[PATCH 6/9] virtio-net: unmark scatterlist ending after virtqueue_add_buf
Prepare for when virtqueue_add_buf will use sg_next instead of
ignoring ending markers.
Note that for_each_sg (and thus virtqueue_add_sg) allows you
to pass a "truncated" scatterlist that does not have a marker
on the last item. We rely on this in add_recvbuf_mergeable.
Signed-off-by: Paolo Bonzini
---
drivers/net/virtio_net.c | 19 ++-
1 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 35c00c5..78b6f51 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -440,13 +440,16 @@ static int add_recvbuf_small(struct receive_queue *rq,
gfp_t gfp)
hdr = skb_vnet_hdr(skb);
sg_set_buf(rq->sg, >hdr, sizeof hdr->hdr);
-
skb_to_sgvec(skb, rq->sg + 1, 0, skb->len);
err = virtqueue_add_buf(rq->vq, rq->sg, 0, 2, skb, gfp);
if (err < 0)
dev_kfree_skb(skb);
+ /* An optimization: clear the end bit set by skb_to_sgvec, so
+* we can simply re-use rq->sg[] next time.
+*/
+ sg_unmark_end(rq->sg + 1);
return err;
}
@@ -505,8 +508,7 @@ static int add_recvbuf_mergeable(struct receive_queue *rq,
gfp_t gfp)
if (!page)
return -ENOMEM;
- sg_init_one(rq->sg, page_address(page), PAGE_SIZE);
-
+ sg_set_page(rq->sg, page, PAGE_SIZE, 0);
err = virtqueue_add_buf(rq->vq, rq->sg, 0, 1, page, gfp);
if (err < 0)
give_pages(rq, page);
@@ -671,6 +673,7 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff
*skb)
const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
struct virtnet_info *vi = sq->vq->vdev->priv;
unsigned num_sg;
+ int ret;
pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest);
@@ -710,8 +713,14 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff
*skb)
sg_set_buf(sq->sg, >hdr, sizeof hdr->hdr);
num_sg = skb_to_sgvec(skb, sq->sg + 1, 0, skb->len) + 1;
- return virtqueue_add_buf(sq->vq, sq->sg, num_sg,
-0, skb, GFP_ATOMIC);
+ ret = virtqueue_add_buf(sq->vq, sq->sg, num_sg,
+ 0, skb, GFP_ATOMIC);
+
+ /* An optimization: clear the end bit set by skb_to_sgvec, so
+* we can simply re-use sq->sg[] next time.
+*/
+ sg_unmark_end(>sg[num_sg-1]);
+ return ret;
}
static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
--
1.7.1
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[PATCH 6/9] virtio-net: unmark scatterlist ending after virtqueue_add_buf
Prepare for when virtqueue_add_buf will use sg_next instead of ignoring ending markers. Note that for_each_sg (and thus virtqueue_add_sg) allows you to pass a truncated scatterlist that does not have a marker on the last item. We rely on this in add_recvbuf_mergeable. Signed-off-by: Paolo Bonzini pbonz...@redhat.com --- drivers/net/virtio_net.c | 19 ++- 1 files changed, 14 insertions(+), 5 deletions(-) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 35c00c5..78b6f51 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -440,13 +440,16 @@ static int add_recvbuf_small(struct receive_queue *rq, gfp_t gfp) hdr = skb_vnet_hdr(skb); sg_set_buf(rq-sg, hdr-hdr, sizeof hdr-hdr); - skb_to_sgvec(skb, rq-sg + 1, 0, skb-len); err = virtqueue_add_buf(rq-vq, rq-sg, 0, 2, skb, gfp); if (err 0) dev_kfree_skb(skb); + /* An optimization: clear the end bit set by skb_to_sgvec, so +* we can simply re-use rq-sg[] next time. +*/ + sg_unmark_end(rq-sg + 1); return err; } @@ -505,8 +508,7 @@ static int add_recvbuf_mergeable(struct receive_queue *rq, gfp_t gfp) if (!page) return -ENOMEM; - sg_init_one(rq-sg, page_address(page), PAGE_SIZE); - + sg_set_page(rq-sg, page, PAGE_SIZE, 0); err = virtqueue_add_buf(rq-vq, rq-sg, 0, 1, page, gfp); if (err 0) give_pages(rq, page); @@ -671,6 +673,7 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb) const unsigned char *dest = ((struct ethhdr *)skb-data)-h_dest; struct virtnet_info *vi = sq-vq-vdev-priv; unsigned num_sg; + int ret; pr_debug(%s: xmit %p %pM\n, vi-dev-name, skb, dest); @@ -710,8 +713,14 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb) sg_set_buf(sq-sg, hdr-hdr, sizeof hdr-hdr); num_sg = skb_to_sgvec(skb, sq-sg + 1, 0, skb-len) + 1; - return virtqueue_add_buf(sq-vq, sq-sg, num_sg, -0, skb, GFP_ATOMIC); + ret = virtqueue_add_buf(sq-vq, sq-sg, num_sg, + 0, skb, GFP_ATOMIC); + + /* An optimization: clear the end bit set by skb_to_sgvec, so +* we can simply re-use sq-sg[] next time. +*/ + sg_unmark_end(sq-sg[num_sg-1]); + return ret; } static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) -- 1.7.1 -- To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
