media: rc: ensure that uevent can be read directly after rc device re…

…gister

commit 896111d upstream.

There is a race condition where if the /sys/class/rc0/uevent file is read
before rc_dev->registered is set to true, -ENODEV will be returned.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1901089

Cc: stable@vger.kernel.org
Fixes: a2e2d73 ("media: rc: do not access device via sysfs after rc_unregister_device()")
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/media/rc/rc-main.c

@@ -1928,6 +1928,8 @@ int rc_register_device(struct rc_dev *dev)
 			goto out_raw;
 	}
 
+	dev->registered = true;
+
 	rc = device_add(&dev->dev);
 	if (rc)
 		goto out_rx_free;
@@ -1937,8 +1939,6 @@ int rc_register_device(struct rc_dev *dev)
 		 dev->device_name ?: "Unspecified device", path ?: "N/A");
 	kfree(path);
 
-	dev->registered = true;
-
 	/*
 	 * once the the input device is registered in rc_setup_rx_device,
 	 * userspace can open the input device and rc_open() will be called