Re: [PATCH] ledtrig-cpu: use spin_lock to replace mutex lock

From: Bryan Wu
Date: Mon Oct 22 2012 - 19:16:11 EST


On Mon, Oct 22, 2012 at 3:38 PM, Rafael J. Wysocki <rjw@xxxxxxx> wrote:
> On Monday 22 of October 2012 11:59:19 Bryan Wu wrote:
>> Hiya,
>>
>> Can I get some Acked or Tested-by from Rafael or Miles before I put it
>> in my linux-leds tree?
>
> Well, I just explained why the current code didn't work. :-)
>
> Anyway, please feel free to add
>
> Acked-by: Rafael J. Wysocki <rjw@xxxxxxx>
>

I was just reminded by Nathan Lynch <ntl@xxxxxxxxx> most of
led-trigger API like register/unregister/event are potentially sleep.
They should not be used in atomic context. Any suggestion to fix it?

Thanks,
-Bryan

>
>> On Thu, Oct 18, 2012 at 12:34 PM, Bryan Wu <cooloney@xxxxxxxxx> wrote:
>> > On Thu, Oct 18, 2012 at 11:35 AM, Linus Walleij
>> > <linus.walleij@xxxxxxxxxx> wrote:
>> >> On Thu, Oct 18, 2012 at 8:18 PM, Bryan Wu <cooloney@xxxxxxxxx> wrote:
>> >>
>> >>> Mutex lock is not safe in atomic context like the bug reported by
>> >>> Miles Lane:
>> >> (...)
>> >>> This patch replace mutex lock with spin lock which is safe for this case.
>> >>>
>> >>> Reported-by: Miles Lane <miles.lane@xxxxxxxxx>
>> >>> Reported-by: Rafael J. Wysocki <rjw@xxxxxxx>
>> >>> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
>> >>> Signed-off-by: Bryan Wu <cooloney@xxxxxxxxx>
>> >>
>> >> Looks correct to me:
>> >> Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
>> >>
>> >
>> > Thanks, Linus.
>> >
>> > Miles, could you please help to try this patch on your testing system?
>> > I really appreciate it.
>> >
>> > -Bryan
>>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
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