net/smc: Introduce generic netlink interface for diagnostic purposes

Introduce generic netlink interface infrastructure to expose
the diagnostic information regarding smc linkgroups, links and devices.

Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

include/uapi/linux/smc.h

@@ -33,4 +33,15 @@ enum {				/* SMC PNET Table commands */
 #define SMCR_GENL_FAMILY_NAME		"SMC_PNETID"
 #define SMCR_GENL_FAMILY_VERSION	1
 
+/* gennetlink interface to access non-socket information from SMC module */
+#define SMC_GENL_FAMILY_NAME		"SMC_GEN_NETLINK"
+#define SMC_GENL_FAMILY_VERSION		1
+
+/* SMC_GENL_FAMILY top level attributes */
+enum {
+	SMC_GEN_UNSPEC,
+	__SMC_GEN_MAX,
+	SMC_GEN_MAX = __SMC_GEN_MAX - 1
+};
+
 #endif /* _UAPI_LINUX_SMC_H */

net/smc/Makefile

@@ -2,4 +2,4 @@
 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-y += smc_cdc.o smc_tx.o smc_rx.o smc_close.o smc_ism.o smc_netlink.o

net/smc/af_smc.c

@@ -45,6 +45,7 @@
 #include "smc_ib.h"
 #include "smc_ism.h"
 #include "smc_pnet.h"
+#include "smc_netlink.h"
 #include "smc_tx.h"
 #include "smc_rx.h"
 #include "smc_close.h"
@@ -2495,10 +2496,14 @@ static int __init smc_init(void)
 	smc_ism_init();
 	smc_clc_init();
 
-	rc = smc_pnet_init();
+	rc = smc_nl_init();
 	if (rc)
 		goto out_pernet_subsys;
 
+	rc = smc_pnet_init();
+	if (rc)
+		goto out_nl;
+
 	rc = -ENOMEM;
 	smc_hs_wq = alloc_workqueue("smc_hs_wq", 0, 0);
 	if (!smc_hs_wq)
@@ -2569,6 +2574,8 @@ static int __init smc_init(void)
 	destroy_workqueue(smc_hs_wq);
 out_pnet:
 	smc_pnet_exit();
+out_nl:
+	smc_nl_exit();
 out_pernet_subsys:
 	unregister_pernet_subsys(&smc_net_ops);
 
@@ -2586,6 +2593,7 @@ static void __exit smc_exit(void)
 	proto_unregister(&smc_proto6);
 	proto_unregister(&smc_proto);
 	smc_pnet_exit();
+	smc_nl_exit();
 	unregister_pernet_subsys(&smc_net_ops);
 	rcu_barrier();
 }

net/smc/smc_netlink.c

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ *  Generic netlink support functions to interact with SMC module
+ *
+ *  Copyright IBM Corp. 2020
+ *
+ *  Author(s):	Guvenc Gulce <guvenc@linux.ibm.com>
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/ctype.h>
+#include <linux/mutex.h>
+#include <linux/if.h>
+#include <linux/smc.h>
+
+#include "smc_core.h"
+#include "smc_netlink.h"
+
+#define SMC_CMD_MAX_ATTR 1
+
+/* SMC_GENL generic netlink operation definition */
+static const struct genl_ops smc_gen_nl_ops[] = {
+};
+
+static const struct nla_policy smc_gen_nl_policy[2] = {
+	[SMC_CMD_MAX_ATTR]	= { .type = NLA_REJECT, },
+};
+
+/* SMC_GENL family definition */
+struct genl_family smc_gen_nl_family __ro_after_init = {
+	.hdrsize =	0,
+	.name =		SMC_GENL_FAMILY_NAME,
+	.version =	SMC_GENL_FAMILY_VERSION,
+	.maxattr =	SMC_CMD_MAX_ATTR,
+	.policy =	smc_gen_nl_policy,
+	.netnsok =	true,
+	.module =	THIS_MODULE,
+	.ops =		smc_gen_nl_ops,
+	.n_ops =	ARRAY_SIZE(smc_gen_nl_ops)
+};
+
+int __init smc_nl_init(void)
+{
+	return genl_register_family(&smc_gen_nl_family);
+}
+
+void smc_nl_exit(void)
+{
+	genl_unregister_family(&smc_gen_nl_family);
+}

net/smc/smc_netlink.h

@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ *  SMC Generic netlink operations
+ *
+ *  Copyright IBM Corp. 2020
+ *
+ *  Author(s):	Guvenc Gulce <guvenc@linux.ibm.com>
+ */
+
+#ifndef _SMC_NETLINK_H
+#define _SMC_NETLINK_H
+
+#include <net/netlink.h>
+#include <net/genetlink.h>
+
+extern struct genl_family smc_gen_nl_family;
+
+int smc_nl_init(void) __init;
+void smc_nl_exit(void);
+
+#endif