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Commit 1c32c5ad authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

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: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1470ddf7

include/net/ip.h

+16 −0
Original line number Diff line number Diff line
@@ -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,

net/ipv4/ip_output.c

+51 −14
Original line number Diff line number Diff line
@@ -1267,7 +1267,7 @@ static void ip_cork_release(struct inet_cork *cork) 
 *	Combined all pending IP fragments on the socket as one IP datagram

 *	and push them out.

 */

static int __ip_push_pending_frames(struct sock *sk,

struct sk_buff *__ip_make_skb(struct sock *sk,

			      struct sk_buff_head *queue,

			      struct inet_cork *cork)

{
@@ -1280,7 +1280,6 @@ static int __ip_push_pending_frames(struct sock *sk, 
	struct iphdr *iph;

	__be16 df = 0;

	__u8 ttl;

	int err = 0;



	if ((skb = __skb_dequeue(queue)) == NULL)

		goto out;
@@ -1351,28 +1350,37 @@ static int __ip_push_pending_frames(struct sock *sk, 
		icmp_out_count(net, ((struct icmphdr *)

			skb_transport_header(skb))->type);



	/* Netfilter gets whole the not fragmented skb. */

	ip_cork_release(cork);

out:

	return skb;

}



int ip_send_skb(struct sk_buff *skb)

{

	struct net *net = sock_net(skb->sk);

	int err;



	err = ip_local_out(skb);

	if (err) {

		if (err > 0)

			err = net_xmit_errno(err);

		if (err)

			goto error;

			IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);

	}



out:

	ip_cork_release(cork);

	return err;



error:

	IP_INC_STATS(net, IPSTATS_MIB_OUTDISCARDS);

	goto out;

}



int ip_push_pending_frames(struct sock *sk)

{

	return __ip_push_pending_frames(sk, &sk->sk_write_queue,

					&inet_sk(sk)->cork);

	struct sk_buff *skb;



	skb = ip_finish_skb(sk);

	if (!skb)

		return 0;



	/* Netfilter gets whole the not fragmented skb. */

	return ip_send_skb(skb);

}



/*
@@ -1395,6 +1403,35 @@ void ip_flush_pending_frames(struct sock *sk) 
	__ip_flush_pending_frames(sk, &sk->sk_write_queue, &inet_sk(sk)->cork);

}



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)

{

	struct inet_cork cork = {};

	struct sk_buff_head queue;

	int err;



	if (flags & MSG_PROBE)

		return NULL;



	__skb_queue_head_init(&queue);



	err = ip_setup_cork(sk, &cork, ipc, rtp);

	if (err)

		return ERR_PTR(err);



	err = __ip_append_data(sk, &queue, &cork, getfrag,

			       from, length, transhdrlen, flags);

	if (err) {

		__ip_flush_pending_frames(sk, &queue, &cork);

		return ERR_PTR(err);

	}



	return __ip_make_skb(sk, &queue, &cork);

}



/*

 *	Fetch data from kernel space and fill in checksum if needed.