[PATCH] drm: Wake up next in drm_read() chain if we are forced to putback the event

[Chris Wilson]

Quoting Daniel Vetter (2017-08-07 10:28:58)
> On Fri, Aug 04, 2017 at 09:23:28AM +0100, Chris Wilson wrote:
> > After an event is sent, we try to copy it into the user buffer of the
> > first waiter in drm_read() and if the user buffer doesn't have enough
> > room we put it back onto the list. However, we didn't wake up any
> > subsequent waiter, so that event may sit on the list until either a new
> > vblank event is sent or a new waiter appears. Rare, but in the worst
> > case may lead to a stuck process.
> > 
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> New subtestcase in igt at drm_read?

Caught it!
Testcase: igt/drm_read/short-buffer-wakeup
-Chris