From: Li Zefan <lizf@cn.fujitsu.com>
Date: Fri, 7 May 2010 06:57:00 +0000 (+0200)
Subject: blk-cgroup: Fix an RCU warning in blkiocg_create()
X-Git-Tag: v2.6.34-rc7~5^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0341509fdfc9519f7de6aabc5dd23217cef72b73;p=pandora-kernel.git

blk-cgroup: Fix an RCU warning in blkiocg_create()

with CONFIG_PROVE_RCU=y, a warning can be triggered:

  # mount -t cgroup -o blkio xxx /mnt
  # mkdir /mnt/subgroup

...
kernel/cgroup.c:4442 invoked rcu_dereference_check() without protection!
...

To fix this, we avoid caling css_depth() here, which is a bit simpler
than the original code.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---

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