diff options
| -rw-r--r-- | net/ipv4/tcp_input.c | 56 |
1 files changed, 36 insertions, 20 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 0aa17243d369..5187870d0333 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -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 |