1 files changed, 50 insertions, 21 deletions

diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 8816a20c2597..74c54b30600f 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);
@@ -39,7 +41,6 @@ void tcp_init_xmit_timers(struct sock *sk)
         inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer,
                                   &tcp_keepalive_timer);
 }
-
 EXPORT_SYMBOL(tcp_init_xmit_timers);
 
 static void tcp_write_err(struct sock *sk)
@@ -65,18 +66,18 @@ static void tcp_write_err(struct sock *sk)
 static int tcp_out_of_resources(struct sock *sk, int do_reset)
 {
         struct tcp_sock *tp = tcp_sk(sk);
-        int orphans = percpu_counter_read_positive(&tcp_orphan_count);
+        int shift = 0;
 
         /* If peer does not open window for long time, or did not transmit
          * anything for long time, penalize it. */
         if ((s32)(tcp_time_stamp - tp->lsndtime) > 2*TCP_RTO_MAX || !do_reset)
-                orphans <<= 1;
+                shift++;
 
         /* If some dubious ICMP arrived, penalize even more. */
         if (sk->sk_err_soft)
-                orphans <<= 1;
+                shift++;
 
-        if (tcp_too_many_orphans(sk, orphans)) {
+        if (tcp_too_many_orphans(sk, shift)) {
                 if (net_ratelimit())
                         printk(KERN_INFO "Out of socket memory\n");
 
@@ -133,14 +134,17 @@ 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" unsucessful, exponentially backed-off
- * retransmissions with an initial RTO of TCP_RTO_MIN.
+ * TCP connection after "boundary" unsuccessful, exponentially backed-off
+ * retransmissions with an initial RTO of TCP_RTO_MIN or TCP_TIMEOUT_INIT if
+ * syn_set flag is set.
  */
 static bool retransmits_timed_out(struct sock *sk,
-                                  unsigned int boundary)
+                                  unsigned int boundary,
+                                  bool syn_set)
 {
         unsigned int timeout, linear_backoff_thresh;
         unsigned int start_ts;
+        unsigned int rto_base = syn_set ? TCP_TIMEOUT_INIT : TCP_RTO_MIN;
 
         if (!inet_csk(sk)->icsk_retransmits)
                 return false;
@@ -150,12 +154,12 @@ static bool retransmits_timed_out(struct sock *sk,
         else
                 start_ts = tcp_sk(sk)->retrans_stamp;
 
-        linear_backoff_thresh = ilog2(TCP_RTO_MAX/TCP_RTO_MIN);
+        linear_backoff_thresh = ilog2(TCP_RTO_MAX/rto_base);
 
         if (boundary <= linear_backoff_thresh)
-                timeout = ((2 << boundary) - 1) * TCP_RTO_MIN;
+                timeout = ((2 << boundary) - 1) * rto_base;
         else
-                timeout = ((2 << linear_backoff_thresh) - 1) * TCP_RTO_MIN +
+                timeout = ((2 << linear_backoff_thresh) - 1) * rto_base +
                           (boundary - linear_backoff_thresh) * TCP_RTO_MAX;
 
         return (tcp_time_stamp - start_ts) >= timeout;
@@ -166,18 +170,19 @@ static int tcp_write_timeout(struct sock *sk)
 {
         struct inet_connection_sock *icsk = inet_csk(sk);
         int retry_until;
-        bool do_reset;
+        bool do_reset, syn_set = 0;
 
         if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
                 if (icsk->icsk_retransmits)
-                        dst_negative_advice(&sk->sk_dst_cache, sk);
+                        dst_negative_advice(sk);
                 retry_until = icsk->icsk_syn_retries ? : sysctl_tcp_syn_retries;
+                syn_set = 1;
         } else {
-                if (retransmits_timed_out(sk, sysctl_tcp_retries1)) {
+                if (retransmits_timed_out(sk, sysctl_tcp_retries1, 0)) {
                         /* Black hole detection */
                         tcp_mtu_probing(icsk, sk);
 
-                        dst_negative_advice(&sk->sk_dst_cache, sk);
+                        dst_negative_advice(sk);
                 }
 
                 retry_until = sysctl_tcp_retries2;
@@ -186,14 +191,14 @@ static int tcp_write_timeout(struct sock *sk)
 
                         retry_until = tcp_orphan_retries(sk, alive);
                         do_reset = alive ||
-                                   !retransmits_timed_out(sk, retry_until);
+                                   !retransmits_timed_out(sk, retry_until, 0);
 
                         if (tcp_out_of_resources(sk, do_reset))
                                 return 1;
                 }
         }
 
-        if (retransmits_timed_out(sk, retry_until)) {
+        if (retransmits_timed_out(sk, retry_until, syn_set)) {
                 /* Has it gone just too far? */
                 tcp_write_err(sk);
                 return 1;
@@ -415,9 +420,27 @@ 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))
+        if (retransmits_timed_out(sk, sysctl_tcp_retries1 + 1, 0))
                 __sk_dst_reset(sk);
 
 out:;
@@ -474,6 +497,12 @@ 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))
@@ -491,7 +520,7 @@ static void tcp_keepalive_timer (unsigned long data)
         struct sock *sk = (struct sock *) data;
         struct inet_connection_sock *icsk = inet_csk(sk);
         struct tcp_sock *tp = tcp_sk(sk);
-        __u32 elapsed;
+        u32 elapsed;
 
         /* Only process if socket is not in use. */
         bh_lock_sock(sk);
@@ -528,7 +557,7 @@ static void tcp_keepalive_timer (unsigned long data)
         if (tp->packets_out || tcp_send_head(sk))
                 goto resched;
 
-        elapsed = tcp_time_stamp - tp->rcv_tstamp;
+        elapsed = keepalive_time_elapsed(tp);
 
         if (elapsed >= keepalive_time_when(tp)) {
                 if (icsk->icsk_probes_out >= keepalive_probes(tp)) {