[Intel-gfx] [PATCH] drm/i915: don't update the dri1 breadcrumb with modesetting

[Daniel Vetter]

On Tue, Dec 10, 2013 at 12:44:12PM +0000, Chris Wilson wrote:
> On Tue, Dec 10, 2013 at 01:24:01PM +0100, Daniel Vetter wrote:
> > The update is horribly racy since it doesn't protect at all against
> > concurrent closing of the master fd. And it can't really since that
> > requires us to grab a mutex.
> > 
> > Instead of jumping through hoops and offloading this to a worker
> > thread just block this bit of code for the modesetting driver.
> > 
> > Reported-by: Eugene Shatokhin <eugene.shatokhin at rosalab.ru>
> > Cc: Eugene Shatokhin <eugene.shatokhin at rosalab.ru>
> > Cc: stable at vger.kernel.org
> > Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
> 
> We should also not be calling update_dri1_breadcrumb unless we have a
> USER_INTERRUPT. The other updates to the breadcrumb hws index do not
> appear to be serialised by anything other than polling.

Well, this is what's been there before and I don't really want to touch
dri1/ums code at all. So I think we'll just keep this here until we'll all
put it on the big pyre ;-)
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch