net/smc: fix fallback failed while sendmsg with fastopen

[ Upstream commit ce7ca794712f186da99719e8b4e97bd5ddbb04c3 ]

Before determining whether the msg has unsupported options, it has been
prematurely terminated by the wrong status check.

For the application, the general usages of MSG_FASTOPEN likes

fd = socket(...)
/* rather than connect */
sendto(fd, data, len, MSG_FASTOPEN)

Hence, We need to check the flag before state check, because the sock
state here is always SMC_INIT when applications tries MSG_FASTOPEN.
Once we found unsupported options, fallback it to TCP.

Fixes: ecf28acb843b ("net/smc: handle sockopts forcing fallback")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
v2 -> v1: Optimize code style
Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 5d696b7fb47e10226ba5c7f888c471234c7b61e0..b398d72a7bc395efbe27aacb13e748fa7de2b7ef 100644 (file)
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1542,16 +1542,14 @@ static int smc_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
 {
        struct sock *sk = sock->sk;
        struct smc_sock *smc;
-       int rc = -EPIPE;
+       int rc;
 
        smc = smc_sk(sk);
        lock_sock(sk);
-       if ((sk->sk_state != SMC_ACTIVE) &&
-           (sk->sk_state != SMC_APPCLOSEWAIT1) &&
-           (sk->sk_state != SMC_INIT))
-               goto out;
 
+       /* SMC does not support connect with fastopen */
        if (msg->msg_flags & MSG_FASTOPEN) {
+               /* not connected yet, fallback */
                if (sk->sk_state == SMC_INIT && !smc->connect_nonblock) {
                        smc_switch_to_fallback(smc);
                        smc->fallback_rsn = SMC_CLC_DECL_OPTUNSUPP;
@@ -1559,6 +1557,11 @@ static int smc_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
                        rc = -EINVAL;
                        goto out;
                }
+       } else if ((sk->sk_state != SMC_ACTIVE) &&
+                  (sk->sk_state != SMC_APPCLOSEWAIT1) &&
+                  (sk->sk_state != SMC_INIT)) {
+               rc = -EPIPE;
+               goto out;
        }
 
        if (smc->use_fallback)