This is a note to let you know that I've just added the patch titled net/smc: fix fallback failed while sendmsg with fastopen to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-smc-fix-fallback-failed-while-sendmsg-with-fasto.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit a3f763d342f8bf0cecebf73d7102e86eb4536413 Author: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx> Date: Tue Mar 7 11:23:46 2023 +0800 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: ee9dfbef02d1 ("net/smc: handle sockopts forcing fallback") Signed-off-by: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx> Signed-off-by: Simon Horman <simon.horman@xxxxxxxxxxxx> v2 -> v1: Optimize code style Reviewed-by: Tony Lu <tonylu@xxxxxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index 5d696b7fb47e1..b398d72a7bc39 100644 --- 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)