diff options
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/tcp_input.c | 29 | ||||
| -rw-r--r-- | net/ipv4/tcp_timer.c | 4 |
2 files changed, 20 insertions, 13 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 7832d941dbcd..6a2984507755 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1904,16 +1904,17 @@ void tcp_clear_retrans(struct tcp_sock *tp) tp->sacked_out = 0; } -/* Enter Loss state. If "how" is not zero, forget all SACK information +/* Enter Loss state. If we detect SACK reneging, forget all SACK information * and reset tags completely, otherwise preserve SACKs. If receiver * dropped its ofo queue, we will know this due to reneging detection. */ -void tcp_enter_loss(struct sock *sk, int how) +void tcp_enter_loss(struct sock *sk) { const struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *skb; bool new_recovery = false; + bool is_reneg; /* is receiver reneging on SACKs? */ /* Reduce ssthresh if it has not yet been made inside this window. */ if (icsk->icsk_ca_state <= TCP_CA_Disorder || @@ -1934,7 +1935,11 @@ void tcp_enter_loss(struct sock *sk, int how) tcp_reset_reno_sack(tp); tp->undo_marker = tp->snd_una; - if (how) { + + skb = tcp_write_queue_head(sk); + is_reneg = skb && (TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED); + if (is_reneg) { + NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSACKRENEGING); tp->sacked_out = 0; tp->fackets_out = 0; } @@ -1948,7 +1953,7 @@ void tcp_enter_loss(struct sock *sk, int how) tp->undo_marker = 0; TCP_SKB_CB(skb)->sacked &= (~TCPCB_TAGBITS)|TCPCB_SACKED_ACKED; - if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || how) { + if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || is_reneg) { TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED; TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; tp->lost_out += tcp_skb_pcount(skb); @@ -1981,19 +1986,21 @@ void tcp_enter_loss(struct sock *sk, int how) * remembered SACKs do not reflect real state of receiver i.e. * receiver _host_ is heavily congested (or buggy). * - * Do processing similar to RTO timeout. + * To avoid big spurious retransmission bursts due to transient SACK + * scoreboard oddities that look like reneging, we give the receiver a + * little time (max(RTT/2, 10ms)) to send us some more ACKs that will + * restore sanity to the SACK scoreboard. If the apparent reneging + * persists until this RTO then we'll clear the SACK scoreboard. */ static bool tcp_check_sack_reneging(struct sock *sk, int flag) { if (flag & FLAG_SACK_RENEGING) { - struct inet_connection_sock *icsk = inet_csk(sk); - NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPSACKRENEGING); + struct tcp_sock *tp = tcp_sk(sk); + unsigned long delay = max(usecs_to_jiffies(tp->srtt_us >> 4), + msecs_to_jiffies(10)); - tcp_enter_loss(sk, 1); - icsk->icsk_retransmits++; - tcp_retransmit_skb(sk, tcp_write_queue_head(sk)); inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, - icsk->icsk_rto, TCP_RTO_MAX); + delay, TCP_RTO_MAX); return true; } return false; diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 286227abed10..df90cd1ce37f 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -391,7 +391,7 @@ void tcp_retransmit_timer(struct sock *sk) tcp_write_err(sk); goto out; } - tcp_enter_loss(sk, 0); + tcp_enter_loss(sk); tcp_retransmit_skb(sk, tcp_write_queue_head(sk)); __sk_dst_reset(sk); goto out_reset_timer; @@ -422,7 +422,7 @@ void tcp_retransmit_timer(struct sock *sk) NET_INC_STATS_BH(sock_net(sk), mib_idx); } - tcp_enter_loss(sk, 0); + tcp_enter_loss(sk); if (tcp_retransmit_skb(sk, tcp_write_queue_head(sk)) > 0) { /* Retransmission failed because of local congestion, |