From: Ming Lei <tom.leiming@gmail.com>
Date: Tue, 26 Mar 2013 02:49:55 +0000 (+0800)
Subject: USB: serial: fix hang when opening port
X-Git-Tag: v3.4.87~63
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=cebd154bd43fee9cc7f1a20757119c5be2a99043;p=thirdparty%2Fkernel%2Fstable.git

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@gmail.com>
Acked-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 810695b3b4eff..9a145e4b8169b 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -908,6 +908,7 @@ int usb_serial_probe(struct usb_interface *interface,
 		port->port.ops = &serial_port_ops;
 		port->serial = serial;
 		spin_lock_init(&port->lock);
+		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);