af_rxrpc: Add sysctls for configuring RxRPC parameters

Add sysctls for configuring RxRPC protocol handling, specifically controls on
delays before ack generation, the delay before resending a packet, the maximum
lifetime of a call and the expiration times of calls, connections and
transports that haven't been recently used.

More info added in Documentation/networking/rxrpc.txt.

Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/net/rxrpc/sysctl.c b/net/rxrpc/sysctl.c
new file mode 100644
index 0000000..cdc85e7
--- /dev/null
+++ b/net/rxrpc/sysctl.c
@@ -0,0 +1,113 @@
+/* sysctls for configuring RxRPC operating parameters
+ *
+ * Copyright (C) 2014 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/sysctl.h>
+#include <net/sock.h>
+#include <net/af_rxrpc.h>
+#include "ar-internal.h"
+
+static struct ctl_table_header *rxrpc_sysctl_reg_table;
+static const unsigned zero = 0;
+static const unsigned one = 1;
+
+/*
+ * RxRPC operating parameters.
+ *
+ * See Documentation/networking/rxrpc.txt and the variable definitions for more
+ * information on the individual parameters.
+ */
+static struct ctl_table rxrpc_sysctl_table[] = {
+	/* Values measured in milliseconds */
+	{
+		.procname	= "req_ack_delay",
+		.data		= &rxrpc_requested_ack_delay,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_ms_jiffies,
+		.extra1		= (void *)&zero,
+	},
+	{
+		.procname	= "soft_ack_delay",
+		.data		= &rxrpc_soft_ack_delay,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_ms_jiffies,
+		.extra1		= (void *)&one,
+	},
+	{
+		.procname	= "idle_ack_delay",
+		.data		= &rxrpc_idle_ack_delay,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_ms_jiffies,
+		.extra1		= (void *)&one,
+	},
+	{
+		.procname	= "resend_timeout",
+		.data		= &rxrpc_resend_timeout,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_ms_jiffies,
+		.extra1		= (void *)&one,
+	},
+
+	/* Values measured in seconds but used in jiffies */
+	{
+		.procname	= "max_call_lifetime",
+		.data		= &rxrpc_max_call_lifetime,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+		.extra1		= (void *)&one,
+	},
+	{
+		.procname	= "dead_call_expiry",
+		.data		= &rxrpc_dead_call_expiry,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_jiffies,
+		.extra1		= (void *)&one,
+	},
+
+	/* Values measured in seconds */
+	{
+		.procname	= "connection_expiry",
+		.data		= &rxrpc_connection_expiry,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= (void *)&one,
+	},
+	{
+		.procname	= "transport_expiry",
+		.data		= &rxrpc_transport_expiry,
+		.maxlen		= sizeof(unsigned),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= (void *)&one,
+	},
+	{ }
+};
+
+int __init rxrpc_sysctl_init(void)
+{
+	rxrpc_sysctl_reg_table = register_net_sysctl(&init_net, "net/rxrpc",
+						     rxrpc_sysctl_table);
+	if (!rxrpc_sysctl_reg_table)
+		return -ENOMEM;
+	return 0;
+}
+
+void rxrpc_sysctl_exit(void)
+{
+	if (rxrpc_sysctl_reg_table)
+		unregister_net_sysctl_table(rxrpc_sysctl_reg_table);
+}