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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: 7053ea1a34 ("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>
This commit is contained in:
Peter Zijlstra 2014-02-28 13:39:05 +01:00 committed by Ingo Molnar
parent d44753b843
commit 177c53d943
1 changed files with 1 additions and 1 deletions
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2
kernel/stop_machine.c
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@ -293,7 +293,7 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
*/
smp_call_function_single(min(cpu1, cpu2),
&irq_cpu_stop_queue_work,
&call_args, 0);
&call_args, 1);
lg_local_unlock(&stop_cpus_lock);
preempt_enable();