Bluetooth: hci_core: fix init for HCI_USER_CHANNEL

During the setup() stage, HCI device drivers expect the chip to
acknowledge its setup() completion via vendor specific frames.

If userspace opens() such HCI device in HCI_USER_CHANNEL [1] mode,
the vendor specific frames are never tranmitted to the driver, as
they are filtered in hci_rx_work().

Allow HCI devices which operate in HCI_USER_CHANNEL mode to receive
frames if the HCI device is is HCI_INIT state.

[1] https://www.spinics.net/lists/linux-bluetooth/msg37345.html

Fixes: 2350018 ("Bluetooth: Introduce new HCI socket channel for user operation")
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_core.c

@@ -4440,7 +4440,14 @@ static void hci_rx_work(struct work_struct *work)
 			hci_send_to_sock(hdev, skb);
 		}
 
-		if (hci_dev_test_flag(hdev, HCI_USER_CHANNEL)) {
+		/* If the device has been opened in HCI_USER_CHANNEL,
+		 * the userspace has exclusive access to device.
+		 * When device is HCI_INIT, we still need to process
+		 * the data packets to the driver in order
+		 * to complete its setup().
+		 */
+		if (hci_dev_test_flag(hdev, HCI_USER_CHANNEL) &&
+		    !test_bit(HCI_INIT, &hdev->flags)) {
 			kfree_skb(skb);
 			continue;
 		}