From: Mandeep Singh Baines <msb@chromium.org>
Date: Wed, 4 Jan 2012 05:18:30 +0000 (-0800)
Subject: cgroup: simplify double-check locking in cgroup_attach_proc
X-Git-Tag: v3.4-rc1~179^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b78949ebfb563c29808a9d0a772e3adb5561bc80;p=pandora-kernel.git

cgroup: simplify double-check locking in cgroup_attach_proc

To keep the complexity of the double-check locking in one place, move
the thread_group_leader check up into attach_task_by_pid().  This
allows us to use a goto instead of returning -EAGAIN.

While at it, convert a couple of returns to gotos and use rcu for the
!pid case also in order to simplify the logic.

Changes in V2:
* https://lkml.org/lkml/2011/12/22/86 (Tejun Heo)
  * Use a goto instead of returning -EAGAIN

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Acked-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: containers@lists.linux-foundation.org
Cc: cgroups@vger.kernel.org
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Menage <paul@paulmenage.org>
---

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