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tcp: let tcp_send_syn_data() build headless packets

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tcp_send_syn_data() is the last component in TCP transmit
path to put payload in skb->head.

Switch it to use page frags, so that we can remove dead
code later.

This allows to put more payload than previous implementation.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2023-06-09 20:42:44 +00:00 committed by David S. Miller
parent f2f069da4c
commit fbf934068f
3 changed files with 21 additions and 13 deletions
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1
include/net/tcp.h
View File

@ -333,6 +333,7 @@ int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size,
int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset,
size_t size, int flags);
int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
int tcp_wmem_schedule(struct sock *sk, int copy);
void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle,
int size_goal);
void tcp_release_cb(struct sock *sk);

2
net/ipv4/tcp.c
View File

@ -957,7 +957,7 @@ static int tcp_downgrade_zcopy_pure(struct sock *sk, struct sk_buff *skb)
}
static int tcp_wmem_schedule(struct sock *sk, int copy)
int tcp_wmem_schedule(struct sock *sk, int copy)
{
int left;

31
net/ipv4/tcp_output.c
View File

@ -3802,8 +3802,9 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
struct tcp_fastopen_request *fo = tp->fastopen_req;
int space, err = 0;
struct page_frag *pfrag = sk_page_frag(sk);
struct sk_buff *syn_data;
int space, err = 0;
tp->rx_opt.mss_clamp = tp->advmss; /* If MSS is not cached */
if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie))
@ -3822,25 +3823,31 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn)
space = min_t(size_t, space, fo->size);
/* limit to order-0 allocations */
space = min_t(size_t, space, SKB_MAX_HEAD(MAX_TCP_HEADER));
syn_data = tcp_stream_alloc_skb(sk, space, sk->sk_allocation, false);
if (space &&
!skb_page_frag_refill(min_t(size_t, space, PAGE_SIZE),
pfrag, sk->sk_allocation))
goto fallback;
syn_data = tcp_stream_alloc_skb(sk, 0, sk->sk_allocation, false);
if (!syn_data)
goto fallback;
memcpy(syn_data->cb, syn->cb, sizeof(syn->cb));
if (space) {
int copied = copy_from_iter(skb_put(syn_data, space), space,
&fo->data->msg_iter);
if (unlikely(!copied)) {
space = min_t(size_t, space, pfrag->size - pfrag->offset);
space = tcp_wmem_schedule(sk, space);
}
if (space) {
space = copy_page_from_iter(pfrag->page, pfrag->offset,
space, &fo->data->msg_iter);
if (unlikely(!space)) {
tcp_skb_tsorted_anchor_cleanup(syn_data);
kfree_skb(syn_data);
goto fallback;
}
if (copied != space) {
skb_trim(syn_data, copied);
space = copied;
}
skb_fill_page_desc(syn_data, 0, pfrag->page,
pfrag->offset, space);
page_ref_inc(pfrag->page);
pfrag->offset += space;
skb_len_add(syn_data, space);
skb_zcopy_set(syn_data, fo->uarg, NULL);
}
/* No more data pending in inet_wait_for_connect() */