linux-kernel - Re: [PATCH] drm/msm/a6xx: fix uninitialised lock in init error path

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Message-ID: <ZHheiJfdp7-597XT@hovoldconsulting.com>
Date:   Thu, 1 Jun 2023 11:02:00 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Doug Anderson <dianders@...omium.org>,
        Rob Clark <robdclark@...il.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     'Johan Hovold <johan+linaro@...nel.org>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Bjorn Andersson <andersson@...nel.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] drm/msm/a6xx: fix uninitialised lock in init error path

On Wed, May 31, 2023 at 07:22:49AM -0700, Doug Anderson wrote:
> Hi,
> 
> On Wed, May 31, 2023 at 1:00 AM Johan Hovold <johan+linaro@...nel.org> wrote:
> >
> > A recent commit started taking the GMU lock in the GPU destroy path,
> > which on GPU initialisation failure is called before the GMU and its
> > lock have been initialised.
> >
> > Make sure that the GMU has been initialised before taking the lock in
> > a6xx_destroy() and drop the now redundant check from a6xx_gmu_remove().
> >
> > Fixes: 4cd15a3e8b36 ("drm/msm/a6xx: Make GPU destroy a bit safer")
> > Cc: stable@...r.kernel.org      # 6.3
> > Cc: Douglas Anderson <dianders@...omium.org>
> > Signed-off-by: Johan Hovold <johan+linaro@...nel.org>
> > ---
> >  drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 3 ---
> >  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 9 ++++++---
> >  2 files changed, 6 insertions(+), 6 deletions(-)
> 
> I think Dmitry already posted a patch 1.5 months ago to fix this.
> 
> https://lore.kernel.org/r/20230410165908.3094626-1-dmitry.baryshkov@linaro.org

Bah, I checked if Bjorn had hit this with his recent A690 v3 series and
posted a fix, but did not look further than that.

> Can you confirm that works for you?

That looks like it would work too, but I think I prefer my version which
keeps the initialisation of the GMU struct in a6xx_gmu_init().

Dmitry or Rob, could you see to that either version gets merged soon so
that we don't end up with even more people having to debug and fix the
same issue?

Johan