Re: poll: allow f_op->poll to sleep, take #3

[Ingo Molnar <mingo@elte.hu>]

* Davide Libenzi <davidel@xmailserver.org> wrote:

> On Sun, 23 Nov 2008, Tejun Heo wrote:
> 
> > +static int pollwake(wait_queue_t *wait, unsigned mode, int sync, void *key)
> > +{
> > +	struct poll_wqueues *pwq = wait->private;
> > +	DECLARE_WAITQUEUE(dummy_wait, pwq->polling_task);
> > +
> > +	set_mb(pwq->triggered, 1);
> > +
> > +	/* perform the default wake up operation */
> > +	return default_wake_function(&dummy_wait, mode, sync, key);
> > +}
> 
> Wouldn't it be nicer to un-static try_to_wake_up() (or a wrapper) 
> instead of setting up a fake wait queue just to use 
> default_wake_function(), just to wake up a task?

the already existing single-task-wakeup shortcut method made available 
by the scheduler is wake_up_process(). A number of primitives where 
waitqueue overhead is of concern already make use of it. 
(mutexes/rtmutexes and more)

if you need a different mode flag, then please extend the 
wake_up_process() family of APIs.

	Ingo