From: Tejun Heo <tj@kernel.org>
Date: Thu, 13 Jun 2013 03:43:06 +0000 (-0700)
Subject: percpu-refcount: consistently use plain (non-sched) RCU
X-Git-Tag: omap-for-v3.11/fixes-for-merge-window~46^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6a24474da83ea7c8b7d32f05f858b1259994067a;p=pandora-kernel.git

percpu-refcount: consistently use plain (non-sched) RCU

percpu_ref_get/put() are using preempt_disable/enable() while
percpu_ref_kill() is using plain call_rcu() instead of
call_rcu_sched().  This is buggy as grace periods of the two may not
match.  Fix it by using plain RCU in percpu_ref_get/put().

(I suggested using sched RCU in the first place but there's no actual
 benefit in doing so unless we're gonna introduce different variants
 of get/put to be called while preemption is alredy disabled, which we
 definitely shouldn't.)

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Kent Overstreet <koverstreet@google.com>
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