On Wed, May 29, 2019 at 08:36:37PM +0000, Vineeth Remanan Pillai wrote:
> From: Peter Zijlstra <pet...@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) <pet...@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
>
