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>

5 files changed, 53 insertions, 52 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index c389f4258681..d35463bab487 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -876,7 +876,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
                  * Release the subsystem state objects.
                  */
                 for_each_subsys(cgrp->root, ss)
-                        ss->destroy(cgrp);
+                        ss->css_free(cgrp);
 
                 cgrp->root->number_of_cgroups--;
                 mutex_unlock(&cgroup_mutex);
@@ -4048,8 +4048,8 @@ static int online_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
 
         lockdep_assert_held(&cgroup_mutex);
 
-        if (ss->post_create)
-                ret = ss->post_create(cgrp);
+        if (ss->css_online)
+                ret = ss->css_online(cgrp);
         if (!ret)
                 cgrp->subsys[ss->subsys_id]->flags |= CSS_ONLINE;
         return ret;
@@ -4067,14 +4067,14 @@ static void offline_css(struct cgroup_subsys *ss, struct cgroup *cgrp)
                 return;
 
         /*
-         * pre_destroy() should be called with cgroup_mutex unlocked.  See
+         * css_offline() should be called with cgroup_mutex unlocked.  See
          * 3fa59dfbc3 ("cgroup: fix potential deadlock in pre_destroy") for
          * details.  This temporary unlocking should go away once
          * cgroup_mutex is unexported from controllers.
          */
-        if (ss->pre_destroy) {
+        if (ss->css_offline) {
                 mutex_unlock(&cgroup_mutex);
-                ss->pre_destroy(cgrp);
+                ss->css_offline(cgrp);
                 mutex_lock(&cgroup_mutex);
         }
 
@@ -4136,7 +4136,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
         for_each_subsys(root, ss) {
                 struct cgroup_subsys_state *css;
 
-                css = ss->create(cgrp);
+                css = ss->css_alloc(cgrp);
                 if (IS_ERR(css)) {
                         err = PTR_ERR(css);
                         goto err_free_all;
@@ -4147,7 +4147,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
                         if (err)
                                 goto err_free_all;
                 }
-                /* At error, ->destroy() callback has to free assigned ID. */
+                /* At error, ->css_free() callback has to free assigned ID. */
                 if (clone_children(parent) && ss->post_clone)
                         ss->post_clone(cgrp);
 
@@ -4201,7 +4201,7 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
 err_free_all:
         for_each_subsys(root, ss) {
                 if (cgrp->subsys[ss->subsys_id])
-                        ss->destroy(cgrp);
+                        ss->css_free(cgrp);
         }
         mutex_unlock(&cgroup_mutex);
         /* Release the reference count that we took on the superblock */
@@ -4381,7 +4381,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss)
         /* Create the top cgroup state for this subsystem */
         list_add(&ss->sibling, &rootnode.subsys_list);
         ss->root = &rootnode;
-        css = ss->create(dummytop);
+        css = ss->css_alloc(dummytop);
         /* We don't handle early failures gracefully */
         BUG_ON(IS_ERR(css));
         init_cgroup_css(css, ss, dummytop);
@@ -4425,7 +4425,7 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
 
         /* check name and function validity */
         if (ss->name == NULL || strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN ||
-            ss->create == NULL || ss->destroy == NULL)
+            ss->css_alloc == NULL || ss->css_free == NULL)
                 return -EINVAL;
 
         /*
@@ -4454,10 +4454,11 @@ int __init_or_module cgroup_load_subsys(struct cgroup_subsys *ss)
         subsys[ss->subsys_id] = ss;
 
         /*
-         * no ss->create seems to need anything important in the ss struct, so
-         * this can happen first (i.e. before the rootnode attachment).
+         * no ss->css_alloc seems to need anything important in the ss
+         * struct, so this can happen first (i.e. before the rootnode
+         * attachment).
          */
-        css = ss->create(dummytop);
+        css = ss->css_alloc(dummytop);
         if (IS_ERR(css)) {
                 /* failure case - need to deassign the subsys[] slot. */
                 subsys[ss->subsys_id] = NULL;
@@ -4577,12 +4578,12 @@ void cgroup_unload_subsys(struct cgroup_subsys *ss)
         write_unlock(&css_set_lock);
 
         /*
-         * remove subsystem's css from the dummytop and free it - need to free
-         * before marking as null because ss->destroy needs the cgrp->subsys
-         * pointer to find their state. note that this also takes care of
-         * freeing the css_id.
+         * remove subsystem's css from the dummytop and free it - need to
+         * free before marking as null because ss->css_free needs the
+         * cgrp->subsys pointer to find their state. note that this also
+         * takes care of freeing the css_id.
          */
-        ss->destroy(dummytop);
+        ss->css_free(dummytop);
         dummytop->subsys[ss->subsys_id] = NULL;
 
         mutex_unlock(&cgroup_mutex);
@@ -4626,8 +4627,8 @@ int __init cgroup_init_early(void)
 
                 BUG_ON(!ss->name);
                 BUG_ON(strlen(ss->name) > MAX_CGROUP_TYPE_NAMELEN);
-                BUG_ON(!ss->create);
-                BUG_ON(!ss->destroy);
+                BUG_ON(!ss->css_alloc);
+                BUG_ON(!ss->css_free);
                 if (ss->subsys_id != i) {
                         printk(KERN_ERR "cgroup: Subsys %s id == %d\n",
                                ss->name, ss->subsys_id);
@@ -5439,7 +5440,7 @@ struct cgroup_subsys_state *cgroup_css_from_dir(struct file *f, int id)
 }
 
 #ifdef CONFIG_CGROUP_DEBUG
-static struct cgroup_subsys_state *debug_create(struct cgroup *cont)
+static struct cgroup_subsys_state *debug_css_alloc(struct cgroup *cont)
 {
         struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
 
@@ -5449,7 +5450,7 @@ static struct cgroup_subsys_state *debug_create(struct cgroup *cont)
         return css;
 }
 
-static void debug_destroy(struct cgroup *cont)
+static void debug_css_free(struct cgroup *cont)
 {
         kfree(cont->subsys[debug_subsys_id]);
 }
@@ -5578,8 +5579,8 @@ static struct cftype debug_files[] =  {
 
 struct cgroup_subsys debug_subsys = {
         .name = "debug",
-        .create = debug_create,
-        .destroy = debug_destroy,
+        .css_alloc = debug_css_alloc,
+        .css_free = debug_css_free,
         .subsys_id = debug_subsys_id,
         .base_cftypes = debug_files,
 };
diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c
index ee8bb671688c..75dda1ea5026 100644
--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -92,7 +92,7 @@ static const char *freezer_state_strs(unsigned int state)
 
 struct cgroup_subsys freezer_subsys;
 
-static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup)
+static struct cgroup_subsys_state *freezer_css_alloc(struct cgroup *cgroup)
 {
         struct freezer *freezer;
 
@@ -105,14 +105,14 @@ static struct cgroup_subsys_state *freezer_create(struct cgroup *cgroup)
 }
 
 /**
- * freezer_post_create - commit creation of a freezer cgroup
+ * freezer_css_online - commit creation of a freezer cgroup
  * @cgroup: cgroup being created
  *
  * We're committing to creation of @cgroup.  Mark it online and inherit
  * parent's freezing state while holding both parent's and our
  * freezer->lock.
  */
-static int freezer_post_create(struct cgroup *cgroup)
+static int freezer_css_online(struct cgroup *cgroup)
 {
         struct freezer *freezer = cgroup_freezer(cgroup);
         struct freezer *parent = parent_freezer(freezer);
@@ -141,13 +141,13 @@ static int freezer_post_create(struct cgroup *cgroup)
 }
 
 /**
- * freezer_pre_destroy - initiate destruction of @cgroup
+ * freezer_css_offline - initiate destruction of @cgroup
  * @cgroup: cgroup being destroyed
  *
  * @cgroup is going away.  Mark it dead and decrement system_freezing_count
  * if it was holding one.
  */
-static void freezer_pre_destroy(struct cgroup *cgroup)
+static void freezer_css_offline(struct cgroup *cgroup)
 {
         struct freezer *freezer = cgroup_freezer(cgroup);
 
@@ -161,7 +161,7 @@ static void freezer_pre_destroy(struct cgroup *cgroup)
         spin_unlock_irq(&freezer->lock);
 }
 
-static void freezer_destroy(struct cgroup *cgroup)
+static void freezer_css_free(struct cgroup *cgroup)
 {
         kfree(cgroup_freezer(cgroup));
 }
@@ -477,10 +477,10 @@ static struct cftype files[] = {
 
 struct cgroup_subsys freezer_subsys = {
         .name           = "freezer",
-        .create         = freezer_create,
-        .post_create    = freezer_post_create,
-        .pre_destroy    = freezer_pre_destroy,
-        .destroy        = freezer_destroy,
+        .css_alloc      = freezer_css_alloc,
+        .css_online     = freezer_css_online,
+        .css_offline    = freezer_css_offline,
+        .css_free       = freezer_css_free,
         .subsys_id      = freezer_subsys_id,
         .attach         = freezer_attach,
         .fork           = freezer_fork,
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index f33c7153b6d7..06931337c4e5 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -1821,11 +1821,11 @@ static void cpuset_post_clone(struct cgroup *cgroup)
 }
 
 /*
- *      cpuset_create - create a cpuset
+ *      cpuset_css_alloc - allocate a cpuset css
  *      cont:   control group that the new cpuset will be part of
  */
 
-static struct cgroup_subsys_state *cpuset_create(struct cgroup *cont)
+static struct cgroup_subsys_state *cpuset_css_alloc(struct cgroup *cont)
 {
         struct cpuset *cs;
         struct cpuset *parent;
@@ -1864,7 +1864,7 @@ static struct cgroup_subsys_state *cpuset_create(struct cgroup *cont)
  * will call async_rebuild_sched_domains().
  */
 
-static void cpuset_destroy(struct cgroup *cont)
+static void cpuset_css_free(struct cgroup *cont)
 {
         struct cpuset *cs = cgroup_cs(cont);
 
@@ -1878,8 +1878,8 @@ static void cpuset_destroy(struct cgroup *cont)
 
 struct cgroup_subsys cpuset_subsys = {
         .name = "cpuset",
-        .create = cpuset_create,
-        .destroy = cpuset_destroy,
+        .css_alloc = cpuset_css_alloc,
+        .css_free = cpuset_css_free,
         .can_attach = cpuset_can_attach,
         .attach = cpuset_attach,
         .post_clone = cpuset_post_clone,
diff --git a/kernel/events/core.c b/kernel/events/core.c
index dbccf83c134d..f9ff5493171d 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -7434,7 +7434,7 @@ unlock:
 device_initcall(perf_event_sysfs_init);
 
 #ifdef CONFIG_CGROUP_PERF
-static struct cgroup_subsys_state *perf_cgroup_create(struct cgroup *cont)
+static struct cgroup_subsys_state *perf_cgroup_css_alloc(struct cgroup *cont)
 {
         struct perf_cgroup *jc;
 
@@ -7451,7 +7451,7 @@ static struct cgroup_subsys_state *perf_cgroup_create(struct cgroup *cont)
         return &jc->css;
 }
 
-static void perf_cgroup_destroy(struct cgroup *cont)
+static void perf_cgroup_css_free(struct cgroup *cont)
 {
         struct perf_cgroup *jc;
         jc = container_of(cgroup_subsys_state(cont, perf_subsys_id),
@@ -7492,8 +7492,8 @@ static void perf_cgroup_exit(struct cgroup *cgrp, struct cgroup *old_cgrp,
 struct cgroup_subsys perf_subsys = {
         .name           = "perf_event",
         .subsys_id      = perf_subsys_id,
-        .create         = perf_cgroup_create,
-        .destroy        = perf_cgroup_destroy,
+        .css_alloc      = perf_cgroup_css_alloc,
+        .css_free       = perf_cgroup_css_free,
         .exit           = perf_cgroup_exit,
         .attach         = perf_cgroup_attach,
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2d8927fda712..6f20c8fb2326 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7468,7 +7468,7 @@ static inline struct task_group *cgroup_tg(struct cgroup *cgrp)
                             struct task_group, css);
 }
 
-static struct cgroup_subsys_state *cpu_cgroup_create(struct cgroup *cgrp)
+static struct cgroup_subsys_state *cpu_cgroup_css_alloc(struct cgroup *cgrp)
 {
         struct task_group *tg, *parent;
 
@@ -7485,7 +7485,7 @@ static struct cgroup_subsys_state *cpu_cgroup_create(struct cgroup *cgrp)
         return &tg->css;
 }
 
-static void cpu_cgroup_destroy(struct cgroup *cgrp)
+static void cpu_cgroup_css_free(struct cgroup *cgrp)
 {
         struct task_group *tg = cgroup_tg(cgrp);
 
@@ -7845,8 +7845,8 @@ static struct cftype cpu_files[] = {
 
 struct cgroup_subsys cpu_cgroup_subsys = {
         .name           = "cpu",
-        .create         = cpu_cgroup_create,
-        .destroy        = cpu_cgroup_destroy,
+        .css_alloc      = cpu_cgroup_css_alloc,
+        .css_free       = cpu_cgroup_css_free,
         .can_attach     = cpu_cgroup_can_attach,
         .attach         = cpu_cgroup_attach,
         .exit           = cpu_cgroup_exit,
@@ -7869,7 +7869,7 @@ struct cgroup_subsys cpu_cgroup_subsys = {
 struct cpuacct root_cpuacct;
 
 /* create a new cpu accounting group */
-static struct cgroup_subsys_state *cpuacct_create(struct cgroup *cgrp)
+static struct cgroup_subsys_state *cpuacct_css_alloc(struct cgroup *cgrp)
 {
         struct cpuacct *ca;
 
@@ -7899,7 +7899,7 @@ out:
 }
 
 /* destroy an existing cpu accounting group */
-static void cpuacct_destroy(struct cgroup *cgrp)
+static void cpuacct_css_free(struct cgroup *cgrp)
 {
         struct cpuacct *ca = cgroup_ca(cgrp);
 
@@ -8070,8 +8070,8 @@ void cpuacct_charge(struct task_struct *tsk, u64 cputime)
 
 struct cgroup_subsys cpuacct_subsys = {
         .name = "cpuacct",
-        .create = cpuacct_create,
-        .destroy = cpuacct_destroy,
+        .css_alloc = cpuacct_css_alloc,
+        .css_free = cpuacct_css_free,
         .subsys_id = cpuacct_subsys_id,
         .base_cftypes = files,
 };