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/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index e61aa60..7b16704 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -838,6 +838,12 @@
 		goto error_key_type_s;
 	}
 
+	ret = rxrpc_sysctl_init();
+	if (ret < 0) {
+		printk(KERN_CRIT "RxRPC: Cannot register sysctls\n");
+		goto error_sysctls;
+	}
+
 #ifdef CONFIG_PROC_FS
 	proc_create("rxrpc_calls", 0, init_net.proc_net, &rxrpc_call_seq_fops);
 	proc_create("rxrpc_conns", 0, init_net.proc_net,
@@ -845,6 +851,8 @@
 #endif
 	return 0;
 
+error_sysctls:
+	unregister_key_type(&key_type_rxrpc_s);
 error_key_type_s:
 	unregister_key_type(&key_type_rxrpc);
 error_key_type:
@@ -865,6 +873,7 @@
 static void __exit af_rxrpc_exit(void)
 {
 	_enter("");
+	rxrpc_sysctl_exit();
 	unregister_key_type(&key_type_rxrpc_s);
 	unregister_key_type(&key_type_rxrpc);
 	sock_unregister(PF_RXRPC);