Re: [PATCH v8 1/2] drm/gem: Properly annotate WW context on drm_gem_lock_reservations() error

[Christian König]

Am 10.08.22 um 10:33 schrieb Daniel Vetter:
> On Wed, 10 Aug 2022 at 08:52, Christian König <christian.koenig@xxxxxxx> wrote:
> > Am 09.08.22 um 18:44 schrieb Daniel Vetter:
> > > On Tue, Jul 05, 2022 at 01:33:51PM +0200, Christian König wrote:
> > > > Am 01.07.22 um 11:02 schrieb Dmitry Osipenko:
> > > > > Use ww_acquire_fini() in the error code paths. Otherwise lockdep
> > > > > thinks that lock is held when lock's memory is freed after the
> > > > > drm_gem_lock_reservations() error. The ww_acquire_context needs to be
> > > > > annotated as "released", which fixes the noisy "WARNING: held lock freed!"
> > > > > splat of VirtIO-GPU driver with CONFIG_DEBUG_MUTEXES=y and enabled lockdep.
> > > > >
> > > > > Cc: stable@xxxxxxxxxxxxxxx
> > > > > Fixes: 7edc3e3b975b5 ("drm: Add helpers for locking an array of BO reservations.")
> > > > > Reviewed-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> > > > > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
> > > > Reviewed-by: Christian König <christian.koenig@xxxxxxx>
> > > Also added this r-b tag when merging to drm-misc-next-fixes.
> > IIRC I've already pushed this to drm-misc-fixes with a CC stable tag
> > about 2 weeks ago.
> >
> > Please double check, it probably just hasn't come down the stream again yet.
> Hm quickly check and I didn't spot it? There's a few patches from
> Dmitry in the last few pulls, and some more stuff pending, but not
> these two afaics?

Mhm, there is some potential that I wanted to push it but got distracted 
by the re-occurring drm-tip build breakages.

Anyway what I wanted to say is that this stuff should probably go to 
drm-misc-fixes with a CC: stable tag :)

Christian.

> -Daniel
>
> > Christian.
> >
> > > -Daniel
> > >
> > > > > ---
> > > > >     drivers/gpu/drm/drm_gem.c | 4 ++--
> > > > >     1 file changed, 2 insertions(+), 2 deletions(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
> > > > > index eb0c2d041f13..86d670c71286 100644
> > > > > --- a/drivers/gpu/drm/drm_gem.c
> > > > > +++ b/drivers/gpu/drm/drm_gem.c
> > > > > @@ -1226,7 +1226,7 @@ drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
> > > > >              ret = dma_resv_lock_slow_interruptible(obj->resv,
> > > > >                                                               acquire_ctx);
> > > > >              if (ret) {
> > > > > -                   ww_acquire_done(acquire_ctx);
> > > > > +                   ww_acquire_fini(acquire_ctx);
> > > > >                      return ret;
> > > > >              }
> > > > >      }
> > > > > @@ -1251,7 +1251,7 @@ drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
> > > > >                              goto retry;
> > > > >                      }
> > > > > -                   ww_acquire_done(acquire_ctx);
> > > > > +                   ww_acquire_fini(acquire_ctx);
> > > > >                      return ret;
> > > > >              }
> > > > >      }