[media] media: Add flags to tell whether to take graph mutex for an IOCTL

New IOCTLs (especially for the request API) do not necessarily need the
graph mutex acquired. Leave this up to the drivers.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/media-device.c

@@ -381,31 +381,36 @@ static long copy_arg_to_user(void __user *uarg, void *karg, unsigned int cmd)
 	return 0;
 }
 
-#define MEDIA_IOC_ARG(__cmd, func, from_user, to_user)	\
-	[_IOC_NR(MEDIA_IOC_##__cmd)] = {		\
-		.cmd = MEDIA_IOC_##__cmd,		\
+/* Do acquire the graph mutex */
+#define MEDIA_IOC_FL_GRAPH_MUTEX	BIT(0)
+
+#define MEDIA_IOC_ARG(__cmd, func, fl, from_user, to_user)		\
+	[_IOC_NR(MEDIA_IOC_##__cmd)] = {				\
+		.cmd = MEDIA_IOC_##__cmd,				\
 		.fn = (long (*)(struct media_device *, void *))func,	\
-		.arg_from_user = from_user,		\
-		.arg_to_user = to_user,			\
+		.flags = fl,						\
+		.arg_from_user = from_user,				\
+		.arg_to_user = to_user,					\
 	}
 
-#define MEDIA_IOC(__cmd, func)						\
-	MEDIA_IOC_ARG(__cmd, func, copy_arg_from_user, copy_arg_to_user)
+#define MEDIA_IOC(__cmd, func, fl)					\
+	MEDIA_IOC_ARG(__cmd, func, fl, copy_arg_from_user, copy_arg_to_user)
 
 /* the table is indexed by _IOC_NR(cmd) */
 struct media_ioctl_info {
 	unsigned int cmd;
+	unsigned short flags;
 	long (*fn)(struct media_device *dev, void *arg);
 	long (*arg_from_user)(void *karg, void __user *uarg, unsigned int cmd);
 	long (*arg_to_user)(void __user *uarg, void *karg, unsigned int cmd);
 };
 
 static const struct media_ioctl_info ioctl_info[] = {
-	MEDIA_IOC(DEVICE_INFO, media_device_get_info),
-	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities),
-	MEDIA_IOC(ENUM_LINKS, media_device_enum_links),
-	MEDIA_IOC(SETUP_LINK, media_device_setup_link),
-	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology),
+	MEDIA_IOC(DEVICE_INFO, media_device_get_info, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(ENUM_ENTITIES, media_device_enum_entities, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(ENUM_LINKS, media_device_enum_links, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(SETUP_LINK, media_device_setup_link, MEDIA_IOC_FL_GRAPH_MUTEX),
+	MEDIA_IOC(G_TOPOLOGY, media_device_get_topology, MEDIA_IOC_FL_GRAPH_MUTEX),
 };
 
 static long media_device_ioctl(struct file *filp, unsigned int cmd,
@@ -436,9 +441,13 @@ static long media_device_ioctl(struct file *filp, unsigned int cmd,
 			goto out_free;
 	}
 
-	mutex_lock(&dev->graph_mutex);
+	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
+		mutex_lock(&dev->graph_mutex);
+
 	ret = info->fn(dev, karg);
-	mutex_unlock(&dev->graph_mutex);
+
+	if (info->flags & MEDIA_IOC_FL_GRAPH_MUTEX)
+		mutex_unlock(&dev->graph_mutex);
 
 	if (!ret && info->arg_to_user)
 		ret = info->arg_to_user(arg, karg, cmd);