[TCP]: Extract DSACK detection code from tcp_sacktag_write_queue(). (d06e021d) · Commits · e / devices / android_kernel_xiaomi_markw

net/ipv4/tcp_input.c

+36 −20

Original line number	Diff line number	Diff line
		@@ -960,6 +960,39 @@ static void tcp_update_reordering(struct sock *sk, const int metric,
		* Both of these heuristics are not used in Loss state, when we cannot
		* account for retransmits accurately.
		*/
		static int tcp_check_dsack(struct tcp_sock tp, struct sk_buff ack_skb,
		struct tcp_sack_block_wire *sp, int num_sacks,
		u32 prior_snd_una)
		{
		u32 start_seq_0 = ntohl(get_unaligned(&sp[0].start_seq));
		u32 end_seq_0 = ntohl(get_unaligned(&sp[0].end_seq));
		int dup_sack = 0;

		if (before(start_seq_0, TCP_SKB_CB(ack_skb)->ack_seq)) {
		dup_sack = 1;
		tp->rx_opt.sack_ok \|= 4;
		NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
		} else if (num_sacks > 1) {
		u32 end_seq_1 = ntohl(get_unaligned(&sp[1].end_seq));
		u32 start_seq_1 = ntohl(get_unaligned(&sp[1].start_seq));

		if (!after(end_seq_0, end_seq_1) &&
		!before(start_seq_0, start_seq_1)) {
		dup_sack = 1;
		tp->rx_opt.sack_ok \|= 4;
		NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
		}
		}

		/* D-SACK for already forgotten data... Do dumb counting. */
		if (dup_sack &&
		!after(end_seq_0, prior_snd_una) &&
		after(end_seq_0, tp->undo_marker))
		tp->undo_retrans--;

		return dup_sack;
		}

		static int
		tcp_sacktag_write_queue(struct sock sk, struct sk_buff ack_skb, u32 prior_snd_una)
		{
		@@ -985,27 +1018,10 @@ tcp_sacktag_write_queue(struct sock sk, struct sk_buff ack_skb, u32 prior_snd_
		}
		prior_fackets = tp->fackets_out;

		/* Check for D-SACK. */
		if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) {
		flag \|= FLAG_DSACKING_ACK;
		found_dup_sack = 1;
		tp->rx_opt.sack_ok \|= 4;
		NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
		} else if (num_sacks > 1 &&
		!after(ntohl(sp[0].end_seq), ntohl(sp[1].end_seq)) &&
		!before(ntohl(sp[0].start_seq), ntohl(sp[1].start_seq))) {
		found_dup_sack = tcp_check_dsack(tp, ack_skb, sp,
		num_sacks, prior_snd_una);
		if (found_dup_sack)
		flag \|= FLAG_DSACKING_ACK;
		found_dup_sack = 1;
		tp->rx_opt.sack_ok \|= 4;
		NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
		}

		/* D-SACK for already forgotten data...
		* Do dumb counting. */
		if (found_dup_sack &&
		!after(ntohl(sp[0].end_seq), prior_snd_una) &&
		after(ntohl(sp[0].end_seq), tp->undo_marker))
		tp->undo_retrans--;

		/* Eliminate too old ACKs, but take into
		* account more or less fresh ones, they can