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Commit 98787c05 authored by Chris Wilson's avatar Chris Wilson Committed by Eric Anholt
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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: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarEric Anholt <eric@anholt.net>
parent bf5a269a

drivers/gpu/drm/i915/i915_dma.c

+6 −3
Original line number Diff line number Diff line
@@ -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 (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;