Commit ce7ca794 authored Mar 07, 2023 by D. Wythe Committed by David S. Miller Mar 08, 2023

net/smc: fix fallback failed while sendmsg with fastopen



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: ee9dfbef ("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>

parent 37d9df22

net/smc/af_smc.c

+8 −5

Original line number	Diff line number	Diff line
		@@ -2657,16 +2657,14 @@ 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) {
		rc = smc_switch_to_fallback(smc, SMC_CLC_DECL_OPTUNSUPP);
		if (rc)
		@@ -2675,6 +2673,11 @@ 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) {