[TCP]: Extract DSACK detection code from tcp_sacktag_write_queue().
Signed-off-by: David S. Miller <davem@davemloft.net>
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19b2b48658
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d06e021d71
@ -960,6 +960,39 @@ static void tcp_update_reordering(struct sock *sk, const int metric,
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* Both of these heuristics are not used in Loss state, when we cannot
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* account for retransmits accurately.
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*/
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static int tcp_check_dsack(struct tcp_sock *tp, struct sk_buff *ack_skb,
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struct tcp_sack_block_wire *sp, int num_sacks,
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u32 prior_snd_una)
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{
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u32 start_seq_0 = ntohl(get_unaligned(&sp[0].start_seq));
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u32 end_seq_0 = ntohl(get_unaligned(&sp[0].end_seq));
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int dup_sack = 0;
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if (before(start_seq_0, TCP_SKB_CB(ack_skb)->ack_seq)) {
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dup_sack = 1;
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tp->rx_opt.sack_ok |= 4;
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NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
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} else if (num_sacks > 1) {
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u32 end_seq_1 = ntohl(get_unaligned(&sp[1].end_seq));
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u32 start_seq_1 = ntohl(get_unaligned(&sp[1].start_seq));
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if (!after(end_seq_0, end_seq_1) &&
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!before(start_seq_0, start_seq_1)) {
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dup_sack = 1;
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tp->rx_opt.sack_ok |= 4;
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NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
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}
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}
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/* D-SACK for already forgotten data... Do dumb counting. */
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if (dup_sack &&
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!after(end_seq_0, prior_snd_una) &&
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after(end_seq_0, tp->undo_marker))
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tp->undo_retrans--;
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return dup_sack;
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}
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static int
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tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_una)
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{
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@ -985,27 +1018,10 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_
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}
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prior_fackets = tp->fackets_out;
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/* Check for D-SACK. */
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if (before(ntohl(sp[0].start_seq), TCP_SKB_CB(ack_skb)->ack_seq)) {
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found_dup_sack = tcp_check_dsack(tp, ack_skb, sp,
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num_sacks, prior_snd_una);
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if (found_dup_sack)
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flag |= FLAG_DSACKING_ACK;
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found_dup_sack = 1;
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tp->rx_opt.sack_ok |= 4;
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NET_INC_STATS_BH(LINUX_MIB_TCPDSACKRECV);
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} else if (num_sacks > 1 &&
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!after(ntohl(sp[0].end_seq), ntohl(sp[1].end_seq)) &&
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!before(ntohl(sp[0].start_seq), ntohl(sp[1].start_seq))) {
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flag |= FLAG_DSACKING_ACK;
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found_dup_sack = 1;
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tp->rx_opt.sack_ok |= 4;
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NET_INC_STATS_BH(LINUX_MIB_TCPDSACKOFORECV);
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}
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/* D-SACK for already forgotten data...
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* Do dumb counting. */
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if (found_dup_sack &&
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!after(ntohl(sp[0].end_seq), prior_snd_una) &&
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after(ntohl(sp[0].end_seq), tp->undo_marker))
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tp->undo_retrans--;
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/* Eliminate too old ACKs, but take into
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* account more or less fresh ones, they can
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