[Intel-gfx] [PATCH 4/8] drm/i915: NULL checking when capturing buffer objects during error state capture

[Tomas Elf]

In the past vmas have sometimes turned out to be NULL when capturing buffer
objects during error state capture. To avoid NULL pointer exceptions throw a
WARNING and exit early and be prepared for the error state not being fully
accurate following this point.

Signed-off-by: Tomas Elf <tomas.elf at intel.com>
---
 drivers/gpu/drm/i915/i915_gpu_error.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index cc75ca4..ae24971 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -691,9 +691,17 @@ unwind:
 static void capture_bo(struct drm_i915_error_buffer *err,
 		       struct i915_vma *vma)
 {
-	struct drm_i915_gem_object *obj = vma->obj;
+	struct drm_i915_gem_object *obj;
 	int i;
 
+	if (WARN_ON(!vma))
+	    return;
+
+	if (WARN_ON(!vma->obj))
+	    return;
+
+	obj = vma->obj;
+
 	err->size = obj->base.size;
 	err->name = obj->base.name;
 	for (i = 0; i < I915_NUM_RINGS; i++)
-- 
1.9.1