drm/gem: Check locking in drm_gem_object_unreference

danvet · danvet · commit ef4c6270bf28 · 2015-10-19T11:00:35.000+02:00
Pretty soon only some drivers will need dev->struct_mutex in their gem_free_object callbacks. Hence it's really important to make sure everything still keeps getting this right. v2: Don't check for locking before we check for non-NULL obj. Spotted by Dan Carpenter. Link: http://mid.gmane.org/1444894601-5200-10-git-send-email-daniel.vetter@ffwll.ch Reviewed-by: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
@@ -142,8 +142,11 @@ drm_gem_object_reference(struct drm_gem_object *obj)
 static inline void
 drm_gem_object_unreference(struct drm_gem_object *obj)
 {
-	if (obj != NULL)
+	if (obj != NULL) {
+		WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));
+
 		kref_put(&obj->refcount, drm_gem_object_free);
+	}
 }
 
 static inline void

Original file line number	Diff line number	Diff line change
`@@ -142,8 +142,11 @@ drm_gem_object_reference(struct drm_gem_object *obj)`
`142`	`142`	`static inline void`
`143`	`143`	`drm_gem_object_unreference(struct drm_gem_object *obj)`
`144`	`144`	`{`
`145`		`- if (obj != NULL)`
	`145`	`+ if (obj != NULL) {`
	`146`	`+ WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));`
	`147`	`+`
`146`	`148`	`kref_put(&obj->refcount, drm_gem_object_free);`
	`149`	`+ }`
`147`	`150`	`}`
`148`	`151`
`149`	`152`	`static inline void`