Subject: Re: [PATCH net-next v4 3/3] net/smc: Introduce IPPROTO_SMC

From: Dust Li <[email-masked]>
Date: Wed, 29 May 2024 19:12:00 +0800

On 2024-05-29 11:59:07, D. Wythe wrote:
>From: "D. Wythe" <[email-masked]>
>
>This patch allows to create smc socket via AF_INET,
>similar to the following code,
>
>/* create v4 smc sock */
>v4 = socket(AF_INET, SOCK_STREAM, IPPROTO_SMC);
>
>/* create v6 smc sock */
>v6 = socket(AF_INET6, SOCK_STREAM, IPPROTO_SMC);
>
>There are several reasons why we believe it is appropriate here:
>
>1. For smc sockets, it actually use IPv4 (AF-INET) or IPv6 (AF-INET6)
>address. There is no AF_SMC address at all.
>
>2. Create smc socket in the AF_INET(6) path, which allows us to reuse
>the infrastructure of AF_INET(6) path, such as common ebpf hooks.
>Otherwise, smc have to implement it again in AF_SMC path.
>
>Signed-off-by: D. Wythe <[email-masked]>
>---
> include/uapi/linux/in.h |   2 +
> net/smc/Makefile        |   2 +-
> net/smc/af_smc.c        |  36 ++++++++++++++++
> net/smc/inet_smc.c      | 108 ++++++++++++++++++++++++++++++++++++++++++++++++
> net/smc/inet_smc.h      |  34 +++++++++++++++
> 5 files changed, 181 insertions(+), 1 deletion(-)
> create mode 100644 net/smc/inet_smc.c
> create mode 100644 net/smc/inet_smc.h
>
>diff --git a/include/uapi/linux/in.h b/include/uapi/linux/in.h
>index e682ab6..0c6322b 100644
>--- a/include/uapi/linux/in.h
>+++ b/include/uapi/linux/in.h
>@@ -83,6 +83,8 @@ enum {
> #define IPPROTO_RAW		IPPROTO_RAW
>   IPPROTO_MPTCP = 262,		/* Multipath TCP connection		*/
> #define IPPROTO_MPTCP		IPPROTO_MPTCP
>+  IPPROTO_SMC = 263,		/* Shared Memory Communications		*/
>+#define IPPROTO_SMC		IPPROTO_SMC
>   IPPROTO_MAX
> };
> #endif
>diff --git a/net/smc/Makefile b/net/smc/Makefile
>index 2c510d54..472b9ee 100644
>--- a/net/smc/Makefile
>+++ b/net/smc/Makefile
>@@ -4,6 +4,6 @@ obj-$(CONFIG_SMC)	+= smc.o
> obj-$(CONFIG_SMC_DIAG)	+= smc_diag.o
> smc-y := af_smc.o smc_pnet.o smc_ib.o smc_clc.o smc_core.o smc_wr.o smc_llc.o
> smc-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o smc_stats.o
>-smc-y += smc_tracepoint.o
>+smc-y += smc_tracepoint.o inet_smc.o
> smc-$(CONFIG_SYSCTL) += smc_sysctl.o
> smc-$(CONFIG_SMC_LO) += smc_loopback.o
>diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
>index 8e3ce76..320624c 100644
>--- a/net/smc/af_smc.c
>+++ b/net/smc/af_smc.c
>@@ -54,6 +54,7 @@
> #include "smc_tracepoint.h"
> #include "smc_sysctl.h"
> #include "smc_loopback.h"
>+#include "inet_smc.h"
> 
> static DEFINE_MUTEX(smc_server_lgr_pending);	/* serialize link group
> 						 * creation on server
>@@ -3594,9 +3595,31 @@ static int __init smc_init(void)
> 		goto out_lo;
> 	}
> 
>+	rc = proto_register(&smc_inet_prot, 1);
>+	if (rc) {
>+		pr_err("%s: proto_register smc_inet_prot fails with %d\n", __func__, rc);
>+		goto out_ulp;
>+	}
>+	inet_register_protosw(&smc_inet_protosw);
>+#if IS_ENABLED(CONFIG_IPV6)
>+	rc = proto_register(&smc_inet6_prot, 1);
>+	if (rc) {
>+		pr_err("%s: proto_register smc_inet6_prot fails with %d\n", __func__, rc);
>+		goto out_inet_prot;
>+	}
>+	inet6_register_protosw(&smc_inet6_protosw);
>+#endif
>+

What do you think of moving all those inet initialization code into
something like smc_inet_init() and move it to smc_inet.c ?

> 	static_branch_enable(&tcp_have_smc);
> 	return 0;
> 
>+#if IS_ENABLED(CONFIG_IPV6)
>+out_inet_prot:
>+	inet_unregister_protosw(&smc_inet_protosw);
>+	proto_unregister(&smc_inet_prot);
>+#endif
>+out_ulp:
>+	tcp_unregister_ulp(&smc_ulp_ops);
> out_lo:
> 	smc_loopback_exit();
> out_ib:
>@@ -3633,6 +3656,10 @@ static int __init smc_init(void)
> static void __exit smc_exit(void)
> {
> 	static_branch_disable(&tcp_have_smc);
>+	inet_unregister_protosw(&smc_inet_protosw);
>+#if IS_ENABLED(CONFIG_IPV6)
>+	inet6_unregister_protosw(&smc_inet6_protosw);
>+#endif
> 	tcp_unregister_ulp(&smc_ulp_ops);
> 	sock_unregister(PF_SMC);
> 	smc_core_exit();
>@@ -3644,6 +3671,10 @@ static void __exit smc_exit(void)
> 	destroy_workqueue(smc_hs_wq);
> 	proto_unregister(&smc_proto6);
> 	proto_unregister(&smc_proto);
>+	proto_unregister(&smc_inet_prot);
>+#if IS_ENABLED(CONFIG_IPV6)
>+	proto_unregister(&smc_inet6_prot);
>+#endif
> 	smc_pnet_exit();
> 	smc_nl_exit();
> 	smc_clc_exit();
>@@ -3660,4 +3691,9 @@ static void __exit smc_exit(void)
> MODULE_LICENSE("GPL");
> MODULE_ALIAS_NETPROTO(PF_SMC);
> MODULE_ALIAS_TCP_ULP("smc");
>+/* 263 for IPPROTO_SMC and 1 for SOCK_STREAM */
>+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET, 263, 1);
>+#if IS_ENABLED(CONFIG_IPV6)
>+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_INET6, 263, 1);
>+#endif
> MODULE_ALIAS_GENL_FAMILY(SMC_GENL_FAMILY_NAME);
>diff --git a/net/smc/inet_smc.c b/net/smc/inet_smc.c
>new file mode 100644
>index 00000000..1ba73d7
>--- /dev/null
>+++ b/net/smc/inet_smc.c
>@@ -0,0 +1,108 @@
>+// SPDX-License-Identifier: GPL-2.0-only
>+/*
>+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
>+ *
>+ *  Definitions for the IPPROTO_SMC (socket related)
>+ *
>+ *  Copyright IBM Corp. 2016, 2018
>+ *  Copyright (c) 2024, Alibaba Inc.
>+ *
>+ *  Author: D. Wythe <[email-masked]>
>+ */
>+
>+#include "inet_smc.h"
>+#include "smc.h"
>+
>+struct proto smc_inet_prot = {
>+	.name		= "INET_SMC",
>+	.owner		= THIS_MODULE,
>+	.init		= smc_inet_init_sock,
>+	.hash		= smc_hash_sk,
>+	.unhash		= smc_unhash_sk,
>+	.release_cb	= smc_release_cb,
>+	.obj_size	= sizeof(struct smc_sock),
>+	.h.smc_hash	= &smc_v4_hashinfo,
>+	.slab_flags	= SLAB_TYPESAFE_BY_RCU,
>+};
>+
>+const struct proto_ops smc_inet_stream_ops = {
>+	.family		= PF_INET,
>+	.owner		= THIS_MODULE,
>+	.release	= smc_release,
>+	.bind		= smc_bind,
>+	.connect	= smc_connect,
>+	.socketpair	= sock_no_socketpair,
>+	.accept		= smc_accept,
>+	.getname	= smc_getname,
>+	.poll		= smc_poll,
>+	.ioctl		= smc_ioctl,
>+	.listen		= smc_listen,
>+	.shutdown	= smc_shutdown,
>+	.setsockopt	= smc_setsockopt,
>+	.getsockopt	= smc_getsockopt,
>+	.sendmsg	= smc_sendmsg,
>+	.recvmsg	= smc_recvmsg,
>+	.mmap		= sock_no_mmap,
>+	.splice_read	= smc_splice_read,
>+};
>+
>+struct inet_protosw smc_inet_protosw = {
>+	.type		= SOCK_STREAM,
>+	.protocol	= IPPROTO_SMC,
>+	.prot		= &smc_inet_prot,
>+	.ops		= &smc_inet_stream_ops,
>+	.flags		= INET_PROTOSW_ICSK,
>+};
>+
>+#if IS_ENABLED(CONFIG_IPV6)
>+struct proto smc_inet6_prot = {
>+	.name		= "INET6_SMC",
>+	.owner		= THIS_MODULE,
>+	.init		= smc_inet_init_sock,
>+	.hash		= smc_hash_sk,
>+	.unhash		= smc_unhash_sk,
>+	.release_cb	= smc_release_cb,
>+	.obj_size	= sizeof(struct smc_sock),
>+	.h.smc_hash	= &smc_v6_hashinfo,
>+	.slab_flags	= SLAB_TYPESAFE_BY_RCU,
>+};
>+
>+const struct proto_ops smc_inet6_stream_ops = {
>+	.family		= PF_INET6,
>+	.owner		= THIS_MODULE,
>+	.release	= smc_release,
>+	.bind		= smc_bind,
>+	.connect	= smc_connect,
>+	.socketpair	= sock_no_socketpair,
>+	.accept		= smc_accept,
>+	.getname	= smc_getname,
>+	.poll		= smc_poll,
>+	.ioctl		= smc_ioctl,
>+	.listen		= smc_listen,
>+	.shutdown	= smc_shutdown,
>+	.setsockopt	= smc_setsockopt,
>+	.getsockopt	= smc_getsockopt,
>+	.sendmsg	= smc_sendmsg,
>+	.recvmsg	= smc_recvmsg,
>+	.mmap		= sock_no_mmap,
>+	.splice_read	= smc_splice_read,
>+};
>+
>+struct inet_protosw smc_inet6_protosw = {
>+	.type		= SOCK_STREAM,
>+	.protocol	= IPPROTO_SMC,
>+	.prot		= &smc_inet6_prot,
>+	.ops		= &smc_inet6_stream_ops,
>+	.flags		= INET_PROTOSW_ICSK,
>+};
>+#endif
>+
>+int smc_inet_init_sock(struct sock *sk)
>+{
>+	struct net *net = sock_net(sk);
>+
>+	/* init common smc sock */
>+	smc_sk_init(net, sk, IPPROTO_SMC);
>+	/* create clcsock */
>+	return smc_create_clcsk(net, sk, sk->sk_family);
>+}
>diff --git a/net/smc/inet_smc.h b/net/smc/inet_smc.h
>new file mode 100644
>index 00000000..c55345d
>--- /dev/null
>+++ b/net/smc/inet_smc.h
>@@ -0,0 +1,34 @@
>+/* SPDX-License-Identifier: GPL-2.0 */
>+/*
>+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
>+ *
>+ *  Definitions for the IPPROTO_SMC (socket related)
>+
>+ *  Copyright IBM Corp. 2016
>+ *  Copyright (c) 2024, Alibaba Inc.
>+ *
>+ *  Author: D. Wythe <[email-masked]>
>+ */
>+#ifndef __INET_SMC
>+#define __INET_SMC
>+
>+#include <net/protocol.h>
>+#include <net/sock.h>
>+#include <net/tcp.h>

Why not put those 'include's in the .c file ?

>+
>+extern struct proto smc_inet_prot;
>+extern const struct proto_ops smc_inet_stream_ops;
>+extern struct inet_protosw smc_inet_protosw;
>+
>+#if IS_ENABLED(CONFIG_IPV6)
>+#include <net/ipv6.h>
>+/* MUST after net/tcp.h or warning */
>+#include <net/transp_v6.h>
>+extern struct proto smc_inet6_prot;
>+extern const struct proto_ops smc_inet6_stream_ops;
>+extern struct inet_protosw smc_inet6_protosw;
>+#endif
>+
>+int smc_inet_init_sock(struct sock *sk);

Seems smc_inet_init_sock() is only used in smc_inet.c,
why not defined it as a static function ?

Best regards,
Dust

>+
>+#endif /* __INET_SMC */
>-- 
>1.8.3.1