udpv6: Fix HW checksum support for outgoing UFO packets

- add HW checksum support for outgoing large UDP/IPv6 packets destined for
  a UFO enabled device.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 47 insertions, 1 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 33b59bd92c4d..f31b1b9b0e0e 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -638,6 +638,47 @@ static void udp_v6_flush_pending_frames(struct sock *sk)
         }
 }
 
+/**
+ *      udp6_hwcsum_outgoing  -  handle outgoing HW checksumming
+ *      @sk:    socket we are sending on
+ *      @skb:   sk_buff containing the filled-in UDP header
+ *              (checksum field must be zeroed out)
+ */
+static void udp6_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
+                                 const struct in6_addr *saddr,
+                                 const struct in6_addr *daddr, int len)
+{
+        unsigned int offset;
+        struct udphdr *uh = udp_hdr(skb);
+        __wsum csum = 0;
+
+        if (skb_queue_len(&sk->sk_write_queue) == 1) {
+                /* Only one fragment on the socket.  */
+                skb->csum_start = skb_transport_header(skb) - skb->head;
+                skb->csum_offset = offsetof(struct udphdr, check);
+                uh->check = ~csum_ipv6_magic(saddr, daddr, len, IPPROTO_UDP, 0);
+        } else {
+                /*
+                 * HW-checksum won't work as there are two or more
+                 * fragments on the socket so that all csums of sk_buffs
+                 * should be together
+                 */
+                offset = skb_transport_offset(skb);
+                skb->csum = skb_checksum(skb, offset, skb->len - offset, 0);
+
+                skb->ip_summed = CHECKSUM_NONE;
+
+                skb_queue_walk(&sk->sk_write_queue, skb) {
+                        csum = csum_add(csum, skb->csum);
+                }
+
+                uh->check = csum_ipv6_magic(saddr, daddr, len, IPPROTO_UDP,
+                                            csum);
+                if (uh->check == 0)
+                        uh->check = CSUM_MANGLED_0;
+        }
+}
+
 /*
  *      Sending
  */
@@ -668,7 +709,11 @@ static int udp_v6_push_pending_frames(struct sock *sk)
 
         if (is_udplite)
                 csum = udplite_csum_outgoing(sk, skb);
-         else
+        else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
+                udp6_hwcsum_outgoing(sk, skb, &fl->fl6_src, &fl->fl6_dst,
+                                     up->len);
+                goto send;
+        } else
                 csum = udp_csum_outgoing(sk, skb);
 
         /* add protocol-dependent pseudo-header */
@@ -677,6 +722,7 @@ static int udp_v6_push_pending_frames(struct sock *sk)
         if (uh->check == 0)
                 uh->check = CSUM_MANGLED_0;
 
+send:
         err = ip6_push_pending_frames(sk);
 out:
         up->len = 0;