Re: [PATCH 1/1] Fix: trace sched switch start/stop racy updates
From: Mathieu Desnoyers
Date: Sat Aug 17 2019 - 11:58:42 EST
----- On Aug 17, 2019, at 11:26 AM, rostedt rostedt@xxxxxxxxxxx wrote:
> On Sat, 17 Aug 2019 10:40:31 -0400 (EDT)
> Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>
>> > I'm now even more against adding the READ_ONCE() or WRITE_ONCE().
>>
>> I'm not convinced by your arguments.
>
> Prove to me that there's an issue here beyond theoretical analysis,
> then I'll consider that patch.
>
> Show me a compiler used to compile the kernel that zeros out the
> increment. Show me were the race actually occurs.
>
> I think the READ/WRITE_ONCE() is more confusing than helpful. And
> unneeded churn to the code. And really not needed for something that's
> not critical to execution.
I'll have to let the authors of the LWN article speak up on this, because
I have limited time to replicate this investigation myself.
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com