From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eugene Shatokhin Subject: Re: [PATCH] drm/i915: don't update the dri1 breadcrumb with modesetting Date: Wed, 11 Dec 2013 17:04:14 +0400 Message-ID: <52A862CE.2080000@rosalab.ru> References: <1386678241-18228-1-git-send-email-daniel.vetter@ffwll.ch> <20131210124412.GE10793@nuc-i3427.alporthouse.com> <20131210134823.GI9804@phenom.ffwll.local> <20131211110617.GZ9804@phenom.ffwll.local> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from collab.rosalab.ru (collab.rosalab.ru [195.19.76.181]) by gabe.freedesktop.org (Postfix) with ESMTP id B609CFB3E1 for ; Wed, 11 Dec 2013 05:06:34 -0800 (PST) In-Reply-To: <20131211110617.GZ9804@phenom.ffwll.local> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces@lists.freedesktop.org Errors-To: intel-gfx-bounces@lists.freedesktop.org To: Daniel Vetter , Chris Wilson , Intel Graphics Development , stable@vger.kernel.org List-Id: intel-gfx@lists.freedesktop.org On 12/11/2013 03:06 PM, Daniel Vetter wrote: > 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 >>>> Cc: Eugene Shatokhin >>>> Cc: stable@vger.kernel.org >>>> Signed-off-by: Daniel Vetter >>> >>> 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 > Built 3.10.23 with the fix, tested today. The problem has not shown up so far. Tested-by: Eugene Shatokhin -- Eugene Shatokhin, ROSA Laboratory. www.rosalab.com