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

[Christian König]

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

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;
>>>    		}
>>>    	}