Re: [RFC PATCH v2 1/2] membarrier: Provide register expedited private command

[Mathieu Desnoyers]

----- On Sep 21, 2017, at 8:13 AM, Peter Zijlstra peterz@xxxxxxxxxxxxx wrote:

> On Mon, Sep 18, 2017 at 06:36:47PM -0400, Mathieu Desnoyers wrote:
>> @@ -3373,6 +3362,7 @@ static void __sched notrace __schedule(bool preempt)
>>  
>>  		/* Also unlocks the rq: */
>>  		rq = context_switch(rq, prev, next, &rf);
>> +		membarrier_arch_sched_in(prev, next);
> 
> That's wrong iirc; we just switched stacks, you cannot use @prev and
> @next.

Yes, it did indeed explode spectacularly at boot in testing. RFC v3 fixes that.

Thanks,

Mathieu


> 
>>  	} else {
>>  		rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
> >  		rq_unlock_irq(rq, &rf);

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com