drm/i915: Retire the VMA's fence tracker before unbinding

Since we may track unfenced access (GPU access to the vma that
explicitly requires no fence), vma->last_fence may be set without any
attached fence (vma->fence) and so will not be flushed when we call
i915_vma_put_fence(). Since we stopped doing a full retire of the
activity trackers for unbind, we need to explicitly retire each tracker.

Fixes: b0decaf7 ("drm/i915: Track active vma requests")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170620124321.1108-1-chris@chris-wilson.co.ukReviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>

drivers/gpu/drm/i915/i915_vma.c

@@ -672,6 +672,11 @@ int i915_vma_unbind(struct i915_vma *vma)
 				break;
 		}
 
+		if (!ret) {
+			ret = i915_gem_active_retire(&vma->last_fence,
+						     &vma->vm->i915->drm.struct_mutex);
+		}
+
 		__i915_vma_unpin(vma);
 		if (ret)
 			return ret;