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

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

From: Johan Hovold <jhov...@gmail.com>

commit e5b33dc9d16053c2ae4c2c669cf008829530364b upstream.

Add modem-status-change wait queue to struct usb_serial_port that
subdrivers can use to implement TIOCMIWAIT.

Currently subdrivers use a private wait queue which may have been
released when waking up after device disconnected.

Note that we're adding a new wait queue rather than reusing the tty-port
one as we do not want to get woken up at hangup (yet).

Signed-off-by: Johan Hovold <jhov...@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriq...@canonical.com>
---
 include/linux/usb/serial.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 86c0b45..0b61f01 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -66,6 +66,7 @@
  *     port.
  * @flags: usb serial port flags
  * @write_wait: a wait_queue_head_t used by the port.
+ * @delta_msr_wait: modem-status-change wait queue
  * @work: work queue entry for the line discipline waking up.
  * @throttled: nonzero if the read urb is inactive to throttle the device
  * @throttle_req: nonzero if the tty wants to throttle us
@@ -112,6 +113,7 @@ struct usb_serial_port {
 
        unsigned long           flags;
        wait_queue_head_t       write_wait;
+       wait_queue_head_t       delta_msr_wait;
        struct work_struct      work;
        char                    throttled;
        char                    throttle_req;
-- 
1.8.1.2

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