[PATCH bpf-next v5 0/5] net/smc: Introduce smc_ops

[PATCH bpf-next v5 0/5] net/smc: Introduce smc_ops

[D. Wythe]

This patch aims to introduce BPF injection capabilities for SMC and
includes a self-test to ensure code stability.

Since the SMC protocol isn't ideal for every situation, especially
short-lived ones, most applications can't guarantee the absence of
such scenarios. Consequently, applications may need specific strategies
to decide whether to use SMC. For example, an application might limit SMC
usage to certain IP addresses or ports.

To maintain the principle of transparent replacement, we want applications
to remain unaffected even if they need specific SMC strategies. In other
words, they should not require recompilation of their code.

Additionally, we need to ensure the scalability of strategy implementation.
While using socket options or sysctl might be straightforward, it could
complicate future expansions.

Fortunately, BPF addresses these concerns effectively. Users can write
their own strategies in eBPF to determine whether to use SMC, and they can
easily modify those strategies in the future.

v2:
  1. Rename smc_bpf_ops to smc_ops.
  2. Change the scope of smc_ops from global to per netns.
  3. Directly pass parameters to ops instead of smc_ops_ctx.
  4. Remove struct smc_ops_ctx.
  5. Remove exports that are no longer needed.

v3:
  1. Remove find_ksym_btf_id_by_prefix_kind.
  2. Enhance selftest, introduce a complete ops for filtering smc
     connections based on ip pairs and a realistic topology test
     to verify it.

v4:
  1. Remove unless func: smc_bpf_ops_check_member()
  2. Remove unless inline func: smc_ops_find_by_name()
  3. Change CONFIG_SMC=y to complete CI testing
  4. Change smc_sock to smc_sock___local in test to avoid
     compiling failed with CONFIG_SMC=y
  5. Improve test cases, remove unnecessary timeouts and multi-thread
     test, using network_helpers to start testing between server and
     client.
  6. Fix issues when the return value of the ops function is neither 0
     nor 1.

v5:
  1. Fix incorrect CI config from CONFIG_SMC=Y to CONFIG_SMC=y.

D. Wythe (5):
  bpf: export necessary sympols for modules with struct_ops
  net/smc: Introduce generic hook smc_ops
  net/smc: bpf: register smc_ops info struct_ops
  libbpf: fix error when st-prefix_ops and ops from differ btf
  bpf/selftests: add selftest for bpf_smc_ops

 include/net/netns/smc.h                       |   3 +
 include/net/smc.h                             |  51 +++
 kernel/bpf/bpf_struct_ops.c                   |   2 +
 kernel/bpf/syscall.c                          |   1 +
 net/ipv4/tcp_output.c                         |  15 +-
 net/smc/Kconfig                               |  12 +
 net/smc/Makefile                              |   1 +
 net/smc/af_smc.c                              |  10 +
 net/smc/smc_ops.c                             | 130 ++++++
 net/smc/smc_ops.h                             |  30 ++
 net/smc/smc_sysctl.c                          |  95 +++++
 tools/lib/bpf/libbpf.c                        |  25 +-
 tools/testing/selftests/bpf/config            |   4 +
 .../selftests/bpf/prog_tests/test_bpf_smc.c   | 390 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/bpf_smc.c   | 116 ++++++
 15 files changed, 873 insertions(+), 12 deletions(-)
 create mode 100644 net/smc/smc_ops.c
 create mode 100644 net/smc/smc_ops.h
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_bpf_smc.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_smc.c

-- 
2.45.0

[PATCH bpf-next v5 1/5] bpf: export necessary sympols for modules with struct_ops

[D. Wythe]

Exports three necessary symbols for implementing struct_ops with
tristate subsystem.

To hold or release refcnt of struct_ops refcnt by inline funcs
bpf_try_module_get and bpf_module_put which use bpf_struct_ops_get(put)
conditionally.

And to copy obj name from one to the other with effective checks by
bpf_obj_name_cpy.

Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
 kernel/bpf/bpf_struct_ops.c | 2 ++
 kernel/bpf/syscall.c        | 1 +
 2 files changed, 3 insertions(+)

diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 606efe32485a..00c212e0ad39 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -1119,6 +1119,7 @@ bool bpf_struct_ops_get(const void *kdata)
 	map = __bpf_map_inc_not_zero(&st_map->map, false);
 	return !IS_ERR(map);
 }
+EXPORT_SYMBOL_GPL(bpf_struct_ops_get);
 
 void bpf_struct_ops_put(const void *kdata)
 {
@@ -1130,6 +1131,7 @@ void bpf_struct_ops_put(const void *kdata)
 
 	bpf_map_put(&st_map->map);
 }
+EXPORT_SYMBOL_GPL(bpf_struct_ops_put);
 
 int bpf_struct_ops_supported(const struct bpf_struct_ops *st_ops, u32 moff)
 {
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 5684e8ce132d..62238ec989dc 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1167,6 +1167,7 @@ int bpf_obj_name_cpy(char *dst, const char *src, unsigned int size)
 
 	return src - orig_src;
 }
+EXPORT_SYMBOL_GPL(bpf_obj_name_cpy);
 
 int map_check_no_btf(const struct bpf_map *map,
 		     const struct btf *btf,
-- 
2.45.0

[PATCH bpf-next v5 2/5] net/smc: Introduce generic hook smc_ops

[D. Wythe]

The introduction of IPPROTO_SMC enables eBPF programs to determine
whether to use SMC based on the context of socket creation, such as
network namespaces, PID and comm name, etc.

As a subsequent enhancement, to introduce a new generic hook that
allows decisions on whether to use SMC or not at runtime, including
but not limited to local/remote IP address or ports.

Moreover, in the future, we can achieve more complex extensions to the
protocol stack by extending this ops.

Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
 include/net/netns/smc.h |  3 ++
 include/net/smc.h       | 51 ++++++++++++++++++++++
 net/ipv4/tcp_output.c   | 15 +++++--
 net/smc/Kconfig         | 12 ++++++
 net/smc/Makefile        |  1 +
 net/smc/smc_ops.c       | 51 ++++++++++++++++++++++
 net/smc/smc_ops.h       | 25 +++++++++++
 net/smc/smc_sysctl.c    | 95 +++++++++++++++++++++++++++++++++++++++++
 8 files changed, 249 insertions(+), 4 deletions(-)
 create mode 100644 net/smc/smc_ops.c
 create mode 100644 net/smc/smc_ops.h

diff --git a/include/net/netns/smc.h b/include/net/netns/smc.h
index fc752a50f91b..59d069f56b2d 100644
--- a/include/net/netns/smc.h
+++ b/include/net/netns/smc.h
@@ -17,6 +17,9 @@ struct netns_smc {
 #ifdef CONFIG_SYSCTL
 	struct ctl_table_header		*smc_hdr;
 #endif
+#if IS_ENABLED(CONFIG_SMC_OPS)
+	struct smc_ops __rcu *ops;
+#endif /* CONFIG_SMC_OPS */
 	unsigned int			sysctl_autocorking_size;
 	unsigned int			sysctl_smcr_buf_type;
 	int				sysctl_smcr_testlink_time;
diff --git a/include/net/smc.h b/include/net/smc.h
index db84e4e35080..326a217001d4 100644
--- a/include/net/smc.h
+++ b/include/net/smc.h
@@ -18,6 +18,8 @@
 #include "linux/ism.h"
 
 struct sock;
+struct tcp_sock;
+struct inet_request_sock;
 
 #define SMC_MAX_PNETID_LEN	16	/* Max. length of PNET id */
 
@@ -97,4 +99,53 @@ struct smcd_dev {
 	u8 going_away : 1;
 };
 
+#define  SMC_OPS_NAME_MAX 16
+
+enum {
+	/* ops can be inherit from init_net */
+	SMC_OPS_FLAG_INHERITABLE = 0x1,
+
+	SMC_OPS_ALL_FLAGS = SMC_OPS_FLAG_INHERITABLE,
+};
+
+struct smc_ops {
+	/* priavte */
+
+	struct list_head list;
+	struct module *owner;
+
+	/* public */
+
+	/* unique name */
+	char name[SMC_OPS_NAME_MAX];
+	int flags;
+
+	/* Invoked before computing SMC option for SYN packets.
+	 * We can control whether to set SMC options by returning varios value.
+	 * Return 0 to disable SMC, or return any other value to enable it.
+	 */
+	int (*set_option)(struct tcp_sock *tp);
+
+	/* Invoked before Set up SMC options for SYN-ACK packets
+	 * We can control whether to respond SMC options by returning varios value.
+	 * Return 0 to disable SMC, or return any other value to enable it.
+	 */
+	int (*set_option_cond)(const struct tcp_sock *tp, struct inet_request_sock *ireq);
+};
+
+#if IS_ENABLED(CONFIG_SMC_OPS)
+#define smc_call_retops(init_val, sk, func, ...) ({	\
+	typeof(init_val) __ret = (init_val);		\
+	struct smc_ops *ops;				\
+	rcu_read_lock();				\
+	ops = READ_ONCE(sock_net(sk)->smc.ops);		\
+	if (ops && ops->func)				\
+		__ret = ops->func(__VA_ARGS__);		\
+	rcu_read_unlock();				\
+	!!__ret;					\
+})
+#else
+#define smc_call_retops(init_val, ...) (init_val)
+#endif /* CONFIG_SMC_OPS */
+
 #endif	/* _SMC_H */
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 5485a70b5fe5..7b402167fb4d 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -48,6 +48,7 @@
 #include <linux/skbuff_ref.h>
 
 #include <trace/events/tcp.h>
+#include <net/smc.h>
 
 /* Refresh clocks of a TCP socket,
  * ensuring monotically increasing values.
@@ -759,14 +760,17 @@ static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp,
 	mptcp_options_write(th, ptr, tp, opts);
 }
 
-static void smc_set_option(const struct tcp_sock *tp,
+static void smc_set_option(struct tcp_sock *tp,
 			   struct tcp_out_options *opts,
 			   unsigned int *remaining)
 {
 #if IS_ENABLED(CONFIG_SMC)
 	if (static_branch_unlikely(&tcp_have_smc)) {
 		if (tp->syn_smc) {
-			if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
+			tp->syn_smc = smc_call_retops(1, &tp->inet_conn.icsk_inet.sk,
+						      set_option, tp);
+			/* re-check syn_smc */
+			if (tp->syn_smc && *remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
 				opts->options |= OPTION_SMC;
 				*remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED;
 			}
@@ -776,14 +780,17 @@ static void smc_set_option(const struct tcp_sock *tp,
 }
 
 static void smc_set_option_cond(const struct tcp_sock *tp,
-				const struct inet_request_sock *ireq,
+				struct inet_request_sock *ireq,
 				struct tcp_out_options *opts,
 				unsigned int *remaining)
 {
 #if IS_ENABLED(CONFIG_SMC)
 	if (static_branch_unlikely(&tcp_have_smc)) {
 		if (tp->syn_smc && ireq->smc_ok) {
-			if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
+			ireq->smc_ok = smc_call_retops(1, &tp->inet_conn.icsk_inet.sk,
+						       set_option_cond, tp, ireq);
+			/* re-check smc_ok */
+			if (ireq->smc_ok && *remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
 				opts->options |= OPTION_SMC;
 				*remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED;
 			}
diff --git a/net/smc/Kconfig b/net/smc/Kconfig
index ba5e6a2dd2fd..0ee16ec8dceb 100644
--- a/net/smc/Kconfig
+++ b/net/smc/Kconfig
@@ -33,3 +33,15 @@ config SMC_LO
 	  of architecture or hardware.
 
 	  if unsure, say N.
+
+config SMC_OPS
+	bool "Generic hook for SMC subsystem"
+	depends on SMC && BPF_SYSCALL
+	default n
+	help
+	  SMC_OPS enables support to register genericfor hook via eBPF programs
+	  for SMC subsystem. eBPF programs offer much greater flexibility
+	  in modifying the behavior of the SMC protocol stack compared
+	  to a complete kernel-based approach.
+
+	  if unsure, say N.
diff --git a/net/smc/Makefile b/net/smc/Makefile
index 60f1c87d5212..5dd706b2927a 100644
--- a/net/smc/Makefile
+++ b/net/smc/Makefile
@@ -7,3 +7,4 @@ smc-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o smc_sta
 smc-y += smc_tracepoint.o smc_inet.o
 smc-$(CONFIG_SYSCTL) += smc_sysctl.o
 smc-$(CONFIG_SMC_LO) += smc_loopback.o
+smc-$(CONFIG_SMC_OPS) += smc_ops.o
\ No newline at end of file
diff --git a/net/smc/smc_ops.c b/net/smc/smc_ops.c
new file mode 100644
index 000000000000..0fc19cadd760
--- /dev/null
+++ b/net/smc/smc_ops.c
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ *  Generic hook for SMC subsystem.
+ *
+ *  Copyright IBM Corp. 2016
+ *  Copyright (c) 2024, Alibaba Inc.
+ *
+ *  Author: D. Wythe <alibuda@linux.alibaba.com>
+ */
+
+#include "smc_ops.h"
+
+static DEFINE_SPINLOCK(smc_ops_list_lock);
+static LIST_HEAD(smc_ops_list);
+
+static int smc_ops_reg(struct smc_ops *ops)
+{
+	int ret = 0;
+
+	spin_lock(&smc_ops_list_lock);
+	/* already exist or duplicate name */
+	if (smc_ops_find_by_name(ops->name))
+		ret = -EEXIST;
+	else
+		list_add_tail_rcu(&ops->list, &smc_ops_list);
+	spin_unlock(&smc_ops_list_lock);
+	return ret;
+}
+
+static void smc_ops_unreg(struct smc_ops *ops)
+{
+	spin_lock(&smc_ops_list_lock);
+	list_del_rcu(&ops->list);
+	spin_unlock(&smc_ops_list_lock);
+
+	/* Ensure that all readers to complete */
+	synchronize_rcu();
+}
+
+struct smc_ops *smc_ops_find_by_name(const char *name)
+{
+	struct smc_ops *ops;
+
+	list_for_each_entry_rcu(ops, &smc_ops_list, list) {
+		if (strcmp(ops->name, name) == 0)
+			return ops;
+	}
+	return NULL;
+}
diff --git a/net/smc/smc_ops.h b/net/smc/smc_ops.h
new file mode 100644
index 000000000000..4b33dc2d65b9
--- /dev/null
+++ b/net/smc/smc_ops.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ *  Generic hook for SMC subsystem.
+ *
+ *  Copyright IBM Corp. 2016
+ *  Copyright (c) 2024, Alibaba Inc.
+ *
+ *  Author: D. Wythe <alibuda@linux.alibaba.com>
+ */
+
+#ifndef __SMC_OPS
+#define __SMC_OPS
+
+#include <net/smc.h>
+
+/* Find ops by the target name, which required to be a c-string.
+ * Return NULL if no such ops was found,otherwise, return a valid ops.
+ *
+ * Note: Caller MUST ensure it's was invoked under rcu_read_lock.
+ */
+struct smc_ops *smc_ops_find_by_name(const char *name);
+
+#endif /* __SMC_OPS */
diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
index 2fab6456f765..2aa3f19025f4 100644
--- a/net/smc/smc_sysctl.c
+++ b/net/smc/smc_sysctl.c
@@ -18,6 +18,7 @@
 #include "smc_core.h"
 #include "smc_llc.h"
 #include "smc_sysctl.h"
+#include "smc_ops.h"
 
 static int min_sndbuf = SMC_BUF_MIN_SIZE;
 static int min_rcvbuf = SMC_BUF_MIN_SIZE;
@@ -30,6 +31,70 @@ static int links_per_lgr_max = SMC_LINKS_ADD_LNK_MAX;
 static int conns_per_lgr_min = SMC_CONN_PER_LGR_MIN;
 static int conns_per_lgr_max = SMC_CONN_PER_LGR_MAX;
 
+#if IS_ENABLED(CONFIG_SMC_OPS)
+static int smc_net_replace_smc_ops(struct net *net, const char *name)
+{
+	struct smc_ops *ops = NULL;
+
+	rcu_read_lock();
+	/* null or empty name ask to clear current ops */
+	if (name && name[0]) {
+		ops = smc_ops_find_by_name(name);
+		if (!ops) {
+			rcu_read_unlock();
+			return -EINVAL;
+		}
+		/* no change, just return */
+		if (ops == rcu_dereference(net->smc.ops)) {
+			rcu_read_unlock();
+			return 0;
+		}
+	}
+	if (!ops || bpf_try_module_get(ops, ops->owner)) {
+		/* xhcg */
+		ops = rcu_replace_pointer(net->smc.ops, ops, true);
+		/* release old ops */
+		if (ops)
+			bpf_module_put(ops, ops->owner);
+	} else if (ops) {
+		rcu_read_unlock();
+		return -EBUSY;
+	}
+	rcu_read_unlock();
+	return 0;
+}
+
+static int proc_smc_ops(const struct ctl_table *ctl, int write,
+			void *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct net *net = container_of(ctl->data, struct net,
+				       smc.ops);
+	char val[SMC_OPS_NAME_MAX];
+	struct ctl_table tbl = {
+		.data = val,
+		.maxlen = SMC_OPS_NAME_MAX,
+	};
+	struct smc_ops *ops;
+	int ret;
+
+	rcu_read_lock();
+	ops = rcu_dereference(net->smc.ops);
+	if (ops)
+		memcpy(val, ops->name, sizeof(ops->name));
+	else
+		val[0] = '\0';
+	rcu_read_unlock();
+
+	ret = proc_dostring(&tbl, write, buffer, lenp, ppos);
+	if (ret)
+		return ret;
+
+	if (write)
+		ret = smc_net_replace_smc_ops(net, val);
+	return ret;
+}
+#endif /* CONFIG_SMC_OPS */
+
 static struct ctl_table smc_table[] = {
 	{
 		.procname       = "autocorking_size",
@@ -99,6 +164,15 @@ static struct ctl_table smc_table[] = {
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
+#if IS_ENABLED(CONFIG_SMC_OPS)
+	{
+		.procname	= "ops",
+		.data		= &init_net.smc.ops,
+		.mode		= 0644,
+		.maxlen		= SMC_OPS_NAME_MAX,
+		.proc_handler	= proc_smc_ops,
+	},
+#endif /* CONFIG_SMC_OPS */
 };
 
 int __net_init smc_sysctl_net_init(struct net *net)
@@ -109,6 +183,20 @@ int __net_init smc_sysctl_net_init(struct net *net)
 	table = smc_table;
 	if (!net_eq(net, &init_net)) {
 		int i;
+#if IS_ENABLED(CONFIG_SMC_OPS)
+		struct smc_ops *ops;
+
+		rcu_read_lock();
+		ops = rcu_dereference(init_net.smc.ops);
+		if (ops && ops->flags & SMC_OPS_FLAG_INHERITABLE) {
+			if (!bpf_try_module_get(ops, ops->owner)) {
+				rcu_read_unlock();
+				return -EBUSY;
+			}
+			rcu_assign_pointer(net->smc.ops, ops);
+		}
+		rcu_read_unlock();
+#endif /* CONFIG_SMC_OPS */
 
 		table = kmemdup(table, sizeof(smc_table), GFP_KERNEL);
 		if (!table)
@@ -139,6 +227,9 @@ int __net_init smc_sysctl_net_init(struct net *net)
 	if (!net_eq(net, &init_net))
 		kfree(table);
 err_alloc:
+#if IS_ENABLED(CONFIG_SMC_OPS)
+	smc_net_replace_smc_ops(net, NULL);
+#endif /* CONFIG_SMC_OPS */
 	return -ENOMEM;
 }
 
@@ -148,6 +239,10 @@ void __net_exit smc_sysctl_net_exit(struct net *net)
 
 	table = net->smc.smc_hdr->ctl_table_arg;
 	unregister_net_sysctl_table(net->smc.smc_hdr);
+#if IS_ENABLED(CONFIG_SMC_OPS)
+	smc_net_replace_smc_ops(net, NULL);
+#endif /* CONFIG_SMC_OPS */
+
 	if (!net_eq(net, &init_net))
 		kfree(table);
 }
-- 
2.45.0

Re: [PATCH bpf-next v5 2/5] net/smc: Introduce generic hook smc_ops

[Dust Li]

On 2025-01-07 12:17:12, D. Wythe wrote:
>The introduction of IPPROTO_SMC enables eBPF programs to determine
>whether to use SMC based on the context of socket creation, such as
>network namespaces, PID and comm name, etc.
>
>As a subsequent enhancement, to introduce a new generic hook that
>allows decisions on whether to use SMC or not at runtime, including
>but not limited to local/remote IP address or ports.
>
>Moreover, in the future, we can achieve more complex extensions to the
>protocol stack by extending this ops.
>
>Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
>---
> include/net/netns/smc.h |  3 ++
> include/net/smc.h       | 51 ++++++++++++++++++++++
> net/ipv4/tcp_output.c   | 15 +++++--
> net/smc/Kconfig         | 12 ++++++
> net/smc/Makefile        |  1 +
> net/smc/smc_ops.c       | 51 ++++++++++++++++++++++
> net/smc/smc_ops.h       | 25 +++++++++++
> net/smc/smc_sysctl.c    | 95 +++++++++++++++++++++++++++++++++++++++++
> 8 files changed, 249 insertions(+), 4 deletions(-)
> create mode 100644 net/smc/smc_ops.c
> create mode 100644 net/smc/smc_ops.h
>
>diff --git a/include/net/netns/smc.h b/include/net/netns/smc.h
>index fc752a50f91b..59d069f56b2d 100644
>--- a/include/net/netns/smc.h
>+++ b/include/net/netns/smc.h
>@@ -17,6 +17,9 @@ struct netns_smc {
> #ifdef CONFIG_SYSCTL
> 	struct ctl_table_header		*smc_hdr;
> #endif
>+#if IS_ENABLED(CONFIG_SMC_OPS)
>+	struct smc_ops __rcu *ops;
                              ^^^
Align with other fields

>+#endif /* CONFIG_SMC_OPS */
> 	unsigned int			sysctl_autocorking_size;
> 	unsigned int			sysctl_smcr_buf_type;
> 	int				sysctl_smcr_testlink_time;
>diff --git a/include/net/smc.h b/include/net/smc.h
>index db84e4e35080..326a217001d4 100644
>--- a/include/net/smc.h
>+++ b/include/net/smc.h
>@@ -18,6 +18,8 @@
> #include "linux/ism.h"
> 
> struct sock;
>+struct tcp_sock;
>+struct inet_request_sock;
> 
> #define SMC_MAX_PNETID_LEN	16	/* Max. length of PNET id */
> 
>@@ -97,4 +99,53 @@ struct smcd_dev {
> 	u8 going_away : 1;
> };
> 
>+#define  SMC_OPS_NAME_MAX 16
>+
>+enum {
>+	/* ops can be inherit from init_net */
>+	SMC_OPS_FLAG_INHERITABLE = 0x1,
>+
>+	SMC_OPS_ALL_FLAGS = SMC_OPS_FLAG_INHERITABLE,
>+};
>+
>+struct smc_ops {
>+	/* priavte */
>+
>+	struct list_head list;
>+	struct module *owner;
>+
>+	/* public */
>+
>+	/* unique name */
>+	char name[SMC_OPS_NAME_MAX];
>+	int flags;
>+
>+	/* Invoked before computing SMC option for SYN packets.
>+	 * We can control whether to set SMC options by returning varios value.
>+	 * Return 0 to disable SMC, or return any other value to enable it.
>+	 */
>+	int (*set_option)(struct tcp_sock *tp);
>+
>+	/* Invoked before Set up SMC options for SYN-ACK packets
>+	 * We can control whether to respond SMC options by returning varios value.
>+	 * Return 0 to disable SMC, or return any other value to enable it.
>+	 */
>+	int (*set_option_cond)(const struct tcp_sock *tp, struct inet_request_sock *ireq);
>+};
>+
>+#if IS_ENABLED(CONFIG_SMC_OPS)
>+#define smc_call_retops(init_val, sk, func, ...) ({	\
>+	typeof(init_val) __ret = (init_val);		\
>+	struct smc_ops *ops;				\
>+	rcu_read_lock();				\
>+	ops = READ_ONCE(sock_net(sk)->smc.ops);		\
>+	if (ops && ops->func)				\
>+		__ret = ops->func(__VA_ARGS__);		\
>+	rcu_read_unlock();				\
>+	!!__ret;					\
>+})
>+#else
>+#define smc_call_retops(init_val, ...) (init_val)
>+#endif /* CONFIG_SMC_OPS */
>+
> #endif	/* _SMC_H */
>diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
>index 5485a70b5fe5..7b402167fb4d 100644
>--- a/net/ipv4/tcp_output.c
>+++ b/net/ipv4/tcp_output.c
>@@ -48,6 +48,7 @@
> #include <linux/skbuff_ref.h>
> 
> #include <trace/events/tcp.h>
>+#include <net/smc.h>

Put this include right after #include <net/proto_memory.h> ?
I notice all the includes here are well classified.


> 
> /* Refresh clocks of a TCP socket,
>  * ensuring monotically increasing values.
>@@ -759,14 +760,17 @@ static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp,
> 	mptcp_options_write(th, ptr, tp, opts);
> }
> 
>-static void smc_set_option(const struct tcp_sock *tp,
>+static void smc_set_option(struct tcp_sock *tp,
> 			   struct tcp_out_options *opts,
> 			   unsigned int *remaining)
> {
> #if IS_ENABLED(CONFIG_SMC)
> 	if (static_branch_unlikely(&tcp_have_smc)) {
> 		if (tp->syn_smc) {
>-			if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
>+			tp->syn_smc = smc_call_retops(1, &tp->inet_conn.icsk_inet.sk,
>+						      set_option, tp);
>+			/* re-check syn_smc */
>+			if (tp->syn_smc && *remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
> 				opts->options |= OPTION_SMC;
> 				*remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED;
> 			}
>@@ -776,14 +780,17 @@ static void smc_set_option(const struct tcp_sock *tp,
> }
> 
> static void smc_set_option_cond(const struct tcp_sock *tp,
>-				const struct inet_request_sock *ireq,
>+				struct inet_request_sock *ireq,
> 				struct tcp_out_options *opts,
> 				unsigned int *remaining)
> {
> #if IS_ENABLED(CONFIG_SMC)
> 	if (static_branch_unlikely(&tcp_have_smc)) {
> 		if (tp->syn_smc && ireq->smc_ok) {
>-			if (*remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
>+			ireq->smc_ok = smc_call_retops(1, &tp->inet_conn.icsk_inet.sk,
>+						       set_option_cond, tp, ireq);
>+			/* re-check smc_ok */
>+			if (ireq->smc_ok && *remaining >= TCPOLEN_EXP_SMC_BASE_ALIGNED) {
> 				opts->options |= OPTION_SMC;
> 				*remaining -= TCPOLEN_EXP_SMC_BASE_ALIGNED;
> 			}
>diff --git a/net/smc/Kconfig b/net/smc/Kconfig
>index ba5e6a2dd2fd..0ee16ec8dceb 100644
>--- a/net/smc/Kconfig
>+++ b/net/smc/Kconfig
>@@ -33,3 +33,15 @@ config SMC_LO
> 	  of architecture or hardware.
> 
> 	  if unsure, say N.
>+
>+config SMC_OPS
>+	bool "Generic hook for SMC subsystem"
>+	depends on SMC && BPF_SYSCALL
>+	default n
>+	help
>+	  SMC_OPS enables support to register genericfor hook via eBPF programs

genericfor ?

>+	  for SMC subsystem. eBPF programs offer much greater flexibility
>+	  in modifying the behavior of the SMC protocol stack compared
>+	  to a complete kernel-based approach.
>+
>+	  if unsure, say N.
>diff --git a/net/smc/Makefile b/net/smc/Makefile
>index 60f1c87d5212..5dd706b2927a 100644
>--- a/net/smc/Makefile
>+++ b/net/smc/Makefile
>@@ -7,3 +7,4 @@ smc-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o smc_sta
> smc-y += smc_tracepoint.o smc_inet.o
> smc-$(CONFIG_SYSCTL) += smc_sysctl.o
> smc-$(CONFIG_SMC_LO) += smc_loopback.o
>+smc-$(CONFIG_SMC_OPS) += smc_ops.o
>\ No newline at end of file
>diff --git a/net/smc/smc_ops.c b/net/smc/smc_ops.c
>new file mode 100644
>index 000000000000..0fc19cadd760
>--- /dev/null
>+++ b/net/smc/smc_ops.c
>@@ -0,0 +1,51 @@
>+// SPDX-License-Identifier: GPL-2.0-only
>+/*
>+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
>+ *
>+ *  Generic hook for SMC subsystem.
>+ *
>+ *  Copyright IBM Corp. 2016
>+ *  Copyright (c) 2024, Alibaba Inc.
>+ *
>+ *  Author: D. Wythe <alibuda@linux.alibaba.com>
>+ */
>+
>+#include "smc_ops.h"
>+
>+static DEFINE_SPINLOCK(smc_ops_list_lock);
>+static LIST_HEAD(smc_ops_list);
>+
>+static int smc_ops_reg(struct smc_ops *ops)
>+{
>+	int ret = 0;
>+
>+	spin_lock(&smc_ops_list_lock);
>+	/* already exist or duplicate name */
>+	if (smc_ops_find_by_name(ops->name))
>+		ret = -EEXIST;
>+	else
>+		list_add_tail_rcu(&ops->list, &smc_ops_list);
>+	spin_unlock(&smc_ops_list_lock);
>+	return ret;
>+}
>+
>+static void smc_ops_unreg(struct smc_ops *ops)
>+{
>+	spin_lock(&smc_ops_list_lock);
>+	list_del_rcu(&ops->list);
>+	spin_unlock(&smc_ops_list_lock);
>+
>+	/* Ensure that all readers to complete */
>+	synchronize_rcu();
>+}
>+
>+struct smc_ops *smc_ops_find_by_name(const char *name)
>+{
>+	struct smc_ops *ops;
>+
>+	list_for_each_entry_rcu(ops, &smc_ops_list, list) {
>+		if (strcmp(ops->name, name) == 0)
>+			return ops;
>+	}
>+	return NULL;
>+}
>diff --git a/net/smc/smc_ops.h b/net/smc/smc_ops.h
>new file mode 100644
>index 000000000000..4b33dc2d65b9
>--- /dev/null
>+++ b/net/smc/smc_ops.h
>@@ -0,0 +1,25 @@
>+/* SPDX-License-Identifier: GPL-2.0 */
>+/*
>+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
>+ *
>+ *  Generic hook for SMC subsystem.
>+ *
>+ *  Copyright IBM Corp. 2016
>+ *  Copyright (c) 2024, Alibaba Inc.
>+ *
>+ *  Author: D. Wythe <alibuda@linux.alibaba.com>
>+ */
>+
>+#ifndef __SMC_OPS
>+#define __SMC_OPS
>+
>+#include <net/smc.h>
>+
>+/* Find ops by the target name, which required to be a c-string.
>+ * Return NULL if no such ops was found,otherwise, return a valid ops.
>+ *
>+ * Note: Caller MUST ensure it's was invoked under rcu_read_lock.
>+ */
>+struct smc_ops *smc_ops_find_by_name(const char *name);
>+
>+#endif /* __SMC_OPS */
>diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
>index 2fab6456f765..2aa3f19025f4 100644
>--- a/net/smc/smc_sysctl.c
>+++ b/net/smc/smc_sysctl.c
>@@ -18,6 +18,7 @@
> #include "smc_core.h"
> #include "smc_llc.h"
> #include "smc_sysctl.h"
>+#include "smc_ops.h"
> 
> static int min_sndbuf = SMC_BUF_MIN_SIZE;
> static int min_rcvbuf = SMC_BUF_MIN_SIZE;
>@@ -30,6 +31,70 @@ static int links_per_lgr_max = SMC_LINKS_ADD_LNK_MAX;
> static int conns_per_lgr_min = SMC_CONN_PER_LGR_MIN;
> static int conns_per_lgr_max = SMC_CONN_PER_LGR_MAX;
> 
>+#if IS_ENABLED(CONFIG_SMC_OPS)
>+static int smc_net_replace_smc_ops(struct net *net, const char *name)
>+{
>+	struct smc_ops *ops = NULL;
>+
>+	rcu_read_lock();
>+	/* null or empty name ask to clear current ops */
>+	if (name && name[0]) {
>+		ops = smc_ops_find_by_name(name);
>+		if (!ops) {
>+			rcu_read_unlock();
>+			return -EINVAL;
>+		}
>+		/* no change, just return */
>+		if (ops == rcu_dereference(net->smc.ops)) {
>+			rcu_read_unlock();
>+			return 0;
>+		}
>+	}
>+	if (!ops || bpf_try_module_get(ops, ops->owner)) {
>+		/* xhcg */
>+		ops = rcu_replace_pointer(net->smc.ops, ops, true);
>+		/* release old ops */
>+		if (ops)
>+			bpf_module_put(ops, ops->owner);
>+	} else if (ops) {
>+		rcu_read_unlock();
>+		return -EBUSY;
>+	}
>+	rcu_read_unlock();
>+	return 0;
>+}
>+
>+static int proc_smc_ops(const struct ctl_table *ctl, int write,
>+			void *buffer, size_t *lenp, loff_t *ppos)
>+{
>+	struct net *net = container_of(ctl->data, struct net,
>+				       smc.ops);

This line won't exceed 80 characters, no need to split into 2 lines.


Best regards,
Dust

Re: [PATCH bpf-next v5 2/5] net/smc: Introduce generic hook smc_ops

[D. Wythe]

On Mon, Jan 13, 2025 at 07:40:12PM +0800, Dust Li wrote:
> On 2025-01-07 12:17:12, D. Wythe wrote:
> >The introduction of IPPROTO_SMC enables eBPF programs to determine
> >whether to use SMC based on the context of socket creation, such as
> >network namespaces, PID and comm name, etc.
> >
> >As a subsequent enhancement, to introduce a new generic hook that
> >allows decisions on whether to use SMC or not at runtime, including
> >but not limited to local/remote IP address or ports.
> >
> >Moreover, in the future, we can achieve more complex extensions to the
> >protocol stack by extending this ops.
> >
> >Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
> >---
> > include/net/netns/smc.h |  3 ++
> > include/net/smc.h       | 51 ++++++++++++++++++++++
> > net/ipv4/tcp_output.c   | 15 +++++--
> > net/smc/Kconfig         | 12 ++++++
> > net/smc/Makefile        |  1 +
> > net/smc/smc_ops.c       | 51 ++++++++++++++++++++++
> > net/smc/smc_ops.h       | 25 +++++++++++
> > net/smc/smc_sysctl.c    | 95 +++++++++++++++++++++++++++++++++++++++++
> > 8 files changed, 249 insertions(+), 4 deletions(-)
> > create mode 100644 net/smc/smc_ops.c
> > create mode 100644 net/smc/smc_ops.h
> >
> >diff --git a/include/net/netns/smc.h b/include/net/netns/smc.h
> >index fc752a50f91b..59d069f56b2d 100644
> >--- a/include/net/netns/smc.h
> >+++ b/include/net/netns/smc.h
> >@@ -17,6 +17,9 @@ struct netns_smc {
> > #ifdef CONFIG_SYSCTL
> > 	struct ctl_table_header		*smc_hdr;
> > #endif
> >+#if IS_ENABLED(CONFIG_SMC_OPS)
> >+	struct smc_ops __rcu *ops;
>                               ^^^
> Align with other fields
> 
Oops, nice catch.
> >+#endif /* CONFIG_SMC_OPS */
> > 	unsigned int			sysctl_autocorking_size;
> > 	unsigned int			sysctl_smcr_buf_type;
> > 	int				sysctl_smcr_testlink_time;
> >diff --git a/include/net/smc.h b/include/net/smc.h
> >index db84e4e35080..326a217001d4 100644
> >--- a/include/net/smc.h
> >+++ b/include/net/smc.h
> >+#include <net/smc.h>
> 
> Put this include right after #include <net/proto_memory.h> ?
> I notice all the includes here are well classified.
> 
> 
Done, I didn't notice this detail before.
> > 
> > /* Refresh clocks of a TCP socket,
> >  * ensuring monotically increasing values.
> >@@ -759,14 +760,17 @@ static void tcp_options_write(struct tcphdr *th, struct tcp_sock *tp,
> > 	mptcp_options_write(th, ptr, tp, opts);
> > }
> > 
> >-static void smc_set_option(const struct tcp_sock *tp,
> >+static void smc_set_option(struct tcp_sock *tp,
> > 			   struct tcp_out_options *opts,
> > 			   unsigned int *remaining)
> > {
> >+	  SMC_OPS enables support to register genericfor hook via eBPF programs
> 
> genericfor ?
> 
generic.. I will fix it in next version. 
> >+	  for SMC subsystem. eBPF programs offer much greater flexibility
> >+	  in modifying the behavior of the SMC protocol stack compared
> >+	  to a complete kernel-based approach.
> >+
> >+	  if unsure, say N.
> >diff --git a/net/smc/Makefile b/net/smc/Makefile
> >index 60f1c87d5212..5dd706b2927a 100644
> >--- a/net/smc/Makefile
> >+++ b/net/smc/Makefile
> >+	struct net *net = container_of(ctl->data, struct net,
> >+				       smc.ops);
> 
> This line won't exceed 80 characters, no need to split into 2 lines.
> 
Take it. Thanks for all the advices.

Best wishes,
D. Wythe

> 
> Best regards,
> Dust

Re: [PATCH bpf-next v5 2/5] net/smc: Introduce generic hook smc_ops

[Dust Li]

On 2025-01-07 12:17:12, D. Wythe wrote:
>The introduction of IPPROTO_SMC enables eBPF programs to determine
>whether to use SMC based on the context of socket creation, such as
>network namespaces, PID and comm name, etc.
>
>As a subsequent enhancement, to introduce a new generic hook that
>allows decisions on whether to use SMC or not at runtime, including
>but not limited to local/remote IP address or ports.
>
>Moreover, in the future, we can achieve more complex extensions to the
>protocol stack by extending this ops.
>
>Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
>---
> include/net/netns/smc.h |  3 ++
> include/net/smc.h       | 51 ++++++++++++++++++++++
> net/ipv4/tcp_output.c   | 15 +++++--
> net/smc/Kconfig         | 12 ++++++
> net/smc/Makefile        |  1 +
> net/smc/smc_ops.c       | 51 ++++++++++++++++++++++
> net/smc/smc_ops.h       | 25 +++++++++++
> net/smc/smc_sysctl.c    | 95 +++++++++++++++++++++++++++++++++++++++++
> 8 files changed, 249 insertions(+), 4 deletions(-)
> create mode 100644 net/smc/smc_ops.c
> create mode 100644 net/smc/smc_ops.h
>
>diff --git a/include/net/netns/smc.h b/include/net/netns/smc.h
>index fc752a50f91b..59d069f56b2d 100644
>--- a/include/net/netns/smc.h
>+++ b/include/net/netns/smc.h
>@@ -17,6 +17,9 @@ struct netns_smc {
> #ifdef CONFIG_SYSCTL
> 	struct ctl_table_header		*smc_hdr;
> #endif
>+#if IS_ENABLED(CONFIG_SMC_OPS)
>+	struct smc_ops __rcu *ops;
>+#endif /* CONFIG_SMC_OPS */
> 	unsigned int			sysctl_autocorking_size;
> 	unsigned int			sysctl_smcr_buf_type;
> 	int				sysctl_smcr_testlink_time;
>diff --git a/include/net/smc.h b/include/net/smc.h
>index db84e4e35080..326a217001d4 100644
>--- a/include/net/smc.h
>+++ b/include/net/smc.h
>@@ -18,6 +18,8 @@
> #include "linux/ism.h"
> 
> struct sock;
>+struct tcp_sock;
>+struct inet_request_sock;
> 
> #define SMC_MAX_PNETID_LEN	16	/* Max. length of PNET id */
> 
>@@ -97,4 +99,53 @@ struct smcd_dev {
> 	u8 going_away : 1;
> };
> 
>+#define  SMC_OPS_NAME_MAX 16
>+
>+enum {
>+	/* ops can be inherit from init_net */
>+	SMC_OPS_FLAG_INHERITABLE = 0x1,
>+
>+	SMC_OPS_ALL_FLAGS = SMC_OPS_FLAG_INHERITABLE,
>+};
>+
>+struct smc_ops {

One more thing.
Can we call it smc_bpf_ops ? I think smc_ops is a bit ambiguous.
Same for smc_ops.h/c source file.

Best regards,
Dust

Re: [PATCH bpf-next v5 2/5] net/smc: Introduce generic hook smc_ops

[D. Wythe]

On Mon, Jan 13, 2025 at 07:49:44PM +0800, Dust Li wrote:
> On 2025-01-07 12:17:12, D. Wythe wrote:
> >The introduction of IPPROTO_SMC enables eBPF programs to determine
> >whether to use SMC based on the context of socket creation, such as
> >network namespaces, PID and comm name, etc.
> >
> >As a subsequent enhancement, to introduce a new generic hook that
> >allows decisions on whether to use SMC or not at runtime, including
> >but not limited to local/remote IP address or ports.
> >
> >Moreover, in the future, we can achieve more complex extensions to the
> >protocol stack by extending this ops.
> >
> >Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
> >---
> > include/net/netns/smc.h |  3 ++
> > include/net/smc.h       | 51 ++++++++++++++++++++++
> > net/ipv4/tcp_output.c   | 15 +++++--
> > net/smc/Kconfig         | 12 ++++++
> > net/smc/Makefile        |  1 +
> > net/smc/smc_ops.c       | 51 ++++++++++++++++++++++
> > net/smc/smc_ops.h       | 25 +++++++++++
> > net/smc/smc_sysctl.c    | 95 +++++++++++++++++++++++++++++++++++++++++
> > 8 files changed, 249 insertions(+), 4 deletions(-)
> > create mode 100644 net/smc/smc_ops.c
> > create mode 100644 net/smc/smc_ops.h
> >
> >+
> >+struct smc_ops {
> 
> One more thing.
> Can we call it smc_bpf_ops ? I think smc_ops is a bit ambiguous.
> Same for smc_ops.h/c source file.

I don't think smc_bpf_ops is a good idea. BPF is just a way to implement
smc_ops. Similarly, we can also implement this ops within the kernel module,
just like tcp_congestion_ops dose. If you think this is ambiguous, perhaps
we can call it as smc_handshake_ops ? This should eliminate the ambiguity.

Best wishes,
D. Wythe
> 
> Best regards,
> Dust

[PATCH bpf-next v5 3/5] net/smc: bpf: register smc_ops info struct_ops

[D. Wythe]

To implement injection capability for smc via struct_ops, so that
user can make their own smc_ops to modify the behavior of smc stack.

Currently, user can write their own implememtion to choose whether to
use SMC or not before TCP 3rd handshake to be comleted. In the future,
users can implement more complex functions on smc by expanding it.

Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
 net/smc/af_smc.c  | 10 ++++++
 net/smc/smc_ops.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++
 net/smc/smc_ops.h |  5 +++
 3 files changed, 94 insertions(+)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 9d76e902fd77..6adedae2986d 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -55,6 +55,7 @@
 #include "smc_sysctl.h"
 #include "smc_loopback.h"
 #include "smc_inet.h"
+#include "smc_ops.h"
 
 static DEFINE_MUTEX(smc_server_lgr_pending);	/* serialize link group
 						 * creation on server
@@ -3576,8 +3577,17 @@ static int __init smc_init(void)
 		pr_err("%s: smc_inet_init fails with %d\n", __func__, rc);
 		goto out_ulp;
 	}
+
+	rc = smc_bpf_struct_ops_init();
+	if (rc) {
+		pr_err("%s: smc_bpf_struct_ops_init fails with %d\n", __func__, rc);
+		goto out_inet;
+	}
+
 	static_branch_enable(&tcp_have_smc);
 	return 0;
+out_inet:
+	smc_inet_exit();
 out_ulp:
 	tcp_unregister_ulp(&smc_ulp_ops);
 out_lo:
diff --git a/net/smc/smc_ops.c b/net/smc/smc_ops.c
index 0fc19cadd760..67b6b2b92771 100644
--- a/net/smc/smc_ops.c
+++ b/net/smc/smc_ops.c
@@ -10,6 +10,10 @@
  *  Author: D. Wythe <alibuda@linux.alibaba.com>
  */
 
+#include <linux/bpf_verifier.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+
 #include "smc_ops.h"
 
 static DEFINE_SPINLOCK(smc_ops_list_lock);
@@ -49,3 +53,78 @@ struct smc_ops *smc_ops_find_by_name(const char *name)
 	}
 	return NULL;
 }
+
+static int __bpf_smc_stub_set_tcp_option(struct tcp_sock *tp) { return 1; }
+static int __bpf_smc_stub_set_tcp_option_cond(const struct tcp_sock *tp,
+					      struct inet_request_sock *ireq)
+{
+	return 1;
+}
+
+static struct smc_ops __bpf_smc_bpf_ops = {
+	.set_option		= __bpf_smc_stub_set_tcp_option,
+	.set_option_cond	= __bpf_smc_stub_set_tcp_option_cond,
+};
+
+static int smc_bpf_ops_init(struct btf *btf) { return 0; }
+
+static int smc_bpf_ops_reg(void *kdata, struct bpf_link *link)
+{
+	return smc_ops_reg(kdata);
+}
+
+static void smc_bpf_ops_unreg(void *kdata, struct bpf_link *link)
+{
+	smc_ops_unreg(kdata);
+}
+
+static int smc_bpf_ops_init_member(const struct btf_type *t,
+				   const struct btf_member *member,
+				   void *kdata, const void *udata)
+{
+	const struct smc_ops *u_ops;
+	struct smc_ops *k_ops;
+	u32 moff;
+
+	u_ops = (const struct smc_ops *)udata;
+	k_ops = (struct smc_ops *)kdata;
+
+	moff = __btf_member_bit_offset(t, member) / 8;
+	switch (moff) {
+	case offsetof(struct smc_ops, name):
+		if (bpf_obj_name_cpy(k_ops->name, u_ops->name,
+				     sizeof(u_ops->name)) <= 0)
+			return -EINVAL;
+		return 1;
+	case offsetof(struct smc_ops, flags):
+		if (u_ops->flags & ~SMC_OPS_ALL_FLAGS)
+			return -EINVAL;
+		k_ops->flags = u_ops->flags;
+		return 1;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static const struct bpf_verifier_ops smc_bpf_verifier_ops = {
+	.get_func_proto		= bpf_base_func_proto,
+	.is_valid_access	= bpf_tracing_btf_ctx_access,
+};
+
+static struct bpf_struct_ops bpf_smc_bpf_ops = {
+	.name		= "smc_ops",
+	.init		= smc_bpf_ops_init,
+	.reg		= smc_bpf_ops_reg,
+	.unreg		= smc_bpf_ops_unreg,
+	.cfi_stubs	= &__bpf_smc_bpf_ops,
+	.verifier_ops	= &smc_bpf_verifier_ops,
+	.init_member	= smc_bpf_ops_init_member,
+	.owner		= THIS_MODULE,
+};
+
+int smc_bpf_struct_ops_init(void)
+{
+	return register_bpf_struct_ops(&bpf_smc_bpf_ops, smc_ops);
+}
diff --git a/net/smc/smc_ops.h b/net/smc/smc_ops.h
index 4b33dc2d65b9..06dc30363a83 100644
--- a/net/smc/smc_ops.h
+++ b/net/smc/smc_ops.h
@@ -21,5 +21,10 @@
  * Note: Caller MUST ensure it's was invoked under rcu_read_lock.
  */
 struct smc_ops *smc_ops_find_by_name(const char *name);
+#if IS_ENABLED(CONFIG_SMC_OPS)
+int smc_bpf_struct_ops_init(void);
+#else
+static inline int smc_bpf_struct_ops_init(void) { return 0; }
+#endif
 
 #endif /* __SMC_OPS */
-- 
2.45.0

[PATCH bpf-next v5 4/5] libbpf: fix error when st-prefix_ops and ops from differ btf

[D. Wythe]

When a struct_ops named xxx_ops was registered by a module, and
it will be used in both built-in modules and the module itself,
so that the btf_type of xxx_ops will be present in btf_vmlinux
instead of in btf_mod, which means that the btf_type of
bpf_struct_ops_xxx_ops and xxx_ops will not be in the same btf.

Here are four possible case:

+--------+-------------+-------------+---------------------------------+
|        | st_opx_xxx  | xxx         |                                 |
+--------+-------------+-------------+---------------------------------+
| case 0 | btf_vmlinux | bft_vmlinux | be used and reg only in vmlinux |
+--------+-------------+-------------+---------------------------------+
| case 1 | btf_vmlinux | bpf_mod     | INVALID                         |
+--------+-------------+-------------+---------------------------------+
| case 2 | btf_mod     | btf_vmlinux | reg in mod but be used both in  |
|        |             |             | vmlinux and mod.                |
+--------+-------------+-------------+---------------------------------+
| case 3 | btf_mod     | btf_mod     | be used and reg only in mod     |
+--------+-------------+-------------+---------------------------------+

At present, cases 0, 1, and 3 can be correctly identified, because
st_ops_xxx is searched from the same btf with xxx. In order to
handle case 2 correctly without affecting other cases, we cannot simply
change the search method for st_ops_xxx from find_btf_by_prefix_kind()
to find_ksym_btf_id(), because in this way, case 1 will not be
recognized anymore.

To address this issue, if st_ops_xxx cannot be found in the btf with xxx
and mod_btf does not exist, do find_ksym_btf_id() again to
avoid such issue.

Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support")
Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
 tools/lib/bpf/libbpf.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 66173ddb5a2d..56bf74894110 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1005,7 +1005,8 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw,
 	const struct btf_member *kern_data_member;
 	struct btf *btf = NULL;
 	__s32 kern_vtype_id, kern_type_id;
-	char tname[256];
+	char tname[256], stname[256];
+	int ret;
 	__u32 i;
 
 	snprintf(tname, sizeof(tname), "%.*s",
@@ -1020,17 +1021,25 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw,
 	}
 	kern_type = btf__type_by_id(btf, kern_type_id);
 
+	ret = snprintf(stname, sizeof(stname), "%s%s", STRUCT_OPS_VALUE_PREFIX, tname);
+	if (ret < 0 || ret >= sizeof(stname))
+		return -ENAMETOOLONG;
+
 	/* Find the corresponding "map_value" type that will be used
 	 * in map_update(BPF_MAP_TYPE_STRUCT_OPS).  For example,
 	 * find "struct bpf_struct_ops_tcp_congestion_ops" from the
 	 * btf_vmlinux.
 	 */
-	kern_vtype_id = find_btf_by_prefix_kind(btf, STRUCT_OPS_VALUE_PREFIX,
-						tname, BTF_KIND_STRUCT);
+	kern_vtype_id = btf__find_by_name_kind(btf, stname, BTF_KIND_STRUCT);
 	if (kern_vtype_id < 0) {
-		pr_warn("struct_ops init_kern: struct %s%s is not found in kernel BTF\n",
-			STRUCT_OPS_VALUE_PREFIX, tname);
-		return kern_vtype_id;
+		if (kern_vtype_id == -ENOENT && !*mod_btf)
+			kern_vtype_id = find_ksym_btf_id(obj, stname, BTF_KIND_STRUCT,
+							 &btf, mod_btf);
+		if (kern_vtype_id < 0) {
+			pr_warn("struct_ops init_kern: struct %s is not found in kernel BTF\n",
+				stname);
+			return kern_vtype_id;
+		}
 	}
 	kern_vtype = btf__type_by_id(btf, kern_vtype_id);
 
@@ -1046,8 +1055,8 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw,
 			break;
 	}
 	if (i == btf_vlen(kern_vtype)) {
-		pr_warn("struct_ops init_kern: struct %s data is not found in struct %s%s\n",
-			tname, STRUCT_OPS_VALUE_PREFIX, tname);
+		pr_warn("struct_ops init_kern: struct %s data is not found in struct %s\n",
+			tname, stname);
 		return -EINVAL;
 	}
 
-- 
2.45.0

[PATCH bpf-next v5 5/5] bpf/selftests: add selftest for bpf_smc_ops

[D. Wythe]

This tests introduces a tiny smc_ops for filtering SMC connections based on
IP pairs, and also adds a realistic topology model to verify this ops.

Also, we can only use SMC loopback under CI test, so an
additional configuration needs to be enabled.

Follow the steps below to run this test.

make -C tools/testing/selftests/bpf
cd tools/testing/selftests/bpf
sudo ./test_progs -t smc

Results shows:
Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: D. Wythe <alibuda@linux.alibaba.com>
---
 tools/testing/selftests/bpf/config            |   4 +
 .../selftests/bpf/prog_tests/test_bpf_smc.c   | 390 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/bpf_smc.c   | 116 ++++++
 3 files changed, 510 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/test_bpf_smc.c
 create mode 100644 tools/testing/selftests/bpf/progs/bpf_smc.c

diff --git a/tools/testing/selftests/bpf/config b/tools/testing/selftests/bpf/config
index c378d5d07e02..fac2f2a9d02f 100644
--- a/tools/testing/selftests/bpf/config
+++ b/tools/testing/selftests/bpf/config
@@ -113,3 +113,7 @@ CONFIG_XDP_SOCKETS=y
 CONFIG_XFRM_INTERFACE=y
 CONFIG_TCP_CONG_DCTCP=y
 CONFIG_TCP_CONG_BBR=y
+CONFIG_INFINIBAND=y
+CONFIG_SMC=y
+CONFIG_SMC_OPS=y
+CONFIG_SMC_LO=y
\ No newline at end of file
diff --git a/tools/testing/selftests/bpf/prog_tests/test_bpf_smc.c b/tools/testing/selftests/bpf/prog_tests/test_bpf_smc.c
new file mode 100644
index 000000000000..689ac13fb6ec
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/test_bpf_smc.c
@@ -0,0 +1,390 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <linux/genetlink.h>
+#include "network_helpers.h"
+#include "bpf_smc.skel.h"
+
+#ifndef IPPROTO_SMC
+#define IPPROTO_SMC 256
+#endif
+
+#define CLIENT_IP			"127.0.0.1"
+#define SERVER_IP			"127.0.1.0"
+#define SERVER_IP_VIA_RISK_PATH	"127.0.2.0"
+
+#define SERVICE_1	11234
+#define SERVICE_2	22345
+#define SERVICE_3	33456
+
+#define TEST_NS	"bpf_smc_netns"
+
+enum {
+	SMC_NETLINK_ADD_UEID = 10,
+	SMC_NETLINK_REMOVE_UEID
+};
+
+enum {
+	SMC_NLA_EID_TABLE_UNSPEC,
+	SMC_NLA_EID_TABLE_ENTRY,    /* string */
+};
+
+struct smc_strat_ip_key {
+	__u32  sip;
+	__u32  dip;
+};
+
+struct smc_strat_ip_value {
+	__u8	mode;
+};
+
+struct msgtemplate {
+	struct nlmsghdr n;
+	struct genlmsghdr g;
+	char buf[1024];
+};
+
+#define GENLMSG_DATA(glh)	((void *)(NLMSG_DATA(glh) + GENL_HDRLEN))
+#define GENLMSG_PAYLOAD(glh)	(NLMSG_PAYLOAD(glh, 0) - GENL_HDRLEN)
+#define NLA_DATA(na)		((void *)((char *)(na) + NLA_HDRLEN))
+#define NLA_PAYLOAD(len)	((len) - NLA_HDRLEN)
+
+#define MAX_MSG_SIZE		1024
+
+#define SMC_GENL_FAMILY_NAME	"SMC_GEN_NETLINK"
+#define SMC_BPFTEST_UEID	"SMC-BPFTEST-UEID"
+
+static uint16_t smc_nl_family_id = -1;
+static struct nstoken *nstoken;
+
+static int send_cmd(int fd, __u16 nlmsg_type, __u32 nlmsg_pid, __u16 nlmsg_flags,
+			__u8 genl_cmd, __u16 nla_type,
+			void *nla_data, int nla_len)
+{
+	struct nlattr *na;
+	struct sockaddr_nl nladdr;
+	int r, buflen;
+	char *buf;
+
+	struct msgtemplate msg = {0};
+
+	msg.n.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
+	msg.n.nlmsg_type = nlmsg_type;
+	msg.n.nlmsg_flags = nlmsg_flags;
+	msg.n.nlmsg_seq = 0;
+	msg.n.nlmsg_pid = nlmsg_pid;
+	msg.g.cmd = genl_cmd;
+	msg.g.version = 1;
+	na = (struct nlattr *) GENLMSG_DATA(&msg);
+	na->nla_type = nla_type;
+	na->nla_len = nla_len + 1 + NLA_HDRLEN;
+	memcpy(NLA_DATA(na), nla_data, nla_len);
+	msg.n.nlmsg_len += NLMSG_ALIGN(na->nla_len);
+
+	buf = (char *) &msg;
+	buflen = msg.n.nlmsg_len;
+	memset(&nladdr, 0, sizeof(nladdr));
+	nladdr.nl_family = AF_NETLINK;
+
+	while ((r = sendto(fd, buf, buflen, 0, (struct sockaddr *) &nladdr,
+			   sizeof(nladdr))) < buflen) {
+		if (r > 0) {
+			buf += r;
+			buflen -= r;
+		} else if (errno != EAGAIN)
+			return -1;
+		}
+	return 0;
+}
+
+static bool get_smc_nl_family_id(void)
+{
+	struct sockaddr_nl nl_src;
+	struct msgtemplate msg;
+	struct nlattr *nl;
+	int fd, ret;
+	pid_t pid;
+
+	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
+	if (!ASSERT_GT(fd, 0, "nl_family socket"))
+		return false;
+
+	pid = getpid();
+
+	memset(&nl_src, 0, sizeof(nl_src));
+	nl_src.nl_family = AF_NETLINK;
+	nl_src.nl_pid = pid;
+
+	ret = bind(fd, (struct sockaddr *) &nl_src, sizeof(nl_src));
+	if (!ASSERT_GE(ret, 0, "nl_family bind"))
+		goto fail;
+
+	ret = send_cmd(fd, GENL_ID_CTRL, pid,
+		       NLM_F_REQUEST, CTRL_CMD_GETFAMILY,
+		       CTRL_ATTR_FAMILY_NAME, (void *)SMC_GENL_FAMILY_NAME,
+		       strlen(SMC_GENL_FAMILY_NAME));
+	if (!ASSERT_EQ(ret, 0, "nl_family query"))
+		goto fail;
+
+	ret = recv(fd, &msg, sizeof(msg), 0);
+	if (!ASSERT_FALSE(msg.n.nlmsg_type == NLMSG_ERROR || (ret < 0) ||
+			  !NLMSG_OK((&msg.n), ret), "nl_family response"))
+		goto fail;
+
+	nl = (struct nlattr *) GENLMSG_DATA(&msg);
+	nl = (struct nlattr *) ((char *) nl + NLA_ALIGN(nl->nla_len));
+	if (!ASSERT_EQ(nl->nla_type, CTRL_ATTR_FAMILY_ID, "nl_family nla type"))
+		goto fail;
+
+	smc_nl_family_id = *(uint16_t *) NLA_DATA(nl);
+	close(fd);
+	return true;
+fail:
+	close(fd);
+	return false;
+}
+
+static bool smc_ueid(int op)
+{
+	struct sockaddr_nl nl_src;
+	struct msgtemplate msg;
+	struct nlmsgerr *err;
+	char test_ueid[32];
+	int fd, ret;
+	pid_t pid;
+
+	/* UEID required */
+	memset(test_ueid, '\x20', sizeof(test_ueid));
+	memcpy(test_ueid, SMC_BPFTEST_UEID, strlen(SMC_BPFTEST_UEID));
+	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
+	if (!ASSERT_GT(fd, 0, "ueid socket"))
+		return false;
+
+	pid = getpid();
+	memset(&nl_src, 0, sizeof(nl_src));
+	nl_src.nl_family = AF_NETLINK;
+	nl_src.nl_pid = pid;
+
+	ret = bind(fd, (struct sockaddr *) &nl_src, sizeof(nl_src));
+	if (!ASSERT_GE(ret, 0, "ueid bind"))
+		goto fail;
+
+	ret = send_cmd(fd, smc_nl_family_id, pid,
+		       NLM_F_REQUEST | NLM_F_ACK, op, SMC_NLA_EID_TABLE_ENTRY,
+	(void *)test_ueid, sizeof(test_ueid));
+	if (!ASSERT_EQ(ret, 0, "ueid cmd"))
+		goto fail;
+
+	ret = recv(fd, &msg, sizeof(msg), 0);
+	if (!ASSERT_FALSE((ret < 0) || !NLMSG_OK((&msg.n), ret), "ueid response"))
+		goto fail;
+
+	if (msg.n.nlmsg_type == NLMSG_ERROR) {
+		err = NLMSG_DATA(&msg);
+		switch (op) {
+		case SMC_NETLINK_REMOVE_UEID:
+			if (!ASSERT_FALSE((err->error && err->error != -ENOENT), "ueid remove"))
+				goto fail;
+			break;
+		case SMC_NETLINK_ADD_UEID:
+			if (!ASSERT_EQ(err->error, 0, "ueid add"))
+				goto fail;
+			break;
+		default:
+			break;
+		}
+	}
+	close(fd);
+	return true;
+fail:
+	close(fd);
+	return false;
+}
+
+static bool setup_netns(void)
+{
+	if (!ASSERT_OK(make_netns(TEST_NS), "create net namespace"))
+		return false;
+
+	nstoken = open_netns(TEST_NS);
+	if (!ASSERT_OK_PTR(nstoken, "open net namespace"))
+		goto fail_open_netns;
+
+	if (!ASSERT_OK(system("ip addr add 127.0.1.0/8 dev lo"), "add server node"))
+		goto fail_ip;
+
+	if (!ASSERT_OK(system("ip addr add 127.0.2.0/8 dev lo"), "server via risk path"))
+		goto fail_ip;
+
+	return true;
+fail_open_netns:
+	remove_netns(TEST_NS);
+fail_ip:
+	close_netns(nstoken);
+	return false;
+}
+
+static void cleanup_netns(void)
+{
+	close_netns(nstoken);
+	remove_netns(TEST_NS);
+}
+
+static bool setup_ueid(void)
+{
+	/* get smc nl id */
+	if (!get_smc_nl_family_id())
+		return false;
+	/* clear old ueid for bpftest */
+	smc_ueid(SMC_NETLINK_REMOVE_UEID);
+	/* smc-loopback required ueid */
+	return smc_ueid(SMC_NETLINK_ADD_UEID);
+}
+
+static void cleanup_ueid(void)
+{
+	smc_ueid(SMC_NETLINK_REMOVE_UEID);
+}
+
+static bool setup_smc(void)
+{
+	if (!setup_ueid())
+		return false;
+
+	if (!setup_netns())
+		goto fail_netns;
+
+	return true;
+fail_netns:
+	cleanup_ueid();
+	return false;
+}
+
+static int set_client_addr_cb(int fd, void *opts)
+{
+	const char *src = (const char *)opts;
+	struct sockaddr_in localaddr;
+
+	localaddr.sin_family = AF_INET;
+	localaddr.sin_port = htons(0);
+	localaddr.sin_addr.s_addr = inet_addr(src);
+	return !ASSERT_EQ(bind(fd, &localaddr, sizeof(localaddr)), 0, "client bind");
+}
+
+static void run_link(const char *src, const char *dst, int port)
+{
+	struct network_helper_opts opts = {0};
+	int server, client;
+
+	server = start_server_str(AF_INET, SOCK_STREAM, dst, port, NULL);
+	if (!ASSERT_OK_FD(server, "start service_1"))
+		return;
+
+	opts.proto = IPPROTO_TCP;
+	opts.post_socket_cb = set_client_addr_cb;
+	opts.cb_opts = (void *)src;
+
+	client = connect_to_fd_opts(server, &opts);
+	if (!ASSERT_OK_FD(client, "start connect"))
+		goto fail_client;
+
+	close(client);
+fail_client:
+	close(server);
+}
+
+static void block_link(int map_fd, const char *src, const char *dst)
+{
+	struct smc_strat_ip_value val = { .mode = /* block */ 0 };
+	struct smc_strat_ip_key key = {
+		.sip = inet_addr(src),
+		.dip = inet_addr(dst),
+	};
+
+	bpf_map_update_elem(map_fd, &key, &val, BPF_ANY);
+}
+
+/*
+ * This test describes a real-life service topology as follows:
+ *
+ *                             +-------------> service_1
+ *            link1            |                     |
+ *   +--------------------> server                   |  link 2
+ *   |                         |                     V
+ *   |                         +-------------> service_2
+ *   |        link 3
+ *  client -------------------> server_via_unsafe_path -> service_3
+ *
+ * Among them,
+ * 1. link-1 is very suitable for using SMC.
+ * 2. link-2 is not suitable for using SMC, because the mode of this link is kind of
+ *     short-link services.
+ * 3. link-3 is also not suitable for using SMC, because the RDMA link is unavailable and
+ *     needs to go through a long timeout before it can fallback to TCP.
+ *
+ * To achieve this goal, we use a customized SMC ip strategy via smc_ops.
+ */
+static void test_topo(void)
+{
+	struct bpf_smc *skel;
+	int rc, map_fd;
+
+	skel = bpf_smc__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "bpf_smc__open_and_load"))
+		return;
+
+	rc = bpf_smc__attach(skel);
+	if (!ASSERT_EQ(rc, 0, "bpf_smc__attach"))
+		goto fail;
+
+	map_fd = bpf_map__fd(skel->maps.smc_strats_ip);
+	if (!ASSERT_GT(map_fd, 0, "bpf_map__fd"))
+		goto fail;
+
+	/* Mock the process of transparent replacement, since we will modify protocol
+	 * to ipproto_smc accropding to it via fmod_ret/update_socket_protocol.
+	 */
+	system("sysctl -w net.smc.ops=linkcheck");
+
+	/* Configure ip strat */
+	block_link(map_fd, CLIENT_IP, SERVER_IP_VIA_RISK_PATH);
+	block_link(map_fd, SERVER_IP, SERVER_IP);
+	close(map_fd);
+
+	/* should go with smc */
+	run_link(CLIENT_IP, SERVER_IP, SERVICE_1);
+	/* should go with smc fallback */
+	run_link(SERVER_IP, SERVER_IP, SERVICE_2);
+
+	ASSERT_EQ(skel->bss->smc_cnt, 2, "smc count");
+	ASSERT_EQ(skel->bss->fallback_cnt, 1, "fallback count");
+
+	/* should go with smc */
+	run_link(CLIENT_IP, SERVER_IP, SERVICE_2);
+
+	ASSERT_EQ(skel->bss->smc_cnt, 3, "smc count");
+	ASSERT_EQ(skel->bss->fallback_cnt, 1, "fallback count");
+
+	/* should go with smc fallback */
+	run_link(CLIENT_IP, SERVER_IP_VIA_RISK_PATH, SERVICE_3);
+
+	ASSERT_EQ(skel->bss->smc_cnt, 4, "smc count");
+	ASSERT_EQ(skel->bss->fallback_cnt, 2, "fallback count");
+
+fail:
+	bpf_smc__destroy(skel);
+}
+
+void test_bpf_smc(void)
+{
+	if (!setup_smc()) {
+		printf("setup for smc test failed, test SKIP:\n");
+		test__skip();
+		return;
+	}
+
+	if (test__start_subtest("topo"))
+		test_topo();
+
+	cleanup_ueid();
+	cleanup_netns();
+}
diff --git a/tools/testing/selftests/bpf/progs/bpf_smc.c b/tools/testing/selftests/bpf/progs/bpf_smc.c
new file mode 100644
index 000000000000..a8c62a9882c7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_smc.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_tracing_net.h"
+
+char _license[] SEC("license") = "GPL";
+
+enum {
+	BPF_SMC_LISTEN	= 10,
+};
+
+struct smc_sock___local {
+	struct sock sk;
+	struct smc_sock *listen_smc;
+	bool use_fallback;
+} __attribute__((preserve_access_index));
+
+int smc_cnt = 0;
+int fallback_cnt = 0;
+
+SEC("fentry/smc_release")
+int BPF_PROG(bpf_smc_release, struct socket *sock)
+{
+	/* only count from one side (client) */
+	if (sock->sk->__sk_common.skc_state == BPF_SMC_LISTEN)
+		return 0;
+	smc_cnt++;
+	return 0;
+}
+
+SEC("fentry/smc_switch_to_fallback")
+int BPF_PROG(bpf_smc_switch_to_fallback, struct smc_sock___local *smc)
+{
+	/* only count from one side (client) */
+	if (smc && !BPF_CORE_READ(smc, listen_smc))
+		fallback_cnt++;
+	return 0;
+}
+
+/* go with default value if no strat was found */
+bool default_ip_strat_value = true;
+
+struct smc_strat_ip_key {
+	__u32	sip;
+	__u32	dip;
+};
+
+struct smc_strat_ip_value {
+	__u8	mode;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(key_size, sizeof(struct smc_strat_ip_key));
+	__uint(value_size, sizeof(struct smc_strat_ip_value));
+	__uint(max_entries, 128);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+} smc_strats_ip SEC(".maps");
+
+static bool smc_check_ip(__u32 src, __u32 dst)
+{
+	struct smc_strat_ip_value *value;
+	struct smc_strat_ip_key key = {
+		.sip = src,
+		.dip = dst,
+	};
+
+	value = bpf_map_lookup_elem(&smc_strats_ip, &key);
+	return value ? value->mode : default_ip_strat_value;
+}
+
+SEC("fmod_ret/update_socket_protocol")
+int BPF_PROG(smc_run, int family, int type, int protocol)
+{
+	struct task_struct *task;
+
+	if (family != AF_INET && family != AF_INET6)
+		return protocol;
+
+	if ((type & 0xf) != SOCK_STREAM)
+		return protocol;
+
+	if (protocol != 0 && protocol != IPPROTO_TCP)
+		return protocol;
+
+	task = bpf_get_current_task_btf();
+	/* Prevent from affecting other tests */
+	if (!task || !task->nsproxy->net_ns->smc.ops)
+		return protocol;
+
+	return IPPROTO_SMC;
+}
+
+SEC("struct_ops/bpf_smc_set_tcp_option_cond")
+int BPF_PROG(bpf_smc_set_tcp_option_cond, const struct tcp_sock *tp, struct inet_request_sock *ireq)
+{
+	return smc_check_ip(ireq->req.__req_common.skc_daddr,
+			    ireq->req.__req_common.skc_rcv_saddr);
+}
+
+SEC("struct_ops/bpf_smc_set_tcp_option")
+int BPF_PROG(bpf_smc_set_tcp_option, struct tcp_sock *tp)
+{
+	return smc_check_ip(tp->inet_conn.icsk_inet.sk.__sk_common.skc_rcv_saddr,
+			    tp->inet_conn.icsk_inet.sk.__sk_common.skc_daddr);
+}
+
+SEC(".struct_ops.link")
+struct smc_ops  linkcheck = {
+	.name			= "linkcheck",
+	.set_option		= (void *) bpf_smc_set_tcp_option,
+	.set_option_cond	= (void *) bpf_smc_set_tcp_option_cond,
+};
-- 
2.45.0

Re: [PATCH bpf-next v5 5/5] bpf/selftests: add selftest for bpf_smc_ops

[Martin KaFai Lau]

On 1/6/25 8:17 PM, D. Wythe wrote:
> +static int send_cmd(int fd, __u16 nlmsg_type, __u32 nlmsg_pid, __u16 nlmsg_flags,
> +			__u8 genl_cmd, __u16 nla_type,
> +			void *nla_data, int nla_len)
> +{
> +	struct nlattr *na;
> +	struct sockaddr_nl nladdr;
> +	int r, buflen;
> +	char *buf;
> +
> +	struct msgtemplate msg = {0};
> +
> +	msg.n.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
> +	msg.n.nlmsg_type = nlmsg_type;
> +	msg.n.nlmsg_flags = nlmsg_flags;
> +	msg.n.nlmsg_seq = 0;
> +	msg.n.nlmsg_pid = nlmsg_pid;
> +	msg.g.cmd = genl_cmd;
> +	msg.g.version = 1;
> +	na = (struct nlattr *) GENLMSG_DATA(&msg);
> +	na->nla_type = nla_type;
> +	na->nla_len = nla_len + 1 + NLA_HDRLEN;
> +	memcpy(NLA_DATA(na), nla_data, nla_len);
> +	msg.n.nlmsg_len += NLMSG_ALIGN(na->nla_len);
> +
> +	buf = (char *) &msg;
> +	buflen = msg.n.nlmsg_len;
> +	memset(&nladdr, 0, sizeof(nladdr));
> +	nladdr.nl_family = AF_NETLINK;
> +
> +	while ((r = sendto(fd, buf, buflen, 0, (struct sockaddr *) &nladdr,
> +			   sizeof(nladdr))) < buflen) {
> +		if (r > 0) {
> +			buf += r;
> +			buflen -= r;
> +		} else if (errno != EAGAIN)
> +			return -1;
> +		}

The "}" indentation is off.

I was wondering if it missed a "}" for the while loop. Turns out the "else if" 
does not have braces while the "if" has. I would add braces to the "else if" 
also to avoid confusion like this.

> +	return 0;
> +}
> +
> +static bool get_smc_nl_family_id(void)
> +{
> +	struct sockaddr_nl nl_src;
> +	struct msgtemplate msg;
> +	struct nlattr *nl;
> +	int fd, ret;
> +	pid_t pid;
> +
> +	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
> +	if (!ASSERT_GT(fd, 0, "nl_family socket"))
> +		return false;
> +
> +	pid = getpid();
> +
> +	memset(&nl_src, 0, sizeof(nl_src));
> +	nl_src.nl_family = AF_NETLINK;
> +	nl_src.nl_pid = pid;
> +
> +	ret = bind(fd, (struct sockaddr *) &nl_src, sizeof(nl_src));
> +	if (!ASSERT_GE(ret, 0, "nl_family bind"))
> +		goto fail;
> +
> +	ret = send_cmd(fd, GENL_ID_CTRL, pid,
> +		       NLM_F_REQUEST, CTRL_CMD_GETFAMILY,
> +		       CTRL_ATTR_FAMILY_NAME, (void *)SMC_GENL_FAMILY_NAME,
> +		       strlen(SMC_GENL_FAMILY_NAME));
> +	if (!ASSERT_EQ(ret, 0, "nl_family query"))
> +		goto fail;
> +
> +	ret = recv(fd, &msg, sizeof(msg), 0);
> +	if (!ASSERT_FALSE(msg.n.nlmsg_type == NLMSG_ERROR || (ret < 0) ||
> +			  !NLMSG_OK((&msg.n), ret), "nl_family response"))
> +		goto fail;
> +
> +	nl = (struct nlattr *) GENLMSG_DATA(&msg);
> +	nl = (struct nlattr *) ((char *) nl + NLA_ALIGN(nl->nla_len));
> +	if (!ASSERT_EQ(nl->nla_type, CTRL_ATTR_FAMILY_ID, "nl_family nla type"))
> +		goto fail;
> +
> +	smc_nl_family_id = *(uint16_t *) NLA_DATA(nl);
> +	close(fd);
> +	return true;
> +fail:
> +	close(fd);
> +	return false;
> +}
> +
> +static bool smc_ueid(int op)
> +{
> +	struct sockaddr_nl nl_src;
> +	struct msgtemplate msg;
> +	struct nlmsgerr *err;
> +	char test_ueid[32];
> +	int fd, ret;
> +	pid_t pid;
> +
> +	/* UEID required */
> +	memset(test_ueid, '\x20', sizeof(test_ueid));
> +	memcpy(test_ueid, SMC_BPFTEST_UEID, strlen(SMC_BPFTEST_UEID));
> +	fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_GENERIC);
> +	if (!ASSERT_GT(fd, 0, "ueid socket"))
> +		return false;
> +
> +	pid = getpid();
> +	memset(&nl_src, 0, sizeof(nl_src));
> +	nl_src.nl_family = AF_NETLINK;
> +	nl_src.nl_pid = pid;
> +
> +	ret = bind(fd, (struct sockaddr *) &nl_src, sizeof(nl_src));
> +	if (!ASSERT_GE(ret, 0, "ueid bind"))
> +		goto fail;
> +
> +	ret = send_cmd(fd, smc_nl_family_id, pid,
> +		       NLM_F_REQUEST | NLM_F_ACK, op, SMC_NLA_EID_TABLE_ENTRY,
> +	(void *)test_ueid, sizeof(test_ueid));

Same. Indentation is off.

> +	if (!ASSERT_EQ(ret, 0, "ueid cmd"))
> +		goto fail;
> +
> +	ret = recv(fd, &msg, sizeof(msg), 0);
> +	if (!ASSERT_FALSE((ret < 0) || !NLMSG_OK((&msg.n), ret), "ueid response"))
> +		goto fail;
> +
> +	if (msg.n.nlmsg_type == NLMSG_ERROR) {
> +		err = NLMSG_DATA(&msg);
> +		switch (op) {
> +		case SMC_NETLINK_REMOVE_UEID:
> +			if (!ASSERT_FALSE((err->error && err->error != -ENOENT), "ueid remove"))
> +				goto fail;
> +			break;
> +		case SMC_NETLINK_ADD_UEID:
> +			if (!ASSERT_EQ(err->error, 0, "ueid add"))
> +				goto fail;
> +			break;
> +		default:
> +			break;
> +		}
> +	}
> +	close(fd);
> +	return true;
> +fail:
> +	close(fd);
> +	return false;
> +}
> +
> +static bool setup_netns(void)
> +{
> +	if (!ASSERT_OK(make_netns(TEST_NS), "create net namespace"))
> +		return false;
> +
> +	nstoken = open_netns(TEST_NS);

Instead of make_netns and then immediately open_netns, try netns_new(TEST_NS, 
true) from the test_progs.c.

> +	if (!ASSERT_OK_PTR(nstoken, "open net namespace"))
> +		goto fail_open_netns;
> +
> +	if (!ASSERT_OK(system("ip addr add 127.0.1.0/8 dev lo"), "add server node"))
> +		goto fail_ip;
> +
> +	if (!ASSERT_OK(system("ip addr add 127.0.2.0/8 dev lo"), "server via risk path"))
> +		goto fail_ip;
> +
> +	return true;
> +fail_open_netns:
> +	remove_netns(TEST_NS);
> +fail_ip:
> +	close_netns(nstoken);
> +	return false;
> +}
> +
> +static void cleanup_netns(void)
> +{
> +	close_netns(nstoken);
> +	remove_netns(TEST_NS);
> +}
> +
> +static bool setup_ueid(void)
> +{
> +	/* get smc nl id */
> +	if (!get_smc_nl_family_id())
> +		return false;
> +	/* clear old ueid for bpftest */
> +	smc_ueid(SMC_NETLINK_REMOVE_UEID);
> +	/* smc-loopback required ueid */
> +	return smc_ueid(SMC_NETLINK_ADD_UEID);
> +}
> +
> +static void cleanup_ueid(void)
> +{
> +	smc_ueid(SMC_NETLINK_REMOVE_UEID);
> +}
> +
> +static bool setup_smc(void)
> +{
> +	if (!setup_ueid())
> +		return false;
> +
> +	if (!setup_netns())
> +		goto fail_netns;
> +
> +	return true;
> +fail_netns:
> +	cleanup_ueid();
> +	return false;
> +}
> +
> +static int set_client_addr_cb(int fd, void *opts)
> +{
> +	const char *src = (const char *)opts;
> +	struct sockaddr_in localaddr;
> +
> +	localaddr.sin_family = AF_INET;
> +	localaddr.sin_port = htons(0);
> +	localaddr.sin_addr.s_addr = inet_addr(src);
> +	return !ASSERT_EQ(bind(fd, &localaddr, sizeof(localaddr)), 0, "client bind");
> +}
> +
> +static void run_link(const char *src, const char *dst, int port)
> +{
> +	struct network_helper_opts opts = {0};
> +	int server, client;
> +
> +	server = start_server_str(AF_INET, SOCK_STREAM, dst, port, NULL);
> +	if (!ASSERT_OK_FD(server, "start service_1"))
> +		return;
> +
> +	opts.proto = IPPROTO_TCP;
> +	opts.post_socket_cb = set_client_addr_cb;
> +	opts.cb_opts = (void *)src;
> +
> +	client = connect_to_fd_opts(server, &opts);
> +	if (!ASSERT_OK_FD(client, "start connect"))
> +		goto fail_client;
> +
> +	close(client);
> +fail_client:
> +	close(server);
> +}
> +
> +static void block_link(int map_fd, const char *src, const char *dst)
> +{
> +	struct smc_strat_ip_value val = { .mode = /* block */ 0 };
> +	struct smc_strat_ip_key key = {
> +		.sip = inet_addr(src),
> +		.dip = inet_addr(dst),
> +	};
> +
> +	bpf_map_update_elem(map_fd, &key, &val, BPF_ANY);
> +}
> +
> +/*
> + * This test describes a real-life service topology as follows:
> + *
> + *                             +-------------> service_1
> + *            link1            |                     |
> + *   +--------------------> server                   |  link 2
> + *   |                         |                     V
> + *   |                         +-------------> service_2
> + *   |        link 3
> + *  client -------------------> server_via_unsafe_path -> service_3
> + *
> + * Among them,
> + * 1. link-1 is very suitable for using SMC.
> + * 2. link-2 is not suitable for using SMC, because the mode of this link is kind of
> + *     short-link services.
> + * 3. link-3 is also not suitable for using SMC, because the RDMA link is unavailable and
> + *     needs to go through a long timeout before it can fallback to TCP.
> + *
> + * To achieve this goal, we use a customized SMC ip strategy via smc_ops.
> + */
> +static void test_topo(void)
> +{
> +	struct bpf_smc *skel;
> +	int rc, map_fd;
> +
> +	skel = bpf_smc__open_and_load();
> +	if (!ASSERT_OK_PTR(skel, "bpf_smc__open_and_load"))
> +		return;
> +
> +	rc = bpf_smc__attach(skel);
> +	if (!ASSERT_EQ(rc, 0, "bpf_smc__attach"))
> +		goto fail;
> +
> +	map_fd = bpf_map__fd(skel->maps.smc_strats_ip);
> +	if (!ASSERT_GT(map_fd, 0, "bpf_map__fd"))
> +		goto fail;
> +
> +	/* Mock the process of transparent replacement, since we will modify protocol
> +	 * to ipproto_smc accropding to it via fmod_ret/update_socket_protocol.
> +	 */
> +	system("sysctl -w net.smc.ops=linkcheck");
> +
> +	/* Configure ip strat */
> +	block_link(map_fd, CLIENT_IP, SERVER_IP_VIA_RISK_PATH);
> +	block_link(map_fd, SERVER_IP, SERVER_IP);
> +	close(map_fd);

No need to close(map-fd) here. bpf_smc__destroy(skel) will do it.

It seems the new selftest fails also. not always though which is concerning.

pw-bot: cr

> +
> +	/* should go with smc */
> +	run_link(CLIENT_IP, SERVER_IP, SERVICE_1);
> +	/* should go with smc fallback */
> +	run_link(SERVER_IP, SERVER_IP, SERVICE_2);
> +
> +	ASSERT_EQ(skel->bss->smc_cnt, 2, "smc count");
> +	ASSERT_EQ(skel->bss->fallback_cnt, 1, "fallback count");
> +
> +	/* should go with smc */
> +	run_link(CLIENT_IP, SERVER_IP, SERVICE_2);
> +
> +	ASSERT_EQ(skel->bss->smc_cnt, 3, "smc count");
> +	ASSERT_EQ(skel->bss->fallback_cnt, 1, "fallback count");
> +
> +	/* should go with smc fallback */
> +	run_link(CLIENT_IP, SERVER_IP_VIA_RISK_PATH, SERVICE_3);
> +
> +	ASSERT_EQ(skel->bss->smc_cnt, 4, "smc count");
> +	ASSERT_EQ(skel->bss->fallback_cnt, 2, "fallback count");
> +
> +fail:
> +	bpf_smc__destroy(skel);
> +}

Re: [PATCH bpf-next v5 5/5] bpf/selftests: add selftest for bpf_smc_ops

[D. Wythe]

On Tue, Jan 07, 2025 at 04:48:51PM -0800, Martin KaFai Lau wrote:
> On 1/6/25 8:17 PM, D. Wythe wrote:
> >+static int send_cmd(int fd, __u16 nlmsg_type, __u32 nlmsg_pid, __u16 nlmsg_flags,
> >+			__u8 genl_cmd, __u16 nla_type,
> >+	while ((r = sendto(fd, buf, buflen, 0, (struct sockaddr *) &nladdr,
> >+			   sizeof(nladdr))) < buflen) {
> >+		if (r > 0) {
> >+			buf += r;
> >+			buflen -= r;
> >+		} else if (errno != EAGAIN)
> >+			return -1;
> >+		}
> 
> The "}" indentation is off.
> 
> I was wondering if it missed a "}" for the while loop. Turns out the
> "else if" does not have braces while the "if" has. I would add
> braces to the "else if" also to avoid confusion like this.
> 
Take it. I fix change it in next version.
> >+	return 0;
> >+}
> >+
> >+static bool get_smc_nl_family_id(void)
> >+{
> >+	struct sockaddr_nl nl_src;
> >+	struct msgtemplate msg;
> >+	ret = send_cmd(fd, smc_nl_family_id, pid,
> >+		       NLM_F_REQUEST | NLM_F_ACK, op, SMC_NLA_EID_TABLE_ENTRY,
> >+	(void *)test_ueid, sizeof(test_ueid));
> 
> Same. Indentation is off.
Take it. Thanks for pointing it out.
> 
> >+	if (!ASSERT_EQ(ret, 0, "ueid cmd"))
> >+		goto fail;
> >+
> >+	nstoken = open_netns(TEST_NS);
> 
> Instead of make_netns and then immediately open_netns, try
> netns_new(TEST_NS, true) from the test_progs.c.
Got it, I'll try it in next version.
> 
> >+	if (!ASSERT_OK_PTR(nstoken, "open net namespace"))
> >+		goto fail_open_netns;
> >+
> >+	if (!ASSERT_OK(system("ip addr add 127.0.1.0/8 dev lo"), "add server node"))
> >+		goto fail_ip;
> >+
> >+	if (!ASSERT_OK(system("ip addr add 127.0.2.0/8 dev lo"), "server via risk path"))
> >+	close_netns(nstoken);
> >+	return false;
> >+}
> >+
> >+	/* Configure ip strat */
> >+	block_link(map_fd, CLIENT_IP, SERVER_IP_VIA_RISK_PATH);
> >+	block_link(map_fd, SERVER_IP, SERVER_IP);
> >+	close(map_fd);
> 
> No need to close(map-fd) here. bpf_smc__destroy(skel) will do it.
Got it. Many thanks.
> 
> It seems the new selftest fails also. not always though which is concerning.
> 
This might not be a random failure, but rather related to s390x, which
carries a seid by default, which may affect my action of deleting ueid.
I am requesting IBM folks to help me analyze this issue since i have no
s390x machine.

Anyway, I will solve it in the next version.

Best wishes,
D. Wythe

> pw-bot: cr
> 
> >+
> >+	/* should go with smc */
> >+	run_link(CLIENT_IP, SERVER_IP, SERVICE_1);
> >+	/* should go with smc fallback */
> >+	run_link(SERVER_IP, SERVER_IP, SERVICE_2);
> >+
> >+	ASSERT_EQ(skel->bss->smc_cnt, 2, "smc count");
> >+	ASSERT_EQ(skel->bss->fallback_cnt, 1, "fallback count");
> >+
> >+	/* should go with smc */
> >+	run_link(CLIENT_IP, SERVER_IP, SERVICE_2);
> >+
> >+	ASSERT_EQ(skel->bss->smc_cnt, 3, "smc count");
> >+	ASSERT_EQ(skel->bss->fallback_cnt, 1, "fallback count");
> >+
> >+	/* should go with smc fallback */
> >+	run_link(CLIENT_IP, SERVER_IP_VIA_RISK_PATH, SERVICE_3);
> >+
> >+	ASSERT_EQ(skel->bss->smc_cnt, 4, "smc count");
> >+	ASSERT_EQ(skel->bss->fallback_cnt, 2, "fallback count");
> >+
> >+fail:
> >+	bpf_smc__destroy(skel);
> >+}
> 

Re: [PATCH bpf-next v5 0/5] net/smc: Introduce smc_ops

[D. Wythe]

On Tue, Jan 07, 2025 at 12:17:10PM +0800, D. Wythe wrote:

Hi smc folks,

Given that there are almost no more serious issues blocking the progress
of this series in the BPF community regarding the BPF part, your input on
the SMC part of this series are very valuable.

Additionally, I encountered some errors during CI testing on the S390x architecture.
These errors seem to be related to adding ueid via netlink, and I suspect they
might be connected to seid. However, since I have no s390x machine, I am unable to
further pinpoint the exact cause of the problem. If IBM could help confirm this,
it would be greatly appreciated. If there is no time to address this issue, I plan
to temporarily skip the BPF CI testing of my case in S390x.

Best wishes,
D. Wythe

> This patch aims to introduce BPF injection capabilities for SMC and
> includes a self-test to ensure code stability.
> 
> Since the SMC protocol isn't ideal for every situation, especially
> short-lived ones, most applications can't guarantee the absence of
> such scenarios. Consequently, applications may need specific strategies
> to decide whether to use SMC. For example, an application might limit SMC
> usage to certain IP addresses or ports.
> 
> To maintain the principle of transparent replacement, we want applications
> to remain unaffected even if they need specific SMC strategies. In other
> words, they should not require recompilation of their code.
> 
> Additionally, we need to ensure the scalability of strategy implementation.
> While using socket options or sysctl might be straightforward, it could
> complicate future expansions.
> 
> Fortunately, BPF addresses these concerns effectively. Users can write
> their own strategies in eBPF to determine whether to use SMC, and they can
> easily modify those strategies in the future.
> 
> v2:
>   1. Rename smc_bpf_ops to smc_ops.
>   2. Change the scope of smc_ops from global to per netns.
>   3. Directly pass parameters to ops instead of smc_ops_ctx.
>   4. Remove struct smc_ops_ctx.
>   5. Remove exports that are no longer needed.
> 
> v3:
>   1. Remove find_ksym_btf_id_by_prefix_kind.
>   2. Enhance selftest, introduce a complete ops for filtering smc
>      connections based on ip pairs and a realistic topology test
>      to verify it.
> 
> v4:
>   1. Remove unless func: smc_bpf_ops_check_member()
>   2. Remove unless inline func: smc_ops_find_by_name()
>   3. Change CONFIG_SMC=y to complete CI testing
>   4. Change smc_sock to smc_sock___local in test to avoid
>      compiling failed with CONFIG_SMC=y
>   5. Improve test cases, remove unnecessary timeouts and multi-thread
>      test, using network_helpers to start testing between server and
>      client.
>   6. Fix issues when the return value of the ops function is neither 0
>      nor 1.
> 
> v5:
>   1. Fix incorrect CI config from CONFIG_SMC=Y to CONFIG_SMC=y.
> 
> D. Wythe (5):
>   bpf: export necessary sympols for modules with struct_ops
>   net/smc: Introduce generic hook smc_ops
>   net/smc: bpf: register smc_ops info struct_ops
>   libbpf: fix error when st-prefix_ops and ops from differ btf
>   bpf/selftests: add selftest for bpf_smc_ops
> 
>  include/net/netns/smc.h                       |   3 +
>  include/net/smc.h                             |  51 +++
>  kernel/bpf/bpf_struct_ops.c                   |   2 +
>  kernel/bpf/syscall.c                          |   1 +
>  net/ipv4/tcp_output.c                         |  15 +-
>  net/smc/Kconfig                               |  12 +
>  net/smc/Makefile                              |   1 +
>  net/smc/af_smc.c                              |  10 +
>  net/smc/smc_ops.c                             | 130 ++++++
>  net/smc/smc_ops.h                             |  30 ++
>  net/smc/smc_sysctl.c                          |  95 +++++
>  tools/lib/bpf/libbpf.c                        |  25 +-
>  tools/testing/selftests/bpf/config            |   4 +
>  .../selftests/bpf/prog_tests/test_bpf_smc.c   | 390 ++++++++++++++++++
>  tools/testing/selftests/bpf/progs/bpf_smc.c   | 116 ++++++
>  15 files changed, 873 insertions(+), 12 deletions(-)
>  create mode 100644 net/smc/smc_ops.c
>  create mode 100644 net/smc/smc_ops.h
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/test_bpf_smc.c
>  create mode 100644 tools/testing/selftests/bpf/progs/bpf_smc.c
> 
> -- 
> 2.45.0
>