| #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> |
| #include <linux/percpu-refcount.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 css is attached to */ |
| struct cgroup *cgroup; |
| |
| /* the cgroup subsystem that this css is attached to */ |
| struct cgroup_subsys *ss; |
| |
| /* reference count - access via css_[try]get() and css_put() */ |
| struct percpu_ref refcnt; |
| |
| /* the parent css */ |
| struct cgroup_subsys_state *parent; |
| |
| unsigned long flags; |
| /* ID for this css, if possible */ |
| struct css_id __rcu *id; |
| |
| /* percpu_ref killing and RCU release */ |
| struct rcu_head rcu_head; |
| struct work_struct destroy_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() */ |
| }; |
| |
| /** |
| * 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)) |
| percpu_ref_get(&css->refcnt); |
| } |
| |
| /** |
| * 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) |
| return true; |
| return percpu_ref_tryget(&css->refcnt); |
| } |
| |
| /** |
| * 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)) |
| percpu_ref_put(&css->refcnt); |
| } |
| |
| /* bits in struct cgroup flags field */ |
| enum { |
| /* Control Group is dead */ |
| CGRP_DEAD, |
| /* |
| * 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 */ |
| |
| /* |
| * idr allocated in-hierarchy ID. |
| * |
| * The ID of the root cgroup is always 0, and a new cgroup |
| * will be assigned with a smallest available ID. |
| */ |
| int id; |
| |
| /* the number of attached css's */ |
| int nr_css; |
| |
| /* |
| * 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 */ |
| |
| /* |
| * 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(). |
| * |
| * 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 __rcu *subsys[CGROUP_SUBSYS_COUNT]; |
| |
| struct cgroupfs_root *root; |
| |
| /* |
| * List of cgrp_cset_links pointing at css_sets with tasks in this |
| * cgroup. Protected by css_set_lock. |
| */ |
| struct list_head cset_links; |
| |
| /* |
| * 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; |
| |
| /* dummy css with NULL ->ss, points back to this cgroup */ |
| struct cgroup_subsys_state dummy_css; |
| |
| /* For css percpu_ref killing and RCU-protected deletion */ |
| struct rcu_head rcu_head; |
| struct work_struct destroy_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. |
| * |
| * - rename(2) is disallowed. |
| * |
| * - "tasks" is removed. Everything should be at process |
| * granularity. Use "cgroup.procs" instead. |
| * |
| * - "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. |
| * |
| * - blkcg: blk-throttle becomes properly hierarchical. |
| */ |
| 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 */ |
| }; |
| |
| /* |
| * 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 attached to this hierarchy */ |
| unsigned long subsys_mask; |
| |
| /* Unique id for this hierarchy. */ |
| int hierarchy_id; |
| |
| /* 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; |
| |
| /* Hierarchy-specific flags */ |
| unsigned long flags; |
| |
| /* IDs for cgroups in this hierarchy */ |
| struct idr cgroup_idr; |
| |
| /* 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 cgrp_cset_links pointing at cgroups referenced from this |
| * css_set. Protected by css_set_lock. |
| */ |
| struct list_head cgrp_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 */ |
| enum { |
| CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cgrp */ |
| CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cgrp */ |
| CFTYPE_INSANE = (1 << 2), /* don't create if sane_behavior */ |
| CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */ |
| }; |
| |
| #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; |
| |
| /* |
| * The subsys this file belongs to. Initialized automatically |
| * during registration. NULL for cgroup core files. |
| */ |
| struct cgroup_subsys *ss; |
| |
| int (*open)(struct inode *inode, struct file *file); |
| ssize_t (*read)(struct cgroup_subsys_state *css, 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_subsys_state *css, struct cftype *cft); |
| /* |
| * read_s64() is a signed version of read_u64() |
| */ |
| s64 (*read_s64)(struct cgroup_subsys_state *css, 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_subsys_state *css, 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_subsys_state *css, |
| struct cftype *cft, struct seq_file *m); |
| |
| ssize_t (*write)(struct cgroup_subsys_state *css, 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_subsys_state *css, struct cftype *cft, |
| u64 val); |
| /* |
| * write_s64() is a signed version of write_u64() |
| */ |
| int (*write_s64)(struct cgroup_subsys_state *css, 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_subsys_state *css, 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_subsys_state *css, 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_subsys_state *css, |
| 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_subsys_state *css, |
| 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; |
| }; |
| |
| /* |
| * 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 cftype *cfts); |
| |
| 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(struct task_struct *task, 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_subsys_state *cgroup_taskset_cur_css(struct cgroup_taskset *tset, |
| int subsys_id); |
| int cgroup_taskset_size(struct cgroup_taskset *tset); |
| |
| /** |
| * cgroup_taskset_for_each - iterate cgroup_taskset |
| * @task: the loop cursor |
| * @skip_css: skip if task's css matches this, %NULL to iterate through all |
| * @tset: taskset to iterate |
| */ |
| #define cgroup_taskset_for_each(task, skip_css, tset) \ |
| for ((task) = cgroup_taskset_first((tset)); (task); \ |
| (task) = cgroup_taskset_next((tset))) \ |
| if (!(skip_css) || \ |
| cgroup_taskset_cur_css((tset), \ |
| (skip_css)->ss->subsys_id) != (skip_css)) |
| |
| /* |
| * Control Group subsystem type. |
| * See Documentation/cgroups/cgroups.txt for details |
| */ |
| |
| struct cgroup_subsys { |
| struct cgroup_subsys_state *(*css_alloc)(struct cgroup_subsys_state *parent_css); |
| int (*css_online)(struct cgroup_subsys_state *css); |
| void (*css_offline)(struct cgroup_subsys_state *css); |
| void (*css_free)(struct cgroup_subsys_state *css); |
| |
| int (*can_attach)(struct cgroup_subsys_state *css, |
| struct cgroup_taskset *tset); |
| void (*cancel_attach)(struct cgroup_subsys_state *css, |
| struct cgroup_taskset *tset); |
| void (*attach)(struct cgroup_subsys_state *css, |
| struct cgroup_taskset *tset); |
| void (*fork)(struct task_struct *task); |
| void (*exit)(struct cgroup_subsys_state *css, |
| struct cgroup_subsys_state *old_css, |
| struct task_struct *task); |
| void (*bind)(struct cgroup_subsys_state *root_css); |
| |
| int subsys_id; |
| int disabled; |
| int early_init; |
| |
| /* |
| * 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; |
| |
| /* 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 |
| |
| /** |
| * css_parent - find the parent css |
| * @css: the target cgroup_subsys_state |
| * |
| * Return the parent css of @css. This function is guaranteed to return |
| * non-NULL parent as long as @css isn't the root. |
| */ |
| static inline |
| struct cgroup_subsys_state *css_parent(struct cgroup_subsys_state *css) |
| { |
| return css->parent; |
| } |
| |
| /** |
| * 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_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_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); |
| } |
| |
| static inline struct cgroup *task_cgroup(struct task_struct *task, |
| int subsys_id) |
| { |
| return task_css(task, subsys_id)->cgroup; |
| } |
| |
| struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos, |
| struct cgroup_subsys_state *parent); |
| |
| struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss); |
| |
| /** |
| * 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(). A child |
| * css 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 css 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 css_for_each_child(pos, parent) \ |
| for ((pos) = css_next_child(NULL, (parent)); (pos); \ |
| (pos) = css_next_child((pos), (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); |
| |
| /** |
| * 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(). A |
| * descendant css 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 css which finished ->css_online() 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(@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))) |
| |
| struct cgroup_subsys_state * |
| css_next_descendant_post(struct cgroup_subsys_state *pos, |
| struct cgroup_subsys_state *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. Note that the walk visibility guarantee 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))) |
| |
| /* A css_task_iter should be treated as an opaque object */ |
| struct css_task_iter { |
| struct cgroup_subsys_state *origin_css; |
| struct list_head *cset_link; |
| struct list_head *task; |
| }; |
| |
| 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); |
| |
| int css_scan_tasks(struct cgroup_subsys_state *css, |
| bool (*test)(struct task_struct *, void *), |
| void (*process)(struct task_struct *, void *), |
| void *data, struct ptr_heap *heap); |
| |
| int cgroup_attach_task_all(struct task_struct *from, struct task_struct *); |
| int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from); |
| |
| struct cgroup_subsys_state *css_from_dir(struct dentry *dentry, |
| struct cgroup_subsys *ss); |
| |
| #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 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 */ |