From: Alan Cox <alan@linux.intel.com>
Date: Sat, 19 Sep 2009 20:13:23 +0000 (-0700)
Subject: tty: USB hangup is racy
X-Git-Tag: firefly_0821_release~12907^2~42
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d2b391822a11302add9e46476f3da4e18e6de84c;p=firefly-linux-kernel-4.4.55.git

tty: USB hangup is racy

The USB layer uses tty_hangup to deal with unplugs of the physical hardware
(analogous to loss of carrier) and then frees the resources. However the
tty_hangup is asynchronous. As the hangup can sleep we can use tty_vhangup
which is the non async version to avoid freeing resources too early.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 99188c92068b..21dd72a5a715 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -1161,10 +1161,7 @@ void usb_serial_disconnect(struct usb_interface *interface)
 		if (port) {
 			struct tty_struct *tty = tty_port_tty_get(&port->port);
 			if (tty) {
-				/* The hangup will occur asynchronously but
-				   the object refcounts will sort out all the
-				   cleanup */
-				tty_hangup(tty);
+				tty_vhangup(tty);
 				tty_kref_put(tty);
 			}
 			kill_traffic(port);