drm/i915: Don't clobber crtc->fb when queue_flip fails

Restore crtc->fb to the old framebuffer if queue_flip fails.

While at it, kill the pointless intel_fb temp variable.

v2: Update crtc->fb before queue_flip and restore it back
    after a failure.

Cc: stable@vger.kernel.org
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Reported-and-Tested-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 4 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 0ff10b3af9ea..09659ff6d24d 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7264,8 +7264,8 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 {
         struct drm_device *dev = crtc->dev;
         struct drm_i915_private *dev_priv = dev->dev_private;
-        struct intel_framebuffer *intel_fb;
-        struct drm_i915_gem_object *obj;
+        struct drm_framebuffer *old_fb = crtc->fb;
+        struct drm_i915_gem_object *obj = to_intel_framebuffer(fb)->obj;
         struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
         struct intel_unpin_work *work;
         unsigned long flags;
@@ -7290,8 +7290,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 
         work->event = event;
         work->crtc = crtc;
-        intel_fb = to_intel_framebuffer(crtc->fb);
-        work->old_fb_obj = intel_fb->obj;
+        work->old_fb_obj = to_intel_framebuffer(old_fb)->obj;
         INIT_WORK(&work->work, intel_unpin_work_fn);
 
         ret = drm_vblank_get(dev, intel_crtc->pipe);
@@ -7311,9 +7310,6 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
         intel_crtc->unpin_work = work;
         spin_unlock_irqrestore(&dev->event_lock, flags);
 
-        intel_fb = to_intel_framebuffer(fb);
-        obj = intel_fb->obj;
-
         if (atomic_read(&intel_crtc->unpin_work_count) >= 2)
                 flush_workqueue(dev_priv->wq);
 
@@ -7348,6 +7344,7 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc,
 
 cleanup_pending:
         atomic_dec(&intel_crtc->unpin_work_count);
+        crtc->fb = old_fb;
         drm_gem_object_unreference(&work->old_fb_obj->base);
         drm_gem_object_unreference(&obj->base);
         mutex_unlock(&dev->struct_mutex);