1 files changed, 11 insertions, 2 deletions

diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c
index 78ecc4a01712..a51d63a43e33 100644
--- a/net/ipv4/tcp_metrics.c
+++ b/net/ipv4/tcp_metrics.c
@@ -28,7 +28,8 @@ static struct tcp_metrics_block *__tcp_get_metrics(const struct inetpeer_addr *s
 
 struct tcp_fastopen_metrics {
         u16     mss;
-        u16     syn_loss:10;            /* Recurring Fast Open SYN losses */
+        u16     syn_loss:10,            /* Recurring Fast Open SYN losses */
+                try_exp:2;              /* Request w/ exp. option (once) */
         unsigned long   last_syn_loss;  /* Last Fast Open SYN loss */
         struct  tcp_fastopen_cookie     cookie;
 };
@@ -131,6 +132,8 @@ static void tcpm_suck_dst(struct tcp_metrics_block *tm,
         if (fastopen_clear) {
                 tm->tcpm_fastopen.mss = 0;
                 tm->tcpm_fastopen.syn_loss = 0;
+                tm->tcpm_fastopen.try_exp = 0;
+                tm->tcpm_fastopen.cookie.exp = false;
                 tm->tcpm_fastopen.cookie.len = 0;
         }
 }
@@ -713,6 +716,8 @@ void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
                         if (tfom->mss)
                                 *mss = tfom->mss;
                         *cookie = tfom->cookie;
+                        if (cookie->len <= 0 && tfom->try_exp == 1)
+                                cookie->exp = true;
                         *syn_loss = tfom->syn_loss;
                         *last_syn_loss = *syn_loss ? tfom->last_syn_loss : 0;
                 } while (read_seqretry(&fastopen_seqlock, seq));
@@ -721,7 +726,8 @@ void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
 }
 
 void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
-                            struct tcp_fastopen_cookie *cookie, bool syn_lost)
+                            struct tcp_fastopen_cookie *cookie, bool syn_lost,
+                            u16 try_exp)
 {
         struct dst_entry *dst = __sk_dst_get(sk);
         struct tcp_metrics_block *tm;
@@ -738,6 +744,9 @@ void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
                         tfom->mss = mss;
                 if (cookie && cookie->len > 0)
                         tfom->cookie = *cookie;
+                else if (try_exp > tfom->try_exp &&
+                         tfom->cookie.len <= 0 && !tfom->cookie.exp)
+                        tfom->try_exp = try_exp;
                 if (syn_lost) {
                         ++tfom->syn_loss;
                         tfom->last_syn_loss = jiffies;