Re: [PATCH AUTOSEL 5.13 03/12] ASoC: wm_adsp: Let soc_cleanup_component_debugfs remove debugfs

[Sasha Levin]

On Wed, Aug 18, 2021 at 01:15:44PM +0000, Charles Keepax wrote:
> On Mon, Aug 16, 2021 at 08:35:27PM -0400, Sasha Levin wrote:
> > From: Lucas Tanure <tanureal@xxxxxxxxxxxxxxxxxxxxx>
> >
> > [ Upstream commit acbf58e530416e167c3b323111f4013d9f2b0a7d ]
> >
> > soc_cleanup_component_debugfs will debugfs_remove_recursive
> > the component->debugfs_root, so adsp doesn't need to also
> > remove the same entry.
> > By doing that adsp also creates a race with core component,
> > which causes a NULL pointer dereference
> >
> > Signed-off-by: Lucas Tanure <tanureal@xxxxxxxxxxxxxxxxxxxxx>
> > Link: https://lore.kernel.org/r/20210728104416.636591-1-tanureal@xxxxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
> > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> > ---
> >  sound/soc/codecs/wm_adsp.c | 1 -
> >  1 file changed, 1 deletion(-)
> >
> > diff --git a/sound/soc/codecs/wm_adsp.c b/sound/soc/codecs/wm_adsp.c
> > index cef05d81c39b..6698b5343974 100644
> > --- a/sound/soc/codecs/wm_adsp.c
> > +++ b/sound/soc/codecs/wm_adsp.c
> > @@ -746,7 +746,6 @@ static void wm_adsp2_init_debugfs(struct wm_adsp *dsp,
> >  static void wm_adsp2_cleanup_debugfs(struct wm_adsp *dsp)
> >  {
> >  	wm_adsp_debugfs_clear(dsp);
> > -	debugfs_remove_recursive(dsp->debugfs_root);
> >  }
>
> It might be better not to backport this patch to the stable
> kernels. The issue has only been seen on one out of tree driver
> and the patch looks a little off to me. This
> debugfs_remove_recursive should run before the
> soc_cleanup_component_debugfs one, and as such it's hard to see
> what is actually going on. We are currently investigating internally
> but we might end up reverting the change, and it only seems to be
> causing issues on the one not upstreamed part.
>
> Apologies for missing the review of this one when it went up
> Mark, I was on holiday at the time.

I'll drop it, it didn't go anywhere yet :) Thanks!

--
Thanks,
Sasha