/* 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
- */
+ /* 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;
struct cgroup {
unsigned long flags; /* "unsigned long" so bitops work */
- int id; /* ida allocated in-hierarchy ID */
+ /*
+ * 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;
/*
* We link our 'sibling' struct into our parent's 'children'.
*
* - 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),
unsigned long flags;
/* IDs for cgroups in this hierarchy */
- struct ida cgroup_ida;
+ struct idr cgroup_idr;
/* The path to use for release notifications. */
char release_agent_path[PATH_MAX];
/* cftype->flags */
enum {
- CFTYPE_ONLY_ON_ROOT = (1 << 0), /* only create on root cg */
- CFTYPE_NOT_ON_ROOT = (1 << 1), /* don't create on root cg */
+ CFTYPE_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 */
};
};
struct cgroup_scanner {
- struct cgroup *cg;
+ struct cgroup *cgrp;
int (*test_task)(struct task_struct *p, struct cgroup_scanner *scan);
void (*process_task)(struct task_struct *p,
struct cgroup_scanner *scan);
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 task_cgroup_path(struct task_struct *task, char *buf, size_t buflen);
int cgroup_task_count(const struct cgroup *cgrp);
*/
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);
+ 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 *cgrp, struct cgroup *old_cgrp,
+ void (*exit)(struct cgroup_subsys_state *css,
+ struct cgroup_subsys_state *old_css,
struct task_struct *task);
- void (*bind)(struct cgroup *root);
+ void (*bind)(struct cgroup_subsys_state *root_css);
int subsys_id;
int disabled;
#undef IS_SUBSYS_ENABLED
#undef SUBSYS
-static inline struct cgroup_subsys_state *cgroup_subsys_state(
- struct cgroup *cgrp, int subsys_id)
+/**
+ * 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)
+{
+ struct cgroup *parent_cgrp = css->cgroup->parent;
+
+ return parent_cgrp ? parent_cgrp->subsys[css->ss->subsys_id] : NULL;
+}
+
+/**
+ * cgroup_css - obtain a cgroup's css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @subsys_id: the subsystem of interest
+ *
+ * Return @cgrp's css (cgroup_subsys_state) associated with @subsys_id.
+ */
+static inline struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
+ int subsys_id)
{
return cgrp->subsys[subsys_id];
}
#endif
/**
- * task_subsys_state_check - obtain css for (task, subsys) w/ extra access conds
+ * 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_subsys_state_check(task, subsys_id, __c) \
+#define task_css_check(task, subsys_id, __c) \
task_css_set_check((task), (__c))->subsys[(subsys_id)]
/**
}
/**
- * task_subsys_state - obtain css for (task, subsys)
+ * task_css - obtain css for (task, subsys)
* @task: the target task
* @subsys_id: the target subsystem ID
*
- * See task_subsys_state_check().
+ * See task_css_check().
*/
-static inline struct cgroup_subsys_state *
-task_subsys_state(struct task_struct *task, int subsys_id)
+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_subsys_state_check(task, subsys_id, false);
+ return task_css(task, subsys_id)->cgroup;
}
-static inline struct cgroup* task_cgroup(struct task_struct *task,
- int subsys_id)
+/**
+ * cgroup_from_id - lookup cgroup by id
+ * @ss: cgroup subsys to be looked into
+ * @id: the cgroup id
+ *
+ * Returns the cgroup if there's valid one with @id, otherwise returns NULL.
+ * Should be called under rcu_read_lock().
+ */
+static inline struct cgroup *cgroup_from_id(struct cgroup_subsys *ss, int id)
{
- return task_subsys_state(task, subsys_id)->cgroup;
+#ifdef CONFIG_PROVE_RCU
+ rcu_lockdep_assert(rcu_read_lock_held() ||
+ lockdep_is_held(&cgroup_mutex),
+ "cgroup_from_id() needs proper protection");
+#endif
+ return idr_find(&ss->root->cgroup_idr, id);
}
struct cgroup *cgroup_next_sibling(struct cgroup *pos);
projects / linux-2.6-block.git / blobdiff