(struct cgroup *cgrp) {} + +#endif /* CONFIG_CGROUP_BPF */ + +struct cgroup *task_get_cgroup1(struct task_struct *tsk, int hierarchy_id); + +struct cgroup_of_peak *of_peak(struct kernfs_open_file *of); + +#endif /* _LINUX_CGROUP_H */ |