On Tue 28-01-14 18:59:43, Tejun Heo wrote:
> cgroup->name handling became quite complicated over time involving
> dedicated struct cgroup_name for RCU protection. Now that cgroup is
> on kernfs, we can drop all of it and simply use kernfs_name/path() and
> friends. Replace cgroup->name and all related code with kernfs
> name/path constructs.
>
> * Reimplement cgroup_name() and cgroup_path() as thin wrappers on top
> of kernfs counterparts, which involves semantic changes.
> pr_cont_cgroup_name() and pr_cont_cgroup_path() added.
>
> * cgroup->name handling dropped from cgroup_rename().
>
> * All users of cgroup_name/path() updated to the new semantics. Users
> which were formatting the string just to printk them are converted
> to use pr_cont_cgroup_name/path() instead, which simplifies things
> quite a bit. As cgroup_name() no longer requires RCU read lock
> around it, RCU lockings which were protecting only cgroup_name() are
> removed.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Li Zefan <lizefan@xxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> Cc: Balbir Singh <bsingharora@xxxxxxxxx>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Nice. I hated the way how we retrieved the name previously.
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Btw. after this change we should drop part of the comment above
oom_info_lock:
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 19d5d4274e22..d998baec5deb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1684,8 +1684,7 @@ static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
{
/*
- * protects memcg_name and makes sure that parallel ooms do not
- * interleave
+ * Makes sure that parallel ooms do not interleave
*/
static DEFINE_SPINLOCK(oom_info_lock);
struct cgroup *task_cgrp;
--
Michal Hocko
SUSE Labs
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