Re: smp_call_function_single with wait=0 considered harmful

[Rik van Riel]

On 02/28/2014 07:39 AM, Peter Zijlstra wrote:

> Subject: 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()")
> Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

Reviewed-by: Rik van Riel <riel@xxxxxxxxxx>

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