drm/i915: Check for dev->primary->master before dereference.

I've hit the occasional oops inside i915_wait_ring() with an indication of
a NULL derefence of dev->primary->master.  Adding a NULL check is
consistent with the other potential users of dev->primary->master.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
This commit is contained in:
Chris Wilson 2009-03-06 23:27:52 +00:00 committed by Eric Anholt
parent bf5a269a4c
commit 98787c057f

View File

@ -41,7 +41,6 @@
int i915_wait_ring(struct drm_device * dev, int n, const char *caller)
{
drm_i915_private_t *dev_priv = dev->dev_private;
struct drm_i915_master_private *master_priv = dev->primary->master->driver_priv;
drm_i915_ring_buffer_t *ring = &(dev_priv->ring);
u32 acthd_reg = IS_I965G(dev) ? ACTHD_I965 : ACTHD;
u32 last_acthd = I915_READ(acthd_reg);
@ -58,8 +57,12 @@ int i915_wait_ring(struct drm_device * dev, int n, const char *caller)
if (ring->space >= n)
return 0;
if (master_priv->sarea_priv)
master_priv->sarea_priv->perf_boxes |= I915_BOX_WAIT;
if (dev->primary->master) {
struct drm_i915_master_private *master_priv = dev->primary->master->driver_priv;
if (master_priv->sarea_priv)
master_priv->sarea_priv->perf_boxes |= I915_BOX_WAIT;
}
if (ring->head != last_head)
i = 0;