From af82f4e84866ecd360a53f770d6217637116e6c1 Mon Sep 17 00:00:00 2001 From: Yuchung Cheng Date: Fri, 16 Oct 2015 21:57:43 -0700 Subject: [PATCH] tcp: remove tcp_mark_lost_retrans() Remove the existing lost retransmit detection because RACK subsumes it completely. This also stops the overloading the ack_seq field of the skb control block. Signed-off-by: Yuchung Cheng Signed-off-by: Neal Cardwell Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- include/linux/tcp.h | 2 -- net/ipv4/tcp_input.c | 65 --------------------------------------------------- net/ipv4/tcp_output.c | 6 ----- 3 files changed, 73 deletions(-) diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 90edef5..8c54863 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -283,8 +283,6 @@ struct tcp_sock { int lost_cnt_hint; u32 retransmit_high; /* L-bits may be on up to this seqno */ - u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */ - u32 prior_ssthresh; /* ssthresh saved at recovery start */ u32 high_seq; /* snd_nxt at onset of congestion */ diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index eedb25d..5a77689 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1048,70 +1048,6 @@ static bool tcp_is_sackblock_valid(struct tcp_sock *tp, bool is_dsack, return !before(start_seq, end_seq - tp->max_window); } -/* Check for lost retransmit. This superb idea is borrowed from "ratehalving". - * Event "B". Later note: FACK people cheated me again 8), we have to account - * for reordering! Ugly, but should help. - * - * Search retransmitted skbs from write_queue that were sent when snd_nxt was - * less than what is now known to be received by the other end (derived from - * highest SACK block). Also calculate the lowest snd_nxt among the remaining - * retransmitted skbs to avoid some costly processing per ACKs. - */ -static void tcp_mark_lost_retrans(struct sock *sk, int *flag) -{ - const struct inet_connection_sock *icsk = inet_csk(sk); - struct tcp_sock *tp = tcp_sk(sk); - struct sk_buff *skb; - int cnt = 0; - u32 new_low_seq = tp->snd_nxt; - u32 received_upto = tcp_highest_sack_seq(tp); - - if (!tcp_is_fack(tp) || !tp->retrans_out || - !after(received_upto, tp->lost_retrans_low) || - icsk->icsk_ca_state != TCP_CA_Recovery) - return; - - tcp_for_write_queue(skb, sk) { - u32 ack_seq = TCP_SKB_CB(skb)->ack_seq; - - if (skb == tcp_send_head(sk)) - break; - if (cnt == tp->retrans_out) - break; - if (!after(TCP_SKB_CB(skb)->end_seq, tp->snd_una)) - continue; - - if (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_RETRANS)) - continue; - - /* TODO: We would like to get rid of tcp_is_fack(tp) only - * constraint here (see above) but figuring out that at - * least tp->reordering SACK blocks reside between ack_seq - * and received_upto is not easy task to do cheaply with - * the available datastructures. - * - * Whether FACK should check here for tp->reordering segs - * in-between one could argue for either way (it would be - * rather simple to implement as we could count fack_count - * during the walk and do tp->fackets_out - fack_count). - */ - if (after(received_upto, ack_seq)) { - TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS; - tp->retrans_out -= tcp_skb_pcount(skb); - *flag |= FLAG_LOST_RETRANS; - tcp_skb_mark_lost_uncond_verify(tp, skb); - NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT); - } else { - if (before(ack_seq, new_low_seq)) - new_low_seq = ack_seq; - cnt += tcp_skb_pcount(skb); - } - } - - if (tp->retrans_out) - tp->lost_retrans_low = new_low_seq; -} - static bool tcp_check_dsack(struct sock *sk, const struct sk_buff *ack_skb, struct tcp_sack_block_wire *sp, int num_sacks, u32 prior_snd_una) @@ -1838,7 +1774,6 @@ advance_sp: ((inet_csk(sk)->icsk_ca_state != TCP_CA_Loss) || tp->undo_marker)) tcp_update_reordering(sk, tp->fackets_out - state->reord, 0); - tcp_mark_lost_retrans(sk, &state->flag); tcp_verify_left_out(tp); out: diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 19adedb..f6f7f9b 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2655,8 +2655,6 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) net_dbg_ratelimited("retrans_out leaked\n"); } #endif - if (!tp->retrans_out) - tp->lost_retrans_low = tp->snd_nxt; TCP_SKB_CB(skb)->sacked |= TCPCB_RETRANS; tp->retrans_out += tcp_skb_pcount(skb); @@ -2664,10 +2662,6 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) if (!tp->retrans_stamp) tp->retrans_stamp = tcp_skb_timestamp(skb); - /* snd_nxt is stored to detect loss of retransmitted segment, - * see tcp_input.c tcp_sacktag_write_queue(). - */ - TCP_SKB_CB(skb)->ack_seq = tp->snd_nxt; } else if (err != -EBUSY) { NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPRETRANSFAIL); } -- 2.7.4