drm/radeon: Track the status of a page flip more explicitly

This prevents a panic: radeon_crtc_handle_page_flip() could run before
radeon_flip_work_func(), triggering the BUG_ON() in drm_vblank_put().

Tested-by: Dieter Nützel <Dieter@nuetzel-hh.de>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 8fc362aa6a1a3abba3880202c120a00e7dbce383..13896edcf0b6507337e728269732e4c391883115 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -285,7 +285,6 @@ static void radeon_unpin_work_func(struct work_struct *__work)
 void radeon_crtc_handle_vblank(struct radeon_device *rdev, int crtc_id)
 {
        struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc_id];
-       struct radeon_flip_work *work;
        unsigned long flags;
        u32 update_pending;
        int vpos, hpos;
@@ -295,8 +294,11 @@ void radeon_crtc_handle_vblank(struct radeon_device *rdev, int crtc_id)
                return;
 
        spin_lock_irqsave(&rdev->ddev->event_lock, flags);
-       work = radeon_crtc->flip_work;
-       if (work == NULL) {
+       if (radeon_crtc->flip_status != RADEON_FLIP_SUBMITTED) {
+               DRM_DEBUG_DRIVER("radeon_crtc->flip_status = %d != "
+                                "RADEON_FLIP_SUBMITTED(%d)\n",
+                                radeon_crtc->flip_status,
+                                RADEON_FLIP_SUBMITTED);
                spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
                return;
        }
@@ -344,12 +346,17 @@ void radeon_crtc_handle_flip(struct radeon_device *rdev, int crtc_id)
 
        spin_lock_irqsave(&rdev->ddev->event_lock, flags);
        work = radeon_crtc->flip_work;
-       if (work == NULL) {
+       if (radeon_crtc->flip_status != RADEON_FLIP_SUBMITTED) {
+               DRM_DEBUG_DRIVER("radeon_crtc->flip_status = %d != "
+                                "RADEON_FLIP_SUBMITTED(%d)\n",
+                                radeon_crtc->flip_status,
+                                RADEON_FLIP_SUBMITTED);
                spin_unlock_irqrestore(&rdev->ddev->event_lock, flags);
                return;
        }
 
        /* Pageflip completed. Clean up. */
+       radeon_crtc->flip_status = RADEON_FLIP_NONE;
        radeon_crtc->flip_work = NULL;
 
        /* wakeup userspace */
@@ -476,6 +483,7 @@ static void radeon_flip_work_func(struct work_struct *__work)
        /* do the flip (mmio) */
        radeon_page_flip(rdev, radeon_crtc->crtc_id, base);
 
+       radeon_crtc->flip_status = RADEON_FLIP_SUBMITTED;
        spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
        up_read(&rdev->exclusive_lock);
 
@@ -544,7 +552,7 @@ static int radeon_crtc_page_flip(struct drm_crtc *crtc,
        /* We borrow the event spin lock for protecting flip_work */
        spin_lock_irqsave(&crtc->dev->event_lock, flags);
 
-       if (radeon_crtc->flip_work) {
+       if (radeon_crtc->flip_status != RADEON_FLIP_NONE) {
                DRM_DEBUG_DRIVER("flip queue: crtc already busy\n");
                spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
                drm_gem_object_unreference_unlocked(&work->old_rbo->gem_base);
@@ -552,6 +560,7 @@ static int radeon_crtc_page_flip(struct drm_crtc *crtc,
                kfree(work);
                return -EBUSY;
        }
+       radeon_crtc->flip_status = RADEON_FLIP_PENDING;
        radeon_crtc->flip_work = work;
 
        /* update crtc fb */

diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index 98a125d4e50b8b7218bc91b902c82243a751b6e8..0592ddb0904b732384d09f73114f4d41566c3c4a 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -306,6 +306,12 @@ struct radeon_atom_ss {
        uint16_t amount;
 };
 
+enum radeon_flip_status {
+       RADEON_FLIP_NONE,
+       RADEON_FLIP_PENDING,
+       RADEON_FLIP_SUBMITTED
+};
+
 struct radeon_crtc {
        struct drm_crtc base;
        int crtc_id;
@@ -331,6 +337,7 @@ struct radeon_crtc {
        /* page flipping */
        struct workqueue_struct *flip_queue;
        struct radeon_flip_work *flip_work;
+       enum radeon_flip_status flip_status;
        /* pll sharing */
        struct radeon_atom_ss ss;
        bool ss_enabled;