[PATCH 3.4 18/43] USB: usb_wwan: fix urb leak in write error path

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: xiao jin <jin.xiao@intel.com>

commit db0904737947d509844e171c9863ecc5b4534005 upstream.

When enable usb serial for modem data, sometimes the tty is blocked
in tty_wait_until_sent because portdata->out_busy always is set and
have no chance to be cleared.

We find a bug in write error path. usb_wwan_write set portdata->out_busy
firstly, then try autopm async with error. No out urb submit and no
usb_wwan_outdat_callback to this write, portdata->out_busy can't be
cleared.

This patch clear portdata->out_busy if usb_wwan_write try autopm async
with error.

Fixes: 383cedc3bb43 ("USB: serial: full autosuspend support for the
option driver")

Signed-off-by: xiao jin <jin.xiao@intel.com>
Signed-off-by: Zhang, Qi1 <qi1.zhang@intel.com>
Reviewed-by: David Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/usb/serial/usb_wwan.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/usb/serial/usb_wwan.c
+++ b/drivers/usb/serial/usb_wwan.c
@@ -236,8 +236,10 @@ int usb_wwan_write(struct tty_struct *tt
 		    usb_pipeendpoint(this_urb->pipe), i);
 
 		err = usb_autopm_get_interface_async(port->serial->interface);
-		if (err < 0)
+		if (err < 0) {
+			clear_bit(i, &portdata->out_busy);
 			break;
+		}
 
 		/* send the data */
 		memcpy(this_urb->transfer_buffer, buf, todo);