v4l: Reset subdev v4l2_dev field to NULL if registration fails

commit 317efce991620adc589b3005b9baed433dcb2a56 upstream.

When subdev registration fails the subdev v4l2_dev field is left to a
non-NULL value. Later calls to v4l2_device_unregister_subdev() will
consider the subdev as registered and will module_put() the subdev
module without any matching module_get().
Fix this by setting the subdev v4l2_dev field to NULL in
v4l2_device_register_subdev() when the function fails.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
[bwh: Backported to 3.2: adjust context, filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index 0edd618..8b0777f 100644 (file)
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -159,31 +159,21 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
        sd->v4l2_dev = v4l2_dev;
        if (sd->internal_ops && sd->internal_ops->registered) {
                err = sd->internal_ops->registered(sd);
-               if (err) {
-                       module_put(sd->owner);
-                       return err;
-               }
+               if (err)
+                       goto error_module;
        }
 
        /* This just returns 0 if either of the two args is NULL */
        err = v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler);
-       if (err) {
-               if (sd->internal_ops && sd->internal_ops->unregistered)
-                       sd->internal_ops->unregistered(sd);
-               module_put(sd->owner);
-               return err;
-       }
+       if (err)
+               goto error_unregister;
 
 #if defined(CONFIG_MEDIA_CONTROLLER)
        /* Register the entity. */
        if (v4l2_dev->mdev) {
                err = media_device_register_entity(v4l2_dev->mdev, entity);
-               if (err < 0) {
-                       if (sd->internal_ops && sd->internal_ops->unregistered)
-                               sd->internal_ops->unregistered(sd);
-                       module_put(sd->owner);
-                       return err;
-               }
+               if (err < 0)
+                       goto error_unregister;
        }
 #endif
 
@@ -192,6 +182,14 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
        spin_unlock(&v4l2_dev->lock);
 
        return 0;
+
+error_unregister:
+       if (sd->internal_ops && sd->internal_ops->unregistered)
+               sd->internal_ops->unregistered(sd);
+error_module:
+       module_put(sd->owner);
+       sd->v4l2_dev = NULL;
+       return err;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);