--- drivers/block/virtio_blk.c | 31 ++++++++++++++++++------------- drivers/char/virtio_console.c | 4 ++-- drivers/net/virtio_net.c | 31 +++++++++++++++++++------------ 3 files changed, 39 insertions(+), 27 deletions(-) diff -r 913cb29cde3c drivers/block/virtio_blk.c --- a/drivers/block/virtio_blk.c Mon Jan 07 13:55:26 2008 +1100 +++ b/drivers/block/virtio_blk.c Mon Jan 07 14:26:10 2008 +1100 @@ -26,8 +26,10 @@ struct virtio_blk mempool_t *pool; - /* Scatterlist: can be too big for stack. */ - struct scatterlist sg[VIRTIO_MAX_SG]; + /* Scatterlist: can be too big for stack. +1 required for chaining. */ + struct scatterlist out_sg[2]; + struct scatterlist in_sg[1]; + struct scatterlist req_sg[MAX_PHYS_SEGMENTS+1]; }; struct virtblk_req @@ -72,7 +74,8 @@ static bool do_req(struct request_queue static bool do_req(struct request_queue *q, struct virtio_blk *vblk, struct request *req) { - unsigned long num, out, in; + unsigned long num; + struct scatterlist *in_sg; struct virtblk_req *vbr; vbr = mempool_alloc(vblk->pool, GFP_ATOMIC); @@ -98,22 +101,24 @@ static bool do_req(struct request_queue vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER; /* This init could be done at vblk creation time */ - sg_init_table(vblk->sg, VIRTIO_MAX_SG); - sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr)); - num = blk_rq_map_sg(q, vbr->req, vblk->sg+1); - sg_set_buf(&vblk->sg[num+1], &vbr->in_hdr, sizeof(vbr->in_hdr)); + sg_init_table(vblk->req_sg, VIRTIO_MAX_SG); + num = blk_rq_map_sg(q, vbr->req, vblk->req_sg); + sg_init_one(&vblk->out_sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr)); + sg_init_one(&vblk->in_sg[0], &vbr->in_hdr, sizeof(vbr->in_hdr)); if (rq_data_dir(vbr->req) == WRITE) { vbr->out_hdr.type |= VIRTIO_BLK_T_OUT; - out = 1 + num; - in = 1; + /* Chain write request onto output buffers. */ + sg_chain(vblk->out_sg, 2, vblk->req_sg); + in_sg = vblk->in_sg; } else { vbr->out_hdr.type |= VIRTIO_BLK_T_IN; - out = 1; - in = 1 + num; + /* Chain input (status) buffer at end of read buffers. */ + sg_chain(vblk->req_sg, num+1, vblk->in_sg); + in_sg = vblk->req_sg; } - if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) { + if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->out_sg, in_sg, vbr)) { mempool_free(vbr, vblk->pool); return false; } @@ -130,7 +135,7 @@ static void do_virtblk_request(struct re while ((req = elv_next_request(q)) != NULL) { vblk = req->rq_disk->private_data; - BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg)); + BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->req_sg)-1); /* If this request fails, stop queue and wait for something to finish to restart it. */ diff -r 913cb29cde3c drivers/char/virtio_console.c --- a/drivers/char/virtio_console.c Mon Jan 07 13:55:26 2008 +1100 +++ b/drivers/char/virtio_console.c Mon Jan 07 14:26:10 2008 +1100 @@ -62,7 +62,7 @@ static int put_chars(u32 vtermno, const /* add_buf wants a token to identify this buffer: we hand it any * non-NULL pointer, since there's only ever one buffer. */ - if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) == 0) { + if (out_vq->vq_ops->add_buf(out_vq, sg, NULL, (void *)1) == 0) { /* Tell Host to go! */ out_vq->vq_ops->kick(out_vq); /* Chill out until it's done with the buffer. */ @@ -82,7 +82,7 @@ static void add_inbuf(void) sg_init_one(sg, inbuf, PAGE_SIZE); /* We should always be able to add one buffer to an empty queue. */ - if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) != 0) + if (in_vq->vq_ops->add_buf(in_vq, NULL, sg, inbuf) != 0) BUG(); in_vq->vq_ops->kick(in_vq); } diff -r 913cb29cde3c drivers/net/virtio_net.c --- a/drivers/net/virtio_net.c Mon Jan 07 13:55:26 2008 +1100 +++ b/drivers/net/virtio_net.c Mon Jan 07 14:26:10 2008 +1100 @@ -183,21 +183,25 @@ static void try_fill_recv(struct virtnet static void try_fill_recv(struct virtnet_info *vi) { struct sk_buff *skb; - struct scatterlist sg[1+MAX_SKB_FRAGS]; - int num, err; + /* +1 for chaining. */ + struct scatterlist hdr_sg[2]; + struct scatterlist skb_sg[MAX_SKB_FRAGS]; + int err; - sg_init_table(sg, 1+MAX_SKB_FRAGS); + sg_init_table(skb_sg, MAX_SKB_FRAGS); for (;;) { skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN); if (unlikely(!skb)) break; skb_put(skb, MAX_PACKET_LEN); - vnet_hdr_to_sg(sg, skb); - num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1; + vnet_hdr_to_sg(&hdr_sg[0], skb); + skb_to_sgvec(skb, skb_sg, 0, skb->len); skb_queue_head(&vi->recv, skb); - err = vi->rvq->vq_ops->add_buf(vi->rvq, sg, 0, num, skb); + sg_chain(hdr_sg, 2, skb_sg); + + err = vi->rvq->vq_ops->add_buf(vi->rvq, NULL, hdr_sg, skb); if (err) { skb_unlink(skb, &vi->recv); kfree_skb(skb); @@ -266,13 +270,15 @@ static int start_xmit(struct sk_buff *sk static int start_xmit(struct sk_buff *skb, struct net_device *dev) { struct virtnet_info *vi = netdev_priv(dev); - int num, err; - struct scatterlist sg[1+MAX_SKB_FRAGS]; + int err; + /* +1 for chaining. */ + struct scatterlist hdr_sg[2]; + struct scatterlist skb_sg[MAX_SKB_FRAGS]; struct virtio_net_hdr *hdr; const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest; DECLARE_MAC_BUF(mac); - sg_init_table(sg, 1+MAX_SKB_FRAGS); + sg_init_table(skb_sg, MAX_SKB_FRAGS); pr_debug("%s: xmit %p %s\n", dev->name, skb, print_mac(mac, dest)); @@ -304,12 +310,13 @@ static int start_xmit(struct sk_buff *sk hdr->gso_size = 0; } - vnet_hdr_to_sg(sg, skb); - num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1; + vnet_hdr_to_sg(&hdr_sg[0], skb); + skb_to_sgvec(skb, skb_sg, 0, skb->len); __skb_queue_head(&vi->send, skb); + sg_chain(hdr_sg, 2, skb_sg); again: - err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb); + err = vi->svq->vq_ops->add_buf(vi->svq, hdr_sg, NULL, skb); if (err) { /* Can we free any used skbs? */ if (free_old_xmit_skbs(vi))