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:
#define ___wait_cond_timeout(condition) \
({ \
bool __cond = (condition); \
if (__cond && !__ret) \
__ret = 1; \
__cond || !__ret; \
})
#define ___wait_event(wq, condition, state, exclusive, ret, cmd) \
({ \
__label__ __out; \
DEFINE_WAIT(__wait); \
long __ret = ret; \
\
for (;;) { \
if (exclusive) \
prepare_to_wait_exclusive(&wq, &__wait, state); \
else \
prepare_to_wait(&wq, &__wait, state); \
\
if (condition) \
break; \
\
if (___wait_signal_pending(state)) { \
__ret = -ERESTARTSYS; \
if (exclusive) { \
abort_exclusive_wait(&wq, &__wait, \
state, NULL); \
goto __out; \
} \
break; \
} \
\
cmd; \
} \
finish_wait(&wq, &__wait); \
__out: __ret; \
})
So wait_event_timeout(wq, true, 0) turns into:
({
DEFINE_WAIT(__wait);
long __ret = 0;
for (;;) {
prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE);
if (({
bool __cond = (true);
if (__cond && !__ret)
__ret = 1;
__cond || !__ret;
}))
break;
schedule();
}
finish_wait(&wq, &__wait);
__ret;
})
Which; afaict, returns 1, not 0.
> +#define ___wait_schedule_timeout(tout)
> \
> + if (!tout) \
> + break; \
> + tout = schedule_timeout(tout)
> +
> ___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.
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