Re: [RFC][PATCH 02/13] stop_machine: Fix stop_cpus_in_progress ordering

[Phil Auld <pauld@redhat.com>]

On Fri, Jul 26, 2019 at 04:54:11PM +0200 Peter Zijlstra wrote:
> Make sure the entire for loop has stop_cpus_in_progress set.
> 
> Cc: Valentin Schneider <valentin.schneider@arm.com>
> Cc: Aaron Lu <aaron.lwe@gmail.com>
> Cc: keescook@chromium.org
> Cc: mingo@kernel.org
> Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Cc: Phil Auld <pauld@redhat.com>
> Cc: torvalds@linux-foundation.org
> Cc: Tim Chen <tim.c.chen@linux.intel.com>
> Cc: fweisbec@gmail.com
> Cc: subhra.mazumdar@oracle.com
> Cc: tglx@linutronix.de
> Cc: Julien Desfossez <jdesfossez@digitalocean.com>
> Cc: pjt@google.com
> Cc: Nishanth Aravamudan <naravamudan@digitalocean.com>
> Cc: Aubrey Li <aubrey.intel@gmail.com>
> Cc: Mel Gorman <mgorman@techsingularity.net>
> Cc: kerrnel@google.com
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> Link: https://lkml.kernel.org/r/0fd8fd4b99b9b9aa88d8b2dff897f7fd0d88f72c.1559129225.git.vpillai@digitalocean.com
> ---
>  kernel/stop_machine.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> --- a/kernel/stop_machine.c
> +++ b/kernel/stop_machine.c
> @@ -383,6 +383,7 @@ static bool queue_stop_cpus_work(const s
>  	 */
>  	preempt_disable();
>  	stop_cpus_in_progress = true;
> +	barrier();
>  	for_each_cpu(cpu, cpumask) {
>  		work = &per_cpu(cpu_stopper.stop_work, cpu);
>  		work->fn = fn;
> @@ -391,6 +392,7 @@ static bool queue_stop_cpus_work(const s
>  		if (cpu_stop_queue_work(cpu, work))
>  			queued = true;
>  	}
> +	barrier();
>  	stop_cpus_in_progress = false;
>  	preempt_enable();
>  
> 
> 

This looks good.

Reviewed-by: Phil Auld <pauld@redhat.com>


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