From: Amit Shah <amit.shah@redhat.com>
Date: Fri, 28 Jan 2011 13:32:05 -0500
Subject: [char] virtio: Wake console outvq on host notifications
Message-id: <cfff1911e5291b8173101043d34109d8a11bf36c.1296209907.git.amit.shah@redhat.com>
Patchwork-id: 32974
O-Subject: [RHEL 5.7/5.6.z PATCH] virtio: console: Wake up outvq on host
	notifications
Bugzilla: 673459
RH-Acked-by: Rik van Riel <riel@redhat.com>

The outvq needs to be woken up on host notifications so that buffers
consumed by the host can be reclaimed, outvq freed, and application
writes may proceed again.

The need for this is now finally noticed when I have qemu patches ready
to use nonblocking IO and flow control.

CC: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>

Bugzilla: 673459
Upstream: Will post; virtio_console.c got moved out to other location.
          Waiting for that one to be moved back.

diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index 9019c72..392eebd 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1476,6 +1476,17 @@ static void control_work_handler(void *p)
 	spin_unlock(&portdev->cvq_lock);
 }
 
+static void out_intr(struct virtqueue *vq)
+{
+	struct port *port;
+
+	port = find_port_by_vq(vq->vdev->priv, vq);
+	if (!port)
+		return;
+
+	wake_up_interruptible(&port->waitqueue);
+}
+
 static void in_intr(struct virtqueue *vq)
 {
 	struct port *port;
@@ -1599,7 +1610,7 @@ static int init_vqs(struct ports_device *portdev)
 	 */
 	j = 0;
 	io_callbacks[j] = in_intr;
-	io_callbacks[j + 1] = NULL;
+	io_callbacks[j + 1] = out_intr;
 	io_names[j] = "input";
 	io_names[j + 1] = "output";
 	j += 2;
@@ -1613,7 +1624,7 @@ static int init_vqs(struct ports_device *portdev)
 		for (i = 1; i < nr_ports; i++) {
 			j += 2;
 			io_callbacks[j] = in_intr;
-			io_callbacks[j + 1] = NULL;
+			io_callbacks[j + 1] = out_intr;
 			io_names[j] = "input";
 			io_names[j + 1] = "output";
 		}