virtio: console: fix raising SIGIO after port unplug

commit 92d3453815fbe74d539c86b60dab39ecdf01bb99 upstream.

SIGIO should be sent when a port gets unplugged.  It should only be sent
to prcesses that have the port opened, and have asked for SIGIO to be
delivered.  We were clearing out guest_connected before calling
send_sigio_to_port(), resulting in a sigio not getting sent to
processes.

Fix by setting guest_connected to false after invoking the sigio
function.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 1a02ad0..62361eb 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1286,12 +1286,14 @@
 	spin_unlock_irq(&port->portdev->ports_lock);
 
 	if (port->guest_connected) {
-		port->guest_connected = false;
-		port->host_connected = false;
-		wake_up_interruptible(&port->waitqueue);
-
 		/* Let the app know the port is going down. */
 		send_sigio_to_port(port);
+
+		/* Do this after sigio is actually sent */
+		port->guest_connected = false;
+		port->host_connected = false;
+
+		wake_up_interruptible(&port->waitqueue);
 	}
 
 	if (is_console_port(port)) {