Re: Kernel bug: bluetooth meets TTY layer

[David Newall <david@davidnewall.com>]

Hi Arjan,

I've not been able to find this file, "drivers/bluetooth/hci_tty.c", but 
anyway, This seems to be what happens: Hci_uart_close() flushes using 
hci_uart_flush().  Subsequently, in hci_dev_do_close(), (one step in 
hci_unregister_dev()), hci_uart_flush() is called again.  The comment in 
uart_flush_buffer(), relating to the WARN_ON(), indicates you can't 
flush after the port is closed; which sounds reasonable.  I think 
hci_uart_close() should set hdev->flush to NULL before returning.  
Hci_dev_do_close() does check for this.  The code path is rather 
involved and I'm not entirely clear of all steps, but I think that's 
what should be done.

Patch for stupidly obsolete kernel attached.

David

--- hci_ldisc.c	2007-09-11 02:54:02.000000000 +0930
+++ hci_ldisc.c.new	2007-12-21 06:03:11.000000000 +1030
@@ -203,16 +203,17 @@
 static int hci_uart_close(struct hci_dev *hdev)
 {
 	BT_DBG("hdev %p", hdev);
 
 	if (!test_and_clear_bit(HCI_RUNNING, &hdev->flags))
 		return 0;
 
 	hci_uart_flush(hdev);
+	hdev->flush = NULL;
 	return 0;
 }
 
 /* Send frames from HCI layer */
 static int hci_uart_send_frame(struct sk_buff *skb)
 {
 	struct hci_dev* hdev = (struct hci_dev *) skb->dev;
 	struct tty_struct *tty;