Messages in this thread | | | Date | Mon, 30 Sep 2013 20:09:39 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 0/6] sched, wait: Collapse __wait_event macros -v4 |
| |
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.
| |