i915: Reinstate check that drawable has valid information in i915_vblank_swap.

diff --git a/shared-core/i915_irq.c b/shared-core/i915_irq.c
index ea84c708ff1d418424279f6ccdb8f3158e1a176f..7baa23c022262eb17edc71738fead69375cb0baa 100644 (file)
--- a/shared-core/i915_irq.c
+++ b/shared-core/i915_irq.c
@@ -612,6 +612,21 @@ int i915_vblank_swap(struct drm_device *dev, void *data,
                return -EINVAL;
        }
 
+       DRM_SPINLOCK_IRQSAVE(&dev->drw_lock, irqflags);
+
+       /* It makes no sense to schedule a swap for a drawable that doesn't have
+        * valid information at this point. E.g. this could mean that the X
+        * server is too old to push drawable information to the DRM, in which
+        * case all such swaps would become ineffective.
+        */
+       if (!drm_get_drawable_info(dev, swap->drawable)) {
+               DRM_SPINUNLOCK_IRQRESTORE(&dev->drw_lock, irqflags);
+               DRM_DEBUG("Invalid drawable ID %d\n", swap->drawable);
+               return -EINVAL;
+       }
+
+       DRM_SPINUNLOCK_IRQRESTORE(&dev->drw_lock, irqflags);
+
        curseq = atomic_read(pipe ? &dev->vbl_received2 : &dev->vbl_received);
 
        if (seqtype == _DRM_VBLANK_RELATIVE)