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>

1 files changed, 40 insertions, 27 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index e41f017cd479..67a3d70f7ac4 100644
--- 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;