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Commit 9e10c47c authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
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[TCP]: Create tcp_sacktag_one(). 



Worker function that implements the main logic of
the inner-most loop of tcp_sacktag_write_queue().

Idea was originally presented by David S. Miller.

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b7d4815f

net/ipv4/tcp_input.c

+96 −96
Original line number Diff line number Diff line
@@ -1240,6 +1240,99 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb, 
	return in_sack;

}



static int tcp_sacktag_one(struct sk_buff *skb, struct tcp_sock *tp,

			   int *reord, int dup_sack, int fack_count)

{

	u8 sacked = TCP_SKB_CB(skb)->sacked;

	int flag = 0;



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

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

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

			tp->undo_retrans--;

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

		    (sacked & TCPCB_SACKED_ACKED))

			*reord = min(fack_count, *reord);

	}



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

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

		return flag;



	if (!(sacked & TCPCB_SACKED_ACKED)) {

		if (sacked & TCPCB_SACKED_RETRANS) {

			/* If the segment is not tagged as lost,

			 * we do not clear RETRANS, believing

			 * that retransmission is still in flight.

			 */

			if (sacked & TCPCB_LOST) {

				TCP_SKB_CB(skb)->sacked &=

					~(TCPCB_LOST|TCPCB_SACKED_RETRANS);

				tp->lost_out -= tcp_skb_pcount(skb);

				tp->retrans_out -= tcp_skb_pcount(skb);



				/* clear lost hint */

				tp->retransmit_skb_hint = NULL;

			}

		} else {

			if (!(sacked & TCPCB_RETRANS)) {

				/* New sack for not retransmitted frame,

				 * which was in hole. It is reordering.

				 */

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

					   tcp_highest_sack_seq(tp)))

					*reord = min(fack_count, *reord);



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

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

					flag |= FLAG_ONLY_ORIG_SACKED;

			}



			if (sacked & TCPCB_LOST) {

				TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;

				tp->lost_out -= tcp_skb_pcount(skb);



				/* clear lost hint */

				tp->retransmit_skb_hint = NULL;

			}

		}



		TCP_SKB_CB(skb)->sacked |= TCPCB_SACKED_ACKED;

		flag |= FLAG_DATA_SACKED;

		tp->sacked_out += tcp_skb_pcount(skb);



		fack_count += tcp_skb_pcount(skb);



		/* 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))

			tp->lost_cnt_hint += tcp_skb_pcount(skb);



		if (fack_count > tp->fackets_out)

			tp->fackets_out = fack_count;



		if (after(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))

			tp->highest_sack = skb;



	} else {

		if (dup_sack && (sacked & TCPCB_RETRANS))

			*reord = min(fack_count, *reord);

	}



	/* D-SACK. We can detect redundant retransmission in S|R and plain R

	 * frames and clear it. undo_retrans is decreased above, L|R frames

	 * are accounted above as well.

	 */

	if (dup_sack && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)) {

		TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;

		tp->retrans_out -= tcp_skb_pcount(skb);

		tp->retransmit_skb_hint = NULL;

	}



	return flag;

}



static int

tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_una)

{
@@ -1375,7 +1468,6 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 


		tcp_for_write_queue_from(skb, sk) {

			int in_sack = 0;

			u8 sacked;



			if (skb == tcp_send_head(sk))

				break;
@@ -1413,102 +1505,10 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
			if (unlikely(in_sack < 0))

				break;



			if (!in_sack) {

				fack_count += tcp_skb_pcount(skb);

				continue;

			}



			sacked = TCP_SKB_CB(skb)->sacked;



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

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

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

					tp->undo_retrans--;

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

				    (sacked & TCPCB_SACKED_ACKED))

					reord = min(fack_count, reord);

			}





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

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

				fack_count += tcp_skb_pcount(skb);

				continue;

			}



			if (!(sacked&TCPCB_SACKED_ACKED)) {

				if (sacked & TCPCB_SACKED_RETRANS) {

					/* If the segment is not tagged as lost,

					 * we do not clear RETRANS, believing

					 * that retransmission is still in flight.

					 */

					if (sacked & TCPCB_LOST) {

						TCP_SKB_CB(skb)->sacked &= ~(TCPCB_LOST|TCPCB_SACKED_RETRANS);

						tp->lost_out -= tcp_skb_pcount(skb);

						tp->retrans_out -= tcp_skb_pcount(skb);



						/* clear lost hint */

						tp->retransmit_skb_hint = NULL;

					}

				} else {

					if (!(sacked & TCPCB_RETRANS)) {

						/* New sack for not retransmitted frame,

						 * which was in hole. It is reordering.

						 */

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

							   tcp_highest_sack_seq(tp)))

							reord = min(fack_count, reord);



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

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

							flag |= FLAG_ONLY_ORIG_SACKED;

					}



					if (sacked & TCPCB_LOST) {

						TCP_SKB_CB(skb)->sacked &= ~TCPCB_LOST;

						tp->lost_out -= tcp_skb_pcount(skb);



						/* clear lost hint */

						tp->retransmit_skb_hint = NULL;

					}

				}



				TCP_SKB_CB(skb)->sacked |= TCPCB_SACKED_ACKED;

				flag |= FLAG_DATA_SACKED;

				tp->sacked_out += tcp_skb_pcount(skb);

			if (in_sack)

				flag |= tcp_sacktag_one(skb, tp, &reord, dup_sack, fack_count);



			fack_count += tcp_skb_pcount(skb);



				/* 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))

					tp->lost_cnt_hint += tcp_skb_pcount(skb);



				if (fack_count > tp->fackets_out)

					tp->fackets_out = fack_count;



				if (after(TCP_SKB_CB(skb)->seq, tcp_highest_sack_seq(tp)))

					tp->highest_sack = skb;



			} else {

				if (dup_sack && (sacked&TCPCB_RETRANS))

					reord = min(fack_count, reord);



				fack_count += tcp_skb_pcount(skb);

			}



			/* D-SACK. We can detect redundant retransmission

			 * in S|R and plain R frames and clear it.

			 * undo_retrans is decreased above, L|R frames

			 * are accounted above as well.

			 */

			if (dup_sack &&

			    (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS)) {

				TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;

				tp->retrans_out -= tcp_skb_pcount(skb);

				tp->retransmit_skb_hint = NULL;

			}

		}



		/* SACK enhanced FRTO (RFC4138, Appendix B): Clearing correct