From mboxrd@z Thu Jan  1 00:00:00 1970
From: Daniel Vetter <daniel@ffwll.ch>
Subject: Re: [PATCH] drm/i915: don't update the dri1 breadcrumb
 with modesetting
Date: Wed, 11 Dec 2013 12:06:17 +0100
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To: Chris Wilson <chris@chris-wilson.co.uk>, Daniel Vetter <daniel.vetter@ffwll.ch>, Intel Graphics Development <intel-gfx@lists.freedesktop.org>, Eugene Shatokhin <eugene.shatokhin@rosalab.ru>, stable@vger.kernel.org
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On Tue, Dec 10, 2013 at 02:48:23PM +0100, Daniel Vetter wrote:
> 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@rosalab.ru>
> > > Cc: Eugene Shatokhin <eugene.shatokhin@rosalab.ru>
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: Daniel Vetter <daniel.vetter@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 ;-)

Chris and I discusssed the commit message a bit on irc and now the hack
also spurts a code comment. Merged to -fixes for now, but I'd still like
to get a tested by from Eugene before sending off the pull request.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch