ipv6: Introduce udpv6_send_skb()

Now that we can individually construct IPv6 skbs to send, add a
udpv6_send_skb() function to populate the udp header and send the
skb.  This allows udp_v6_push_pending_frames() to re-use this
function as well as enables us to add lockless sendmsg() support.

Signed-off-by: Vladislav Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index e41f017..67a3d70 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -990,9 +990,10 @@ static void udp6_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
 {
        unsigned int offset;
        struct udphdr *uh = udp_hdr(skb);
+       struct sk_buff *frags = skb_shinfo(skb)->frag_list;
        __wsum csum = 0;
 
-       if (skb_queue_len(&sk->sk_write_queue) == 1) {
+       if (!frags) {
                /* Only one fragment on the socket.  */
                skb->csum_start = skb_transport_header(skb) - skb->head;
                skb->csum_offset = offsetof(struct udphdr, check);
@@ -1008,9 +1009,9 @@ static void udp6_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
 
                skb->ip_summed = CHECKSUM_NONE;
 
-               skb_queue_walk(&sk->sk_write_queue, skb) {
-                       csum = csum_add(csum, skb->csum);
-               }
+               do {
+                       csum = csum_add(csum, frags->csum);
+               } while ((frags = frags->next));
 
                uh->check = csum_ipv6_magic(saddr, daddr, len, IPPROTO_UDP,
                                            csum);
@@ -1023,26 +1024,15 @@ static void udp6_hwcsum_outgoing(struct sock *sk, struct sk_buff *skb,
  *     Sending
  */
 
-static int udp_v6_push_pending_frames(struct sock *sk)
+static int udp_v6_send_skb(struct sk_buff *skb, struct flowi6 *fl6)
 {
-       struct sk_buff *skb;
+       struct sock *sk = skb->sk;
        struct udphdr *uh;
-       struct udp_sock  *up = udp_sk(sk);
-       struct inet_sock *inet = inet_sk(sk);
-       struct flowi6 *fl6;
        int err = 0;
        int is_udplite = IS_UDPLITE(sk);
        __wsum csum = 0;
-
-       if (up->pending == AF_INET)
-               return udp_push_pending_frames(sk);
-
-       fl6 = &inet->cork.fl.u.ip6;
-
-       /* Grab the skbuff where UDP header space exists. */
-       skb = skb_peek(&sk->sk_write_queue);
-       if (skb == NULL)
-               goto out;
+       int offset = skb_transport_offset(skb);
+       int len = skb->len - offset;
 
        /*
         * Create a UDP header
@@ -1050,29 +1040,28 @@ static int udp_v6_push_pending_frames(struct sock *sk)
        uh = udp_hdr(skb);
        uh->source = fl6->fl6_sport;
        uh->dest = fl6->fl6_dport;
-       uh->len = htons(up->len);
+       uh->len = htons(len);
        uh->check = 0;
 
        if (is_udplite)
-               csum = udplite_csum_outgoing(sk, skb);
-       else if (up->no_check6_tx) {   /* UDP csum disabled */
+               csum = udplite_csum(skb);
+       else if (udp_sk(sk)->no_check6_tx) {   /* UDP csum disabled */
                skb->ip_summed = CHECKSUM_NONE;
                goto send;
        } else if (skb->ip_summed == CHECKSUM_PARTIAL) { /* UDP hardware csum */
-               udp6_hwcsum_outgoing(sk, skb, &fl6->saddr, &fl6->daddr,
-                                    up->len);
+               udp6_hwcsum_outgoing(sk, skb, &fl6->saddr, &fl6->daddr, len);
                goto send;
        } else
-               csum = udp_csum_outgoing(sk, skb);
+               csum = udp_csum(skb);
 
        /* add protocol-dependent pseudo-header */
        uh->check = csum_ipv6_magic(&fl6->saddr, &fl6->daddr,
-                                   up->len, fl6->flowi6_proto, csum);
+                                   len, fl6->flowi6_proto, csum);
        if (uh->check == 0)
                uh->check = CSUM_MANGLED_0;
 
 send:
-       err = ip6_push_pending_frames(sk);
+       err = ip6_send_skb(skb);
        if (err) {
                if (err == -ENOBUFS && !inet6_sk(sk)->recverr) {
                        UDP6_INC_STATS_USER(sock_net(sk),
@@ -1082,6 +1071,30 @@ send:
        } else
                UDP6_INC_STATS_USER(sock_net(sk),
                                    UDP_MIB_OUTDATAGRAMS, is_udplite);
+       return err;
+}
+
+static int udp_v6_push_pending_frames(struct sock *sk)
+{
+       struct sk_buff *skb;
+       struct udp_sock  *up = udp_sk(sk);
+       struct flowi6 fl6;
+       int err = 0;
+
+       if (up->pending == AF_INET)
+               return udp_push_pending_frames(sk);
+
+       /* ip6_finish_skb will release the cork, so make a copy of
+        * fl6 here.
+        */
+       fl6 = inet_sk(sk)->cork.fl.u.ip6;
+
+       skb = ip6_finish_skb(sk);
+       if (!skb)
+               goto out;
+
+       err = udp_v6_send_skb(skb, &fl6);
+
 out:
        up->len = 0;
        up->pending = 0;