From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 5 Feb 2008 04:50:07 +0000 (-0500)
Subject: virtio: flush buffers on open
X-Git-Tag: v2.6.25-rc1~1058^2~8
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a48bd8f67003c342e147309a331f656a5e75a5e4;p=linux-2.6

virtio: flush buffers on open

Fix bug found by Christian Borntraeger: if the other side fills all
the registered network buffers before we enable NAPI, we will never
get an interrupt.  The simplest fix is to process the input queue once
on open.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index be5688f5e9..bd4d26a36e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -283,6 +283,13 @@ static int virtnet_open(struct net_device *dev)
 	struct virtnet_info *vi = netdev_priv(dev);
 
 	napi_enable(&vi->napi);
+
+	/* If all buffers were filled by other side before we napi_enabled, we
+	 * won't get another interrupt, so process any outstanding packets
+	 * now.  virtnet_poll wants re-enable the queue, so we disable here. */
+	vi->rvq->vq_ops->disable_cb(vi->rvq);
+	netif_rx_schedule(vi->dev, &vi->napi);
+
 	return 0;
 }