Re: [PATCH 1/5] drm/prime: fix potential race in drm_gem_map_detach

From: Daniel Vetter <daniel@ffwll.ch>
To: christian.koenig@amd.com
Cc: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/5] drm/prime: fix potential race in drm_gem_map_detach
Date: Tue, 6 Mar 2018 10:39:38 +0100	[thread overview]
Message-ID: <20180306093938.GR22212@phenom.ffwll.local> (raw)
In-Reply-To: <ef1876c3-68e7-fa20-380f-6d9e57394de1@gmail.com>

On Tue, Mar 06, 2018 at 10:30:56AM +0100, Christian König wrote:
> Am 06.03.2018 um 10:15 schrieb Daniel Vetter:
> > On Wed, Feb 28, 2018 at 11:25:59AM +0100, Christian König wrote:
> > > Am 28.02.2018 um 10:48 schrieb Lucas Stach:
> > > > Hi Christian,
> > > > 
> > > > Am Dienstag, den 27.02.2018, 12:49 +0100 schrieb Christian König:
> > > > > Unpin the GEM object only after freeing the sg table.
> > > > What is the race that is being fixed here? The SG table is private to
> > > > the importer and the importer should hopefully only call map_detach if
> > > > it is done with all operations using the SG table. Thus it shouldn't
> > > > matter that the SG table might point to moved pages during execution of
> > > > this function.
> > > Exactly, it shouldn't matter. This is just a precaution.
> > > 
> > > When the device driver is buggy I want proper error messages from IOMMU and
> > > not accessing pages which might already be reused for something else.
> > Please add this to the commit message, rather crucial to understand the
> > motivation. With that fixed you can have my
> > 
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> > 
> > And pls push to drm-misc.
> 
> Can I use standard git for that now? I really don't want to mess with dim in
> my environment.

Ping Alex to run it for you please. In an ideal world we'd run all that
stuff server-side, but that's not happening anytime soon.

Also if you have any specific issues about dim stomping over your setup,
we'll be happy to fix it. If you set the (relative) paths correctly you
can hide the various additional checkouts it needs rather well.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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