| Date | Thu, 23 Apr 2009 00:20:38 -0700 | From | Chris Wright <> | Subject | [patch 018/100] drm/i915: Check for dev->primary->master before dereference. |
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-stable review patch. If anyone has any objections, please let us know. ---------------------
From: Chris Wilson <chris@chris-wilson.co.uk>
upstream commit: 98787c057fdefdce6230ff46f2c1105835005a4c
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> Signed-off-by: Chris Wright <chrisw@sous-sol.org> --- drivers/gpu/drm/i915/i915_dma.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/i915/i915_dma.c +++ b/drivers/gpu/drm/i915/i915_dma.c @@ -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 * d 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;
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