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Commit 5e01d2f9 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by David S. Miller
Browse files

virtio-net: move sg off stack 



Move sg structure off stack and into virtnet_info structure.
This helps remove extra sg_init_table calls as well as reduce
stack usage.

Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Tested-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b681ee77

drivers/net/virtio_net.c

+25 −27
Original line number Diff line number Diff line
@@ -39,8 +39,7 @@ module_param(gso, bool, 0444); 


#define VIRTNET_SEND_COMMAND_SG_MAX    2



struct virtnet_info

{

struct virtnet_info {

	struct virtio_device *vdev;

	struct virtqueue *rvq, *svq, *cvq;

	struct net_device *dev;
@@ -61,6 +60,10 @@ struct virtnet_info 


	/* Chain pages by the private ptr. */

	struct page *pages;



	/* fragments + linear part + virtio header */

	struct scatterlist rx_sg[MAX_SKB_FRAGS + 2];

	struct scatterlist tx_sg[MAX_SKB_FRAGS + 2];

};



struct skb_vnet_hdr {
@@ -323,10 +326,8 @@ static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp) 
{

	struct sk_buff *skb;

	struct skb_vnet_hdr *hdr;

	struct scatterlist sg[2];

	int err;



	sg_init_table(sg, 2);

	skb = netdev_alloc_skb_ip_align(vi->dev, MAX_PACKET_LEN);

	if (unlikely(!skb))

		return -ENOMEM;
@@ -334,11 +335,11 @@ static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp) 
	skb_put(skb, MAX_PACKET_LEN);



	hdr = skb_vnet_hdr(skb);

	sg_set_buf(sg, &hdr->hdr, sizeof hdr->hdr);

	sg_set_buf(vi->rx_sg, &hdr->hdr, sizeof hdr->hdr);



	skb_to_sgvec(skb, sg + 1, 0, skb->len);

	skb_to_sgvec(skb, vi->rx_sg + 1, 0, skb->len);



	err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, 2, skb);

	err = vi->rvq->vq_ops->add_buf(vi->rvq, vi->rx_sg, 0, 2, skb);

	if (err < 0)

		dev_kfree_skb(skb);
@@ -347,13 +348,11 @@ static int add_recvbuf_small(struct virtnet_info *vi, gfp_t gfp) 


static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp)

{

	struct scatterlist sg[MAX_SKB_FRAGS + 2];

	struct page *first, *list = NULL;

	char *p;

	int i, err, offset;



	sg_init_table(sg, MAX_SKB_FRAGS + 2);

	/* page in sg[MAX_SKB_FRAGS + 1] is list tail */

	/* page in vi->rx_sg[MAX_SKB_FRAGS + 1] is list tail */

	for (i = MAX_SKB_FRAGS + 1; i > 1; --i) {

		first = get_a_page(vi, gfp);

		if (!first) {
@@ -361,7 +360,7 @@ static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp) 
				give_pages(vi, list);

			return -ENOMEM;

		}

		sg_set_buf(&sg[i], page_address(first), PAGE_SIZE);

		sg_set_buf(&vi->rx_sg[i], page_address(first), PAGE_SIZE);



		/* chain new page in list head to match sg */

		first->private = (unsigned long)list;
@@ -375,17 +374,17 @@ static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp) 
	}

	p = page_address(first);



	/* sg[0], sg[1] share the same page */

	/* a separated sg[0] for  virtio_net_hdr only during to QEMU bug*/

	sg_set_buf(&sg[0], p, sizeof(struct virtio_net_hdr));

	/* vi->rx_sg[0], vi->rx_sg[1] share the same page */

	/* a separated vi->rx_sg[0] for virtio_net_hdr only due to QEMU bug */

	sg_set_buf(&vi->rx_sg[0], p, sizeof(struct virtio_net_hdr));



	/* sg[1] for data packet, from offset */

	/* vi->rx_sg[1] for data packet, from offset */

	offset = sizeof(struct padded_vnet_hdr);

	sg_set_buf(&sg[1], p + offset, PAGE_SIZE - offset);

	sg_set_buf(&vi->rx_sg[1], p + offset, PAGE_SIZE - offset);



	/* chain first in list head */

	first->private = (unsigned long)list;

	err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, MAX_SKB_FRAGS + 2,

	err = vi->rvq->vq_ops->add_buf(vi->rvq, vi->rx_sg, 0, MAX_SKB_FRAGS + 2,

				       first);

	if (err < 0)

		give_pages(vi, first);
@@ -396,16 +395,15 @@ static int add_recvbuf_big(struct virtnet_info *vi, gfp_t gfp) 
static int add_recvbuf_mergeable(struct virtnet_info *vi, gfp_t gfp)

{

	struct page *page;

	struct scatterlist sg;

	int err;



	page = get_a_page(vi, gfp);

	if (!page)

		return -ENOMEM;



	sg_init_one(&sg, page_address(page), PAGE_SIZE);

	sg_init_one(vi->rx_sg, page_address(page), PAGE_SIZE);



	err = vi->rvq->vq_ops->add_buf(vi->rvq, &sg, 0, 1, page);

	err = vi->rvq->vq_ops->add_buf(vi->rvq, vi->rx_sg, 0, 1, page);

	if (err < 0)

		give_pages(vi, page);
@@ -514,12 +512,9 @@ static unsigned int free_old_xmit_skbs(struct virtnet_info *vi) 


static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)

{

	struct scatterlist sg[2+MAX_SKB_FRAGS];

	struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb);

	const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;



	sg_init_table(sg, 2+MAX_SKB_FRAGS);



	pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest);



	if (skb->ip_summed == CHECKSUM_PARTIAL) {
@@ -553,12 +548,13 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb) 


	/* Encode metadata header at front. */

	if (vi->mergeable_rx_bufs)

		sg_set_buf(sg, &hdr->mhdr, sizeof hdr->mhdr);

		sg_set_buf(vi->tx_sg, &hdr->mhdr, sizeof hdr->mhdr);

	else

		sg_set_buf(sg, &hdr->hdr, sizeof hdr->hdr);

		sg_set_buf(vi->tx_sg, &hdr->hdr, sizeof hdr->hdr);



	hdr->num_sg = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;

	return vi->svq->vq_ops->add_buf(vi->svq, sg, hdr->num_sg, 0, skb);

	hdr->num_sg = skb_to_sgvec(skb, vi->tx_sg + 1, 0, skb->len) + 1;

	return vi->svq->vq_ops->add_buf(vi->svq, vi->tx_sg, hdr->num_sg,

					0, skb);

}



static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -940,6 +936,8 @@ static int virtnet_probe(struct virtio_device *vdev) 
	vdev->priv = vi;

	vi->pages = NULL;

	INIT_DELAYED_WORK(&vi->refill, refill_work);

	sg_init_table(vi->rx_sg, ARRAY_SIZE(vi->rx_sg));

	sg_init_table(vi->tx_sg, ARRAY_SIZE(vi->tx_sg));



	/* If we can receive ANY GSO packets, we must allocate large ones. */

	if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||