[PATCH 4.4 15/22] USB: serial: sierra: fix potential deadlock at close

[Greg Kroah-Hartman]

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

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

From: John Ogness <john.ogness@xxxxxxxxxxxxx>

commit e60870012e5a35b1506d7b376fddfb30e9da0b27 upstream.

The portdata spinlock can be taken in interrupt context (via
sierra_outdat_callback()).
Disable interrupts when taking the portdata spinlock when discarding
deferred URBs during close to prevent a possible deadlock.

Fixes: 014333f77c0b ("USB: sierra: fix urb and memory leak on disconnect")
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
[ johan: amend commit message and add fixes and stable tags ]
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/usb/serial/sierra.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/usb/serial/sierra.c
+++ b/drivers/usb/serial/sierra.c
@@ -790,9 +790,9 @@ static void sierra_close(struct usb_seri
 		kfree(urb->transfer_buffer);
 		usb_free_urb(urb);
 		usb_autopm_put_interface_async(serial->interface);
-		spin_lock(&portdata->lock);
+		spin_lock_irq(&portdata->lock);
 		portdata->outstanding_urbs--;
-		spin_unlock(&portdata->lock);
+		spin_unlock_irq(&portdata->lock);
 	}
 
 	sierra_stop_rx_urbs(port);