Commit fbf93406 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: let tcp_send_syn_data() build headless packets 



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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f2f069da

include/net/tcp.h

+1 −0
Original line number Diff line number Diff line
@@ -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);

net/ipv4/tcp.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

net/ipv4/tcp_output.c

+19 −12
Original line number Diff line number Diff line
@@ -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() */