virtio_net: formalize skb_vnet_hdr

We put the virtio_net_hdr into the skb's cb region; turn this into a
union to clean up the code slightly and allow future expansion.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Mark McLoughlin <markmc@redhat.com>
Cc: Dinesh Subhraveti <dineshs@us.ibm.com>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 3041e4e..420388a 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -68,9 +68,16 @@ struct virtnet_info
        struct page *pages;
 };
 
-static inline void *skb_vnet_hdr(struct sk_buff *skb)
+struct skb_vnet_hdr {
+       union {
+               struct virtio_net_hdr hdr;
+               struct virtio_net_hdr_mrg_rxbuf mhdr;
+       };
+};
+
+static inline struct skb_vnet_hdr *skb_vnet_hdr(struct sk_buff *skb)
 {
-       return (struct virtio_net_hdr *)skb->cb;
+       return (struct skb_vnet_hdr *)skb->cb;
 }
 
 static void give_a_page(struct virtnet_info *vi, struct page *page)
@@ -115,7 +122,7 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                        unsigned len)
 {
        struct virtnet_info *vi = netdev_priv(dev);
-       struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
+       struct skb_vnet_hdr *hdr = skb_vnet_hdr(skb);
        int err;
        int i;
 
@@ -126,7 +133,6 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
        }
 
        if (vi->mergeable_rx_bufs) {
-               struct virtio_net_hdr_mrg_rxbuf *mhdr = skb_vnet_hdr(skb);
                unsigned int copy;
                char *p = page_address(skb_shinfo(skb)->frags[0].page);
 
@@ -134,8 +140,8 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                        len = PAGE_SIZE;
                len -= sizeof(struct virtio_net_hdr_mrg_rxbuf);
 
-               memcpy(hdr, p, sizeof(*mhdr));
-               p += sizeof(*mhdr);
+               memcpy(&hdr->mhdr, p, sizeof(hdr->mhdr));
+               p += sizeof(hdr->mhdr);
 
                copy = len;
                if (copy > skb_tailroom(skb))
@@ -150,13 +156,13 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                        skb_shinfo(skb)->nr_frags--;
                } else {
                        skb_shinfo(skb)->frags[0].page_offset +=
-                               sizeof(*mhdr) + copy;
+                               sizeof(hdr->mhdr) + copy;
                        skb_shinfo(skb)->frags[0].size = len;
                        skb->data_len += len;
                        skb->len += len;
                }
 
-               while (--mhdr->num_buffers) {
+               while (--hdr->mhdr.num_buffers) {
                        struct sk_buff *nskb;
 
                        i = skb_shinfo(skb)->nr_frags;
@@ -170,7 +176,7 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                        nskb = vi->rvq->vq_ops->get_buf(vi->rvq, &len);
                        if (!nskb) {
                                pr_debug("%s: rx error: %d buffers missing\n",
-                                        dev->name, mhdr->num_buffers);
+                                        dev->name, hdr->mhdr.num_buffers);
                                dev->stats.rx_length_errors++;
                                goto drop;
                        }
@@ -191,7 +197,7 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                        skb->len += len;
                }
        } else {
-               len -= sizeof(struct virtio_net_hdr);
+               len -= sizeof(hdr->hdr);
 
                if (len <= MAX_PACKET_LEN)
                        trim_pages(vi, skb);
@@ -209,9 +215,11 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
        dev->stats.rx_bytes += skb->len;
        dev->stats.rx_packets++;
 
-       if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
+       if (hdr->hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
                pr_debug("Needs csum!\n");
-               if (!skb_partial_csum_set(skb,hdr->csum_start,hdr->csum_offset))
+               if (!skb_partial_csum_set(skb,
+                                         hdr->hdr.csum_start,
+                                         hdr->hdr.csum_offset))
                        goto frame_err;
        }
 
@@ -219,9 +227,9 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
        pr_debug("Receiving skb proto 0x%04x len %i type %i\n",
                 ntohs(skb->protocol), skb->len, skb->pkt_type);
 
-       if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
+       if (hdr->hdr.gso_type != VIRTIO_NET_HDR_GSO_NONE) {
                pr_debug("GSO!\n");
-               switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
+               switch (hdr->hdr.gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
                case VIRTIO_NET_HDR_GSO_TCPV4:
                        skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
                        break;
@@ -234,14 +242,14 @@ static void receive_skb(struct net_device *dev, struct sk_buff *skb,
                default:
                        if (net_ratelimit())
                                printk(KERN_WARNING "%s: bad gso type %u.\n",
-                                      dev->name, hdr->gso_type);
+                                      dev->name, hdr->hdr.gso_type);
                        goto frame_err;
                }
 
-               if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
+               if (hdr->hdr.gso_type & VIRTIO_NET_HDR_GSO_ECN)
                        skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
 
-               skb_shinfo(skb)->gso_size = hdr->gso_size;
+               skb_shinfo(skb)->gso_size = hdr->hdr.gso_size;
                if (skb_shinfo(skb)->gso_size == 0) {
                        if (net_ratelimit())
                                printk(KERN_WARNING "%s: zero gso size.\n",
@@ -272,7 +280,7 @@ static bool try_fill_recv_maxbufs(struct virtnet_info *vi, gfp_t gfp)
 
        sg_init_table(sg, 2+MAX_SKB_FRAGS);
        for (;;) {
-               struct virtio_net_hdr *hdr;
+               struct skb_vnet_hdr *hdr;
 
                skb = netdev_alloc_skb(vi->dev, MAX_PACKET_LEN + NET_IP_ALIGN);
                if (unlikely(!skb)) {
@@ -284,7 +292,7 @@ static bool try_fill_recv_maxbufs(struct virtnet_info *vi, gfp_t gfp)
                skb_put(skb, MAX_PACKET_LEN);
 
                hdr = skb_vnet_hdr(skb);
-               sg_set_buf(sg, hdr, sizeof(*hdr));
+               sg_set_buf(sg, &hdr->hdr, sizeof(hdr->hdr));
 
                if (vi->big_packets) {
                        for (i = 0; i < MAX_SKB_FRAGS; i++) {
@@ -452,8 +460,7 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
 {
        int num;
        struct scatterlist sg[2+MAX_SKB_FRAGS];
-       struct virtio_net_hdr_mrg_rxbuf *mhdr = skb_vnet_hdr(skb);
-       struct virtio_net_hdr *hdr = skb_vnet_hdr(skb);
+       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);
@@ -461,39 +468,39 @@ static int xmit_skb(struct virtnet_info *vi, struct sk_buff *skb)
        pr_debug("%s: xmit %p %pM\n", vi->dev->name, skb, dest);
 
        if (skb->ip_summed == CHECKSUM_PARTIAL) {
-               hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
-               hdr->csum_start = skb->csum_start - skb_headroom(skb);
-               hdr->csum_offset = skb->csum_offset;
+               hdr->hdr.flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+               hdr->hdr.csum_start = skb->csum_start - skb_headroom(skb);
+               hdr->hdr.csum_offset = skb->csum_offset;
        } else {
-               hdr->flags = 0;
-               hdr->csum_offset = hdr->csum_start = 0;
+               hdr->hdr.flags = 0;
+               hdr->hdr.csum_offset = hdr->hdr.csum_start = 0;
        }
 
        if (skb_is_gso(skb)) {
-               hdr->hdr_len = skb_headlen(skb);
-               hdr->gso_size = skb_shinfo(skb)->gso_size;
+               hdr->hdr.hdr_len = skb_headlen(skb);
+               hdr->hdr.gso_size = skb_shinfo(skb)->gso_size;
                if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4)
-                       hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
+                       hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
                else if (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6)
-                       hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
+                       hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
                else if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP)
-                       hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP;
+                       hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_UDP;
                else
                        BUG();
                if (skb_shinfo(skb)->gso_type & SKB_GSO_TCP_ECN)
-                       hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
+                       hdr->hdr.gso_type |= VIRTIO_NET_HDR_GSO_ECN;
        } else {
-               hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
-               hdr->gso_size = hdr->hdr_len = 0;
+               hdr->hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE;
+               hdr->hdr.gso_size = hdr->hdr.hdr_len = 0;
        }
 
-       mhdr->num_buffers = 0;
+       hdr->mhdr.num_buffers = 0;
 
        /* Encode metadata header at front. */
        if (vi->mergeable_rx_bufs)
-               sg_set_buf(sg, mhdr, sizeof(*mhdr));
+               sg_set_buf(sg, &hdr->mhdr, sizeof(hdr->mhdr));
        else
-               sg_set_buf(sg, hdr, sizeof(*hdr));
+               sg_set_buf(sg, &hdr->hdr, sizeof(hdr->hdr));
 
        num = skb_to_sgvec(skb, sg+1, 0, skb->len) + 1;
        return vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb);