| #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/rcupdate.h> |
| #include <linux/rculist.h> |
| #include <linux/cgroupstats.h> |
| #include <linux/prio_heap.h> |
| #include <linux/rwsem.h> |
| #include <linux/idr.h> |
| #include <linux/workqueue.h> |
| #include <linux/xattr.h> |
| #include <linux/fs.h> |
| |
| #ifdef CONFIG_CGROUPS |
| |
| struct cgroupfs_root; |
| struct cgroup_subsys; |
| struct inode; |
| struct cgroup; |
| struct css_id; |
| struct eventfd_ctx; |
| |
| extern int cgroup_init_early(void); |
| extern int cgroup_init(void); |
| extern void cgroup_fork(struct task_struct *p); |
| extern void cgroup_post_fork(struct task_struct *p); |
| extern void cgroup_exit(struct task_struct *p, int run_callbacks); |
| extern int cgroupstats_build(struct cgroupstats *stats, |
| struct dentry *dentry); |
| extern int cgroup_load_subsys(struct cgroup_subsys *ss); |
| extern void cgroup_unload_subsys(struct cgroup_subsys *ss); |
| |
| extern int proc_cgroup_show(struct seq_file *, void *); |
| |
| /* |
| * Define the enumeration of all cgroup subsystems. |
| * |
| * We define ids for builtin subsystems and then modular ones. |
| */ |
| #define SUBSYS(_x) _x ## _subsys_id, |
| enum cgroup_subsys_id { |
| #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) |
| #include <linux/cgroup_subsys.h> |
| #undef IS_SUBSYS_ENABLED |
| CGROUP_BUILTIN_SUBSYS_COUNT, |
| |
| __CGROUP_SUBSYS_TEMP_PLACEHOLDER = CGROUP_BUILTIN_SUBSYS_COUNT - 1, |
| |
| #define IS_SUBSYS_ENABLED(option) IS_MODULE(option) |
| #include <linux/cgroup_subsys.h> |
| #undef IS_SUBSYS_ENABLED |
| CGROUP_SUBSYS_COUNT, |
| }; |
| #undef SUBSYS |
| |
| /* Per-subsystem/per-cgroup state maintained by the system. */ |
| struct cgroup_subsys_state { |
| /* |
| * The cgroup that this subsystem is attached to. Useful |
| * for subsystems that want to know about the cgroup |
| * hierarchy structure |
| */ |
| 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; |
| |
| unsigned long flags; |
| /* ID for this css, if possible */ |
| struct css_id __rcu *id; |
| |
| /* Used to put @cgroup->dentry on the last css_put() */ |
| struct work_struct dput_work; |
| }; |
| |
| /* bits in struct cgroup_subsys_state flags field */ |
| enum { |
| CSS_ROOT = (1 << 0), /* this CSS is the root of the subsystem */ |
| 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 |
| */ |
| |
| 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); |
| } |
| |
| /* |
| * 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); |
| static inline bool css_tryget(struct cgroup_subsys_state *css) |
| { |
| if (css->flags & CSS_ROOT) |
| return true; |
| 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); |
| static inline void css_put(struct cgroup_subsys_state *css) |
| { |
| if (!(css->flags & CSS_ROOT)) |
| __css_put(css); |
| } |
| |
| /* bits in struct cgroup flags field */ |
| enum { |
| /* Control Group is dead */ |
| CGRP_REMOVED, |
| /* |
| * Control Group has previously had a child cgroup or a task, |
| * but no longer (only if CGRP_NOTIFY_ON_RELEASE is set) |
| */ |
| CGRP_RELEASABLE, |
| /* Control Group requires release notifications to userspace */ |
| CGRP_NOTIFY_ON_RELEASE, |
| /* |
| * Clone the parent's configuration when creating a new child |
| * cpuset cgroup. For historical reasons, this option can be |
| * specified at mount time and thus is implemented here. |
| */ |
| CGRP_CPUSET_CLONE_CHILDREN, |
| /* see the comment above CGRP_ROOT_SANE_BEHAVIOR for details */ |
| CGRP_SANE_BEHAVIOR, |
| }; |
| |
| struct cgroup_name { |
| struct rcu_head rcu_head; |
| char 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 */ |
| |
| /* |
| * We link our 'sibling' struct into our parent's 'children'. |
| * Our children link their 'sibling' into our 'children'. |
| */ |
| struct list_head sibling; /* my parent's children */ |
| struct list_head children; /* my children */ |
| struct list_head files; /* my files */ |
| |
| struct cgroup *parent; /* my parent */ |
| struct dentry *dentry; /* cgroup fs entry, RCU protected */ |
| |
| /* |
| * This is a copy of dentry->d_name, and it's needed because |
| * we can't use dentry->d_name in cgroup_path(). |
| * |
| * You must acquire rcu_read_lock() to access cgrp->name, and |
| * the only place that can change it is rename(), which is |
| * protected by parent dir's i_mutex. |
| * |
| * Normally you should use cgroup_name() wrapper rather than |
| * access it directly. |
| */ |
| struct cgroup_name __rcu *name; |
| |
| /* Private pointers for each registered subsystem */ |
| struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
| |
| struct cgroupfs_root *root; |
| |
| /* |
| * List of cg_cgroup_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 */ |
| |
| /* |
| * Linked list running through all cgroups that can |
| * potentially be reaped by the release agent. Protected by |
| * release_list_lock |
| */ |
| struct list_head release_list; |
| |
| /* |
| * list of pidlists, up to two for each namespace (one for procs, one |
| * for tasks); created on demand. |
| */ |
| struct list_head pidlists; |
| struct mutex pidlist_mutex; |
| |
| /* For RCU-protected deletion */ |
| struct rcu_head rcu_head; |
| struct work_struct free_work; |
| |
| /* List of events which userspace want to receive */ |
| struct list_head event_list; |
| spinlock_t event_list_lock; |
| |
| /* directory xattrs */ |
| struct simple_xattrs xattrs; |
| }; |
| |
| #define MAX_CGROUP_ROOT_NAMELEN 64 |
| |
| /* cgroupfs_root->flags */ |
| enum { |
| /* |
| * Unfortunately, cgroup core and various controllers are riddled |
| * with idiosyncrasies and pointless options. The following flag, |
| * when set, will force sane behavior - some options are forced on, |
| * others are disallowed, and some controllers will change their |
| * hierarchical or other behaviors. |
| * |
| * The set of behaviors affected by this flag are still being |
| * determined and developed and the mount option for this flag is |
| * prefixed with __DEVEL__. The prefix will be dropped once we |
| * reach the point where all behaviors are compatible with the |
| * planned unified hierarchy, which will automatically turn on this |
| * flag. |
| * |
| * The followings are the behaviors currently affected this flag. |
| * |
| * - Mount options "noprefix" and "clone_children" are disallowed. |
| * Also, cgroupfs file cgroup.clone_children is not created. |
| * |
| * - When mounting an existing superblock, mount options should |
| * match. |
| * |
| * - Remount is disallowed. |
| * |
| * - memcg: use_hierarchy is on by default and the cgroup file for |
| * the flag is not created. |
| * |
| * The followings are planned changes. |
| * |
| * - release_agent will be disallowed once replacement notification |
| * mechanism is implemented. |
| */ |
| 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 */ |
| }; |
| |
| /* |
| * A cgroupfs_root represents the root of a cgroup hierarchy, and may be |
| * associated with a superblock to form an active hierarchy. This is |
| * internal to cgroup core. Don't access directly from controllers. |
| */ |
| struct cgroupfs_root { |
| struct super_block *sb; |
| |
| /* |
| * The bitmask of subsystems intended to be 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; |
| |
| /* The root cgroup for this hierarchy */ |
| struct cgroup top_cgroup; |
| |
| /* Tracks how many cgroups are currently defined in hierarchy.*/ |
| int number_of_cgroups; |
| |
| /* 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; |
| |
| /* IDs for cgroups in this hierarchy */ |
| struct ida cgroup_ida; |
| |
| /* The path to use for release notifications. */ |
| char release_agent_path[PATH_MAX]; |
| |
| /* The name for this hierarchy - may be empty */ |
| char name[MAX_CGROUP_ROOT_NAMELEN]; |
| }; |
| |
| /* |
| * A css_set is a structure holding pointers to a set of |
| * cgroup_subsys_state objects. This saves space in the task struct |
| * object and speeds up fork()/exit(), since a single inc/dec and a |
| * list_add()/del() can bump the reference count on the entire cgroup |
| * set for a task. |
| */ |
| |
| struct css_set { |
| |
| /* Reference count */ |
| atomic_t refcount; |
| |
| /* |
| * List running through all cgroup groups in the same hash |
| * slot. Protected by css_set_lock |
| */ |
| struct hlist_node hlist; |
| |
| /* |
| * List running through all tasks using this cgroup |
| * group. Protected by css_set_lock |
| */ |
| 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 |
| */ |
| struct list_head cg_links; |
| |
| /* |
| * Set of subsystem states, one for each subsystem. This array |
| * is immutable after creation apart from the init_css_set |
| * during subsystem registration (at boot time) and modular subsystem |
| * loading/unloading. |
| */ |
| struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; |
| |
| /* For RCU-protected deletion */ |
| struct rcu_head rcu_head; |
| }; |
| |
| /* |
| * cgroup_map_cb is an abstract callback API for reporting map-valued |
| * control files |
| */ |
| |
| struct cgroup_map_cb { |
| int (*fill)(struct cgroup_map_cb *cb, const char *key, u64 value); |
| void *state; |
| }; |
| |
| /* |
| * struct cftype: handler definitions for cgroup control files |
| * |
| * When reading/writing to a file: |
| * - the cgroup to use is file->f_dentry->d_parent->d_fsdata |
| * - the 'cftype' of the file is file->f_dentry->d_fsdata |
| */ |
| |
| /* 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 */ |
| |
| #define MAX_CFTYPE_NAME 64 |
| |
| struct cftype { |
| /* |
| * By convention, the name should begin with the name of the |
| * subsystem, followed by a period. Zero length string indicates |
| * end of cftype array. |
| */ |
| char name[MAX_CFTYPE_NAME]; |
| int private; |
| /* |
| * If not 0, file mode is set to this value, otherwise it will |
| * be figured out automatically |
| */ |
| umode_t mode; |
| |
| /* |
| * If non-zero, defines the maximum length of string that can |
| * be passed to write_string; defaults to 64 |
| */ |
| size_t max_write_len; |
| |
| /* CFTYPE_* flags */ |
| unsigned int flags; |
| |
| int (*open)(struct inode *inode, struct file *file); |
| ssize_t (*read)(struct cgroup *cgrp, struct cftype *cft, |
| struct file *file, |
| char __user *buf, size_t nbytes, loff_t *ppos); |
| /* |
| * read_u64() is a shortcut for the common case of returning a |
| * single integer. Use it in place of read() |
| */ |
| u64 (*read_u64)(struct cgroup *cgrp, struct cftype *cft); |
| /* |
| * read_s64() is a signed version of read_u64() |
| */ |
| s64 (*read_s64)(struct cgroup *cgrp, struct cftype *cft); |
| /* |
| * read_map() is used for defining a map of key/value |
| * pairs. It should call cb->fill(cb, key, value) for each |
| * entry. The key/value pairs (and their ordering) should not |
| * change between reboots. |
| */ |
| int (*read_map)(struct cgroup *cont, 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, |
| struct seq_file *m); |
| |
| ssize_t (*write)(struct cgroup *cgrp, struct cftype *cft, |
| struct file *file, |
| const char __user *buf, size_t nbytes, loff_t *ppos); |
| |
| /* |
| * 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 *cgrp, struct cftype *cft, u64 val); |
| /* |
| * write_s64() is a signed version of write_u64() |
| */ |
| int (*write_s64)(struct cgroup *cgrp, struct cftype *cft, s64 val); |
| |
| /* |
| * write_string() is passed a nul-terminated kernelspace |
| * buffer of maximum length determined by max_write_len. |
| * Returns 0 or -ve error code. |
| */ |
| int (*write_string)(struct cgroup *cgrp, struct cftype *cft, |
| const char *buffer); |
| /* |
| * trigger() callback can be used to get some kick from the |
| * userspace, when the actual string written is not important |
| * at all. The private field can be used to determine the |
| * kick type for multiplexing. |
| */ |
| int (*trigger)(struct cgroup *cgrp, unsigned int event); |
| |
| int (*release)(struct inode *inode, struct file *file); |
| |
| /* |
| * register_event() callback will be used to add new userspace |
| * waiter for changes related to the cftype. Implement it if |
| * you want to provide this functionality. Use eventfd_signal() |
| * on eventfd to send notification to userspace. |
| */ |
| int (*register_event)(struct cgroup *cgrp, struct cftype *cft, |
| struct eventfd_ctx *eventfd, const char *args); |
| /* |
| * unregister_event() callback will be called when userspace |
| * closes the eventfd or on cgroup removing. |
| * This callback must be implemented, if you want provide |
| * notification functionality. |
| */ |
| void (*unregister_event)(struct cgroup *cgrp, struct cftype *cft, |
| struct eventfd_ctx *eventfd); |
| }; |
| |
| /* |
| * cftype_sets describe cftypes belonging to a subsystem and are chained at |
| * cgroup_subsys->cftsets. Each cftset points to an array of cftypes |
| * terminated by zero length name. |
| */ |
| struct cftype_set { |
| struct list_head node; /* chained at subsys->cftsets */ |
| struct cftype *cfts; |
| }; |
| |
| struct cgroup_scanner { |
| struct cgroup *cg; |
| int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan); |
| void (*process_task)(struct task_struct *p, |
| struct cgroup_scanner *scan); |
| struct ptr_heap *heap; |
| void *data; |
| }; |
| |
| /* |
| * See the comment above CGRP_ROOT_SANE_BEHAVIOR for details. This |
| * function can be called as long as @cgrp is accessible. |
| */ |
| static inline bool cgroup_sane_behavior(const struct cgroup *cgrp) |
| { |
| return cgrp->root->flags & CGRP_ROOT_SANE_BEHAVIOR; |
| } |
| |
| /* Caller should hold rcu_read_lock() */ |
| static inline const char *cgroup_name(const struct cgroup *cgrp) |
| { |
| return rcu_dereference(cgrp->name)->name; |
| } |
| |
| 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); |
| |
| /* |
| * Control Group taskset, used to pass around set of tasks to cgroup_subsys |
| * methods. |
| */ |
| struct cgroup_taskset; |
| struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset); |
| struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset); |
| struct cgroup *cgroup_taskset_cur_cgroup(struct cgroup_taskset *tset); |
| int cgroup_taskset_size(struct cgroup_taskset *tset); |
| |
| /** |
| * cgroup_taskset_for_each - iterate cgroup_taskset |
| * @task: the loop cursor |
| * @skip_cgrp: skip if task's cgroup matches this, %NULL to iterate through all |
| * @tset: taskset to iterate |
| */ |
| #define cgroup_taskset_for_each(task, skip_cgrp, tset) \ |
| for ((task) = cgroup_taskset_first((tset)); (task); \ |
| (task) = cgroup_taskset_next((tset))) \ |
| if (!(skip_cgrp) || \ |
| cgroup_taskset_cur_cgroup((tset)) != (skip_cgrp)) |
| |
| /* |
| * Control Group subsystem type. |
| * See Documentation/cgroups/cgroups.txt for details |
| */ |
| |
| struct cgroup_subsys { |
| struct cgroup_subsys_state *(*css_alloc)(struct cgroup *cgrp); |
| int (*css_online)(struct cgroup *cgrp); |
| void (*css_offline)(struct cgroup *cgrp); |
| void (*css_free)(struct cgroup *cgrp); |
| |
| int (*can_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset); |
| void (*cancel_attach)(struct cgroup *cgrp, struct cgroup_taskset *tset); |
| void (*attach)(struct cgroup *cgrp, struct cgroup_taskset *tset); |
| void (*fork)(struct task_struct *task); |
| void (*exit)(struct cgroup *cgrp, struct cgroup *old_cgrp, |
| struct task_struct *task); |
| void (*bind)(struct cgroup *root); |
| |
| int subsys_id; |
| int disabled; |
| int early_init; |
| /* |
| * True if this subsys uses ID. ID is not available before cgroup_init() |
| * (not available in early_init time.) |
| */ |
| bool use_id; |
| |
| /* |
| * If %false, this subsystem is properly hierarchical - |
| * configuration, resource accounting and restriction on a parent |
| * cgroup cover those of its children. If %true, hierarchy support |
| * is broken in some ways - some subsystems ignore hierarchy |
| * completely while others are only implemented half-way. |
| * |
| * It's now disallowed to create nested cgroups if the subsystem is |
| * broken and cgroup core will emit a warning message on such |
| * cases. Eventually, all subsystems will be made properly |
| * hierarchical and this will go away. |
| */ |
| bool broken_hierarchy; |
| bool warned_broken_hierarchy; |
| |
| #define MAX_CGROUP_TYPE_NAMELEN 32 |
| const char *name; |
| |
| /* |
| * Link to parent, and list entry in parent's children. |
| * Protected by cgroup_lock() |
| */ |
| struct cgroupfs_root *root; |
| struct list_head sibling; |
| /* used when use_id == true */ |
| struct idr idr; |
| spinlock_t id_lock; |
| |
| /* list of cftype_sets */ |
| struct list_head cftsets; |
| |
| /* base cftypes, automatically [de]registered with subsys itself */ |
| struct cftype *base_cftypes; |
| struct cftype_set base_cftset; |
| |
| /* should be defined only by modular subsystems */ |
| struct module *module; |
| }; |
| |
| #define SUBSYS(_x) extern struct cgroup_subsys _x ## _subsys; |
| #define IS_SUBSYS_ENABLED(option) IS_BUILTIN(option) |
| #include <linux/cgroup_subsys.h> |
| #undef IS_SUBSYS_ENABLED |
| #undef SUBSYS |
| |
| static inline struct cgroup_subsys_state *cgroup_subsys_state( |
| struct cgroup *cgrp, int subsys_id) |
| { |
| 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. |
| */ |
| #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)) |
| #else |
| #define task_subsys_state_check(task, subsys_id, __c) \ |
| rcu_dereference((task)->cgroups->subsys[(subsys_id)]) |
| #endif |
| |
| static inline struct cgroup_subsys_state * |
| task_subsys_state(struct task_struct *task, int subsys_id) |
| { |
| return task_subsys_state_check(task, subsys_id, false); |
| } |
| |
| static inline struct cgroup* task_cgroup(struct task_struct *task, |
| int subsys_id) |
| { |
| return task_subsys_state(task, subsys_id)->cgroup; |
| } |
| |
| /** |
| * 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 |
| * |
| * Walk @cgroup'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. |
| * |
| * 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. |
| */ |
| #define cgroup_for_each_child(pos, cgroup) \ |
| list_for_each_entry_rcu(pos, &(cgroup)->children, sibling) |
| |
| struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos, |
| struct cgroup *cgroup); |
| struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos); |
| |
| /** |
| * cgroup_for_each_descendant_pre - pre-order walk of a cgroup's descendants |
| * @pos: the cgroup * to use as the loop cursor |
| * @cgroup: cgroup whose descendants to walk |
| * |
| * Walk @cgroup's descendants. Must be called under rcu_read_lock(). A |
| * descendant 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. |
| * |
| * If a subsystem synchronizes against the parent in its ->css_online() and |
| * before starting iterating, and synchronizes against @pos on each |
| * iteration, any descendant cgroup which finished ->css_offline() is |
| * guaranteed to be visible in the future iterations. |
| * |
| * In other words, the following guarantees that a descendant can't escape |
| * state updates of its ancestors. |
| * |
| * my_online(@cgrp) |
| * { |
| * Lock @cgrp->parent and @cgrp; |
| * Inherit state from @cgrp->parent; |
| * Unlock both. |
| * } |
| * |
| * my_update_state(@cgrp) |
| * { |
| * Lock @cgrp; |
| * Update @cgrp's state; |
| * Unlock @cgrp; |
| * |
| * cgroup_for_each_descendant_pre(@pos, @cgrp) { |
| * Lock @pos; |
| * Verify @pos is alive and inherit state from @pos->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 cgroup 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. |
| */ |
| #define cgroup_for_each_descendant_pre(pos, cgroup) \ |
| for (pos = cgroup_next_descendant_pre(NULL, (cgroup)); (pos); \ |
| pos = cgroup_next_descendant_pre((pos), (cgroup))) |
| |
| struct cgroup *cgroup_next_descendant_post(struct cgroup *pos, |
| struct cgroup *cgroup); |
| |
| /** |
| * cgroup_for_each_descendant_post - post-order walk of a cgroup's descendants |
| * @pos: the cgroup * to use as the loop cursor |
| * @cgroup: cgroup whose descendants to walk |
| * |
| * Similar to cgroup_for_each_descendant_pre() but performs post-order |
| * traversal instead. Note that the walk visibility guarantee described in |
| * pre-order walk doesn't apply the same to post-order walks. |
| */ |
| #define cgroup_for_each_descendant_post(pos, cgroup) \ |
| for (pos = cgroup_next_descendant_post(NULL, (cgroup)); (pos); \ |
| pos = cgroup_next_descendant_post((pos), (cgroup))) |
| |
| /* A cgroup_iter should be treated as an opaque object */ |
| struct cgroup_iter { |
| struct list_head *cg_link; |
| struct list_head *task; |
| }; |
| |
| /* |
| * To iterate across the tasks in a cgroup: |
| * |
| * 1) call cgroup_iter_start to initialize an iterator |
| * |
| * 2) call cgroup_iter_next() to retrieve member tasks until it |
| * returns NULL or until you want to end the iteration |
| * |
| * 3) call cgroup_iter_end() to destroy the iterator. |
| * |
| * Or, call cgroup_scan_tasks() to iterate through every task in a |
| * cgroup - cgroup_scan_tasks() holds the css_set_lock when calling |
| * the test_task() callback, but not while calling the process_task() |
| * callback. |
| */ |
| void cgroup_iter_start(struct cgroup *cgrp, struct cgroup_iter *it); |
| struct task_struct *cgroup_iter_next(struct cgroup *cgrp, |
| struct cgroup_iter *it); |
| void cgroup_iter_end(struct cgroup *cgrp, struct cgroup_iter *it); |
| int cgroup_scan_tasks(struct cgroup_scanner *scan); |
| int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); |
| int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); |
| |
| /* |
| * CSS ID is ID for cgroup_subsys_state structs under subsys. This only works |
| * if cgroup_subsys.use_id == true. It can be used for looking up and scanning. |
| * CSS ID is assigned at cgroup allocation (create) automatically |
| * and removed when subsys calls free_css_id() function. This is because |
| * the lifetime of cgroup_subsys_state is subsys's matter. |
| * |
| * Looking up and scanning function should be called under rcu_read_lock(). |
| * Taking cgroup_mutex is not necessary for following calls. |
| * But the css returned by this routine can be "not populated yet" or "being |
| * destroyed". The caller should check css and cgroup's status. |
| */ |
| |
| /* |
| * Typically Called at ->destroy(), or somewhere the subsys frees |
| * cgroup_subsys_state. |
| */ |
| void free_css_id(struct cgroup_subsys *ss, struct cgroup_subsys_state *css); |
| |
| /* Find a cgroup_subsys_state which has given ID */ |
| |
| struct cgroup_subsys_state *css_lookup(struct cgroup_subsys *ss, int id); |
| |
| /* Returns true if root is ancestor of cg */ |
| bool css_is_ancestor(struct cgroup_subsys_state *cg, |
| const struct cgroup_subsys_state *root); |
| |
| /* 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 */ |
| |
| static inline int cgroup_init_early(void) { return 0; } |
| static inline int cgroup_init(void) { return 0; } |
| 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) |
| { |
| return -EINVAL; |
| } |
| |
| /* No cgroups - nothing to do */ |
| static inline int cgroup_attach_task_all(struct task_struct *from, |
| struct task_struct *t) |
| { |
| return 0; |
| } |
| |
| #endif /* !CONFIG_CGROUPS */ |
| |
| #endif /* _LINUX_CGROUP_H */ |