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Diffstat (limited to 'include/linux/cgroup.h')
| -rw-r--r-- | include/linux/cgroup.h | 604 |
1 files changed, 604 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h new file mode 100644 index 000000000000..8607c937145f --- /dev/null +++ b/include/linux/cgroup.h @@ -0,0 +1,604 @@ +#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/cpumask.h> +#include <linux/nodemask.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/cgroup-defs.h> + +#ifdef CONFIG_CGROUPS + +/* + * All weight knobs on the default hierarhcy 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 + +/* a css_task_iter should be treated as an opaque object */ +struct css_task_iter { + struct cgroup_subsys *ss; + + struct list_head *cset_pos; + struct list_head *cset_head; + + struct list_head *task_pos; + struct list_head *tasks_head; + struct list_head *mg_tasks_head; + + struct css_set *cur_cset; + struct task_struct *cur_task; + struct list_head iters_node; /* css_set->task_iters */ +}; + +extern struct cgroup_root cgrp_dfl_root; +extern struct css_set init_css_set; + +#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 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_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); + +bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor); +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_rm_cftypes(struct cftype *cfts); +void cgroup_file_notify(struct cgroup_file *cfile); + +char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen); +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, + void *ss_priv[CGROUP_CANFORK_COUNT]); +extern void cgroup_cancel_fork(struct task_struct *p, + void *ss_priv[CGROUP_CANFORK_COUNT]); +extern void cgroup_post_fork(struct task_struct *p, + void *old_ss_priv[CGROUP_CANFORK_COUNT]); +void cgroup_exit(struct task_struct *p); +void cgroup_free(struct task_struct *p); + +int cgroup_init_early(void); +int cgroup_init(void); + +/* + * 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, + 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))) + +/** + * 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: takset 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. + */ + +/** + * css_get - obtain a reference on the specified css + * @css: target css + * + * The caller must already have a reference. + */ +static inline void css_get(struct cgroup_subsys_state *css) +{ + if (!(css->flags & CSS_NO_REF)) + percpu_ref_get(&css->refcnt); +} + +/** + * css_get_many - obtain references on the specified css + * @css: target css + * @n: number of references to get + * + * The caller must already have a reference. + */ +static inline void css_get_many(struct cgroup_subsys_state *css, unsigned int n) +{ + if (!(css->flags & CSS_NO_REF)) + percpu_ref_get_many(&css->refcnt, n); +} + +/** + * css_tryget - try to obtain a reference on the specified css + * @css: target css + * + * Obtain a reference on @css unless it already has reached zero and is + * being released. This function doesn't care whether @css is on or + * offline. The caller naturally needs to ensure that @css is accessible + * but doesn't have to be holding a reference on it - IOW, RCU protected + * access is good enough for this function. Returns %true if a reference + * count was successfully obtained; %false otherwise. + */ +static inline bool css_tryget(struct cgroup_subsys_state *css) +{ + if (!(css->flags & CSS_NO_REF)) + return percpu_ref_tryget(&css->refcnt); + return true; +} + +/** + * css_tryget_online - try to obtain a reference on the specified css if online + * @css: target css + * + * Obtain a reference on @css if it's online. The caller naturally needs + * to ensure that @css is accessible but doesn't have to be holding a + * reference on it - IOW, RCU protected access is good enough for this + * function. Returns %true if a reference count was successfully obtained; + * %false otherwise. + */ +static inline bool css_tryget_online(struct cgroup_subsys_state *css) +{ + if (!(css->flags & CSS_NO_REF)) + return percpu_ref_tryget_live(&css->refcnt); + return true; +} + +/** + * 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_NO_REF) && percpu_ref_is_dying(&css->refcnt); +} + +/** + * css_put - put a css reference + * @css: target css + * + * Put a reference obtained via css_get() and css_tryget_online(). + */ +static inline void css_put(struct cgroup_subsys_state *css) +{ + if (!(css->flags & CSS_NO_REF)) + percpu_ref_put(&css->refcnt); +} + +/** + * css_put_many - put css references + * @css: target css + * @n: number of references to put + * + * Put references obtained via css_get() and css_tryget_online(). + */ +static inline void css_put_many(struct cgroup_subsys_state *css, unsigned int n) +{ + if (!(css->flags & CSS_NO_REF)) + percpu_ref_put_many(&css->refcnt, n); +} + +/** + * 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 +extern struct mutex cgroup_mutex; +extern spinlock_t css_set_lock; +#define task_css_set_check(task, __c) \ + rcu_dereference_check((task)->cgroups, \ + lockdep_is_held(&cgroup_mutex) || \ + lockdep_is_held(&css_set_lock) || \ + ((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; +} + +/* no synchronization, the result can only be used as a hint */ +static inline bool cgroup_is_populated(struct cgroup *cgrp) +{ + return cgrp->populated_cnt; +} + +/* returns ino associated with a cgroup */ +static inline ino_t cgroup_ino(struct cgroup *cgrp) +{ + return cgrp->kn->ino; +} + +/* 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 char * __must_check 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); +} + +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; +} + +#else /* !CONFIG_CGROUPS */ + +struct cgroup_subsys_state; + +static inline void css_put(struct cgroup_subsys_state *css) {} +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, + void *ss_priv[CGROUP_CANFORK_COUNT]) +{ return 0; } +static inline void cgroup_cancel_fork(struct task_struct *p, + void *ss_priv[CGROUP_CANFORK_COUNT]) {} +static inline void cgroup_post_fork(struct task_struct *p, + void *ss_priv[CGROUP_CANFORK_COUNT]) {} +static inline void cgroup_exit(struct task_struct *p) {} +static inline void cgroup_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) {} + +#endif /* !CONFIG_CGROUPS */ + +#endif /* _LINUX_CGROUP_H */ |