From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 28 Feb 2014 12:39:05 +0000 (+0100)
Subject: stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus()
X-Git-Tag: v3.14-rc7~1^2~1
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=177c53d943368fc97644ebc0a250dc8e2d124250;p=pandora-kernel.git

stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus()

We must use smp_call_function_single(.wait=1) for the
irq_cpu_stop_queue_work() to ensure the queueing is actually done under
stop_cpus_lock. Without this we could have dropped the lock by the time
we do the queueing and get the race we tried to fix.

Fixes: 7053ea1a34fa ("stop_machine: Fix race between stop_two_cpus() and stop_cpus()")

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140228123905.GK3104@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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