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

Christian König
2022-07-05T11:34:10Z

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@vger.kernel.org
> Fixes: 7edc3e3b975b5 ("drm: Add helpers for locking an array of BO reservations.")
> Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
> 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;
> }
> }