1 files changed, 17 insertions, 14 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index eb7f82ebf4a3..bef9f04c22ba 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -817,7 +817,7 @@ __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst)
         __u32 cwnd = (dst ? dst_metric(dst, RTAX_INITCWND) : 0);
 
         if (!cwnd)
-                cwnd = rfc3390_bytes_to_packets(tp->mss_cache);
+                cwnd = TCP_INIT_CWND;
         return min_t(__u32, cwnd, tp->snd_cwnd_clamp);
 }
 
@@ -1222,7 +1222,7 @@ static int tcp_check_dsack(struct sock *sk, struct sk_buff *ack_skb,
         }
 
         /* D-SACK for already forgotten data... Do dumb counting. */
-        if (dup_sack &&
+        if (dup_sack && tp->undo_marker && tp->undo_retrans &&
             !after(end_seq_0, prior_snd_una) &&
             after(end_seq_0, tp->undo_marker))
                 tp->undo_retrans--;
@@ -1299,7 +1299,8 @@ static u8 tcp_sacktag_one(struct sk_buff *skb, struct sock *sk,
 
         /* Account D-SACK for retransmitted packet. */
         if (dup_sack && (sacked & TCPCB_RETRANS)) {
-                if (after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker))
+                if (tp->undo_marker && tp->undo_retrans &&
+                    after(TCP_SKB_CB(skb)->end_seq, tp->undo_marker))
                         tp->undo_retrans--;
                 if (sacked & TCPCB_SACKED_ACKED)
                         state->reord = min(fack_count, state->reord);
@@ -2658,7 +2659,7 @@ static void DBGUNDO(struct sock *sk, const char *msg)
 #define DBGUNDO(x...) do { } while (0)
 #endif
 
-static void tcp_undo_cwr(struct sock *sk, const int undo)
+static void tcp_undo_cwr(struct sock *sk, const bool undo_ssthresh)
 {
         struct tcp_sock *tp = tcp_sk(sk);
 
@@ -2670,14 +2671,13 @@ static void tcp_undo_cwr(struct sock *sk, const int undo)
                 else
                         tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh << 1);
 
-                if (undo && tp->prior_ssthresh > tp->snd_ssthresh) {
+                if (undo_ssthresh && tp->prior_ssthresh > tp->snd_ssthresh) {
                         tp->snd_ssthresh = tp->prior_ssthresh;
                         TCP_ECN_withdraw_cwr(tp);
                 }
         } else {
                 tp->snd_cwnd = max(tp->snd_cwnd, tp->snd_ssthresh);
         }
-        tcp_moderate_cwnd(tp);
         tp->snd_cwnd_stamp = tcp_time_stamp;
 }
 
@@ -2698,7 +2698,7 @@ static int tcp_try_undo_recovery(struct sock *sk)
                  * or our original transmission succeeded.
                  */
                 DBGUNDO(sk, inet_csk(sk)->icsk_ca_state == TCP_CA_Loss ? "loss" : "retrans");
-                tcp_undo_cwr(sk, 1);
+                tcp_undo_cwr(sk, true);
                 if (inet_csk(sk)->icsk_ca_state == TCP_CA_Loss)
                         mib_idx = LINUX_MIB_TCPLOSSUNDO;
                 else
@@ -2725,7 +2725,7 @@ static void tcp_try_undo_dsack(struct sock *sk)
 
         if (tp->undo_marker && !tp->undo_retrans) {
                 DBGUNDO(sk, "D-SACK");
-                tcp_undo_cwr(sk, 1);
+                tcp_undo_cwr(sk, true);
                 tp->undo_marker = 0;
                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDSACKUNDO);
         }
@@ -2778,7 +2778,7 @@ static int tcp_try_undo_partial(struct sock *sk, int acked)
                 tcp_update_reordering(sk, tcp_fackets_out(tp) + acked, 1);
 
                 DBGUNDO(sk, "Hoe");
-                tcp_undo_cwr(sk, 0);
+                tcp_undo_cwr(sk, false);
                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPPARTIALUNDO);
 
                 /* So... Do not make Hoe's retransmit yet.
@@ -2807,7 +2807,7 @@ static int tcp_try_undo_loss(struct sock *sk)
 
                 DBGUNDO(sk, "partial loss");
                 tp->lost_out = 0;
-                tcp_undo_cwr(sk, 1);
+                tcp_undo_cwr(sk, true);
                 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSSUNDO);
                 inet_csk(sk)->icsk_retransmits = 0;
                 tp->undo_marker = 0;
@@ -2821,8 +2821,11 @@ static int tcp_try_undo_loss(struct sock *sk)
 static inline void tcp_complete_cwr(struct sock *sk)
 {
         struct tcp_sock *tp = tcp_sk(sk);
-        tp->snd_cwnd = min(tp->snd_cwnd, tp->snd_ssthresh);
-        tp->snd_cwnd_stamp = tcp_time_stamp;
+        /* Do not moderate cwnd if it's already undone in cwr or recovery */
+        if (tp->undo_marker && tp->snd_cwnd > tp->snd_ssthresh) {
+                tp->snd_cwnd = tp->snd_ssthresh;
+                tp->snd_cwnd_stamp = tcp_time_stamp;
+        }
         tcp_ca_event(sk, CA_EVENT_COMPLETE_CWR);
 }
 
@@ -3349,7 +3352,7 @@ static int tcp_clean_rtx_queue(struct sock *sk, int prior_fackets,
                                                  net_invalid_timestamp()))
                                         rtt_us = ktime_us_delta(ktime_get_real(),
                                                                 last_ackt);
-                                else if (ca_seq_rtt > 0)
+                                else if (ca_seq_rtt >= 0)
                                         rtt_us = jiffies_to_usecs(ca_seq_rtt);
                         }
 
@@ -3493,7 +3496,7 @@ static void tcp_undo_spur_to_response(struct sock *sk, int flag)
         if (flag & FLAG_ECE)
                 tcp_ratehalving_spur_to_response(sk);
         else
-                tcp_undo_cwr(sk, 1);
+                tcp_undo_cwr(sk, true);
 }
 
 /* F-RTO spurious RTO detection algorithm (RFC4138)