On 09/30, Peter Zijlstra wrote:
>
> On Mon, Sep 30, 2013 at 07:40:54PM +0200, Oleg Nesterov wrote:
> > Once again, of course I do not blame this series, but
> > wait_event_timeout(wq, true, 0) still returns 0.
>
> So we have:
>
> [...snip...]

> So wait_event_timeout(wq, true, 0) turns into:

Not really, because of fast-path check,

        #define wait_event_timeout(wq, condition, timeout)                      
\
        ({                                                                      
\
                long __ret = timeout;                                           
\
                if (!(condition))                                               
\
                        __ret = __wait_event_timeout(wq, condition, timeout);   
\
                __ret;                                                          
\
        })

we do not even call __wait_event_timeout() if "condition" is already
true at the start.

> >     ___wait_event(wq, ___wait_cond_timeout(condition),              \
> >                   TASK_INTERRUPTIBLE, 0, ret,                       \
> >                   spin_unlock_irq(&lock);                           \
> > -                 __ret = schedule_timeout(__ret);                  \
> > +                 ___wait_schedule_timeout(__ret);                  \
> >                   spin_lock_irq(&lock));
>
> You can't do that; you'll break/return without the lock held.

Yes, see another email, already noticed this.


And let me repeat just in case, I think this series is fine, just
wait.h needs another minor/orthogonal fix.

Oleg.

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