On Tue, Mar 07, 2023 at 11:23:46AM +0800, D. Wythe wrote:
> From: "D. Wythe" <alibuda@xxxxxxxxxxxxxxxxx>
>
> 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>
Reviewed-by: Tony Lu <tonylu@xxxxxxxxxxxxxxxxx>
Thanks.
> v2 -> v1: Optimize code style
>
> ---
> net/smc/af_smc.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
> index b233c94..1c580ac 100644
> --- a/net/smc/af_smc.c
> +++ b/net/smc/af_smc.c
> @@ -2659,16 +2659,14 @@ 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)
> @@ -2677,6 +2675,11 @@ 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) {
> --
> 1.8.3.1
