Re: [PATCH] drm/i915: Don't enable hwmon for selftests

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Fri, 12 Apr 2024 17:35:15 -0700, Dixit, Ashutosh wrote:
>
> On Thu, 11 Apr 2024 03:47:13 -0700, Ville Syrjälä wrote:
> >
> > On Wed, Apr 10, 2024 at 10:09:32PM -0700, Dixit, Ashutosh wrote:
> > > On Wed, 10 Apr 2024 04:42:46 -0700, Ville Syrjälä wrote:
> > > >
> > > > On Tue, Apr 09, 2024 at 09:28:55PM -0700, Ashutosh Dixit wrote:
> > > > > There are no hwmon selftests so there is no need to enable hwmon for
> > > > > selftests. So enable hwmon only for real driver load.
> > > > >
> > > > > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10366
> > > > > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> > > >
> > > > Why are we adding duct tape instead of fixing it properly?
> > >
> > > Yeah pretty much what I said here myself:
> > >
> > > https://patchwork.freedesktop.org/patch/588585/?series=132243&rev=1#comment_1071014
> > >
> > > The issue has been difficult to root-cause. My last effort can be seen here:
> > >
> > > https://patchwork.freedesktop.org/patch/584859/?series=131630&rev=1#comment_1067888
> > >
> > > Though Badal went further and saw that occasionaly the memory would get
> > > freed first and hwmon would get unregistered as much as 2 seconds later,
> > > which will cause the crash if anyone touched hwmon sysfs in those final 2
> > > seconds. So not sure what is causing that 2 second delay.
> >
> > Sounds like someone holding a sysfs file/etc. open. Should be trivial
> > to do that by hand and see what happens.
>
> I checked this out. We see the memory being released before hwmon even when
> we don't access the sysfs, so it has norhing to do with holding a sysfs
> file open. Holding a sysfs file open also takes a reference on the module
> which will prevent the module from being unloaded, which is also what we
> don't see.
>
> So the reordering seems to be happening in devres itself occasionally for
> some reason.
>
> So anyway, I have submitted a new patch getting rid of devm and freeing
> everything explicitly and verified that that fixes the issue:
>
> https://patchwork.freedesktop.org/series/132400/
>
> I have also update https://patchwork.freedesktop.org/series/132400/ with
> more details.

Sorry I meant: https://gitlab.freedesktop.org/drm/intel/-/issues/10366