RFR (S) 8049304: race between VM_Exit and _sync_FutileWakeups->inc()

[Daniel D. Daugherty]

On 8/28/15 12:29 PM, Tom Benson wrote:
> Hi again,
> Just noticed I skipped this question in your reply:
>
>>
>> So in ReenterI() the OM_PERFDATA_OP(FutileWakeups, inc()) call 
>> immediately
>> follows an OrderAccess::fence() call. Doesn't that make that 
>> increment as
>> "safe" as it can be without having a real lock?
>>
>>
> Yes - odd that I noticed the fence after the update in that code, and 
> not the one right before it!

That's because you didn't uncross your eyes before reading that part
of the monitor code... :-)

Dan


> Thanks,
> Tom
>