Re: [PATCH] ARM: smp: Fix suspicious RCU originating from cpu_die()

Stephen Boyd
2012-07-06T21:04:32Z

On 07/06/12 13:30, Russell King - ARM Linux wrote:
> On Fri, Jul 06, 2012 at 11:39:09AM -0700, Stephen Boyd wrote:
>> On 07/05/12 17:24, Paul E. McKenney wrote:
>>> On Thu, Jul 05, 2012 at 04:45:58PM -0700, Stephen Boyd wrote:
>>>> @@ -179,7 +184,7 @@ void __ref cpu_die(void)
>>>> mb();
>>>>
>>>> /* Tell __cpu_die() that this CPU is now safe to dispose of */
>>>> - complete(&cpu_died);
>>>> + __this_cpu_write(cpu_state, CPU_DEAD);
>>> Or you could do something like:
>>>
>>> RCU_NONIDLE(complete(&cpu_died));
>>>
>>> This would tell RCU that it needed to pay attention to this CPU for
>>> the duration of the "complete()" function call despite the CPU's being
>>> idle. And might allow you to dispense with the rest of the patch.
>> Great! I like that more since we get to keep the completion mechanism
>> instead of a busy wait.
>>
>> Russell, which one would you prefer? Here's the other version
> I think I prefer the version below.
>

Ok. I put it in the patch tracker.