From 743c97ca9dc989b0b08ca1fbfd134a83b37fe9ec Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Thu, 11 Feb 2021 14:40:58 -0800 Subject: [PATCH] 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 Suggested-by: Daniel Vetter Fixes: b3d91800d9ac ("drm/msm: Fix race condition in msm driver with async layer updates") Signed-off-by: Stephen Boyd Signed-off-by: Rob Clark --- drivers/gpu/drm/msm/msm_atomic.c | 7 +++++-- drivers/gpu/drm/msm/msm_kms.h | 8 ++------ 2 files changed, 7 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/msm/msm_atomic.c b/drivers/gpu/drm/msm/msm_atomic.c index 6a326761dc4ad..edcaccaa27e60 100644 --- a/drivers/gpu/drm/msm/msm_atomic.c +++ b/drivers/gpu/drm/msm/msm_atomic.c @@ -57,10 +57,13 @@ static void vblank_put(struct msm_kms *kms, unsigned crtc_mask) static void lock_crtcs(struct msm_kms *kms, unsigned int crtc_mask) { + int crtc_index; struct drm_crtc *crtc; - for_each_crtc_mask(kms->dev, crtc, crtc_mask) - mutex_lock(&kms->commit_lock[drm_crtc_index(crtc)]); + for_each_crtc_mask(kms->dev, crtc, crtc_mask) { + crtc_index = drm_crtc_index(crtc); + mutex_lock_nested(&kms->commit_lock[crtc_index], crtc_index); + } } static void unlock_crtcs(struct msm_kms *kms, unsigned int crtc_mask) diff --git a/drivers/gpu/drm/msm/msm_kms.h b/drivers/gpu/drm/msm/msm_kms.h index 4735251a394d8..d8151a89e1631 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; -- 2.30.2