tcp: do not expire TCP fastopen cookies

TCP metric cache expires entries after one hour.

This probably make sense for TCP RTT/RTTVAR/CWND, but not
for TCP fastopen cookies.

Its better to try previous cookie. If it appears to be obsolete,
server will send us new cookie anyway.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 6 deletions

diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index f696d7c2e9fa..f6a005c485a9 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -96,7 +96,8 @@ struct tcpm_hash_bucket {
 
 static DEFINE_SPINLOCK(tcp_metrics_lock);
 
-static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst)
+static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst,
+                          bool fastopen_clear)
 {
         u32 val;
 
@@ -122,9 +123,11 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm, struct dst_entry *dst)
         tm->tcpm_vals[TCP_METRIC_REORDERING] = dst_metric_raw(dst, RTAX_REORDERING);
         tm->tcpm_ts = 0;
         tm->tcpm_ts_stamp = 0;
-        tm->tcpm_fastopen.mss = 0;
-        tm->tcpm_fastopen.syn_loss = 0;
-        tm->tcpm_fastopen.cookie.len = 0;
+        if (fastopen_clear) {
+                tm->tcpm_fastopen.mss = 0;
+                tm->tcpm_fastopen.syn_loss = 0;
+                tm->tcpm_fastopen.cookie.len = 0;
+        }
 }
 
 static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
@@ -154,7 +157,7 @@ static struct tcp_metrics_block *tcpm_new(struct dst_entry *dst,
         }
         tm->tcpm_addr = *addr;
 
-        tcpm_suck_dst(tm, dst);
+        tcpm_suck_dst(tm, dst, true);
 
         if (likely(!reclaim)) {
                 tm->tcpm_next = net->ipv4.tcp_metrics_hash[hash].chain;
@@ -171,7 +174,7 @@ out_unlock:
 static void tcpm_check_stamp(struct tcp_metrics_block *tm, struct dst_entry *dst)
 {
         if (tm && unlikely(time_after(jiffies, tm->tcpm_stamp + TCP_METRICS_TIMEOUT)))
-                tcpm_suck_dst(tm, dst);
+                tcpm_suck_dst(tm, dst, false);
 }
 
 #define TCP_METRICS_RECLAIM_DEPTH       5