Commit 04317daf authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

tcp: introduce TCP_SKB_CB(skb)->tcp_tw_isn 



TCP_SKB_CB(skb)->when has different meaning in output and input paths.

In output path, it contains a timestamp.
In input path, it contains an ISN, chosen by tcp_timewait_state_process()

Lets add a different name to ease code comprehension.

Note that 'when' field will disappear in following patch,
as skb_mstamp already contains timestamp, the anonymous
union will promptly disappear as well.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2ba38943

include/net/tcp.h

+6 −1
Original line number Diff line number Diff line
@@ -698,7 +698,12 @@ struct tcp_skb_cb { 
	} header;	/* For incoming frames		*/

	__u32		seq;		/* Starting sequence number	*/

	__u32		end_seq;	/* SEQ + FIN + SYN + datalen	*/

	union {

		/* used in output path */

		__u32		when;	/* used to compute rtt's	*/

		/* used in input path */

		__u32		tcp_tw_isn; /* isn chosen by tcp_timewait_state_process() */

	};

	__u8		tcp_flags;	/* TCP header flags. (tcp[13])	*/



	__u8		sacked;		/* State flags for SACK/FACK.	*/

net/ipv4/tcp_input.c

+1 −1
Original line number Diff line number Diff line
@@ -5906,7 +5906,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops, 
	struct request_sock *req;

	struct tcp_sock *tp = tcp_sk(sk);

	struct dst_entry *dst = NULL;

	__u32 isn = TCP_SKB_CB(skb)->when;

	__u32 isn = TCP_SKB_CB(skb)->tcp_tw_isn;

	bool want_cookie = false, fastopen;

	struct flowi fl;

	struct tcp_fastopen_cookie foc = { .len = -1 };

net/ipv4/tcp_ipv4.c

+1 −1
Original line number Diff line number Diff line
@@ -1627,7 +1627,7 @@ int tcp_v4_rcv(struct sk_buff *skb) 
	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +

				    skb->len - th->doff * 4);

	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);

	TCP_SKB_CB(skb)->when	 = 0;

	TCP_SKB_CB(skb)->tcp_tw_isn = 0;

	TCP_SKB_CB(skb)->ip_dsfield = ipv4_get_dsfield(iph);

	TCP_SKB_CB(skb)->sacked	 = 0;

net/ipv4/tcp_minisocks.c

+1 −1
Original line number Diff line number Diff line
@@ -232,7 +232,7 @@ kill: 
		u32 isn = tcptw->tw_snd_nxt + 65535 + 2;

		if (isn == 0)

			isn++;

		TCP_SKB_CB(skb)->when = isn;

		TCP_SKB_CB(skb)->tcp_tw_isn = isn;

		return TCP_TW_SYN;

	}

net/ipv6/tcp_ipv6.c

+2 −2
Original line number Diff line number Diff line
@@ -738,7 +738,7 @@ static void tcp_v6_init_req(struct request_sock *req, struct sock *sk, 
	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)

		ireq->ir_iif = inet6_iif(skb);



	if (!TCP_SKB_CB(skb)->when &&

	if (!TCP_SKB_CB(skb)->tcp_tw_isn &&

	    (ipv6_opt_accepted(sk, skb) || np->rxopt.bits.rxinfo ||

	     np->rxopt.bits.rxoinfo || np->rxopt.bits.rxhlim ||

	     np->rxopt.bits.rxohlim || np->repflow)) {
@@ -1412,7 +1412,7 @@ static int tcp_v6_rcv(struct sk_buff *skb) 
	TCP_SKB_CB(skb)->end_seq = (TCP_SKB_CB(skb)->seq + th->syn + th->fin +

				    skb->len - th->doff*4);

	TCP_SKB_CB(skb)->ack_seq = ntohl(th->ack_seq);

	TCP_SKB_CB(skb)->when = 0;

	TCP_SKB_CB(skb)->tcp_tw_isn = 0;

	TCP_SKB_CB(skb)->ip_dsfield = ipv6_get_dsfield(hdr);

	TCP_SKB_CB(skb)->sacked = 0;

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