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SubjectRe: cpu stopper threads and setaffinity leads to deadlock
On 2018-08-03 04:41, Thomas Gleixner wrote:
> Prasad.
>
> On Thu, 2 Aug 2018, Peter Zijlstra wrote:
>>
>> So why didn't you do the 'obvious' parallel to what you did for
>> cpu_stop_queue_two_works(), namely:
>
> Is that patch fixing the issue for you?
<Prasad> Hi Thomas and Peter,

Yes. Tested both versions of patches and both variants are working on
Qualcomm devices
with stress testing of set affinity and tasks cross-migration, which
were previously leading to the deadlock.

-Thanks, Prasad
>
>> --- a/kernel/stop_machine.c
>> +++ b/kernel/stop_machine.c
>> @@ -81,6 +81,7 @@ static bool cpu_stop_queue_work(unsigned
>> unsigned long flags;
>> bool enabled;
>>
>> + preempt_disable();
>> raw_spin_lock_irqsave(&stopper->lock, flags);
>> enabled = stopper->enabled;
>> if (enabled)
>> @@ -90,6 +91,7 @@ static bool cpu_stop_queue_work(unsigned
>> raw_spin_unlock_irqrestore(&stopper->lock, flags);
>>
>> wake_up_q(&wakeq);
>> + preempt_enable();
>>
>> return enabled;
>> }
>>

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum,
Linux Foundation Collaborative Project

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