Re: [PATCH] Remove bogus WARN_ON in futex_wait

Nick Piggin
2004-05-19T11:14:17Z

Andi Kleen wrote:
> On Wed, 19 May 2004 13:43:40 +0300
> Muli Ben-Yehuda <mulix@mulix.org> wrote:
>
>
>>On Wed, May 19, 2004 at 12:23:50PM +0200, Andi Kleen wrote:
>>
>>>futex_wait goes to an interruptible sleep, but does a WARN_ON later
>>>if it wakes up early. But waking up early is totally legal, since
>>>the sleep is interruptible and any signal can wake it up.
>>
>>That's not what the WARN_ON is saynig, unless I'm missing
>>something. It's checking if we were woken up early and there's no
>>signal pending for us.
>
>
> True. Anyways, it seems to happen in practice.
>

Somebody thought an early wakeup there was buggy (but harmless).
There was a patch for kernel/sched.c that was supposed to print
the source of the wakeup. I think the WARN_ON in the futex is
pretty uninteresting without the sched.c patch...