inet: Add ip_make_skb and ip_finish_skb

This patch adds the helper ip_make_skb which is like ip_append_data
and ip_push_pending_frames all rolled into one, except that it does
not send the skb produced.  The sending part is carried out by
ip_send_skb, which the transport protocol can call after it has
tweaked the skb.

It is meant to be called in cases where corking is not used should
have a one-to-one correspondence to sendmsg.

This patch also adds the helper ip_finish_skb which is meant to
be replace ip_push_pending_frames when corking is required.
Previously the protocol stack would peek at the socket write
queue and add its header to the first packet.  With ip_finish_skb,
the protocol stack can directly operate on the final skb instead,
just like the non-corking case with ip_make_skb.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 0 deletions

diff --git a/include/net/ip.h b/include/net/ip.h
index 67fac78a186b..a4f631108c54 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -116,8 +116,24 @@ extern int		ip_append_data(struct sock *sk,
 extern int              ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb);
 extern ssize_t          ip_append_page(struct sock *sk, struct page *page,
                                 int offset, size_t size, int flags);
+extern struct sk_buff  *__ip_make_skb(struct sock *sk,
+                                      struct sk_buff_head *queue,
+                                      struct inet_cork *cork);
+extern int              ip_send_skb(struct sk_buff *skb);
 extern int              ip_push_pending_frames(struct sock *sk);
 extern void             ip_flush_pending_frames(struct sock *sk);
+extern struct sk_buff  *ip_make_skb(struct sock *sk,
+                                    int getfrag(void *from, char *to, int offset, int len,
+                                                int odd, struct sk_buff *skb),
+                                    void *from, int length, int transhdrlen,
+                                    struct ipcm_cookie *ipc,
+                                    struct rtable **rtp,
+                                    unsigned int flags);
+
+static inline struct sk_buff *ip_finish_skb(struct sock *sk)
+{
+        return __ip_make_skb(sk, &sk->sk_write_queue, &inet_sk(sk)->cork);
+}
 
 /* datagram.c */
 extern int              ip4_datagram_connect(struct sock *sk,