drm/msm/kms: Use nested locking for crtc lock instead of custom classes

We don't need to make up custom lock classes here, we can simply use
mutex_lock_nested() and pass in the index of the crtc to the locking
APIs instead. This helps lockdep understand that these are really
different locks while avoiding having to allocate custom lockdep
classes.

Cc: Krishna Manikandan <mkrishn@codeaurora.org>
Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Fixes: b3d91800d9ac ("drm/msm: Fix race condition in msm driver with async layer updates")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>

1 files changed, 2 insertions, 6 deletions

diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h
index 4735251a394d..d8151a89e163 100644
--- a/drivers/gpu/drm/msm/msm_kms.h
+++ b/drivers/gpu/drm/msm/msm_kms.h
@@ -157,7 +157,6 @@ struct msm_kms {
 	 * from the crtc's pending_timer close to end of the frame:
 	 */
 	struct mutex commit_lock[MAX_CRTCS];
-	struct lock_class_key commit_lock_keys[MAX_CRTCS];
 	unsigned pending_crtc_mask;
 	struct msm_pending_timer pending_timers[MAX_CRTCS];
 };
@@ -167,11 +166,8 @@ static inline int msm_kms_init(struct msm_kms *kms,
 {
 	unsigned i, ret;
 
-	for (i = 0; i < ARRAY_SIZE(kms->commit_lock); i++) {
-		lockdep_register_key(&kms->commit_lock_keys[i]);
-		__mutex_init(&kms->commit_lock[i], "&kms->commit_lock[i]",
-			     &kms->commit_lock_keys[i]);
-	}
+	for (i = 0; i < ARRAY_SIZE(kms->commit_lock); i++)
+		mutex_init(&kms->commit_lock[i]);
 
 	kms->funcs = funcs;