Subject: Re: [PATCH net-next 1/2] net/smc: refatoring initialization of smc sock

From: Dust Li <[email-masked]>
Date: Fri, 10 May 2024 17:50:27 +0800

On 2024-05-10 12:12:12, D. Wythe wrote:
>From: "D. Wythe" <[email-masked]>
>
>This patch aims to isolate the shared components of SMC socket
>allocation by introducing smc_sock_init() for sock initialization
>and __smc_create_clcsk() for the initialization of clcsock.
>
>This is in preparation for the subsequent implementation of the
>AF_INET version of SMC.
>
>Signed-off-by: D. Wythe <[email-masked]>
>---
> net/smc/af_smc.c | 93 +++++++++++++++++++++++++++++++-------------------------
> 1 file changed, 52 insertions(+), 41 deletions(-)
>
>diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
>index 9389f0c..1f03724 100644
>--- a/net/smc/af_smc.c
>+++ b/net/smc/af_smc.c
>@@ -361,34 +361,43 @@ static void smc_destruct(struct sock *sk)
> 		return;
> }
> 
>-static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
>-				   int protocol)
>+static void smc_sock_init(struct net *net, struct sock *sk, int protocol)
> {
>-	struct smc_sock *smc;
>-	struct proto *prot;
>-	struct sock *sk;
>-
>-	prot = (protocol == SMCPROTO_SMC6) ? &smc_proto6 : &smc_proto;
>-	sk = sk_alloc(net, PF_SMC, GFP_KERNEL, prot, 0);
>-	if (!sk)
>-		return NULL;
>+	struct smc_sock *smc = smc_sk(sk);
> 
>-	sock_init_data(sock, sk); /* sets sk_refcnt to 1 */
> 	sk->sk_state = SMC_INIT;
>-	sk->sk_destruct = smc_destruct;
> 	sk->sk_protocol = protocol;
>+	mutex_init(&smc->clcsock_release_lock);
> 	WRITE_ONCE(sk->sk_sndbuf, 2 * READ_ONCE(net->smc.sysctl_wmem));
> 	WRITE_ONCE(sk->sk_rcvbuf, 2 * READ_ONCE(net->smc.sysctl_rmem));
>-	smc = smc_sk(sk);
> 	INIT_WORK(&smc->tcp_listen_work, smc_tcp_listen_work);
> 	INIT_WORK(&smc->connect_work, smc_connect_work);
> 	INIT_DELAYED_WORK(&smc->conn.tx_work, smc_tx_work);
> 	INIT_LIST_HEAD(&smc->accept_q);
> 	spin_lock_init(&smc->accept_q_lock);
> 	spin_lock_init(&smc->conn.send_lock);
>-	sk->sk_prot->hash(sk);
>-	mutex_init(&smc->clcsock_release_lock);
> 	smc_init_saved_callbacks(smc);
>+	smc->limit_smc_hs = net->smc.limit_smc_hs;
>+	smc->use_fallback = false; /* assume rdma capability first */
>+	smc->fallback_rsn = 0;
>+
>+	sk->sk_destruct = smc_destruct;
>+	sk->sk_prot->hash(sk);

Why change the order here ? e.g.

Before:
    sk->sk_destruct = smc_destruct;
    mutex_init(&smc->clcsock_release_lock);
After
    mutex_init(&smc->clcsock_release_lock);
    sk->sk_destruct = smc_destruct;

Same for sk->sk_prot->hash(sk)

>+}
>+
>+static struct sock *smc_sock_alloc(struct net *net, struct socket *sock,
>+				   int protocol)
>+{
>+	struct proto *prot;
>+	struct sock *sk;
>+
>+	prot = (protocol == SMCPROTO_SMC6) ? &smc_proto6 : &smc_proto;
>+	sk = sk_alloc(net, PF_SMC, GFP_KERNEL, prot, 0);
>+	if (!sk)
>+		return NULL;
>+
>+	sock_init_data(sock, sk); /* sets sk_refcnt to 1 */
>+	smc_sock_init(net, sk, protocol);
> 
> 	return sk;
> }
>@@ -3321,6 +3330,31 @@ static ssize_t smc_splice_read(struct socket *sock, loff_t *ppos,
> 	.splice_read	= smc_splice_read,
> };
> 
>+static int __smc_create_clcsk(struct net *net, struct sock *sk, int family)

Why add '__' prefix here ?

>+{
>+	struct smc_sock *smc = smc_sk(sk);
>+	int rc;
>+
>+	rc = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP,
>+			      &smc->clcsock);
>+	if (rc) {
>+		sk_common_release(sk);
>+		return rc;
>+	}
>+
>+	/* smc_clcsock_release() does not wait smc->clcsock->sk's
>+	 * destruction;  its sk_state might not be TCP_CLOSE after
>+	 * smc->sk is close()d, and TCP timers can be fired later,
>+	 * which need net ref.
>+	 */
>+	sk = smc->clcsock->sk;
>+	__netns_tracker_free(net, &sk->ns_tracker, false);
>+	sk->sk_net_refcnt = 1;
>+	get_net_track(net, &sk->ns_tracker, GFP_KERNEL);
>+	sock_inuse_add(net, 1);
>+	return 0;
>+}
>+
> static int __smc_create(struct net *net, struct socket *sock, int protocol,
> 			int kern, struct socket *clcsock)
> {
>@@ -3346,35 +3380,12 @@ static int __smc_create(struct net *net, struct socket *sock, int protocol,
> 
> 	/* create internal TCP socket for CLC handshake and fallback */
> 	smc = smc_sk(sk);
>-	smc->use_fallback = false; /* assume rdma capability first */
>-	smc->fallback_rsn = 0;
>-
>-	/* default behavior from limit_smc_hs in every net namespace */
>-	smc->limit_smc_hs = net->smc.limit_smc_hs;
> 
> 	rc = 0;
>-	if (!clcsock) {
>-		rc = sock_create_kern(net, family, SOCK_STREAM, IPPROTO_TCP,
>-				      &smc->clcsock);
>-		if (rc) {
>-			sk_common_release(sk);
>-			goto out;
>-		}
>-
>-		/* smc_clcsock_release() does not wait smc->clcsock->sk's
>-		 * destruction;  its sk_state might not be TCP_CLOSE after
>-		 * smc->sk is close()d, and TCP timers can be fired later,
>-		 * which need net ref.
>-		 */
>-		sk = smc->clcsock->sk;
>-		__netns_tracker_free(net, &sk->ns_tracker, false);
>-		sk->sk_net_refcnt = 1;
>-		get_net_track(net, &sk->ns_tracker, GFP_KERNEL);
>-		sock_inuse_add(net, 1);
>-	} else {
>+	if (!clcsock)
>+		rc = __smc_create_clcsk(net, sk, family);
>+	else
> 		smc->clcsock = clcsock;
>-	}
>-
> out:
> 	return rc;
> }
>-- 
>1.8.3.1
>