[media] uvcvideo: Lock controls mutex when querying menus

uvc_find_control() must be called with the controls mutex locked. Fix
uvc_query_v4l2_menu() accordingly.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/uvc/uvc_ctrl.c

@@ -785,7 +785,7 @@ static void __uvc_find_control(struct uvc_entity *entity, __u32 v4l2_id,
 	}
 }
 
-struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
+static struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
 	__u32 v4l2_id, struct uvc_control_mapping **mapping)
 {
 	struct uvc_control *ctrl = NULL;
@@ -944,6 +944,52 @@ int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
 	return ret;
 }
 
+/*
+ * Mapping V4L2 controls to UVC controls can be straighforward if done well.
+ * Most of the UVC controls exist in V4L2, and can be mapped directly. Some
+ * must be grouped (for instance the Red Balance, Blue Balance and Do White
+ * Balance V4L2 controls use the White Balance Component UVC control) or
+ * otherwise translated. The approach we take here is to use a translation
+ * table for the controls that can be mapped directly, and handle the others
+ * manually.
+ */
+int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
+	struct v4l2_querymenu *query_menu)
+{
+	struct uvc_menu_info *menu_info;
+	struct uvc_control_mapping *mapping;
+	struct uvc_control *ctrl;
+	u32 index = query_menu->index;
+	u32 id = query_menu->id;
+	int ret;
+
+	memset(query_menu, 0, sizeof(*query_menu));
+	query_menu->id = id;
+	query_menu->index = index;
+
+	ret = mutex_lock_interruptible(&chain->ctrl_mutex);
+	if (ret < 0)
+		return -ERESTARTSYS;
+
+	ctrl = uvc_find_control(chain, query_menu->id, &mapping);
+	if (ctrl == NULL || mapping->v4l2_type != V4L2_CTRL_TYPE_MENU) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	if (query_menu->index >= mapping->menu_count) {
+		ret = -EINVAL;
+		goto done;
+	}
+
+	menu_info = &mapping->menu_info[query_menu->index];
+	strlcpy(query_menu->name, menu_info->name, sizeof query_menu->name);
+
+done:
+	mutex_unlock(&chain->ctrl_mutex);
+	return ret;
+}
+
 
 /* --------------------------------------------------------------------------
  * Control transactions

drivers/media/video/uvc/uvc_v4l2.c

@@ -100,40 +100,6 @@ static int uvc_ioctl_ctrl_map(struct uvc_video_chain *chain,
  * V4L2 interface
  */
 
-/*
- * Mapping V4L2 controls to UVC controls can be straighforward if done well.
- * Most of the UVC controls exist in V4L2, and can be mapped directly. Some
- * must be grouped (for instance the Red Balance, Blue Balance and Do White
- * Balance V4L2 controls use the White Balance Component UVC control) or
- * otherwise translated. The approach we take here is to use a translation
- * table for the controls that can be mapped directly, and handle the others
- * manually.
- */
-static int uvc_v4l2_query_menu(struct uvc_video_chain *chain,
-	struct v4l2_querymenu *query_menu)
-{
-	struct uvc_menu_info *menu_info;
-	struct uvc_control_mapping *mapping;
-	struct uvc_control *ctrl;
-	u32 index = query_menu->index;
-	u32 id = query_menu->id;
-
-	ctrl = uvc_find_control(chain, query_menu->id, &mapping);
-	if (ctrl == NULL || mapping->v4l2_type != V4L2_CTRL_TYPE_MENU)
-		return -EINVAL;
-
-	if (query_menu->index >= mapping->menu_count)
-		return -EINVAL;
-
-	memset(query_menu, 0, sizeof(*query_menu));
-	query_menu->id = id;
-	query_menu->index = index;
-
-	menu_info = &mapping->menu_info[query_menu->index];
-	strlcpy(query_menu->name, menu_info->name, sizeof query_menu->name);
-	return 0;
-}
-
 /*
  * Find the frame interval closest to the requested frame interval for the
  * given frame format and size. This should be done by the device as part of
@@ -624,7 +590,7 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 	}
 
 	case VIDIOC_QUERYMENU:
-		return uvc_v4l2_query_menu(chain, arg);
+		return uvc_query_v4l2_menu(chain, arg);
 
 	case VIDIOC_G_EXT_CTRLS:
 	{

drivers/media/video/uvc/uvcvideo.h

@@ -606,10 +606,10 @@ extern int uvc_status_suspend(struct uvc_device *dev);
 extern int uvc_status_resume(struct uvc_device *dev);
 
 /* Controls */
-extern struct uvc_control *uvc_find_control(struct uvc_video_chain *chain,
-		__u32 v4l2_id, struct uvc_control_mapping **mapping);
 extern int uvc_query_v4l2_ctrl(struct uvc_video_chain *chain,
 		struct v4l2_queryctrl *v4l2_ctrl);
+extern int uvc_query_v4l2_menu(struct uvc_video_chain *chain,
+		struct v4l2_querymenu *query_menu);
 
 extern int uvc_ctrl_add_mapping(struct uvc_video_chain *chain,
 		const struct uvc_control_mapping *mapping);