Commit cc9a672e authored by Neal Cardwell's avatar Neal Cardwell Committed by David S. Miller
Browse files

tcp: allow tcp_sacktag_one() to tag ranges not aligned with skbs 



This commit allows callers of tcp_sacktag_one() to pass in sequence
ranges that do not align with skb boundaries, as tcp_shifted_skb()
needs to do in an upcoming fix in this patch series.

In fact, now tcp_sacktag_one() does not need to depend on an input skb
at all, which makes its semantics and dependencies more clear.

Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8df54d62

net/ipv4/tcp_input.c

+22 −14
Original line number Diff line number Diff line
@@ -1307,25 +1307,26 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb, 
	return in_sack;

}



static u8 tcp_sacktag_one(const struct sk_buff *skb, struct sock *sk,

			  struct tcp_sacktag_state *state,

/* Mark the given newly-SACKed range as such, adjusting counters and hints. */

static u8 tcp_sacktag_one(struct sock *sk,

			  struct tcp_sacktag_state *state, u8 sacked,

			  u32 start_seq, u32 end_seq,

			  int dup_sack, int pcount)

{

	struct tcp_sock *tp = tcp_sk(sk);

	u8 sacked = TCP_SKB_CB(skb)->sacked;

	int fack_count = state->fack_count;



	/* Account D-SACK for retransmitted packet. */

	if (dup_sack && (sacked & TCPCB_RETRANS)) {

		if (tp->undo_marker && tp->undo_retrans &&

		    after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker))

		    after(end_seq, tp->undo_marker))

			tp->undo_retrans--;

		if (sacked & TCPCB_SACKED_ACKED)

			state->reord = min(fack_count, state->reord);

	}



	/* Nothing to do; acked frame is about to be dropped (was ACKed). */

	if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una))

	if (!after(end_seq, tp->snd_una))

		return sacked;



	if (!(sacked & TCPCB_SACKED_ACKED)) {
@@ -1344,13 +1345,13 @@ static u8 tcp_sacktag_one(const struct sk_buff *skb, struct sock *sk, 
				/* New sack for not retransmitted frame,

				 * which was in hole. It is reordering.

				 */

				if (before(TCP_SKB_CB(skb)->seq,

				if (before(start_seq,

					   tcp_highest_sack_seq(tp)))

					state->reord = min(fack_count,

							   state->reord);



				/* SACK enhanced F-RTO (RFC4138; Appendix B) */

				if (!after(TCP_SKB_CB(skb)->end_seq, tp->frto_highmark))

				if (!after(end_seq, tp->frto_highmark))

					state->flag |= FLAG_ONLY_ORIG_SACKED;

			}
@@ -1368,8 +1369,7 @@ static u8 tcp_sacktag_one(const struct sk_buff *skb, struct sock *sk, 


		/* Lost marker hint past SACKed? Tweak RFC3517 cnt */

		if (!tcp_is_fack(tp) && (tp->lost_skb_hint != NULL) &&

		    before(TCP_SKB_CB(skb)->seq,

			   TCP_SKB_CB(tp->lost_skb_hint)->seq))

		    before(start_seq, TCP_SKB_CB(tp->lost_skb_hint)->seq))

			tp->lost_cnt_hint += pcount;



		if (fack_count > tp->fackets_out)
@@ -1425,7 +1425,11 @@ static int tcp_shifted_skb(struct sock *sk, struct sk_buff *skb, 
	}



	/* We discard results */

	tcp_sacktag_one(skb, sk, state, dup_sack, pcount);

	tcp_sacktag_one(sk, state,

			TCP_SKB_CB(skb)->sacked,

			TCP_SKB_CB(skb)->seq,

			TCP_SKB_CB(skb)->end_seq,

			dup_sack, pcount);



	/* Difference in this won't matter, both ACKed by the same cumul. ACK */

	TCP_SKB_CB(prev)->sacked |= (TCP_SKB_CB(skb)->sacked & TCPCB_EVER_RETRANS);
@@ -1664,8 +1668,12 @@ static struct sk_buff *tcp_sacktag_walk(struct sk_buff *skb, struct sock *sk, 
			break;



		if (in_sack) {

			TCP_SKB_CB(skb)->sacked = tcp_sacktag_one(skb, sk,

			TCP_SKB_CB(skb)->sacked =

				tcp_sacktag_one(sk,

						state,

						TCP_SKB_CB(skb)->sacked,

						TCP_SKB_CB(skb)->seq,

						TCP_SKB_CB(skb)->end_seq,

						dup_sack,

						tcp_skb_pcount(skb));

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