[PATCH 8/8] drm/i915: NULL check of unpin_work

[Tomas Elf <tomas.elf@intel.com>]

Avoid NULL pointer exceptions in the display driver for certain critical cases
when unpin_work has turned out to be NULL.

Signed-off-by: Tomas Elf <tomas.elf@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 539c373..421bc80 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -10853,6 +10853,8 @@ static inline void intel_mark_page_flip_active(struct intel_crtc *intel_crtc)
 {
 	/* Ensure that the work item is consistent when activating it ... */
 	smp_wmb();
+	if (!intel_crtc->unpin_work)
+	    return;
 	atomic_set(&intel_crtc->unpin_work->pending, INTEL_FLIP_PENDING);
 	/* and that it is marked active as soon as the irq could fire. */
 	smp_wmb();
@@ -11187,6 +11189,9 @@ static void ilk_do_mmio_flip(struct intel_crtc *intel_crtc)
 
 	I915_WRITE(reg, dspcntr);
 
+	if (!intel_crtc->unpin_work)
+	    return;
+
 	I915_WRITE(DSPSURF(intel_crtc->plane),
 		   intel_crtc->unpin_work->gtt_offset);
 	POSTING_READ(DSPSURF(intel_crtc->plane));
-- 
1.9.1

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