cgroup: no need to check css refs for release notification

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We no longer fail rmdir() when there're still css refs, so we don't
need to check css refs in check_for_release().

This also voids a bug. cgroup_has_css_refs() accesses subsys[i]
without cgroup_mutex, so it can race with cgroup_unload_subsys().

cgroup_has_css_refs()
...
  if (ss == NULL || ss->root != cgrp->root)

if ss pointers to net_cls_subsys, and cls_cgroup module is unloaded
right after the former check but before the latter, the memory that
net_cls_subsys resides has become invalid.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

...

This commit is contained in:

Li Zefan 2013-03-01 15:06:07 +08:00 • committed by Tejun Heo

parent f440d98f8e

commit f50daa704f

1 changed files with 8 additions and 59 deletions

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kernel/cgroup.c

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