From: Herbert Xu <herbert@gondor.apana.org.au> Date: Wed, 27 May 2009 15:31:18 +1000 Subject: [net] add skb_gro_receive Message-id: E1M9BjS-0002C0-Di@gondolin.me.apana.org.au O-Subject: [PATCH 13/17] net: Add skb_gro_receive Bugzilla: 499347 RH-Acked-by: David Miller <davem@redhat.com> RH-Acked-by: Neil Horman <nhorman@redhat.com> RH-Acked-by: Thomas Graf <tgraf@redhat.com> RHEL5 bugzilla #499347 net: Add skb_gro_receive This patch adds the helper skb_gro_receive to merge packets for GRO. The current method is to allocate a new header skb and then chain the original packets to its frag_list. This is done to make it easier to integrate into the existing GSO framework. In future as GSO is moved into the drivers, we can undo this and simply chain the original packets together. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 8e81912..b9f15d6 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -707,6 +707,8 @@ extern int dev_restart(struct net_device *dev); extern int netpoll_trap(void); #endif +extern int skb_gro_receive(struct sk_buff **head, + struct sk_buff *skb); extern void skb_gro_reset_offset(struct sk_buff *skb); static inline unsigned int skb_gro_offset(const struct sk_buff *skb) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 975369d..6bd609d 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2080,6 +2080,112 @@ err: } EXPORT_SYMBOL_GPL(skb_segment); +int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb) +{ + struct sk_buff *p = *head; + struct sk_buff *nskb; + struct skb_shared_info *skbinfo = skb_shinfo(skb); + struct skb_shared_info *pinfo = skb_shinfo(p); + unsigned int headroom; + unsigned int len = skb_gro_len(skb); + unsigned int offset = skb_gro_offset(skb); + unsigned int headlen = skb_headlen(skb); + + if (p->len + len >= 65536) + return -E2BIG; + + if (pinfo->frag_list) + goto merge; + else if (headlen <= offset) { + skb_frag_t *frag; + skb_frag_t *frag2; + int i = skbinfo->nr_frags; + int nr_frags = pinfo->nr_frags + i; + + offset -= headlen; + + if (nr_frags > MAX_SKB_FRAGS) + return -E2BIG; + + pinfo->nr_frags = nr_frags; + skbinfo->nr_frags = 0; + + frag = pinfo->frags + nr_frags; + frag2 = skbinfo->frags + i; + do { + *--frag = *--frag2; + } while (--i); + + frag->page_offset += offset; + frag->size -= offset; + + skb->truesize -= skb->data_len; + skb->len -= skb->data_len; + skb->data_len = 0; + + NAPI_GRO_CB(skb)->free = 1; + goto done; + } + + headroom = skb_headroom(p); + nskb = netdev_alloc_skb(p->dev, headroom + skb_gro_offset(p)); + if (unlikely(!nskb)) + return -ENOMEM; + + __copy_skb_header(nskb, p); + nskb->mac_len = p->mac_len; + + skb_reserve(nskb, headroom); + __skb_put(nskb, skb_gro_offset(p)); + + skb_set_mac_header(nskb, skb_mac_header(p) - p->data); + skb_set_network_header(nskb, skb_network_offset(p)); + skb_set_transport_header(nskb, skb_transport_offset(p)); + + __skb_pull(p, skb_gro_offset(p)); + memcpy(skb_mac_header(nskb), skb_mac_header(p), + p->data - skb_mac_header(p)); + + *NAPI_GRO_CB(nskb) = *NAPI_GRO_CB(p); + skb_shinfo(nskb)->frag_list = p; + skb_shinfo(nskb)->gso_size = pinfo->gso_size; + skb_header_release(p); + nskb->prev = p; + + nskb->data_len += p->len; + nskb->truesize += p->len; + nskb->len += p->len; + + *head = nskb; + nskb->next = p->next; + p->next = NULL; + + p = nskb; + +merge: + if (offset > headlen) { + skbinfo->frags[0].page_offset += offset - headlen; + skbinfo->frags[0].size -= offset - headlen; + offset = headlen; + } + + __skb_pull(skb, offset); + + p->prev->next = skb; + p->prev = skb; + skb_header_release(skb); + +done: + NAPI_GRO_CB(p)->count++; + p->data_len += len; + p->truesize += len; + p->len += len; + + NAPI_GRO_CB(skb)->same_flow = 1; + return 0; +} +EXPORT_SYMBOL_GPL(skb_gro_receive); + void __init skb_init(void) { skbuff_head_cache = kmem_cache_create("skbuff_head_cache",