linux-kernel - [161/272] virtio: console: Wake up outvq on host notifications

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Date:	Tue, 15 Feb 2011 16:13:38 -0800
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Hans de Goede <hdegoede@...hat.com>,
	Amit Shah <amit.shah@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: [161/272] virtio: console: Wake up outvq on host notifications

2.6.37-stable review patch.  If anyone has any objections, please let us know.

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

From: Amit Shah <amit.shah@...hat.com>

commit 2770c5ea501be69989a7acf54ec4cb3554c47191 upstream.

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@...hat.com>
Signed-off-by: Amit Shah <amit.shah@...hat.com>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Acked-by: Hans de Goede <hdegoede@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/char/virtio_console.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1462,6 +1462,17 @@ static void control_work_handler(struct
 	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;
@@ -1566,7 +1577,7 @@ static int init_vqs(struct ports_device
 	 */
 	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;
@@ -1580,7 +1591,7 @@ static int init_vqs(struct ports_device
 		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";
 		}


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