linux-kernel - [PATCH 4/6] cgroup: remove duplicate RCU free on struct cgroup

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Message-ID: <50F7B079.50201@huawei.com>
Date:	Thu, 17 Jan 2013 16:04:09 +0800
From:	Li Zefan <lizefan@...wei.com>
To:	Tejun Heo <tj@...nel.org>
CC:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Cgroups <cgroups@...r.kernel.org>
Subject: [PATCH 4/6] cgroup: remove duplicate RCU free on struct cgroup

When destroying cgroup, though in cgroup_diput() we've called
synchronize_rcu(), we then still have to free cgroup via call_rcu().

The story is, long ago to fix a race between reading /proc/sched_debug
and freeing cgroup, the code was changed to utilize call_rcu().

Now we've splitted part of cpu cgroup css_alloc/free to css_online/offline,
which makes the race vanish, and this grants us to remove call_rcu().

Signed-off-by: Li Zefan <lizefan@...wei.com>
---
 kernel/cgroup.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 23a0ce1..d7fefeb 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -892,7 +892,7 @@ static void cgroup_diput(struct dentry *dentry, struct inode *inode)
 		simple_xattrs_free(&cgrp->xattrs);
 
 		ida_simple_remove(&cgrp->root->cgroup_ida, cgrp->id);
-		kfree_rcu(cgrp, rcu_head);
+		kfree(cgrp);
 	} else {
 		struct cfent *cfe = __d_cfe(dentry);
 		struct cgroup *cgrp = dentry->d_parent->d_fsdata;
-- 
1.8.0.2
--
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