[patch 1/2] cls_cgroup: remove unneeded cgroup_lock

[patch 1/2] cls_cgroup: remove unneeded cgroup_lock

[akpm]

From: Li Zefan <lizf@cn.fujitsu.com>

We can remove this lock here, since we are in cgroup write handler and
thus the cgrp is guaranteed to be valid, and no lock is needed when
writing a u32 variable.

Signed-off-by: Li Zefan <lizf@cn.fujitsuc.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 net/sched/cls_cgroup.c |    6 ------
 1 file changed, 6 deletions(-)

diff -puN net/sched/cls_cgroup.c~cls_cgroup-remove-unneeded-cgroup_lock net/sched/cls_cgroup.c
--- a/net/sched/cls_cgroup.c~cls_cgroup-remove-unneeded-cgroup_lock
+++ a/net/sched/cls_cgroup.c
@@ -62,13 +62,7 @@ static u64 read_classid(struct cgroup *c
 
 static int write_classid(struct cgroup *cgrp, struct cftype *cft, u64 value)
 {
-	if (!cgroup_lock_live_group(cgrp))
-		return -ENODEV;
-
 	cgrp_cls_state(cgrp)->classid = (u32) value;
-
-	cgroup_unlock();
-
 	return 0;
 }
 
_

Re: [patch 1/2] cls_cgroup: remove unneeded cgroup_lock

[David Miller]

From: akpm@linux-foundation.org
Date: Tue, 12 May 2009 13:47:33 -0700

> From: Li Zefan <lizf@cn.fujitsu.com>
> 
> We can remove this lock here, since we are in cgroup write handler and
> thus the cgrp is guaranteed to be valid, and no lock is needed when
> writing a u32 variable.
> 
> Signed-off-by: Li Zefan <lizf@cn.fujitsuc.com>
> Acked-by: Paul Menage <menage@google.com>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Applied to net-next-2.6