net: Remove ctl_table sentinel elements from several networking subsystems

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/[e-mail]/)

To avoid lots of small commits, this commit brings together network
changes from (as they appear in MAINTAINERS) LLC, MPTCP, NETROM NETWORK
LAYER, PHONET PROTOCOL, ROSE NETWORK LAYER, RXRPC SOCKETS, SCTP
PROTOCOL, SHARED MEMORY COMMUNICATIONS (SMC), TIPC NETWORK LAYER and
NETWORKING [IPSEC]

* Remove sentinel element from ctl_table structs.
* Replace empty array registration with the register_net_sysctl_sz call
in llc_sysctl_init
* Replace the for loop stop condition that tests for procname == NULL
with one that depends on array size in sctp_sysctl_net_register
* Remove instances where an array element is zeroed out to make it look
like a sentinel in xfrm_sysctl_init. This is not longer needed and is
safe after commit c899710fe7f9 ("networking: Update to
register_net_sysctl_sz") added the array size to the ctl_table
registration
* Use a table_size variable to keep the value of ARRAY_SIZE

Signed-off-by: Joel Granados <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/llc/sysctl_net_llc.c

···
 		.mode		= 0644,
 		.proc_handler   = proc_dointvec_jiffies,
 	},
-	{ },
-};
-
-static struct ctl_table llc_station_table[] = {
-	{ },
 };
 
 static struct ctl_table_header *llc2_timeout_header;
···
 
 int __init llc_sysctl_init(void)
 {
+	struct ctl_table empty[1] = {};
 	llc2_timeout_header = register_net_sysctl(&init_net, "net/llc/llc2/timeout", llc2_timeout_table);
-	llc_station_header = register_net_sysctl(&init_net, "net/llc/station", llc_station_table);
+	llc_station_header = register_net_sysctl_sz(&init_net, "net/llc/station", empty, 0);
 
 	if (!llc2_timeout_header || !llc_station_header) {
 		llc_sysctl_exit();

net/mptcp/ctrl.c

···
 		.mode = 0644,
 		.proc_handler = proc_dointvec_jiffies,
 	},
-	{}
 };
 
 static int mptcp_pernet_new_table(struct net *net, struct mptcp_pernet *pernet)

net/netrom/sysctl_net_netrom.c

···
 		.extra1		= &min_reset,
 		.extra2		= &max_reset
 	},
-	{ }
 };
 
 int __init nr_register_sysctl(void)

net/phonet/sysctl.c

···
 		.mode		= 0644,
 		.proc_handler	= proc_local_port_range,
 	},
-	{ }
 };
 
 int __init phonet_sysctl_init(void)

net/rose/sysctl_net_rose.c

···
 		.extra1		= &min_window,
 		.extra2		= &max_window
 	},
-	{ }
 };
 
 void __init rose_register_sysctl(void)

net/rxrpc/sysctl.c

···
 		.extra1		= (void *)SYSCTL_ONE,
 		.extra2		= (void *)&four,
 	},
-	{ }
 };
 
 int __init rxrpc_sysctl_init(void)

net/sctp/sysctl.c

···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-
-	{ /* sentinel */ }
 };
 
 /* The following index defines are used in sctp_sysctl_net_register().
···
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= &pf_expose_max,
 	},
-
-	{ /* sentinel */ }
 };
 
 static int proc_sctp_do_hmac_alg(struct ctl_table *ctl, int write,
···
 
 int sctp_sysctl_net_register(struct net *net)
 {
+	size_t table_size = ARRAY_SIZE(sctp_net_table);
 	struct ctl_table *table;
 	int i;
 
···
 	if (!table)
 		return -ENOMEM;
 
-	for (i = 0; table[i].data; i++)
+	for (i = 0; i < table_size; i++)
 		table[i].data += (char *)(&net->sctp) - (char *)&init_net.sctp;
 
 	table[SCTP_RTO_MIN_IDX].extra2 = &net->sctp.rto_max;
···
 	table[SCTP_PS_RETRANS_IDX].extra1 = &net->sctp.pf_retrans;
 
 	net->sctp.sysctl_header = register_net_sysctl_sz(net, "net/sctp",
-							 table,
-							 ARRAY_SIZE(sctp_net_table));
+							 table, table_size);
 	if (net->sctp.sysctl_header == NULL) {
 		kfree(table);
 		return -ENOMEM;

net/smc/smc_sysctl.c

···
 		.extra1		= &conns_per_lgr_min,
 		.extra2		= &conns_per_lgr_max,
 	},
-	{  }
 };
 
 int __net_init smc_sysctl_net_init(struct net *net)
 {
+	size_t table_size = ARRAY_SIZE(smc_table);
 	struct ctl_table *table;
 
 	table = smc_table;
···
 		if (!table)
 			goto err_alloc;
 
-		for (i = 0; i < ARRAY_SIZE(smc_table) - 1; i++)
+		for (i = 0; i < table_size; i++)
 			table[i].data += (void *)net - (void *)&init_net;
 	}
 
 	net->smc.smc_hdr = register_net_sysctl_sz(net, "net/smc", table,
-						  ARRAY_SIZE(smc_table));
+						  table_size);
 	if (!net->smc.smc_hdr)
 		goto err_reg;
 

net/tipc/sysctl.c

···
 		.mode		= 0644,
 		.proc_handler	= proc_doulongvec_minmax,
 	},
-	{}
 };
 
 int tipc_register_sysctl(void)

net/xfrm/xfrm_sysctl.c

···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec
 	},
-	{}
 };
 
 int __net_init xfrm_sysctl_init(struct net *net)
···
 	table[3].data = &net->xfrm.sysctl_acq_expires;
 
 	/* Don't export sysctls to unprivileged users */
-	if (net->user_ns != &init_user_ns) {
-		table[0].procname = NULL;
+	if (net->user_ns != &init_user_ns)
 		table_size = 0;
-	}
 
 	net->xfrm.sysctl_hdr = register_net_sysctl_sz(net, "net/core", table,
 						      table_size);