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Commit 3161e453 authored by Rusty Russell's avatar Rusty Russell Committed by David S. Miller
Browse files

virtio: net refill on out-of-memory 



If we run out of memory, use keventd to fill the buffer.  There's a
report of this happening: "Page allocation failures in guest",
Message-ID: <20090713115158.0a4892b0@mjolnir.ossman.eu>

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0b4f2928

drivers/net/virtio_net.c

+46 −15
Original line number Diff line number Diff line
@@ -70,6 +70,9 @@ struct virtnet_info 
	struct sk_buff_head recv;

	struct sk_buff_head send;



	/* Work struct for refilling if we run low on memory. */

	struct delayed_work refill;



	/* Chain pages by the private ptr. */

	struct page *pages;

};
@@ -273,19 +276,22 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb, 
	dev_kfree_skb(skb);

}



static void try_fill_recv_maxbufs(struct virtnet_info *vi)

static bool try_fill_recv_maxbufs(struct virtnet_info *vi, gfp_t gfp)

{

	struct sk_buff *skb;

	struct scatterlist sg[2+MAX_SKB_FRAGS];

	int num, err, i;

	bool oom = false;



	sg_init_table(sg, 2+MAX_SKB_FRAGS);

	for (;;) {

		struct virtio_net_hdr *hdr;



		skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN + NET_IP_ALIGN);

		if (unlikely(!skb))

		if (unlikely(!skb)) {

			oom = true;

			break;

		}



		skb_reserve(skb, NET_IP_ALIGN);

		skb_put(skb, MAX_PACKET_LEN);
@@ -296,7 +302,7 @@ static void try_fill_recv_maxbufs(struct virtnet_info *vi) 
		if (vi->big_packets) {

			for (i = 0; i < MAX_SKB_FRAGS; i++) {

				skb_frag_t *f = &skb_shinfo(skb)->frags[i];

				f->page = get_a_page(vi, GFP_ATOMIC);

				f->page = get_a_page(vi, gfp);

				if (!f->page)

					break;
@@ -325,31 +331,35 @@ static void try_fill_recv_maxbufs(struct virtnet_info *vi) 
	if (unlikely(vi->num > vi->max))

		vi->max = vi->num;

	vi->rvq->vq_ops->kick(vi->rvq);

	return !oom;

}



static void try_fill_recv(struct virtnet_info *vi)

/* Returns false if we couldn't fill entirely (OOM). */

static bool try_fill_recv(struct virtnet_info *vi, gfp_t gfp)

{

	struct sk_buff *skb;

	struct scatterlist sg[1];

	int err;

	bool oom = false;



	if (!vi->mergeable_rx_bufs) {

		try_fill_recv_maxbufs(vi);

		return;

	}

	if (!vi->mergeable_rx_bufs)

		return try_fill_recv_maxbufs(vi, gfp);



	for (;;) {

		skb_frag_t *f;



		skb = netdev_alloc_skb(vi->dev, GOOD_COPY_LEN + NET_IP_ALIGN);

		if (unlikely(!skb))

		if (unlikely(!skb)) {

			oom = true;

			break;

		}



		skb_reserve(skb, NET_IP_ALIGN);



		f = &skb_shinfo(skb)->frags[0];

		f->page = get_a_page(vi, GFP_ATOMIC);

		f->page = get_a_page(vi, gfp);

		if (!f->page) {

			oom = true;

			kfree_skb(skb);

			break;

		}
@@ -373,6 +383,7 @@ static void try_fill_recv(struct virtnet_info *vi) 
	if (unlikely(vi->num > vi->max))

		vi->max = vi->num;

	vi->rvq->vq_ops->kick(vi->rvq);

	return !oom;

}



static void skb_recv_done(struct virtqueue *rvq)
@@ -385,6 +396,23 @@ static void skb_recv_done(struct virtqueue *rvq) 
	}

}



static void refill_work(struct work_struct *work)

{

	struct virtnet_info *vi;

	bool still_empty;



	vi = container_of(work, struct virtnet_info, refill.work);

	napi_disable(&vi->napi);

	try_fill_recv(vi, GFP_KERNEL);

	still_empty = (vi->num == 0);

	napi_enable(&vi->napi);



	/* In theory, this can happen: if we don't get any buffers in

	 * we will *never* try to fill again. */

	if (still_empty)

		schedule_delayed_work(&vi->refill, HZ/2);

}



static int virtnet_poll(struct napi_struct *napi, int budget)

{

	struct virtnet_info *vi = container_of(napi, struct virtnet_info, napi);
@@ -400,10 +428,10 @@ static int virtnet_poll(struct napi_struct *napi, int budget) 
		received++;

	}



	/* FIXME: If we oom and completely run out of inbufs, we need

	 * to start a timer trying to fill more. */

	if (vi->num < vi->max / 2)

		try_fill_recv(vi);

	if (vi->num < vi->max / 2) {

		if (!try_fill_recv(vi, GFP_ATOMIC))

			schedule_delayed_work(&vi->refill, 0);

	}



	/* Out of packets? */

	if (received < budget) {
@@ -893,6 +921,7 @@ static int virtnet_probe(struct virtio_device *vdev) 
	vi->vdev = vdev;

	vdev->priv = vi;

	vi->pages = NULL;

	INIT_DELAYED_WORK(&vi->refill, refill_work);



	/* If they give us a callback when all buffers are done, we don't need

	 * the timer. */
@@ -941,7 +970,7 @@ static int virtnet_probe(struct virtio_device *vdev) 
	}



	/* Last of all, set up some receive buffers. */

	try_fill_recv(vi);

	try_fill_recv(vi, GFP_KERNEL);



	/* If we didn't even get one input buffer, we're useless. */

	if (vi->num == 0) {
@@ -958,6 +987,7 @@ static int virtnet_probe(struct virtio_device *vdev) 


unregister:

	unregister_netdev(dev);

	cancel_delayed_work_sync(&vi->refill);

free_vqs:

	vdev->config->del_vqs(vdev);

free:
@@ -986,6 +1016,7 @@ static void virtnet_remove(struct virtio_device *vdev) 
	BUG_ON(vi->num != 0);



	unregister_netdev(vi->dev);

	cancel_delayed_work_sync(&vi->refill);



	vdev->config->del_vqs(vi->vdev);