4.19-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ Upstream commit 19119f298bb1f2af3bb1093f5f2a1fed8da94e37 ]
Neal pointed out that non sack flows might suffer from ACK compression added in the following patch ("tcp: implement coalescing on backlog queue")
Instead of tweaking tcp_add_backlog() we can take into account how many ACK were coalesced, this information will be available in skb_shinfo(skb)->gso_segs
Signed-off-by: Eric Dumazet edumazet@google.com Acked-by: Neal Cardwell ncardwell@google.com Signed-off-by: David S. Miller davem@davemloft.net Stable-dep-of: a6458ab7fd4f ("UPSTREAM: tcp: fix DSACK undo in fast recovery to call tcp_try_to_open()") Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/tcp_input.c | 58 +++++++++++++++++++++++++------------------- 1 file changed, 33 insertions(+), 25 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 6a8c7c521d36e..022d75c67096a 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1897,16 +1897,20 @@ static void tcp_check_reno_reordering(struct sock *sk, const int addend)
/* Emulate SACKs for SACKless connection: account for a new dupack. */
-static void tcp_add_reno_sack(struct sock *sk) +static void tcp_add_reno_sack(struct sock *sk, int num_dupack) { - struct tcp_sock *tp = tcp_sk(sk); - u32 prior_sacked = tp->sacked_out; + if (num_dupack) { + struct tcp_sock *tp = tcp_sk(sk); + u32 prior_sacked = tp->sacked_out; + s32 delivered;
- tp->sacked_out++; - tcp_check_reno_reordering(sk, 0); - if (tp->sacked_out > prior_sacked) - tp->delivered++; /* Some out-of-order packet is delivered */ - tcp_verify_left_out(tp); + tp->sacked_out += num_dupack; + tcp_check_reno_reordering(sk, 0); + delivered = tp->sacked_out - prior_sacked; + if (delivered > 0) + tp->delivered += delivered; + tcp_verify_left_out(tp); + } }
/* Account for ACK, ACKing some data in Reno Recovery phase. */ @@ -2687,7 +2691,7 @@ void tcp_enter_recovery(struct sock *sk, bool ece_ack) /* Process an ACK in CA_Loss state. Move to CA_Open if lost data are * recovered or spurious. Otherwise retransmits more on partial ACKs. */ -static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack, +static void tcp_process_loss(struct sock *sk, int flag, int num_dupack, int *rexmit) { struct tcp_sock *tp = tcp_sk(sk); @@ -2706,7 +2710,7 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack, return;
if (after(tp->snd_nxt, tp->high_seq)) { - if (flag & FLAG_DATA_SACKED || is_dupack) + if (flag & FLAG_DATA_SACKED || num_dupack) tp->frto = 0; /* Step 3.a. loss was real */ } else if (flag & FLAG_SND_UNA_ADVANCED && !recovered) { tp->high_seq = tp->snd_nxt; @@ -2732,8 +2736,8 @@ static void tcp_process_loss(struct sock *sk, int flag, bool is_dupack, /* A Reno DUPACK means new data in F-RTO step 2.b above are * delivered. Lower inflight to clock out (re)tranmissions. */ - if (after(tp->snd_nxt, tp->high_seq) && is_dupack) - tcp_add_reno_sack(sk); + if (after(tp->snd_nxt, tp->high_seq) && num_dupack) + tcp_add_reno_sack(sk, num_dupack); else if (flag & FLAG_SND_UNA_ADVANCED) tcp_reset_reno_sack(tp); } @@ -2811,13 +2815,13 @@ static bool tcp_force_fast_retransmit(struct sock *sk) * tcp_xmit_retransmit_queue(). */ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una, - bool is_dupack, int *ack_flag, int *rexmit) + int num_dupack, int *ack_flag, int *rexmit) { struct inet_connection_sock *icsk = inet_csk(sk); struct tcp_sock *tp = tcp_sk(sk); int fast_rexmit = 0, flag = *ack_flag; - bool do_lost = is_dupack || ((flag & FLAG_DATA_SACKED) && - tcp_force_fast_retransmit(sk)); + bool do_lost = num_dupack || ((flag & FLAG_DATA_SACKED) && + tcp_force_fast_retransmit(sk));
if (!tp->packets_out && tp->sacked_out) tp->sacked_out = 0; @@ -2864,8 +2868,8 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una, switch (icsk->icsk_ca_state) { case TCP_CA_Recovery: if (!(flag & FLAG_SND_UNA_ADVANCED)) { - if (tcp_is_reno(tp) && is_dupack) - tcp_add_reno_sack(sk); + if (tcp_is_reno(tp)) + tcp_add_reno_sack(sk, num_dupack); } else { if (tcp_try_undo_partial(sk, prior_snd_una)) return; @@ -2880,7 +2884,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una, tcp_identify_packet_loss(sk, ack_flag); break; case TCP_CA_Loss: - tcp_process_loss(sk, flag, is_dupack, rexmit); + tcp_process_loss(sk, flag, num_dupack, rexmit); tcp_identify_packet_loss(sk, ack_flag); if (!(icsk->icsk_ca_state == TCP_CA_Open || (*ack_flag & FLAG_LOST_RETRANS))) @@ -2891,8 +2895,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una, if (tcp_is_reno(tp)) { if (flag & FLAG_SND_UNA_ADVANCED) tcp_reset_reno_sack(tp); - if (is_dupack) - tcp_add_reno_sack(sk); + tcp_add_reno_sack(sk, num_dupack); }
if (icsk->icsk_ca_state <= TCP_CA_Disorder) @@ -3623,7 +3626,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) bool is_sack_reneg = tp->is_sack_reneg; u32 ack_seq = TCP_SKB_CB(skb)->seq; u32 ack = TCP_SKB_CB(skb)->ack_seq; - bool is_dupack = false; + int num_dupack = 0; int prior_packets = tp->packets_out; u32 delivered = tp->delivered; u32 lost = tp->lost; @@ -3743,8 +3746,13 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) tcp_process_tlp_ack(sk, ack, flag);
if (tcp_ack_is_dubious(sk, flag)) { - is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP)); - tcp_fastretrans_alert(sk, prior_snd_una, is_dupack, &flag, + if (!(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP))) { + num_dupack = 1; + /* Consider if pure acks were aggregated in tcp_add_backlog() */ + if (!(flag & FLAG_DATA)) + num_dupack = max_t(u16, 1, skb_shinfo(skb)->gso_segs); + } + tcp_fastretrans_alert(sk, prior_snd_una, num_dupack, &flag, &rexmit); }
@@ -3766,7 +3774,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) no_queue: /* If data was DSACKed, see if we can undo a cwnd reduction. */ if (flag & FLAG_DSACKING_ACK) { - tcp_fastretrans_alert(sk, prior_snd_una, is_dupack, &flag, + tcp_fastretrans_alert(sk, prior_snd_una, num_dupack, &flag, &rexmit); tcp_newly_delivered(sk, delivered, flag); } @@ -3791,7 +3799,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) if (TCP_SKB_CB(skb)->sacked) { flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una, &sack_state); - tcp_fastretrans_alert(sk, prior_snd_una, is_dupack, &flag, + tcp_fastretrans_alert(sk, prior_snd_una, num_dupack, &flag, &rexmit); tcp_newly_delivered(sk, delivered, flag); tcp_xmit_recovery(sk, rexmit);