Attachment 304236 Details for Bug 444765 – 0001-virtio_net-free-transmit-skbs-in-a-timer.patch

[patch] 0001-virtio_net-free-transmit-skbs-in-a-timer.patch

0001-virtio_net-free-transmit-skbs-in-a-timer.patch (text/plain), 2.70 KB, created by Mark McLoughlin on 2008-04-30 14:48:13 UTC

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Creator: Mark McLoughlin

Created: 2008-04-30 14:48:13 UTC

Size: 2.70 KB

patch

obsolete

>From 92c2f4cb3e684fe2586688761efb4a3cc8b7c953 Mon Sep 17 00:00:00 2001
>From: Mark McLoughlin <markmc@redhat.com>
>Date: Wed, 30 Apr 2008 15:14:28 +0100
>Subject: [PATCH] virtio_net: free transmit skbs in a timer
>
>virtio_net currently only frees old transmit skbs just
>before queueing new ones. If the queue is full, it then
>enables interrupts and waits for notification that more
>work has been performed.
>
>However, a side-effect of this scheme is that there are
>always xmit skbs left dangling when no new packets are
>sent, against the Documentation/networking/driver.txt
>guideline:
>
>  "... it is not allowed for your TX mitigation scheme
>   to let TX packets "hang out" in the TX ring unreclaimed
>   forever if no new TX packets are sent."
>
>Add a timer to ensure that any time we queue new TX
>skbs, we will shortly free them again.
>
>This fixes any easily reproduced hang at shutdown where
>iptables attempts to unload nf_conntrack and nf_conntrack
>waits for an skb it is tracking to be freed, but virtio_net
>never frees it.
>
>Signed-off-by: Mark McLoughlin <markmc@redhat.com>
>---
> drivers/net/virtio_net.c |   19 +++++++++++++++++++
> 1 files changed, 19 insertions(+), 0 deletions(-)
>
>diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
>index 555b70c..f331168 100644
>--- a/drivers/net/virtio_net.c
>+++ b/drivers/net/virtio_net.c
>@@ -41,6 +41,8 @@ struct virtnet_info
> 	struct net_device *dev;
> 	struct napi_struct napi;
> 
>+	struct timer_list xmit_free_timer;
>+
> 	/* Number of input buffers, and max we've ever had. */
> 	unsigned int num, max;
> 
>@@ -227,6 +229,15 @@ static void free_old_xmit_skbs(struct virtnet_info *vi)
> 	}
> }
> 
>+static void xmit_free(unsigned long data)
>+{
>+	struct virtnet_info *vi = (void *)data;
>+
>+	netif_tx_lock(vi->dev);
>+	free_old_xmit_skbs(vi);
>+	netif_tx_unlock(vi->dev);
>+}
>+
> static int start_xmit(struct sk_buff *skb, struct net_device *dev)
> {
> 	struct virtnet_info *vi = netdev_priv(dev);
>@@ -295,6 +306,8 @@ again:
> 	}
> 	vi->svq->vq_ops->kick(vi->svq);
> 
>+	mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10));
>+
> 	return 0;
> }
> 
>@@ -396,6 +409,10 @@ static int virtnet_probe(struct virtio_device *vdev)
> 	skb_queue_head_init(&vi->recv);
> 	skb_queue_head_init(&vi->send);
> 
>+	init_timer(&vi->xmit_free_timer);
>+	vi->xmit_free_timer.data = (unsigned long)vi;
>+	vi->xmit_free_timer.function = xmit_free;
>+
> 	err = register_netdev(dev);
> 	if (err) {
> 		pr_debug("virtio_net: registering device failed\n");
>@@ -433,6 +450,8 @@ static void virtnet_remove(struct virtio_device *vdev)
> 	/* Stop all the virtqueues. */
> 	vdev->config->reset(vdev);
> 
>+	del_timer_sync(&vi->xmit_free_timer);
>+
> 	/* Free our skbs in send and recv queues, if any. */
> 	while ((skb = __skb_dequeue(&vi->recv)) != NULL) {
> 		kfree_skb(skb);
>-- 
>1.5.4.1
>

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Attachments on bug 444765: 304236