[Intel-gfx] [PATCH] drm/i915: Only destroy a constructed mmap offset

[Chris Wilson]

drm_ht_remove_item() does not handle removing an absent item and the hlist
in particular is incorrectly initialised. The easy remedy is simply skip
calling i915_gem_free_mmap_offset() unless we have actually created the
offset and associated ht entry.

This also fixes the mishandling of a partially constructed offset which
leaves pointers initialized after freeing them along the
i915_gem_create_mmap_offset() error paths.

In particular this should fix the oops found here:
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-intel/+bug/415357/comments/8

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_gem.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index be0c5dd..6305ea3 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3856,7 +3856,8 @@ void i915_gem_free_object(struct drm_gem_object *obj)
 
 	i915_gem_object_unbind(obj);
 
-	i915_gem_free_mmap_offset(obj);
+	if (obj_priv->mmap_offset)
+		i915_gem_free_mmap_offset(obj);
 
 	kfree(obj_priv->page_cpu_valid);
 	kfree(obj_priv->bit_17);
-- 
1.6.3.3