From: Tejun Heo <tj@kernel.org>
Date: Wed, 14 May 2014 13:15:01 +0000 (-0400)
Subject: cgroup: move cgroup->sibling unlinking to cgroup_put()
X-Git-Tag: omap-for-v3.16/fixes-against-rc1~81^2~23
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4e4e28472365f8c7a7c55f6b5706f68bc40c5b13;p=pandora-kernel.git

cgroup: move cgroup->sibling unlinking to cgroup_put()

Move cgroup->sibling unlinking from cgroup_destroy_css_killed() to
cgroup_put().  This is later but still before the RCU grace period, so
it doesn't break css_next_child() although there now is a larger
window in which a dead cgroup is visible during css iteration.  As css
iteration always could have included offline csses, this doesn't
affect correctness; however, it does make css_next_child() fall back
to reiterting mode more often.  This also makes cgroup_put() directly
take cgroup_mutex, which limits where it can be called from.  These
are not immediately problematic and will be dealt with later.

This change enables simplification of cgroup destruction path.

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