drm/i915: Remove a couple pointless WARN_ONs

Just two WARN_ONs followed by pointer dereference I spotted by accident.

v2: Remove some more of the same.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: http://patchwork.freedesktop.org/patch/msgid/1461080770-14693-1-git-send-email-tvrtko.ursulin@linux.intel.com

drivers/gpu/drm/i915/i915_gem.c

@@ -1444,18 +1444,13 @@ __i915_gem_request_retire__upto(struct drm_i915_gem_request *req)
 int
 i915_wait_request(struct drm_i915_gem_request *req)
 {
-	struct drm_device *dev;
-	struct drm_i915_private *dev_priv;
+	struct drm_i915_private *dev_priv = req->i915;
 	bool interruptible;
 	int ret;
 
-	BUG_ON(req == NULL);
-
-	dev = req->engine->dev;
-	dev_priv = dev->dev_private;
 	interruptible = dev_priv->mm.interruptible;
 
-	BUG_ON(!mutex_is_locked(&dev->struct_mutex));
+	BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
 
 	ret = __i915_wait_request(req, interruptible, NULL, NULL);
 	if (ret)
@@ -4355,7 +4350,6 @@ i915_gem_object_ggtt_unpin_view(struct drm_i915_gem_object *obj,
 {
 	struct i915_vma *vma = i915_gem_obj_to_ggtt_view(obj, view);
 
-	BUG_ON(!vma);
 	WARN_ON(vma->pin_count == 0);
 	WARN_ON(!i915_gem_obj_ggtt_bound_view(obj, view));
 

drivers/gpu/drm/i915/intel_lrc.c

@@ -892,8 +892,6 @@ int intel_logical_ring_begin(struct drm_i915_gem_request *req, int num_dwords)
 {
 	int ret;
 
-	WARN_ON(req == NULL);
-
 	ret = logical_ring_prepare(req, num_dwords * sizeof(uint32_t));
 	if (ret)
 		return ret;

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -2490,14 +2490,9 @@ static int __intel_ring_prepare(struct intel_engine_cs *engine, int bytes)
 int intel_ring_begin(struct drm_i915_gem_request *req,
 		     int num_dwords)
 {
-	struct intel_engine_cs *engine;
-	struct drm_i915_private *dev_priv;
+	struct intel_engine_cs *engine = req->engine;
 	int ret;
 
-	WARN_ON(req == NULL);
-	engine = req->engine;
-	dev_priv = req->i915;
-
 	ret = __intel_ring_prepare(engine, num_dwords * sizeof(uint32_t));
 	if (ret)
 		return ret;