[media] v4l: Do not allow re-registering sub-devices

Albeit not prohibited explicitly, re-registering sub-devices generated a
big, loud warning which quite likely soon was followed by a crash. What
followed was re-initialising a media entity, driver's registered() callback
being called and re-adding a list entry to a list.

Prevent this by returning an error if a sub-device is already registered.

[mchehab@s-opensource.com: reorder logic to check if !sd before dereferencing it]
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/v4l2-core/v4l2-device.c b/drivers/media/v4l2-core/v4l2-device.c
index 06fa5f1b2cfffa833a54cc6eb6584cb0dbaa4be7..62bbed76dbbc401bda8413ec94cc5cf4d065f5de 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-device.c
+++ b/drivers/media/v4l2-core/v4l2-device.c
@@ -160,12 +160,9 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
        int err;
 
        /* Check for valid input */
-       if (v4l2_dev == NULL || sd == NULL || !sd->name[0])
+       if (!v4l2_dev || !sd || sd->v4l2_dev || !sd->name[0])
                return -EINVAL;
 
-       /* Warn if we apparently re-register a subdev */
-       WARN_ON(sd->v4l2_dev != NULL);
-
        /*
         * The reason to acquire the module here is to avoid unloading
         * a module of sub-device which is registered to a media