Date: Wed, 4 Mar 2009 09:59:20 +0530
From: Bharata B Rao <bharata@linux.vnet.ibm.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       Balbir Singh <balbir@linux.vnet.ibm.com>,
       Dhaval Giani <dhaval@linux.vnet.ibm.com>,
       Paul Menage <menage@google.com>, Li Zefan <lizf@cn.fujitsu.com>
Subject: [PATCH mmotm] cgroup: remove rcu_read_lock() from css_get_next()
Message-ID: <20090304042920.GA4508@in.ibm.com>
Reply-To: bharata@linux.vnet.ibm.com
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cgroup: remove rcu_read_lock() from css_get_next()

Callers of css_get_next() are already calling css_get_next()
under rcu_read_lock() and hence there there is no need for
css_get_next() to re-acquire rcu_read_lock(). As per the
comments in css_get_next(), let the callers accquire the
rcu_read_lock().

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
 kernel/cgroup.c |    3 ---
 1 file changed, 3 deletions(-)

--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3553,7 +3553,6 @@ css_get_next(struct cgroup_subsys *ss, i
 		return NULL;
 
 	BUG_ON(!ss->use_id);
-	rcu_read_lock();
 	/* fill start point for scan */
 	tmpid = id;
 	while (1) {
@@ -3577,8 +3576,6 @@ css_get_next(struct cgroup_subsys *ss, i
 		/* continue to scan from next id */
 		tmpid = tmpid + 1;
 	}
-
-	rcu_read_unlock();
 	return ret;
 }
 
Regards,
Bharata.
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