USB: serial: add modem-status-change wait queue

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 <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index b29f70b2ecae7f5fdae3e17ae178a305dce1036b..237d5f8689f2cc15311cec0eae496aea78903589 100644 (file)
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -71,6 +71,7 @@ enum port_dev_state {
  *     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
@@ -114,6 +115,7 @@ 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;