Re: [Bluez-devel] Oops involving RFCOMM and sysfs

Dave Young
2008-01-17T08:12:19Z

On Thu, Jan 17, 2008 at 03:24:50PM +0800, Dave Young wrote:
> On Jan 17, 2008 7:06 AM, Gabor Gombas <gombasg@sztaki.hu> wrote:
> > Hi,
> >
> > On Wed, Jan 16, 2008 at 09:02:05AM +0800, Dave Young wrote:
> >
> > > The rfcomm tty device will possibly retain even when conn is down,
> > > and sysfs doesn't support zombie device moving, so this patch
> > > move the tty device before conn device is destroyed.
> > >
> > > Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
> >
> > This seems to work, both the oops and the hang are gone. I get these
> > messages in syslog when the Bluetooth link hangs and I want to kill pppd
> > with "poff":
> >
> > Jan 16 23:55:59 twister kernel: unregister_netdevice: waiting for ppp0 to become free. Usage count = 1
> > Jan 16 23:56:09 twister kernel: unregister_netdevice: waiting for ppp0 to become free. Usage count = 1
> >
> > But a "killall -9 pppd" seems to help and then the re-connect (after the
> > phone got power-cycled) works.
>
> Weird, I guess "device_move(dev, NULL) two times" cause the problem.
>
> Anyway, device_move should check the old_parent and new_parent , if
> they equal to each other then just return.
>
> Am I right?

Could you apply this patch as well to test? Thanks.

diff -upr linux/net/bluetooth/rfcomm/tty.c linux.new/net/bluetooth/rfcomm/tty.c
--- linux/net/bluetooth/rfcomm/tty.c 2008-01-17 16:09:34.000000000 +0800
+++ linux.new/net/bluetooth/rfcomm/tty.c 2008-01-17 16:10:22.000000000 +0800
@@ -692,7 +692,8 @@ static void rfcomm_tty_close(struct tty_
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);
+ if (dev->tty_dev->parent)
+ device_move(dev->tty_dev, NULL);

/* Close DLC and dettach TTY */
rfcomm_dlc_close(dev->dlc, 0);

>
> >
> >
> > Gabor
> >
> > --
> > ---------------------------------------------------------
> > MTA SZTAKI Computer and Automation Research Institute
> > Hungarian Academy of Sciences
> > ---------------------------------------------------------
> >