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

From: Zhu Yanjun <[email-masked]>
Date: Wed, 29 May 2024 21:55:15 +0200

在 2024/5/29 5:59, D. Wythe 写道:
> 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
> +
>   	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>
> +
> +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

If we append /* CONFIG_IPV6 */ to #endif to indicate that it is the end 
of CONFIG_IPV6, it is a good habit. When browsing the source code, it is 
easy for us to know that it is the end of CONFIG_IPV6.
Just my 2 cent suggestions. It is a trivial problem. You can ignore it.
But if you fix it, it can make the source code more readable.

Zhu Yanjun

> +
> +int smc_inet_init_sock(struct sock *sk);
> +
> +#endif /* __INET_SMC */