Re: [Regression] Bluetooth RFComm: using it locks up the machine

[Mark Lord]

Mark Lord wrote:
> Any attempt to open/use a bluetooth rfcomm device locks up
> scheduling completely on my machine.
>
> Interrupts (ping, alt-sysrq) seem to be alive, but nothing else.
>
> This was working fine in 2.6.20, broken now in 2.6.21-rc2-git*

Further info:  Reverting this change (below) fixes it:

| author	Marcel Holtmann <marcel@xxxxxxxxxxxx>
| 	 Sat, 17 Feb 2007 22:58:57 +0000 (23:58 +0100)
| committer	David S. Miller <davem@xxxxxxxxxxxxxxxxxxxx>
| 	 Mon, 26 Feb 2007 19:42:41 +0000 (11:42 -0800)
| commit	c1a3313698895d8ad4760f98642007bf236af2e8
| tree	337a876f727061362b6a169f8759849c105b8f7a	tree | snapshot
| parent	f5ffd4620aba9e55656483ae1ef5c79ba81f5403	commit | diff
| 
| [Bluetooth] Make use of device_move() for RFCOMM TTY devices
| 
| In the case of bound RFCOMM TTY devices the parent is not available
| before its usage. So when opening a RFCOMM TTY device, move it to
| the corresponding ACL device as a child. When closing the device,
| move it back to the virtual device tree.
| Signed-off-by: Marcel Holtmann <marcel@xxxxxxxxxxxx>

Specifically, I reverted these changes, below, to fix it:

--- 2.6.20/net/bluetooth/rfcomm/tty.c	2007-02-04 13:44:54.000000000 -0500
+++ 2.6.21/net/bluetooth/rfcomm/tty.c	2007-03-02 15:06:32.000000000 -0500
@@ -74,6 +74,8 @@
	wait_queue_head_t       wait;
	struct tasklet_struct   wakeup_task;

+	struct device		*tty_dev;
+
	atomic_t 		wmem_alloc;
};

@@ -261,7 +263,7 @@
		return err;
	}

-	tty_register_device(rfcomm_tty_driver, dev->id, rfcomm_get_device(dev));
+	dev->tty_dev = tty_register_device(rfcomm_tty_driver, dev->id, NULL);

	return dev->id;
}
@@ -630,6 +632,9 @@
	set_current_state(TASK_RUNNING);
	remove_wait_queue(&dev->wait, &wait);

+	if (err == 0)
+		device_move(dev->tty_dev, rfcomm_get_device(dev));
+
	return err;
}

@@ -642,6 +647,8 @@
	BT_DBG("tty %p dev %p dlc %p opened %d", tty, dev, dev->dlc, dev->opened);

	if (--dev->opened == 0) {
+		device_move(dev->tty_dev, NULL);
+
		/* Close DLC and dettach TTY */
		rfcomm_dlc_close(dev->dlc, 0);

-
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