| Date | Mon, 26 Aug 2019 09:19:31 -0700 | From | mark gross <> | Subject | Re: [RFC PATCH v3 01/16] stop_machine: Fix stop_cpus_in_progress ordering |
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On Wed, May 29, 2019 at 08:36:37PM +0000, Vineeth Remanan Pillai wrote: > From: Peter Zijlstra <peterz@infradead.org> > > Make sure the entire for loop has stop_cpus_in_progress set. It is not clear how this commit comment matches the change. Please explain how adding 2 barrier's makes sure stop_cpus_in_progress is set for the entier for loop.
--mark
> > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > --- > kernel/stop_machine.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c > index 067cb83f37ea..583119e0c51c 100644 > --- a/kernel/stop_machine.c > +++ b/kernel/stop_machine.c > @@ -375,6 +375,7 @@ static bool queue_stop_cpus_work(const struct cpumask *cpumask, > */ > preempt_disable(); > stop_cpus_in_progress = true; > + barrier(); > for_each_cpu(cpu, cpumask) { > work = &per_cpu(cpu_stopper.stop_work, cpu); > work->fn = fn; > @@ -383,6 +384,7 @@ static bool queue_stop_cpus_work(const struct cpumask *cpumask, > if (cpu_stop_queue_work(cpu, work)) > queued = true; > } > + barrier(); > stop_cpus_in_progress = false; > preempt_enable(); > > -- > 2.17.1 >
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