On Thu, Oct 02, 2014 at 09:11:14PM +0200, Oleg Nesterov wrote:
> On 10/02, Peter Zijlstra wrote:
> >
> > On Thu, Oct 02, 2014 at 03:52:50PM +0200, Peter Zijlstra wrote:
> > > > If yes, then wakeups from signals don't work either, right?
> > >
> > > Its a kthread, there should not be any signals.
> >
> > That said, in the tty patch we do appear to have this problem.
> >
> > Oleg, do we want something like the below on top to make that work
> > again?
> >
> > ---
> > --- a/kernel/sched/wait.c
> > +++ b/kernel/sched/wait.c
> > @@ -326,8 +326,10 @@ long wait_woken(wait_queue_t *wait, unsi
> > * woken_wake_function() such that if we observe WQ_FLAG_WOKEN we must
> > * also observe all state before the wakeup.
> > */
> > - if (!(wait->flags & WQ_FLAG_WOKEN))
> > - timeout = schedule_timeout(timeout);
> > + if (!(wait->flags & WQ_FLAG_WOKEN)) {
> > + if (___wait_is_interruptible(mode) &&
> > !signal_pending_state(mode, current))
> > + timeout = schedule_timeout(timeout);
> > + }
> > __set_current_state(TASK_RUNNING);
>
> I am a bit confused... but for what?
>
> schedule() won't sleep if signal_pending_state(mode) anyway, so we
> do not need this correctness-wise. And the caller needs to check
> signal_pending() anyway.
Urgh, I always forget how all that signal stuff works. Yes you're right,
we check that right in __schedule().
I'll just make all what I did go away and we'll keep it simple like it
was. Sorry for the confusion.
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