Messages in this thread Patch in this message |  | | Date | Tue, 11 Mar 2014 05:36:47 -0700 | From | tip-bot for Peter Zijlstra <> | Subject | [tip:sched/core] stop_machine: Fix^2 race between stop_two_cpus() and stop_cpus() |
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Commit-ID: 177c53d943368fc97644ebc0a250dc8e2d124250 Gitweb: http://git.kernel.org/tip/177c53d943368fc97644ebc0a250dc8e2d124250 Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Fri, 28 Feb 2014 13:39:05 +0100 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Tue, 11 Mar 2014 11:33:47 +0100
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> --- kernel/stop_machine.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c index 84571e0..01fbae5 100644 --- a/kernel/stop_machine.c +++ b/kernel/stop_machine.c @@ -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();
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