Commit 1a517302 authored Mar 07, 2023 by D. Wythe Committed by Greg Kroah-Hartman Mar 17, 2023

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: 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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 3a747490

net/smc/af_smc.c

+8 −5

Original line number	Diff line number	Diff line
		@@ -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)