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 810695b..9a145e4 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -908,6 +908,7 @@
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);