[ 3.5.y.z extended stable ] Patch "USB: serial: fix hang when opening port" has been added to staging queue

Luis Henriques luis.henriques at canonical.com
Wed Apr 3 10:50:20 UTC 2013

This is a note to let you know that I have just added a patch titled

    USB: serial: fix hang when opening port

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 9346c8be84754997ea76dc22999711709ec46b24 Mon Sep 17 00:00:00 2001
From: Ming Lei <tom.leiming at gmail.com>
Date: Tue, 26 Mar 2013 10:49:55 +0800
Subject: [PATCH] USB: serial: fix hang when opening port

commit eba0e3c3a0ba7b96f01cbe997680f6a4401a0bfc upstream.

Johan's 'fix use-after-free in TIOCMIWAIT' patchset[1] introduces
one bug which can cause kernel hang when opening port.

This patch initialized the 'port->delta_msr_wait' waitqueue head
to fix the bug which is introduced in 3.9-rc4.

[1], http://marc.info/?l=linux-usb&m=136368139627876&w=2

Signed-off-by: Ming Lei <tom.leiming at gmail.com>
Acked-by: Johan Hovold <jhovold at gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
 drivers/usb/serial/usb-serial.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 2418551..fb09885 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -899,6 +899,7 @@ static int usb_serial_probe(struct usb_interface *interface,
 		port->port.ops = &serial_port_ops;
 		port->serial = serial;
+		init_waitqueue_head(&port->delta_msr_wait);
 		/* Keep this for private driver use for the moment but
 		   should probably go away */
 		INIT_WORK(&port->work, usb_serial_port_work);

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