cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offline/free()

Rename cgroup_subsys css lifetime related callbacks to better describe
what their roles are.  Also, update documentation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>

1 files changed, 18 insertions, 17 deletions

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 03d8a92786da..7a2189ca8327 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -82,7 +82,7 @@ struct cgroup_subsys_state {
 /* 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 ->post_create() and ->pre_destroy() */
+        CSS_ONLINE      = (1 << 1), /* between ->css_online() and ->css_offline() */
 };
 
 /* Caller must verify that the css is not for root cgroup */
@@ -439,10 +439,11 @@ int cgroup_taskset_size(struct cgroup_taskset *tset);
  */
 
 struct cgroup_subsys {
-        struct cgroup_subsys_state *(*create)(struct cgroup *cgrp);
-        int (*post_create)(struct cgroup *cgrp);
-        void (*pre_destroy)(struct cgroup *cgrp);
-        void (*destroy)(struct cgroup *cgrp);
+        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);
@@ -541,13 +542,13 @@ static inline struct cgroup* task_cgroup(struct task_struct *task,
  * @cgroup: cgroup whose children to walk
  *
  * Walk @cgroup's children.  Must be called under rcu_read_lock().  A child
- * cgroup which hasn't finished ->post_create() or already has finished
- * ->pre_destroy() may show up during traversal and it's each subsystem's
+ * 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 ->post_create()
- * and before starting iterating, a cgroup which finished ->post_create()
- * is guaranteed to be visible in the future iterations.
+ * 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)
@@ -561,19 +562,19 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
  * @cgroup: cgroup whose descendants to walk
  *
  * Walk @cgroup's descendants.  Must be called under rcu_read_lock().  A
- * descendant cgroup which hasn't finished ->post_create() or already has
- * finished ->pre_destroy() may show up during traversal and it's each
+ * 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 ->post_create()
- * and before starting iterating, and synchronizes against @pos on each
- * iteration, any descendant cgroup which finished ->post_create() is
+ * 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_post_create(@cgrp)
+ * my_online(@cgrp)
  * {
  *      Lock @cgrp->parent and @cgrp;
  *      Inherit state from @cgrp->parent;
@@ -606,7 +607,7 @@ struct cgroup *cgroup_next_descendant_pre(struct cgroup *pos,
  * iteration should lock and unlock both @pos->parent and @pos.
  *
  * Alternatively, a subsystem may choose to use a single global lock to
- * synchronize ->post_create() and ->pre_destroy() against tree-walking
+ * synchronize ->css_online() and ->css_offline() against tree-walking
  * operations.
  */
 #define cgroup_for_each_descendant_pre(pos, cgroup)                     \