cgroup: rename css_tryget*() to css_tryget_online*()
Unlike the more usual refcnting, what css_tryget() provides is the
distinction between online and offline csses instead of protection
against upping a refcnt which already reached zero. cgroup is
planning to provide actual tryget which fails if the refcnt already
reached zero. Let's rename the existing trygets so that they clearly
indicate that they're onliness.
I thought about keeping the existing names as-are and introducing new
names for the planned actual tryget; however, given that each
controller participates in the synchronization of the online state, it
seems worthwhile to make it explicit that these functions are about
on/offline state.
Rename css_tryget() to css_tryget_online() and css_tryget_from_dir()
to css_tryget_online_from_dir(). This is pure rename.
v2: cgroup_freezer grew new usages of css_tryget(). Update
accordingly.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Li Zefan <lizefan@huawei.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c3f82f6..5cf3246 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -567,7 +567,8 @@
memcg = mem_cgroup_from_task(current);
cg_proto = sk->sk_prot->proto_cgroup(memcg);
if (!mem_cgroup_is_root(memcg) &&
- memcg_proto_active(cg_proto) && css_tryget(&memcg->css)) {
+ memcg_proto_active(cg_proto) &&
+ css_tryget_online(&memcg->css)) {
sk->sk_cgrp = cg_proto;
}
rcu_read_unlock();
@@ -834,7 +835,7 @@
*/
__mem_cgroup_remove_exceeded(mz->memcg, mz, mctz);
if (!res_counter_soft_limit_excess(&mz->memcg->res) ||
- !css_tryget(&mz->memcg->css))
+ !css_tryget_online(&mz->memcg->css))
goto retry;
done:
return mz;
@@ -1076,7 +1077,7 @@
memcg = mem_cgroup_from_task(rcu_dereference(mm->owner));
if (unlikely(!memcg))
memcg = root_mem_cgroup;
- } while (!css_tryget(&memcg->css));
+ } while (!css_tryget_online(&memcg->css));
rcu_read_unlock();
return memcg;
}
@@ -1113,7 +1114,8 @@
*/
if (next_css) {
if ((next_css == &root->css) ||
- ((next_css->flags & CSS_ONLINE) && css_tryget(next_css)))
+ ((next_css->flags & CSS_ONLINE) &&
+ css_tryget_online(next_css)))
return mem_cgroup_from_css(next_css);
prev_css = next_css;
@@ -1159,7 +1161,7 @@
* would be returned all the time.
*/
if (position && position != root &&
- !css_tryget(&position->css))
+ !css_tryget_online(&position->css))
position = NULL;
}
return position;
@@ -2785,9 +2787,9 @@
/*
* A helper function to get mem_cgroup from ID. must be called under
- * rcu_read_lock(). The caller is responsible for calling css_tryget if
- * the mem_cgroup is used for charging. (dropping refcnt from swap can be
- * called against removed memcg.)
+ * rcu_read_lock(). The caller is responsible for calling
+ * css_tryget_online() if the mem_cgroup is used for charging. (dropping
+ * refcnt from swap can be called against removed memcg.)
*/
static struct mem_cgroup *mem_cgroup_lookup(unsigned short id)
{
@@ -2810,14 +2812,14 @@
lock_page_cgroup(pc);
if (PageCgroupUsed(pc)) {
memcg = pc->mem_cgroup;
- if (memcg && !css_tryget(&memcg->css))
+ if (memcg && !css_tryget_online(&memcg->css))
memcg = NULL;
} else if (PageSwapCache(page)) {
ent.val = page_private(page);
id = lookup_swap_cgroup_id(ent);
rcu_read_lock();
memcg = mem_cgroup_lookup(id);
- if (memcg && !css_tryget(&memcg->css))
+ if (memcg && !css_tryget_online(&memcg->css))
memcg = NULL;
rcu_read_unlock();
}
@@ -3473,7 +3475,7 @@
}
/* The corresponding put will be done in the workqueue. */
- if (!css_tryget(&memcg->css))
+ if (!css_tryget_online(&memcg->css))
goto out;
rcu_read_unlock();
@@ -4246,8 +4248,8 @@
memcg = mem_cgroup_lookup(id);
if (memcg) {
/*
- * We uncharge this because swap is freed.
- * This memcg can be obsolete one. We avoid calling css_tryget
+ * We uncharge this because swap is freed. This memcg can
+ * be obsolete one. We avoid calling css_tryget_online().
*/
if (!mem_cgroup_is_root(memcg))
res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
@@ -5840,10 +5842,10 @@
* which is then paired with css_put during uncharge resp. here.
*
* Although this might sound strange as this path is called from
- * css_offline() when the referencemight have dropped down to 0
- * and shouldn't be incremented anymore (css_tryget would fail)
- * we do not have other options because of the kmem allocations
- * lifetime.
+ * css_offline() when the referencemight have dropped down to 0 and
+ * shouldn't be incremented anymore (css_tryget_online() would
+ * fail) we do not have other options because of the kmem
+ * allocations lifetime.
*/
css_get(&memcg->css);
@@ -6051,8 +6053,8 @@
* automatically removed on cgroup destruction but the removal is
* asynchronous, so take an extra ref on @css.
*/
- cfile_css = css_tryget_from_dir(cfile.file->f_dentry->d_parent,
- &memory_cgrp_subsys);
+ cfile_css = css_tryget_online_from_dir(cfile.file->f_dentry->d_parent,
+ &memory_cgrp_subsys);
ret = -EINVAL;
if (IS_ERR(cfile_css))
goto out_put_cfile;
@@ -6496,7 +6498,7 @@
/*
* XXX: css_offline() would be where we should reparent all
* memory to prepare the cgroup for destruction. However,
- * memcg does not do css_tryget() and res_counter charging
+ * memcg does not do css_tryget_online() and res_counter charging
* under the same RCU lock region, which means that charging
* could race with offlining. Offlining only happens to
* cgroups with no tasks in them but charges can show up
@@ -6510,9 +6512,9 @@
* lookup_swap_cgroup_id()
* rcu_read_lock()
* mem_cgroup_lookup()
- * css_tryget()
+ * css_tryget_online()
* rcu_read_unlock()
- * disable css_tryget()
+ * disable css_tryget_online()
* call_rcu()
* offline_css()
* reparent_charges()