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

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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.

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;
   		}
   	}




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