#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/rwsem.h>
-#include <linux/idr.h>
-#include <linux/workqueue.h>
#include <linux/fs.h>
-#include <linux/percpu-refcount.h>
#include <linux/seq_file.h>
#include <linux/kernfs.h>
-#include <linux/wait.h>
-#include <linux/work-simple.h>
+#include <linux/jump_label.h>
+
+#include <linux/cgroup-defs.h>
#ifdef CONFIG_CGROUPS
-struct cgroup_root;
-struct cgroup_subsys;
-struct cgroup;
+/*
+ * 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
-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);
-extern int cgroupstats_build(struct cgroupstats *stats,
- struct dentry *dentry);
+/* a css_task_iter should be treated as an opaque object */
+struct css_task_iter {
+ struct cgroup_subsys *ss;
-extern int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
- struct pid *pid, struct task_struct *tsk);
+ struct list_head *cset_pos;
+ struct list_head *cset_head;
-/* define the enumeration of all cgroup subsystems */
-#define SUBSYS(_x) _x ## _cgrp_id,
-enum cgroup_subsys_id {
-#include <linux/cgroup_subsys.h>
- CGROUP_SUBSYS_COUNT,
+ 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);
+
/*
- * Per-subsystem/per-cgroup state maintained by the system. This is the
- * fundamental structural building block that controllers deal with.
+ * 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.
*
- * Fields marked with "PI:" are public and immutable and may be accessed
- * directly without synchronization.
+ * 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.
*/
-struct cgroup_subsys_state {
- /* PI: the cgroup that this css is attached to */
- struct cgroup *cgroup;
-
- /* PI: 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;
-
- /* PI: the parent css */
- struct cgroup_subsys_state *parent;
-
- /* siblings list anchored at the parent's ->children */
- struct list_head sibling;
- struct list_head children;
-
- /*
- * PI: Subsys-unique ID. 0 is unused and root is always 1. The
- * matching css can be looked up using css_from_id().
- */
- int id;
-
- unsigned int flags;
-
- /*
- * Monotonically increasing unique serial number which defines a
- * uniform order among all csses. It's guaranteed that all
- * ->children lists are in the ascending order of ->serial_nr and
- * used to allow interrupting and resuming iterations.
- */
- u64 serial_nr;
-
- /* percpu_ref killing and RCU release */
- struct rcu_head rcu_head;
- struct work_struct destroy_work;
- struct swork_event destroy_swork;
-};
+#define css_for_each_child(pos, parent) \
+ for ((pos) = css_next_child(NULL, (parent)); (pos); \
+ (pos) = css_next_child((pos), (parent)))
-/* bits in struct cgroup_subsys_state flags field */
-enum {
- CSS_NO_REF = (1 << 0), /* no reference counting for this css */
- CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */
- CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */
-};
+/**
+ * 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
percpu_ref_put_many(&css->refcnt, n);
}
-/* bits in struct cgroup flags field */
-enum {
- /* 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,
-};
-
-struct cgroup {
- /* self css with NULL ->ss, points back to this cgroup */
- struct cgroup_subsys_state self;
-
- unsigned long flags; /* "unsigned long" so bitops work */
-
- /*
- * idr allocated in-hierarchy ID.
- *
- * ID 0 is not used, the ID of the root cgroup is always 1, and a
- * new cgroup will be assigned with a smallest available ID.
- *
- * Allocating/Removing ID must be protected by cgroup_mutex.
- */
- int id;
-
- /*
- * If this cgroup contains any tasks, it contributes one to
- * populated_cnt. All children with non-zero popuplated_cnt of
- * their own contribute one. The count is zero iff there's no task
- * in this cgroup or its subtree.
- */
- int populated_cnt;
-
- struct kernfs_node *kn; /* cgroup kernfs entry */
- struct kernfs_node *populated_kn; /* kn for "cgroup.subtree_populated" */
-
- /*
- * The bitmask of subsystems enabled on the child cgroups.
- * ->subtree_control is the one configured through
- * "cgroup.subtree_control" while ->child_subsys_mask is the
- * effective one which may have more subsystems enabled.
- * Controller knobs are made available iff it's enabled in
- * ->subtree_control.
- */
- unsigned int subtree_control;
- unsigned int child_subsys_mask;
-
- /* Private pointers for each registered subsystem */
- struct cgroup_subsys_state __rcu *subsys[CGROUP_SUBSYS_COUNT];
-
- struct cgroup_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;
-
- /*
- * On the default hierarchy, a css_set for a cgroup with some
- * susbsys disabled will point to css's which are associated with
- * the closest ancestor which has the subsys enabled. The
- * following lists all css_sets which point to this cgroup's css
- * for the given subsystem.
- */
- struct list_head e_csets[CGROUP_SUBSYS_COUNT];
-
- /*
- * 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;
-
- /* used to wait for offlining of csses */
- wait_queue_head_t offline_waitq;
-
- /* used to schedule release agent */
- struct work_struct release_agent_work;
-};
-
-#define MAX_CGROUP_ROOT_NAMELEN 64
-
-/* cgroup_root->flags */
-enum {
- CGRP_ROOT_SANE_BEHAVIOR = (1 << 0), /* __DEVEL__sane_behavior specified */
- CGRP_ROOT_NOPREFIX = (1 << 1), /* mounted subsystems have no named prefix */
- CGRP_ROOT_XATTR = (1 << 2), /* supports extended attributes */
-};
-
-/*
- * A cgroup_root represents the root of a cgroup hierarchy, and may be
- * associated with a kernfs_root to form an active hierarchy. This is
- * internal to cgroup core. Don't access directly from controllers.
- */
-struct cgroup_root {
- struct kernfs_root *kf_root;
-
- /* The bitmask of subsystems attached to this hierarchy */
- unsigned int subsys_mask;
-
- /* Unique id for this hierarchy. */
- int hierarchy_id;
-
- /* The root cgroup. Root is destroyed on its release. */
- struct cgroup cgrp;
-
- /* Number of cgroups in the hierarchy, used only for /proc/cgroups */
- atomic_t nr_cgrps;
-
- /* A list running through the active hierarchies */
- struct list_head root_list;
-
- /* Hierarchy-specific flags */
- unsigned int 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;
-
- /*
- * Lists running through all tasks using this cgroup group.
- * mg_tasks lists tasks which belong to this cset but are in the
- * process of being migrated out or in. Protected by
- * css_set_rwsem, but, during migration, once tasks are moved to
- * mg_tasks, it can be read safely while holding cgroup_mutex.
- */
- struct list_head tasks;
- struct list_head mg_tasks;
-
- /*
- * List of cgrp_cset_links pointing at cgroups referenced from this
- * css_set. Protected by css_set_lock.
- */
- struct list_head cgrp_links;
-
- /* the default cgroup associated with this css_set */
- struct cgroup *dfl_cgrp;
-
- /*
- * 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).
- */
- struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
-
- /*
- * List of csets participating in the on-going migration either as
- * source or destination. Protected by cgroup_mutex.
- */
- struct list_head mg_preload_node;
- struct list_head mg_node;
-
- /*
- * If this cset is acting as the source of migration the following
- * two fields are set. mg_src_cgrp is the source cgroup of the
- * on-going migration and mg_dst_cset is the destination cset the
- * target tasks on this cset should be migrated to. Protected by
- * cgroup_mutex.
- */
- struct cgroup *mg_src_cgrp;
- struct css_set *mg_dst_cset;
-
- /*
- * On the default hierarhcy, ->subsys[ssid] may point to a css
- * attached to an ancestor instead of the cgroup this css_set is
- * associated with. The following node is anchored at
- * ->subsys[ssid]->cgroup->e_csets[ssid] and provides a way to
- * iterate through all css's attached to a given cgroup.
- */
- struct list_head e_cset_node[CGROUP_SUBSYS_COUNT];
-
- /* For RCU-protected deletion */
- struct rcu_head rcu_head;
-};
-
-/*
- * struct cftype: handler definitions for cgroup control files
- *
- * When reading/writing to a file:
- * - the cgroup to use is file->f_path.dentry->d_parent->d_fsdata
- * - the 'cftype' of the file is file->f_path.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_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
-
- /* internal flags, do not use outside cgroup core proper */
- __CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
- __CFTYPE_NOT_ON_DFL = (1 << 17), /* not on default hierarchy */
-};
-
-#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;
-
- /*
- * The maximum length of string, excluding trailing nul, that can
- * be passed to write. If < PAGE_SIZE-1, PAGE_SIZE-1 is assumed.
- */
- size_t max_write_len;
-
- /* CFTYPE_* flags */
- unsigned int flags;
-
- /*
- * Fields used for internal bookkeeping. Initialized automatically
- * during registration.
- */
- struct cgroup_subsys *ss; /* NULL for cgroup core files */
- struct list_head node; /* anchored at ss->cfts */
- struct kernfs_ops *kf_ops;
-
- /*
- * 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);
-
- /* generic seq_file read interface */
- int (*seq_show)(struct seq_file *sf, void *v);
-
- /* optional ops, implement all or none */
- void *(*seq_start)(struct seq_file *sf, loff_t *ppos);
- void *(*seq_next)(struct seq_file *sf, void *v, loff_t *ppos);
- void (*seq_stop)(struct seq_file *sf, void *v);
-
- /*
- * 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() is the generic write callback which maps directly to
- * kernfs write operation and overrides all other operations.
- * Maximum write size is determined by ->max_write_len. Use
- * of_css/cft() to access the associated css and cft.
- */
- ssize_t (*write)(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off);
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- struct lock_class_key lockdep_key;
-#endif
-};
-
-extern struct cgroup_root cgrp_dfl_root;
-extern struct css_set init_css_set;
-
-/**
- * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
- * @cgrp: the cgroup of interest
- *
- * The default hierarchy is the v2 interface of cgroup and this function
- * can be used to test whether a cgroup is on the default hierarchy for
- * cases where a subsystem should behave differnetly depending on the
- * interface version.
- *
- * The set of behaviors which change on the default hierarchy are still
- * being determined and the mount option is prefixed with __DEVEL__.
- *
- * List of changed behaviors:
- *
- * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
- * and "name" are disallowed.
- *
- * - 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.
- *
- * - "cgroup.procs" is not sorted. pids will be unique unless they got
- * recycled inbetween reads.
- *
- * - "release_agent" and "notify_on_release" are removed. Replacement
- * notification mechanism will be implemented.
- *
- * - "cgroup.clone_children" is removed.
- *
- * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
- * and its descendants contain no task; otherwise, 1. The file also
- * generates kernfs notification which can be monitored through poll and
- * [di]notify when the value of the file changes.
- *
- * - 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.
- *
- * - debug: disallowed on the default hierarchy.
- */
-static inline bool cgroup_on_dfl(const struct cgroup *cgrp)
-{
- return cgrp->root == &cgrp_dfl_root;
-}
-
-/* no synchronization, the result can only be used as a hint */
-static inline bool cgroup_has_tasks(struct cgroup *cgrp)
-{
- return !list_empty(&cgrp->cset_links);
-}
-
-/* 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);
-}
-
-char *task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
-
-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);
-
-bool cgroup_is_descendant(struct cgroup *cgrp, struct cgroup *ancestor);
-
-/*
- * 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);
-
-/**
- * cgroup_taskset_for_each - iterate cgroup_taskset
- * @task: the loop cursor
- * @tset: taskset to iterate
- */
-#define cgroup_taskset_for_each(task, tset) \
- for ((task) = cgroup_taskset_first((tset)); (task); \
- (task) = cgroup_taskset_next((tset)))
-
-/*
- * 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_released)(struct cgroup_subsys_state *css);
- void (*css_free)(struct cgroup_subsys_state *css);
- void (*css_reset)(struct cgroup_subsys_state *css);
- void (*css_e_css_changed)(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 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;
-
- /* the following two fields are initialized automtically during boot */
- int id;
-#define MAX_CGROUP_TYPE_NAMELEN 32
- const char *name;
-
- /* link to parent, protected by cgroup_lock() */
- struct cgroup_root *root;
-
- /* idr for css->id */
- struct idr css_idr;
-
- /*
- * List of cftypes. Each entry is the first entry of an array
- * terminated by zero length name.
- */
- struct list_head cfts;
-
- /*
- * Base cftypes which are automatically registered. The two can
- * point to the same array.
- */
- struct cftype *dfl_cftypes; /* for the default hierarchy */
- struct cftype *legacy_cftypes; /* for the legacy hierarchies */
-
- /*
- * A subsystem may depend on other subsystems. When such subsystem
- * is enabled on a cgroup, the depended-upon subsystems are enabled
- * together if available. Subsystems enabled due to dependency are
- * not visible to userland until explicitly enabled. The following
- * specifies the mask of subsystems that this one depends on.
- */
- unsigned int depends_on;
-};
-
-#define SUBSYS(_x) extern struct cgroup_subsys _x ## _cgrp_subsys;
-#include <linux/cgroup_subsys.h>
-#undef SUBSYS
-
/**
* task_css_set_check - obtain a task's css_set with extra access conditions
* @task: the task to obtain css_set for
*/
#ifdef CONFIG_PROVE_RCU
extern struct mutex cgroup_mutex;
-extern struct rw_semaphore css_set_rwsem;
+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_rwsem) || \
+ lockdep_is_held(&css_set_lock) || \
((task)->flags & PF_EXITING) || (__c))
#else
#define task_css_set_check(task, __c) \
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.
+ */
+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);
+ if (likely(css_tryget_online(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
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);
+/* no synchronization, the result can only be used as a hint */
+static inline bool cgroup_is_populated(struct cgroup *cgrp)
+{
+ return cgrp->populated_cnt;
+}
-/**
- * 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)))
+/* returns ino associated with a cgroup */
+static inline ino_t cgroup_ino(struct cgroup *cgrp)
+{
+ return cgrp->kn->ino;
+}
-struct cgroup_subsys_state *
-css_next_descendant_pre(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *css);
+/* 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 *
-css_rightmost_descendant(struct cgroup_subsys_state *pos);
+struct cgroup_subsys_state *of_css(struct kernfs_open_file *of);
-/**
- * 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)))
+/* cft/css accessors for cftype->seq_*() operations */
+static inline struct cftype *seq_cft(struct seq_file *seq)
+{
+ return of_cft(seq->private);
+}
-struct cgroup_subsys_state *
-css_next_descendant_post(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *css);
+static inline struct cgroup_subsys_state *seq_css(struct seq_file *seq)
+{
+ return of_css(seq->private);
+}
-/**
- * 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.
+/*
+ * Name / path handling functions. All are thin wrappers around the kernfs
+ * counterparts and can be called under any context.
*/
-#define css_for_each_descendant_post(pos, css) \
- for ((pos) = css_next_descendant_post(NULL, (css)); (pos); \
- (pos) = css_next_descendant_post((pos), (css)))
-
-bool css_has_online_children(struct cgroup_subsys_state *css);
-
-/* 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;
-};
+static inline int cgroup_name(struct cgroup *cgrp, char *buf, size_t buflen)
+{
+ return kernfs_name(cgrp->kn, buf, buflen);
+}
-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);
+static inline char * __must_check cgroup_path(struct cgroup *cgrp, char *buf,
+ size_t buflen)
+{
+ return kernfs_path(cgrp->kn, buf, buflen);
+}
-int cgroup_attach_task_all(struct task_struct *from, struct task_struct *);
-int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from);
+static inline void pr_cont_cgroup_name(struct cgroup *cgrp)
+{
+ pr_cont_kernfs_name(cgrp->kn);
+}
-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);
+static inline void pr_cont_cgroup_path(struct cgroup *cgrp)
+{
+ pr_cont_kernfs_path(cgrp->kn);
+}
#else /* !CONFIG_CGROUPS */
struct cgroup_subsys_state;
-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) {}
-
+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;
-}
+ struct dentry *dentry) { return -EINVAL; }
-static inline void css_put(struct cgroup_subsys_state *css) {}
+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) {}
-/* No cgroups - nothing to do */
-static inline int cgroup_attach_task_all(struct task_struct *from,
- struct task_struct *t)
-{
- return 0;
-}
+static inline int cgroup_init_early(void) { return 0; }
+static inline int cgroup_init(void) { return 0; }
#endif /* !CONFIG_CGROUPS */
Code Review / kvmfornfv.git / blobdiff