tree 84415f35129013b9d8fb3f5f0ef266437a02f09c
parent dcf097b247affd8b88ad410a92298590c5600f44
author Li Zefan <lizf@cn.fujitsu.com> 1273215420 +0200
committer Jens Axboe <jens.axboe@oracle.com> 1273215420 +0200

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>