From 7908632f2927b65f7486ae6b67c24071666ba43f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ADra=20Canal?= <mcanal@igalia.com>
Date: Thu, 14 Sep 2023 07:19:02 -0300
Subject: [PATCH] Revert "drm/vkms: Fix race-condition between the hrtimer and
the atomic commit"
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This reverts commit a0e6a017ab56936c0405fe914a793b241ed25ee0.
Unlocking a mutex in the context of a hrtimer callback is violating mutex
locking rules, as mutex_unlock() from interrupt context is not permitted.
Link: https://lore.kernel.org/dri-devel/ZQLAc%2FFwkv%2FGiVoK@phenom.ffwll.local/T/#t
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230914102024.1789154-1-mcanal@igalia.com
---
drivers/gpu/drm/vkms/vkms_composer.c | 9 ++-------
drivers/gpu/drm/vkms/vkms_crtc.c | 9 ++++-----
drivers/gpu/drm/vkms/vkms_drv.h | 4 +---
3 files changed, 7 insertions(+), 15 deletions(-)
diff --git a/drivers/gpu/drm/vkms/vkms_composer.c b/drivers/gpu/drm/vkms/vkms_composer.c
index d5d4f642d3678..3c99fb8b54e2d 100644
--- a/drivers/gpu/drm/vkms/vkms_composer.c
+++ b/drivers/gpu/drm/vkms/vkms_composer.c
@@ -408,15 +408,10 @@ void vkms_set_composer(struct vkms_output *out, bool enabled)
if (enabled)
drm_crtc_vblank_get(&out->crtc);
- mutex_lock(&out->enabled_lock);
+ spin_lock_irq(&out->lock);
old_enabled = out->composer_enabled;
out->composer_enabled = enabled;
-
- /* the composition wasn't enabled, so unlock the lock to make sure the lock
- * will be balanced even if we have a failed commit
- */
- if (!out->composer_enabled)
- mutex_unlock(&out->enabled_lock);
+ spin_unlock_irq(&out->lock);
if (old_enabled)
drm_crtc_vblank_put(&out->crtc);
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 3c5ebf106b66d..61e500b8c9da2 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -16,7 +16,7 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
struct drm_crtc *crtc = &output->crtc;
struct vkms_crtc_state *state;
u64 ret_overrun;
- bool ret, fence_cookie, composer_enabled;
+ bool ret, fence_cookie;
fence_cookie = dma_fence_begin_signalling();
@@ -25,15 +25,15 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
if (ret_overrun != 1)
pr_warn("%s: vblank timer overrun\n", __func__);
+ spin_lock(&output->lock);
ret = drm_crtc_handle_vblank(crtc);
if (!ret)
DRM_ERROR("vkms failure on handling vblank");
state = output->composer_state;
- composer_enabled = output->composer_enabled;
- mutex_unlock(&output->enabled_lock);
+ spin_unlock(&output->lock);
- if (state && composer_enabled) {
+ if (state && output->composer_enabled) {
u64 frame = drm_crtc_accurate_vblank_count(crtc);
/* update frame_start only if a queued vkms_composer_worker()
@@ -295,7 +295,6 @@ int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
spin_lock_init(&vkms_out->lock);
spin_lock_init(&vkms_out->composer_lock);
- mutex_init(&vkms_out->enabled_lock);
vkms_out->composer_workq = alloc_ordered_workqueue("vkms_composer", 0);
if (!vkms_out->composer_workq)
diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
index c7ae6c2ba1df0..8f5710debb1eb 100644
--- a/drivers/gpu/drm/vkms/vkms_drv.h
+++ b/drivers/gpu/drm/vkms/vkms_drv.h
@@ -108,10 +108,8 @@ struct vkms_output {
struct workqueue_struct *composer_workq;
/* protects concurrent access to composer */
spinlock_t lock;
- /* guarantees that if the composer is enabled, a job will be queued */
- struct mutex enabled_lock;
- /* protected by @enabled_lock */
+ /* protected by @lock */
bool composer_enabled;
struct vkms_crtc_state *composer_state;
--
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