tcp: adjust window probe timers to safer values

[firefly-linux-kernel-4.4.55.git] / include / net / tcp.h

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 6d204f3f9df8cafb82d856db08769a7d24dfd79e..7a2248a35b137f8d82cc0a543fa7a9991f51aeaa 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1043,14 +1043,31 @@ static inline bool tcp_is_cwnd_limited(const struct sock *sk)
        return tp->is_cwnd_limited;
 }
 
-static inline void tcp_check_probe_timer(struct sock *sk)
+/* Something is really bad, we could not queue an additional packet,
+ * because qdisc is full or receiver sent a 0 window.
+ * We do not want to add fuel to the fire, or abort too early,
+ * so make sure the timer we arm now is at least 200ms in the future,
+ * regardless of current icsk_rto value (as it could be ~2ms)
+ */
+static inline unsigned long tcp_probe0_base(const struct sock *sk)
 {
-       const struct tcp_sock *tp = tcp_sk(sk);
-       const struct inet_connection_sock *icsk = inet_csk(sk);
+       return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
+}
 
-       if (!tp->packets_out && !icsk->icsk_pending)
+/* Variant of inet_csk_rto_backoff() used for zero window probes */
+static inline unsigned long tcp_probe0_when(const struct sock *sk,
+                                           unsigned long max_when)
+{
+       u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff;
+
+       return (unsigned long)min_t(u64, when, max_when);
+}
+
+static inline void tcp_check_probe_timer(struct sock *sk)
+{
+       if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
                inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
-                                         icsk->icsk_rto, TCP_RTO_MAX);
+                                         tcp_probe0_base(sk), TCP_RTO_MAX);
 }
 
 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)