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authorAnanda Raju <ananda.raju@neterion.com>2005-10-18 18:46:41 -0400
committerArnaldo Carvalho de Melo <acme@mandriva.com>2005-10-28 14:30:00 -0400
commite89e9cf539a28df7d0eb1d0a545368e9920b34ac (patch)
treeaae6a825f351ce931fcd30f1a865ebe65227c4b8 /net/ipv6/ip6_output.c
parentde5144164f6242ccfa8c9b64eec570564f5eaf14 (diff)
[IPv4/IPv6]: UFO Scatter-gather approach
Attached is kernel patch for UDP Fragmentation Offload (UFO) feature. 1. This patch incorporate the review comments by Jeff Garzik. 2. Renamed USO as UFO (UDP Fragmentation Offload) 3. udp sendfile support with UFO This patches uses scatter-gather feature of skb to generate large UDP datagram. Below is a "how-to" on changes required in network device driver to use the UFO interface. UDP Fragmentation Offload (UFO) Interface: ------------------------------------------- UFO is a feature wherein the Linux kernel network stack will offload the IP fragmentation functionality of large UDP datagram to hardware. This will reduce the overhead of stack in fragmenting the large UDP datagram to MTU sized packets 1) Drivers indicate their capability of UFO using dev->features |= NETIF_F_UFO | NETIF_F_HW_CSUM | NETIF_F_SG NETIF_F_HW_CSUM is required for UFO over ipv6. 2) UFO packet will be submitted for transmission using driver xmit routine. UFO packet will have a non-zero value for "skb_shinfo(skb)->ufo_size" skb_shinfo(skb)->ufo_size will indicate the length of data part in each IP fragment going out of the adapter after IP fragmentation by hardware. skb->data will contain MAC/IP/UDP header and skb_shinfo(skb)->frags[] contains the data payload. The skb->ip_summed will be set to CHECKSUM_HW indicating that hardware has to do checksum calculation. Hardware should compute the UDP checksum of complete datagram and also ip header checksum of each fragmented IP packet. For IPV6 the UFO provides the fragment identification-id in skb_shinfo(skb)->ip6_frag_id. The adapter should use this ID for generating IPv6 fragments. Signed-off-by: Ananda Raju <ananda.raju@neterion.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (forwarded) Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Diffstat (limited to 'net/ipv6/ip6_output.c')
-rw-r--r--net/ipv6/ip6_output.c71
1 files changed, 70 insertions, 1 deletions
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 563b442ffab8..614296a920c6 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -147,7 +147,8 @@ static int ip6_output2(struct sk_buff *skb)
147 147
148int ip6_output(struct sk_buff *skb) 148int ip6_output(struct sk_buff *skb)
149{ 149{
150 if (skb->len > dst_mtu(skb->dst) || dst_allfrag(skb->dst)) 150 if ((skb->len > dst_mtu(skb->dst) && !skb_shinfo(skb)->ufo_size) ||
151 dst_allfrag(skb->dst))
151 return ip6_fragment(skb, ip6_output2); 152 return ip6_fragment(skb, ip6_output2);
152 else 153 else
153 return ip6_output2(skb); 154 return ip6_output2(skb);
@@ -768,6 +769,65 @@ out_err_release:
768 *dst = NULL; 769 *dst = NULL;
769 return err; 770 return err;
770} 771}
772inline int ip6_ufo_append_data(struct sock *sk,
773 int getfrag(void *from, char *to, int offset, int len,
774 int odd, struct sk_buff *skb),
775 void *from, int length, int hh_len, int fragheaderlen,
776 int transhdrlen, int mtu,unsigned int flags)
777
778{
779 struct sk_buff *skb;
780 int err;
781
782 /* There is support for UDP large send offload by network
783 * device, so create one single skb packet containing complete
784 * udp datagram
785 */
786 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) {
787 skb = sock_alloc_send_skb(sk,
788 hh_len + fragheaderlen + transhdrlen + 20,
789 (flags & MSG_DONTWAIT), &err);
790 if (skb == NULL)
791 return -ENOMEM;
792
793 /* reserve space for Hardware header */
794 skb_reserve(skb, hh_len);
795
796 /* create space for UDP/IP header */
797 skb_put(skb,fragheaderlen + transhdrlen);
798
799 /* initialize network header pointer */
800 skb->nh.raw = skb->data;
801
802 /* initialize protocol header pointer */
803 skb->h.raw = skb->data + fragheaderlen;
804
805 skb->ip_summed = CHECKSUM_HW;
806 skb->csum = 0;
807 sk->sk_sndmsg_off = 0;
808 }
809
810 err = skb_append_datato_frags(sk,skb, getfrag, from,
811 (length - transhdrlen));
812 if (!err) {
813 struct frag_hdr fhdr;
814
815 /* specify the length of each IP datagram fragment*/
816 skb_shinfo(skb)->ufo_size = (mtu - fragheaderlen) -
817 sizeof(struct frag_hdr);
818 ipv6_select_ident(skb, &fhdr);
819 skb_shinfo(skb)->ip6_frag_id = fhdr.identification;
820 __skb_queue_tail(&sk->sk_write_queue, skb);
821
822 return 0;
823 }
824 /* There is not enough support do UPD LSO,
825 * so follow normal path
826 */
827 kfree_skb(skb);
828
829 return err;
830}
771 831
772int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to, 832int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
773 int offset, int len, int odd, struct sk_buff *skb), 833 int offset, int len, int odd, struct sk_buff *skb),
@@ -860,6 +920,15 @@ int ip6_append_data(struct sock *sk, int getfrag(void *from, char *to,
860 */ 920 */
861 921
862 inet->cork.length += length; 922 inet->cork.length += length;
923 if (((length > mtu) && (sk->sk_protocol == IPPROTO_UDP)) &&
924 (rt->u.dst.dev->features & NETIF_F_UFO)) {
925
926 if(ip6_ufo_append_data(sk, getfrag, from, length, hh_len,
927 fragheaderlen, transhdrlen, mtu, flags))
928 goto error;
929
930 return 0;
931 }
863 932
864 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL) 933 if ((skb = skb_peek_tail(&sk->sk_write_queue)) == NULL)
865 goto alloc_new_skb; 934 goto alloc_new_skb;