Messages in this thread | | | Date | Mon, 30 Sep 2013 20:13:58 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH 0/6] sched, wait: Collapse __wait_event macros -v4 |
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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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