From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Fri, 13 Mar 2009 11:21:30 +0000 (+0100)
Subject: perf_counter: add comment to barrier
X-Git-Tag: v2.6.31-rc1~383^2~481
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=60b3df9c1e24a18aabb412da9905208c5f04ebea;p=pandora-kernel.git

perf_counter: add comment to barrier

We need to ensure the enabled=0 write happens before we
start disabling the actual counters, so that a pcm_amd_enable()
will not enable one underneath us.

I think the race is impossible anyway, we always balance the
ops within any one context and perform enable() with IRQs disabled.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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