1 files changed, 16 insertions, 6 deletions

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 734cfc8ff76e..45f750e85714 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -508,9 +508,6 @@ static void tcp_rcv_rtt_update(struct tcp_sock *tp, u32 sample, int win_dep)
         u32 new_sample = tp->rcv_rtt_est.rtt_us;
         long m = sample;
 
-        if (m == 0)
-                m = 1;
-
         if (new_sample != 0) {
                 /* If we sample in larger samples in the non-timestamp
                  * case, we could grossly overestimate the RTT especially
@@ -547,6 +544,8 @@ static inline void tcp_rcv_rtt_measure(struct tcp_sock *tp)
         if (before(tp->rcv_nxt, tp->rcv_rtt_est.seq))
                 return;
         delta_us = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcv_rtt_est.time);
+        if (!delta_us)
+                delta_us = 1;
         tcp_rcv_rtt_update(tp, delta_us, 1);
 
 new_measure:
@@ -563,8 +562,11 @@ static inline void tcp_rcv_rtt_measure_ts(struct sock *sk,
             (TCP_SKB_CB(skb)->end_seq -
              TCP_SKB_CB(skb)->seq >= inet_csk(sk)->icsk_ack.rcv_mss)) {
                 u32 delta = tcp_time_stamp(tp) - tp->rx_opt.rcv_tsecr;
-                u32 delta_us = delta * (USEC_PER_SEC / TCP_TS_HZ);
+                u32 delta_us;
 
+                if (!delta)
+                        delta = 1;
+                delta_us = delta * (USEC_PER_SEC / TCP_TS_HZ);
                 tcp_rcv_rtt_update(tp, delta_us, 0);
         }
 }
@@ -579,6 +581,7 @@ void tcp_rcv_space_adjust(struct sock *sk)
         int time;
         int copied;
 
+        tcp_mstamp_refresh(tp);
         time = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcvq_space.time);
         if (time < (tp->rcv_rtt_est.rtt_us >> 3) || tp->rcv_rtt_est.rtt_us == 0)
                 return;
@@ -1941,6 +1944,8 @@ void tcp_enter_loss(struct sock *sk)
         if (is_reneg) {
                 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPSACKRENEGING);
                 tp->sacked_out = 0;
+                /* Mark SACK reneging until we recover from this loss event. */
+                tp->is_sack_reneg = 1;
         }
         tcp_clear_all_retrans_hints(tp);
 
@@ -2326,6 +2331,7 @@ static void tcp_undo_cwnd_reduction(struct sock *sk, bool unmark_loss)
         }
         tp->snd_cwnd_stamp = tcp_jiffies32;
         tp->undo_marker = 0;
+        tp->rack.advanced = 1; /* Force RACK to re-exam losses */
 }
 
 static inline bool tcp_may_undo(const struct tcp_sock *tp)
@@ -2364,6 +2370,7 @@ static bool tcp_try_undo_recovery(struct sock *sk)
                 return true;
         }
         tcp_set_ca_state(sk, TCP_CA_Open);
+        tp->is_sack_reneg = 0;
         return false;
 }
 
@@ -2397,8 +2404,10 @@ static bool tcp_try_undo_loss(struct sock *sk, bool frto_undo)
                         NET_INC_STATS(sock_net(sk),
                                         LINUX_MIB_TCPSPURIOUSRTOS);
                 inet_csk(sk)->icsk_retransmits = 0;
-                if (frto_undo || tcp_is_sack(tp))
+                if (frto_undo || tcp_is_sack(tp)) {
                         tcp_set_ca_state(sk, TCP_CA_Open);
+                        tp->is_sack_reneg = 0;
+                }
                 return true;
         }
         return false;
@@ -3495,6 +3504,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
         struct tcp_sacktag_state sack_state;
         struct rate_sample rs = { .prior_delivered = 0 };
         u32 prior_snd_una = tp->snd_una;
+        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;
@@ -3611,7 +3621,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
 
         delivered = tp->delivered - delivered;  /* freshly ACKed or SACKed */
         lost = tp->lost - lost;                 /* freshly marked lost */
-        tcp_rate_gen(sk, delivered, lost, sack_state.rate);
+        tcp_rate_gen(sk, delivered, lost, is_sack_reneg, sack_state.rate);
         tcp_cong_control(sk, ack, delivered, flag, sack_state.rate);
         tcp_xmit_recovery(sk, rexmit);
         return 1;