From: Tommie Gannert <tom...@gannert.se>
Issuing set_termios() from irtty_close() causes kernel Oops for
unplugged usb-serial devices.
Since no other tty_ldisc calls set_termios() on close and no tty driver
seem to check if tty->device_data is NULL or not on entry to set_termios(),
the only solution I can come up with is to remove the irtty_stop_receiver()
call, which only updates termios.
Signed-off-by: Tommie Gannert <tom...@gannert.se>
---
v2: Resend due to mail format issues. More Thunderbird settings applied.
I know very little of this code, and I'm not sure this is a good solution,
so here's some background:
I have a gadget using IrLAP over RS-232, and it's connected to a
USB-RS232 converter. I have udev rules to start/stop irattach on USB
connect/disconnect, but I see an oops if I simply disconnect the device
while irattach is still running:
Crash log:
[ 631.791294] BUG: unable to handle kernel NULL pointer dereference at
0000000000000024
[ 631.791390] IP: [<ffffffffa0c07e42>] ftdi_set_termios+0x42/0x670 [ftdi_sio]
...
[ 631.793963] [<ffffffffa0b7fba3>] serial_set_termios+0x43/0x90 [usbserial]
[ 631.794031] [<ffffffffa0c013ec>] irtty_close+0x10c/0x190 [irtty_sir]
[ 631.794096] [<ffffffff81356e88>] tty_ldisc_close.isra.1+0x38/0x50
[ 631.794157] [<ffffffff81356eb8>] tty_ldisc_kill+0x18/0x90
[ 631.794209] [<ffffffff81357894>] tty_ldisc_release+0x34/0x90
[ 631.794266] [<ffffffff8134fe00>] tty_release+0x470/0x600
There is a comment in irtty_close() speculating about potential problems
with usb-serial. I'm not sure if that comment belongs to sirdev_put_instance()
or
the irtty_stop_receiver() call. I would guess both, so I let it be.
The effect of this is that /dev/ttyUSB* is still in use, and thus leaking
at least dev nodes. This is a minimal patch that solves that oops.
--- linux-3.12/drivers/net/irda/irtty-sir.c.orig 2014-02-12
21:36:46.132496089 +0000
+++ linux-3.12/drivers/net/irda/irtty-sir.c 2014-02-12 21:57:21.635843884
+0000
@@ -521,7 +521,6 @@ static void irtty_close(struct tty_struc
sirdev_put_instance(priv->dev);
/* Stop tty */
- irtty_stop_receiver(tty, TRUE);
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
if (tty->ops->stop)
tty->ops->stop(tty);
--
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