From 50dbb8528757b1977efd5d270ed9d262cbbef87d Mon Sep 17 00:00:00 2001
From: Johan Hovold <jhovold@gmail.com>
Date: Wed, 17 Mar 2010 23:00:43 +0100
Subject: [PATCH] USB: serial: fix missing locking on fifo in write callback
On errors the fifo was reset without any locking. This could race with
write which do kfifo_put and perhaps also chars_in_buffer and write_room.
Every other access to the fifo is protected using the port lock so
better add it to the error path as well.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/usb/serial/generic.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 8f78d7b8e888..2a3196a2c66c 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -519,10 +519,13 @@ void usb_serial_generic_write_bulk_callback(struct urb *urb)
port->write_urb_busy = 0;
spin_unlock_irqrestore(&port->lock, flags);
- if (status)
+ if (status) {
+ spin_lock_irqsave(&port->lock, flags);
kfifo_reset_out(&port->write_fifo);
- else
+ spin_unlock_irqrestore(&port->lock, flags);
+ } else {
usb_serial_generic_write_start(port);
+ }
}
if (status)