1 files changed, 62 insertions, 7 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index cdb2ca7684d4..8a0ab2977f1f 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -19,6 +19,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/gfp.h>
 #include <net/tcp.h>
 
 int sysctl_tcp_syn_retries __read_mostly = TCP_SYN_RETRIES;
@@ -29,6 +30,7 @@ int sysctl_tcp_keepalive_intvl __read_mostly = TCP_KEEPALIVE_INTVL;
 int sysctl_tcp_retries1 __read_mostly = TCP_RETR1;
 int sysctl_tcp_retries2 __read_mostly = TCP_RETR2;
 int sysctl_tcp_orphan_retries __read_mostly;
+int sysctl_tcp_thin_linear_timeouts __read_mostly;
 
 static void tcp_write_timer(unsigned long);
 static void tcp_delack_timer(unsigned long);
@@ -132,6 +134,35 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
         }
 }
 
+/* This function calculates a "timeout" which is equivalent to the timeout of a
+ * TCP connection after "boundary" unsuccessful, exponentially backed-off
+ * retransmissions with an initial RTO of TCP_RTO_MIN.
+ */
+static bool retransmits_timed_out(struct sock *sk,
+                                  unsigned int boundary)
+{
+        unsigned int timeout, linear_backoff_thresh;
+        unsigned int start_ts;
+
+        if (!inet_csk(sk)->icsk_retransmits)
+                return false;
+
+        if (unlikely(!tcp_sk(sk)->retrans_stamp))
+                start_ts = TCP_SKB_CB(tcp_write_queue_head(sk))->when;
+        else
+                start_ts = tcp_sk(sk)->retrans_stamp;
+
+        linear_backoff_thresh = ilog2(TCP_RTO_MAX/TCP_RTO_MIN);
+
+        if (boundary <= linear_backoff_thresh)
+                timeout = ((2 << boundary) - 1) * TCP_RTO_MIN;
+        else
+                timeout = ((2 << linear_backoff_thresh) - 1) * TCP_RTO_MIN +
+                          (boundary - linear_backoff_thresh) * TCP_RTO_MAX;
+
+        return (tcp_time_stamp - start_ts) >= timeout;
+}
+
 /* A write timeout has occurred. Process the after effects. */
 static int tcp_write_timeout(struct sock *sk)
 {
@@ -141,14 +172,14 @@ static int tcp_write_timeout(struct sock *sk)
 
         if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
                 if (icsk->icsk_retransmits)
-                        dst_negative_advice(&sk->sk_dst_cache);
+                        dst_negative_advice(&sk->sk_dst_cache, sk);
                 retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
         } else {
                 if (retransmits_timed_out(sk, sysctl_tcp_retries1)) {
                         /* Black hole detection */
                         tcp_mtu_probing(icsk, sk);
 
-                        dst_negative_advice(&sk->sk_dst_cache);
+                        dst_negative_advice(&sk->sk_dst_cache, sk);
                 }
 
                 retry_until = sysctl_tcp_retries2;
@@ -303,15 +334,15 @@ void tcp_retransmit_timer(struct sock *sk)
                 struct inet_sock *inet = inet_sk(sk);
                 if (sk->sk_family == AF_INET) {
                         LIMIT_NETDEBUG(KERN_DEBUG "TCP: Peer %pI4:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
-                               &inet->daddr, ntohs(inet->dport),
-                               inet->num, tp->snd_una, tp->snd_nxt);
+                               &inet->inet_daddr, ntohs(inet->inet_dport),
+                               inet->inet_num, tp->snd_una, tp->snd_nxt);
                 }
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
                 else if (sk->sk_family == AF_INET6) {
                         struct ipv6_pinfo *np = inet6_sk(sk);
                         LIMIT_NETDEBUG(KERN_DEBUG "TCP: Peer %pI6:%u/%u unexpectedly shrunk window %u:%u (repaired)\n",
-                               &np->daddr, ntohs(inet->dport),
-                               inet->num, tp->snd_una, tp->snd_nxt);
+                               &np->daddr, ntohs(inet->inet_dport),
+                               inet->inet_num, tp->snd_una, tp->snd_nxt);
                 }
 #endif
 #endif
@@ -386,7 +417,25 @@ void tcp_retransmit_timer(struct sock *sk)
         icsk->icsk_retransmits++;
 
 out_reset_timer:
-        icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
+        /* If stream is thin, use linear timeouts. Since 'icsk_backoff' is
+         * used to reset timer, set to 0. Recalculate 'icsk_rto' as this
+         * might be increased if the stream oscillates between thin and thick,
+         * thus the old value might already be too high compared to the value
+         * set by 'tcp_set_rto' in tcp_input.c which resets the rto without
+         * backoff. Limit to TCP_THIN_LINEAR_RETRIES before initiating
+         * exponential backoff behaviour to avoid continue hammering
+         * linear-timeout retransmissions into a black hole
+         */
+        if (sk->sk_state == TCP_ESTABLISHED &&
+            (tp->thin_lto || sysctl_tcp_thin_linear_timeouts) &&
+            tcp_stream_is_thin(tp) &&
+            icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
+                icsk->icsk_backoff = 0;
+                icsk->icsk_rto = min(__tcp_set_rto(tp), TCP_RTO_MAX);
+        } else {
+                /* Use normal (exponential) backoff */
+                icsk->icsk_rto = min(icsk->icsk_rto << 1, TCP_RTO_MAX);
+        }
         inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX);
         if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1))
                 __sk_dst_reset(sk);
@@ -445,6 +494,12 @@ static void tcp_synack_timer(struct sock *sk)
                                    TCP_TIMEOUT_INIT, TCP_RTO_MAX);
 }
 
+void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req)
+{
+        NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPTIMEOUTS);
+}
+EXPORT_SYMBOL(tcp_syn_ack_timeout);
+
 void tcp_set_keepalive(struct sock *sk, int val)
 {
         if ((1 << sk->sk_state) & (TCPF_CLOSE | TCPF_LISTEN))