diff options
Diffstat (limited to 'include/linux/cgroup.h')
| -rw-r--r-- | include/linux/cgroup.h | 229 |
1 files changed, 138 insertions, 91 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 8bda1294c035..fd097ecfcd97 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -20,6 +20,7 @@ #include <linux/workqueue.h> #include <linux/xattr.h> #include <linux/fs.h> +#include <linux/percpu-refcount.h> #ifdef CONFIG_CGROUPS @@ -72,13 +73,8 @@ struct cgroup_subsys_state { */ struct cgroup *cgroup; - /* - * State maintained by the cgroup system to allow subsystems - * to be "busy". Should be accessed via css_get(), - * css_tryget() and css_put(). - */ - - atomic_t refcnt; + /* reference count - access via css_[try]get() and css_put() */ + struct percpu_ref refcnt; unsigned long flags; /* ID for this css, if possible */ @@ -94,56 +90,52 @@ 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); + percpu_ref_get(&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. +/** + * 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. */ - -extern bool __css_tryget(struct cgroup_subsys_state *css); static inline bool css_tryget(struct cgroup_subsys_state *css) { if (css->flags & CSS_ROOT) return true; - return __css_tryget(css); + return percpu_ref_tryget(&css->refcnt); } -/* - * css_put() should be called to release a reference taken by - * css_get() or css_tryget() +/** + * css_put - put a css reference + * @css: target css + * + * Put a reference obtained via css_get() and css_tryget(). */ - -extern void __css_put(struct cgroup_subsys_state *css); static inline void css_put(struct cgroup_subsys_state *css) { if (!(css->flags & CSS_ROOT)) - __css_put(css); + percpu_ref_put(&css->refcnt); } /* 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 +161,6 @@ 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 +175,14 @@ 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(). * @@ -207,13 +201,10 @@ 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 allcg_node; /* cgroupfs_root->allcg_list */ - struct list_head cft_q_node; /* used during cftype add/rm */ + struct list_head cset_links; /* * Linked list running through all cgroups that can @@ -229,9 +220,10 @@ struct cgroup { struct list_head pidlists; struct mutex pidlist_mutex; - /* For RCU-protected deletion */ + /* For css percpu_ref killing and RCU-protected deletion */ struct rcu_head rcu_head; - struct work_struct free_work; + struct work_struct destroy_work; + atomic_t css_kill_cnt; /* List of events which userspace want to receive */ struct list_head event_list; @@ -269,18 +261,33 @@ enum { * * - Remount is disallowed. * - * - memcg: use_hierarchy is on by default and the cgroup file for - * the flag is not created. + * - rename(2) is disallowed. * - * The followings are planned changes. + * - "tasks" is removed. Everything should be at process + * granularity. Use "cgroup.procs" instead. * - * - release_agent will be disallowed once replacement notification - * mechanism is implemented. + * - "release_agent" and "notify_on_release" are removed. + * Replacement notification mechanism will be implemented. + * + * - cpuset: tasks will be kept in empty cpusets when hotplug happens + * and take masks of ancestors with non-empty cpus/mems, instead of + * being moved to an ancestor. + * + * - cpuset: a task can be moved into an empty cpuset, and again it + * takes masks of ancestors. + * + * - memcg: use_hierarchy is on by default and the cgroup file for + * the flag is not created. */ CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */ CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */ + + /* mount options live below bit 16 */ + CGRP_ROOT_OPTION_MASK = (1 << 16) - 1, + + CGRP_ROOT_SUBSYS_BOUND = (1 << 16), /* subsystems finished binding */ }; /* @@ -291,18 +298,12 @@ enum { struct cgroupfs_root { struct super_block *sb; - /* - * The bitmask of subsystems intended to be attached to this - * hierarchy - */ + /* The bitmask of subsystems attached to this hierarchy */ unsigned long subsys_mask; /* Unique id for this hierarchy. */ int hierarchy_id; - /* The bitmask of subsystems currently attached to this hierarchy */ - unsigned long actual_subsys_mask; - /* A list running through the attached subsystems */ struct list_head subsys_list; @@ -315,9 +316,6 @@ struct cgroupfs_root { /* A list running through the active hierarchies */ struct list_head root_list; - /* All cgroups on this root, cgroup_mutex protected */ - struct list_head allcg_list; - /* Hierarchy-specific flags */ unsigned long flags; @@ -357,11 +355,10 @@ 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 @@ -394,9 +391,11 @@ struct cgroup_map_cb { */ /* cftype->flags */ -#define CFTYPE_ONLY_ON_ROOT (1U << 0) /* only create on root cg */ -#define CFTYPE_NOT_ON_ROOT (1U << 1) /* don't create on root cg */ -#define CFTYPE_INSANE (1U << 2) /* don't create if sane_behavior */ +enum { + CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cg */ + CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cg */ + CFTYPE_INSANE = (1 << 2), /* don't create if sane_behavior */ +}; #define MAX_CFTYPE_NAME 64 @@ -442,13 +441,13 @@ struct cftype { * entry. The key/value pairs (and their ordering) should not * change between reboots. */ - int (*read_map)(struct cgroup *cont, struct cftype *cft, + int (*read_map)(struct cgroup *cgrp, struct cftype *cft, struct cgroup_map_cb *cb); /* * read_seq_string() is used for outputting a simple sequence * using seqfile. */ - int (*read_seq_string)(struct cgroup *cont, struct cftype *cft, + int (*read_seq_string)(struct cgroup *cgrp, struct cftype *cft, struct seq_file *m); ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft, @@ -538,10 +537,11 @@ 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); @@ -646,22 +646,60 @@ static inline struct cgroup_subsys_state *cgroup_subsys_state( return cgrp->subsys[subsys_id]; } -/* - * function to get the cgroup_subsys_state which allows for extra - * rcu_dereference_check() conditions, such as locks used during the - * cgroup_subsys::attach() methods. +/** + * 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; -#define task_subsys_state_check(task, subsys_id, __c) \ - rcu_dereference_check((task)->cgroups->subsys[(subsys_id)], \ - lockdep_is_held(&(task)->alloc_lock) || \ - lockdep_is_held(&cgroup_mutex) || (__c)) +#define task_css_set_check(task, __c) \ + rcu_dereference_check((task)->cgroups, \ + lockdep_is_held(&(task)->alloc_lock) || \ + lockdep_is_held(&cgroup_mutex) || (__c)) #else -#define task_subsys_state_check(task, subsys_id, __c) \ - rcu_dereference((task)->cgroups->subsys[(subsys_id)]) +#define task_css_set_check(task, __c) \ + rcu_dereference((task)->cgroups) #endif +/** + * task_subsys_state_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_subsys_state_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_subsys_state - obtain css for (task, subsys) + * @task: the target task + * @subsys_id: the target subsystem ID + * + * See task_subsys_state_check(). + */ static inline struct cgroup_subsys_state * task_subsys_state(struct task_struct *task, int subsys_id) { @@ -674,12 +712,14 @@ 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 +727,15 @@ 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 +794,10 @@ 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 +821,7 @@ 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 +877,6 @@ 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 +887,6 @@ 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) { |
