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

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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: b3d91800d9 ("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>
This commit is contained in:
Stephen Boyd 2021-02-11 14:40:58 -08:00 committed by Rob Clark
parent 182b4a2d25
commit 743c97ca9d
2 changed files with 7 additions and 8 deletions
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7
drivers/gpu/drm/msm/msm_atomic.c
View File

@ -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)

8
drivers/gpu/drm/msm/msm_kms.h
View File

@ -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;