[PATCH net-next 1/3] net/tcp-fastopen: refactor cookie check logic

[Wei Wang]

From: Wei Wang <wei...@google.com>

Refactor the cookie check logic in tcp_send_syn_data() into a function.
This function will be called else where in later changes.

Signed-off-by: Wei Wang <wei...@google.com>
---
 include/net/tcp.h       |  2 ++
 net/ipv4/tcp_fastopen.c | 21 +++++++++++++++++++++
 net/ipv4/tcp_output.c   | 16 ++--------------
 3 files changed, 25 insertions(+), 14 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index c55d65f74f7f..de67541d7adf 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1493,6 +1493,8 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct 
sk_buff *skb,
                              struct tcp_fastopen_cookie *foc,
                              struct dst_entry *dst);
 void tcp_fastopen_init_key_once(bool publish);
+bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
+                            struct tcp_fastopen_cookie *cookie);
 #define TCP_FASTOPEN_KEY_LENGTH 16
 
 /* Fastopen key context */
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index f51919535ca7..f90e09e1ff4c 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -325,3 +325,24 @@ struct sock *tcp_try_fastopen(struct sock *sk, struct 
sk_buff *skb,
        *foc = valid_foc;
        return NULL;
 }
+
+bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
+                              struct tcp_fastopen_cookie *cookie)
+{
+       unsigned long last_syn_loss = 0;
+       int syn_loss = 0;
+
+       tcp_fastopen_cache_get(sk, mss, cookie, &syn_loss, &last_syn_loss);
+
+       /* Recurring FO SYN losses: no cookie or data in SYN */
+       if (syn_loss > 1 &&
+           time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) {
+               cookie->len = -1;
+               return false;
+       }
+       if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE) {
+               cookie->len = -1;
+               return true;
+       }
+       return cookie->len > 0;
+}
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 9a1a1494b9dd..671c69535671 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3267,23 +3267,11 @@ static int tcp_send_syn_data(struct sock *sk, struct 
sk_buff *syn)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        struct tcp_fastopen_request *fo = tp->fastopen_req;
-       int syn_loss = 0, space, err = 0;
-       unsigned long last_syn_loss = 0;
+       int space, err = 0;
        struct sk_buff *syn_data;
 
        tp->rx_opt.mss_clamp = tp->advmss;  /* If MSS is not cached */
-       tcp_fastopen_cache_get(sk, &tp->rx_opt.mss_clamp, &fo->cookie,
-                              &syn_loss, &last_syn_loss);
-       /* Recurring FO SYN losses: revert to regular handshake temporarily */
-       if (syn_loss > 1 &&
-           time_before(jiffies, last_syn_loss + (60*HZ << syn_loss))) {
-               fo->cookie.len = -1;
-               goto fallback;
-       }
-
-       if (sysctl_tcp_fastopen & TFO_CLIENT_NO_COOKIE)
-               fo->cookie.len = -1;
-       else if (fo->cookie.len <= 0)
+       if (!tcp_fastopen_cookie_check(sk, &tp->rx_opt.mss_clamp, &fo->cookie))
                goto fallback;
 
        /* MSS for SYN-data is based on cached MSS and bounded by PMTU and
-- 
2.11.0.483.g087da7b7c-goog