diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/cgroup.h | 107 |
1 files changed, 59 insertions, 48 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 8bda1294c035..e345d8b90046 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -94,33 +94,31 @@ enum { CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */ }; -/* Caller must verify that the css is not for root cgroup */ -static inline void __css_get(struct cgroup_subsys_state *css, int count) -{ - atomic_add(count, &css->refcnt); -} - -/* - * Call css_get() to hold a reference on the css; it can be used - * for a reference obtained via: - * - an existing ref-counted reference to the css - * - task->cgroups for a locked task +/** + * 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) { /* We don't need to reference count the root state */ if (!(css->flags & CSS_ROOT)) - __css_get(css, 1); + atomic_inc(&css->refcnt); } -/* - * Call css_tryget() to take a reference on a css if your existing - * (known-valid) reference isn't already ref-counted. Returns false if - * the css has been destroyed. - */ - extern bool __css_tryget(struct cgroup_subsys_state *css); + +/** + * css_tryget - try to obtain a reference on the specified css + * @css: target css + * + * Obtain a reference on @css if it's alive. 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_ROOT) @@ -128,12 +126,14 @@ static inline bool css_tryget(struct cgroup_subsys_state *css) return __css_tryget(css); } -/* - * css_put() should be called to release a reference taken by - * css_get() or css_tryget() - */ - extern void __css_put(struct cgroup_subsys_state *css); + +/** + * css_put - put a css reference + * @css: target css + * + * Put a reference obtained via css_get() and css_tryget(). + */ static inline void css_put(struct cgroup_subsys_state *css) { if (!(css->flags & CSS_ROOT)) @@ -143,7 +143,7 @@ static inline void css_put(struct cgroup_subsys_state *css) /* bits in struct cgroup flags field */ enum { /* Control Group is dead */ - CGRP_REMOVED, + CGRP_DEAD, /* * Control Group has previously had a child cgroup or a task, * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) @@ -169,12 +169,6 @@ struct cgroup_name { struct cgroup { unsigned long flags; /* "unsigned long" so bitops work */ - /* - * count users of this cgroup. >0 means busy, but doesn't - * necessarily indicate the number of tasks in the cgroup - */ - atomic_t count; - int id; /* ida allocated in-hierarchy ID */ /* @@ -189,6 +183,14 @@ struct cgroup { struct dentry *dentry; /* cgroup fs entry, RCU protected */ /* + * Monotonically increasing unique serial number which defines a + * uniform order among all cgroups. It's guaranteed that all + * ->children lists are in the ascending order of ->serial_nr. + * It's used to allow interrupting and resuming iterations. + */ + u64 serial_nr; + + /* * This is a copy of dentry->d_name, and it's needed because * we can't use dentry->d_name in cgroup_path(). * @@ -207,10 +209,10 @@ struct cgroup { struct cgroupfs_root *root; /* - * List of cg_cgroup_links pointing at css_sets with - * tasks in this cgroup. Protected by css_set_lock + * List of cgrp_cset_links pointing at css_sets with tasks in this + * cgroup. Protected by css_set_lock. */ - struct list_head css_sets; + struct list_head cset_links; struct list_head allcg_node; /* cgroupfs_root->allcg_list */ struct list_head cft_q_node; /* used during cftype add/rm */ @@ -231,7 +233,7 @@ struct cgroup { /* For RCU-protected deletion */ struct rcu_head rcu_head; - struct work_struct free_work; + struct work_struct destroy_work; /* List of events which userspace want to receive */ struct list_head event_list; @@ -357,11 +359,10 @@ struct css_set { struct list_head tasks; /* - * List of cg_cgroup_link objects on link chains from - * cgroups referenced from this css_set. Protected by - * css_set_lock + * List of cgrp_cset_links pointing at cgroups referenced from this + * css_set. Protected by css_set_lock. */ - struct list_head cg_links; + struct list_head cgrp_links; /* * Set of subsystem states, one for each subsystem. This array @@ -538,10 +539,11 @@ static inline const char *cgroup_name(const struct cgroup *cgrp) int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); int cgroup_rm_cftypes(struct cgroup_subsys *ss, struct cftype *cfts); -int cgroup_is_removed(const struct cgroup *cgrp); bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor); int cgroup_path(const struct cgroup *cgrp, char *buf, int buflen); +int task_cgroup_path_from_hierarchy(struct task_struct *task, int hierarchy_id, + char *buf, size_t buflen); int cgroup_task_count(const struct cgroup *cgrp); @@ -674,12 +676,14 @@ static inline struct cgroup* task_cgroup(struct task_struct *task, return task_subsys_state(task, subsys_id)->cgroup; } +struct cgroup *cgroup_next_sibling(struct cgroup *pos); + /** * cgroup_for_each_child - iterate through children of a cgroup * @pos: the cgroup * to use as the loop cursor - * @cgroup: cgroup whose children to walk + * @cgrp: cgroup whose children to walk * - * Walk @cgroup's children. Must be called under rcu_read_lock(). A child + * Walk @cgrp's children. Must be called under rcu_read_lock(). A child * cgroup which hasn't finished ->css_online() or already has finished * ->css_offline() may show up during traversal and it's each subsystem's * responsibility to verify that each @pos is alive. @@ -687,9 +691,15 @@ static inline struct cgroup* task_cgroup(struct task_struct *task, * If a subsystem synchronizes against the parent in its ->css_online() and * before starting iterating, a cgroup which finished ->css_online() is * guaranteed to be visible in the future iterations. + * + * 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 cgroup_for_each_child(pos, cgroup) \ - list_for_each_entry_rcu(pos, &(cgroup)->children, sibling) +#define cgroup_for_each_child(pos, cgrp) \ + for ((pos) = list_first_or_null_rcu(&(cgrp)->children, \ + struct cgroup, sibling); \ + (pos); (pos) = cgroup_next_sibling((pos))) struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, struct cgroup *cgroup); @@ -748,6 +758,10 @@ struct cgroup *cgroup_rightmost_descendant(struct cgroup *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 cgroup_for_each_descendant_pre(pos, cgroup) \ for (pos = cgroup_next_descendant_pre(NULL, (cgroup)); (pos); \ @@ -771,7 +785,7 @@ struct cgroup *cgroup_next_descendant_post(struct cgroup *pos, /* A cgroup_iter should be treated as an opaque object */ struct cgroup_iter { - struct list_head *cg_link; + struct list_head *cset_link; struct list_head *task; }; @@ -827,7 +841,6 @@ bool css_is_ancestor(struct cgroup_subsys_state *cg, /* Get id and depth of css */ unsigned short css_id(struct cgroup_subsys_state *css); -unsigned short css_depth(struct cgroup_subsys_state *css); struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id); #else /* !CONFIG_CGROUPS */ @@ -838,8 +851,6 @@ static inline void cgroup_fork(struct task_struct *p) {} static inline void cgroup_post_fork(struct task_struct *p) {} static inline void cgroup_exit(struct task_struct *p, int callbacks) {} -static inline void cgroup_lock(void) {} -static inline void cgroup_unlock(void) {} static inline int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry) { |