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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>
This commit is contained in:
Herbert Xu 2011-03-01 02:36:47 +00:00 committed by David S. Miller
parent 1470ddf7f8
commit 1c32c5ad6f
2 changed files with 67 additions and 14 deletions
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16
include/net/ip.h
View File

@ -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,

65
net/ipv4/ip_output.c
View File

@ -1267,9 +1267,9 @@ 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_head *queue,
struct inet_cork *cork)
struct sk_buff *__ip_make_skb(struct sock *sk,
struct sk_buff_head *queue,
struct inet_cork *cork)
{
struct sk_buff *skb, *tmp_skb;
struct sk_buff **tail_skb;
@ -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.