net/smc: add sysctl interface for SMC

This patch add sysctl interface to support container environment
for SMC as we talk in the mail list.

Link: https://lore.kernel.org/netdev/20220224020253.GF5443@linux.alibaba.com
Co-developed-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
Signed-off-by: Dust Li <dust.li@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 70 insertions, 0 deletions

diff --git a/net/smc/smc_sysctl.c b/net/smc/smc_sysctl.c
new file mode 100644
index 000000000000..8a3a8e145976
--- /dev/null
+++ b/net/smc/smc_sysctl.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Shared Memory Communications over RDMA (SMC-R) and RoCE
+ *
+ *  smc_sysctl.c: sysctl interface to SMC subsystem.
+ *
+ *  Copyright (c) 2022, Alibaba Inc.
+ *
+ *  Author: Tony Lu <tonylu@linux.alibaba.com>
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/sysctl.h>
+#include <net/net_namespace.h>
+
+#include "smc_sysctl.h"
+
+static struct ctl_table smc_table[] = {
+	{  }
+};
+
+static __net_init int smc_sysctl_init_net(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = smc_table;
+	if (!net_eq(net, &init_net)) {
+		int i;
+
+		table = kmemdup(table, sizeof(smc_table), GFP_KERNEL);
+		if (!table)
+			goto err_alloc;
+
+		for (i = 0; i < ARRAY_SIZE(smc_table) - 1; i++)
+			table[i].data += (void *)net - (void *)&init_net;
+	}
+
+	net->smc.smc_hdr = register_net_sysctl(net, "net/smc", table);
+	if (!net->smc.smc_hdr)
+		goto err_reg;
+
+	return 0;
+
+err_reg:
+	if (!net_eq(net, &init_net))
+		kfree(table);
+err_alloc:
+	return -ENOMEM;
+}
+
+static __net_exit void smc_sysctl_exit_net(struct net *net)
+{
+	unregister_net_sysctl_table(net->smc.smc_hdr);
+}
+
+static struct pernet_operations smc_sysctl_ops __net_initdata = {
+	.init = smc_sysctl_init_net,
+	.exit = smc_sysctl_exit_net,
+};
+
+int __init smc_sysctl_init(void)
+{
+	return register_pernet_subsys(&smc_sysctl_ops);
+}
+
+void smc_sysctl_exit(void)
+{
+	unregister_pernet_subsys(&smc_sysctl_ops);
+}