[PATCH net-next v2] net/smc: align the connect behaviour with TCP

Guangguan Wang
2022-05-13T02:25:13Z

Connect with O_NONBLOCK will not be completed immediately
and returns -EINPROGRESS. It is possible to use selector/poll
for completion by selecting the socket for writing. After select
indicates writability, a second connect function call will return
0 to indicate connected successfully as TCP does, but smc returns
-EISCONN. Use socket state for smc to indicate connect state, which
can help smc aligning the connect behaviour with TCP.

Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
Acked-by: Karsten Graul <kgraul@linux.ibm.com>
---
net/smc/af_smc.c | 50 ++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 46 insertions(+), 4 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index fce16b9d6e1a..5f70642a8044 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1544,9 +1544,29 @@ static int smc_connect(struct socket *sock, struct sockaddr *addr,
goto out_err;

lock_sock(sk);
+ switch (sock->state) {
+ default:
+ rc = -EINVAL;
+ goto out;
+ case SS_CONNECTED:
+ rc = sk->sk_state == SMC_ACTIVE ? -EISCONN : -EINVAL;
+ goto out;
+ case SS_CONNECTING:
+ if (sk->sk_state == SMC_ACTIVE)
+ goto connected;
+ break;
+ case SS_UNCONNECTED:
+ sock->state = SS_CONNECTING;
+ break;
+ }
+
switch (sk->sk_state) {
default:
goto out;
+ case SMC_CLOSED:
+ rc = sock_error(sk) ? : -ECONNABORTED;
+ sock->state = SS_UNCONNECTED;
+ goto out;
case SMC_ACTIVE:
rc = -EISCONN;
goto out;
@@ -1565,20 +1585,24 @@ static int smc_connect(struct socket *sock, struct sockaddr *addr,
goto out;

sock_hold(&smc->sk); /* sock put in passive closing */
- if (smc->use_fallback)
+ if (smc->use_fallback) {
+ sock->state = rc ? SS_CONNECTING : SS_CONNECTED;
goto out;
+ }
if (flags & O_NONBLOCK) {
if (queue_work(smc_hs_wq, &smc->connect_work))
smc->connect_nonblock = 1;
rc = -EINPROGRESS;
+ goto out;
} else {
rc = __smc_connect(smc);
if (rc < 0)
goto out;
- else
- rc = 0; /* success cases including fallback */
}

+connected:
+ rc = 0;
+ sock->state = SS_CONNECTED;
out:
release_sock(sk);
out_err:
@@ -1693,6 +1717,7 @@ struct sock *smc_accept_dequeue(struct sock *parent,
}
if (new_sock) {
sock_graft(new_sk, new_sock);
+ new_sock->state = SS_CONNECTED;
if (isk->use_fallback) {
smc_sk(new_sk)->clcsock->file = new_sock->file;
isk->clcsock->file->private_data = isk->clcsock;
@@ -2424,7 +2449,7 @@ static int smc_listen(struct socket *sock, int backlog)

rc = -EINVAL;
if ((sk->sk_state != SMC_INIT && sk->sk_state != SMC_LISTEN) ||
- smc->connect_nonblock)
+ smc->connect_nonblock || sock->state != SS_UNCONNECTED)
goto out;

rc = 0;
@@ -2716,6 +2741,17 @@ static int smc_shutdown(struct socket *sock, int how)

lock_sock(sk);

+ if (sock->state == SS_CONNECTING) {
+ if (sk->sk_state == SMC_ACTIVE)
+ sock->state = SS_CONNECTED;
+ else if (sk->sk_state == SMC_PEERCLOSEWAIT1 ||
+ sk->sk_state == SMC_PEERCLOSEWAIT2 ||
+ sk->sk_state == SMC_APPCLOSEWAIT1 ||
+ sk->sk_state == SMC_APPCLOSEWAIT2 ||
+ sk->sk_state == SMC_APPFINCLOSEWAIT)
+ sock->state = SS_DISCONNECTING;
+ }
+
rc = -ENOTCONN;
if ((sk->sk_state != SMC_ACTIVE) &&
(sk->sk_state != SMC_PEERCLOSEWAIT1) &&
@@ -2729,6 +2765,7 @@ static int smc_shutdown(struct socket *sock, int how)
sk->sk_shutdown = smc->clcsock->sk->sk_shutdown;
if (sk->sk_shutdown == SHUTDOWN_MASK) {
sk->sk_state = SMC_CLOSED;
+ sk->sk_socket->state = SS_UNCONNECTED;
sock_put(sk);
}
goto out;
@@ -2754,6 +2791,10 @@ static int smc_shutdown(struct socket *sock, int how)
/* map sock_shutdown_cmd constants to sk_shutdown value range */
sk->sk_shutdown |= how + 1;

+ if (sk->sk_state == SMC_CLOSED)
+ sock->state = SS_UNCONNECTED;
+ else
+ sock->state = SS_DISCONNECTING;
out:
release_sock(sk);
return rc ? rc : rc1;
@@ -3139,6 +3180,7 @@ static int __smc_create(struct net *net, struct socket *sock, int protocol,

rc = -ENOBUFS;
sock->ops = &smc_sock_ops;
+ sock->state = SS_UNCONNECTED;
sk = smc_sock_alloc(net, sock, protocol);
if (!sk)
goto out;
--
2.24.3 (Apple Git-128)