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Commit fda03fbb authored by Baruch Even's avatar Baruch Even Committed by David S. Miller
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[TCP]: Advance fast path pointer for first block only 



Only advance the SACK fast-path pointer for the first block, the
fast-path assumes that only the first block advances next time so we
should not move the cached skb for the next sack blocks.

Signed-off-by: default avatarBaruch Even <baruch@ev-en.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ffbc6111

net/ipv4/tcp_input.c

+24 −10
Original line number Diff line number Diff line
@@ -936,13 +936,16 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
	struct tcp_sock *tp = tcp_sk(sk);

	unsigned char *ptr = ack_skb->h.raw + TCP_SKB_CB(ack_skb)->sacked;

	struct tcp_sack_block_wire *sp = (struct tcp_sack_block_wire *)(ptr+2);

	struct sk_buff *cached_skb;

	int num_sacks = (ptr[1] - TCPOLEN_SACK_BASE)>>3;

	int reord = tp->packets_out;

	int prior_fackets;

	u32 lost_retrans = 0;

	int flag = 0;

	int dup_sack = 0;

	int cached_fack_count;

	int i;

	int first_sack_index;



	if (!tp->sacked_out)

		tp->fackets_out = 0;
@@ -1000,6 +1003,7 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
		}

	}



	first_sack_index = 0;

	if (flag)

		num_sacks = 1;

	else {
@@ -1016,6 +1020,10 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
					tmp = sp[j];

					sp[j] = sp[j+1];

					sp[j+1] = tmp;



					/* Track where the first SACK block goes to */

					if (j == first_sack_index)

						first_sack_index = j+1;

				}



			}
@@ -1025,20 +1033,22 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
	/* clear flag as used for different purpose in following code */

	flag = 0;



	/* Use SACK fastpath hint if valid */

	cached_skb = tp->fastpath_skb_hint;

	cached_fack_count = tp->fastpath_cnt_hint;

	if (!cached_skb) {

		cached_skb = sk->sk_write_queue.next;

		cached_fack_count = 0;

	}



	for (i=0; i<num_sacks; i++, sp++) {

		struct sk_buff *skb;

		__u32 start_seq = ntohl(sp->start_seq);

		__u32 end_seq = ntohl(sp->end_seq);

		int fack_count;



		/* Use SACK fastpath hint if valid */

		if (tp->fastpath_skb_hint) {

			skb = tp->fastpath_skb_hint;

			fack_count = tp->fastpath_cnt_hint;

		} else {

			skb = sk->sk_write_queue.next;

			fack_count = 0;

		}

		skb = cached_skb;

		fack_count = cached_fack_count;



		/* Event "B" in the comment above. */

		if (after(end_seq, tp->high_seq))
@@ -1048,8 +1058,12 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ 
			int in_sack, pcount;

			u8 sacked;



			cached_skb = skb;

			cached_fack_count = fack_count;

			if (i == first_sack_index) {

				tp->fastpath_skb_hint = skb;

				tp->fastpath_cnt_hint = fack_count;

			}



			/* The retransmission queue is always in order, so

			 * we can short-circuit the walk early.