net: ipv{6,4}: Remove the now superfluous sentinel elements from ctl_table array

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]/)

* Remove sentinel element from ctl_table structs.
* Remove the zeroing out of an array element (to make it look like a
sentinel) in sysctl_route_net_init And ipv6_route_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.
* Remove extra sentinel element in the declaration of devinet_vars.
* Removed the "-1" in __devinet_sysctl_register, sysctl_route_net_init,
ipv6_sysctl_net_init and ipv4_sysctl_init_net that adjusted for having
an extra empty element when looping over ctl_table arrays
* Replace the for loop stop condition in __addrconf_sysctl_register that
tests for procname == NULL with one that depends on array size
* Removing the unprivileged user check in ipv6_route_sysctl_init is
safe as it is replaced by calling ipv6_route_sysctl_table_size;
introduced in commit c899710fe7f9 ("networking: Update to
register_net_sysctl_sz")
* 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/ipv4/devinet.c

···
 
 static struct devinet_sysctl_table {
 	struct ctl_table_header *sysctl_header;
-	struct ctl_table devinet_vars[__IPV4_DEVCONF_MAX];
+	struct ctl_table devinet_vars[IPV4_DEVCONF_MAX];
 } devinet_sysctl = {
 	.devinet_vars = {
 		DEVINET_SYSCTL_COMPLEX_ENTRY(FORWARDING, "forwarding",
···
 	if (!t)
 		goto out;
 
-	for (i = 0; i < ARRAY_SIZE(t->devinet_vars) - 1; i++) {
+	for (i = 0; i < ARRAY_SIZE(t->devinet_vars); i++) {
 		t->devinet_vars[i].data += (char *)p - (char *)&ipv4_devconf;
 		t->devinet_vars[i].extra1 = p;
 		t->devinet_vars[i].extra2 = net;
···
 		.extra1		= &ipv4_devconf,
 		.extra2		= &init_net,
 	},
-	{ },
 };
 #endif
 

net/ipv4/ip_fragment.c

···
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= &dist_min,
 	},
-	{ }
 };
 
 /* secret interval has been deprecated */
···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 
 static int __net_init ip4_frags_ns_ctl_register(struct net *net)

net/ipv4/route.c

···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{ }
 };
 
 static const char ipv4_route_flush_procname[] = "flush";
···
 		.mode       = 0644,
 		.proc_handler   = proc_dointvec,
 	},
-	{ },
 };
 
 static __net_init int sysctl_route_net_init(struct net *net)
···
 
 		/* Don't export non-whitelisted sysctls to unprivileged users */
 		if (net->user_ns != &init_user_ns) {
-			if (tbl[0].procname != ipv4_route_flush_procname) {
-				tbl[0].procname = NULL;
+			if (tbl[0].procname != ipv4_route_flush_procname)
 				table_size = 0;
-			}
 		}
 
 		/* Update the variables to point into the current struct net
 		 * except for the first element flush
 		 */
-		for (i = 1; i < ARRAY_SIZE(ipv4_route_netns_table) - 1; i++)
+		for (i = 1; i < table_size; i++)
 			tbl[i].data += (void *)net - (void *)&init_net;
 	}
 	tbl[0].extra1 = net;

net/ipv4/sysctl_net_ipv4.c

···
 		.extra1		= &sysctl_fib_sync_mem_min,
 		.extra2		= &sysctl_fib_sync_mem_max,
 	},
-	{ }
 };
 
 static struct ctl_table ipv4_net_table[] = {
···
 		.proc_handler	= proc_dou8vec_minmax,
 		.extra1		= SYSCTL_ONE,
 	},
-	{ }
 };
 
 static __net_init int ipv4_sysctl_init_net(struct net *net)
 {
+	size_t table_size = ARRAY_SIZE(ipv4_net_table);
 	struct ctl_table *table;
 
 	table = ipv4_net_table;
···
 		if (!table)
 			goto err_alloc;
 
-		for (i = 0; i < ARRAY_SIZE(ipv4_net_table) - 1; i++) {
+		for (i = 0; i < table_size; i++) {
 			if (table[i].data) {
 				/* Update the variables to point into
 				 * the current struct net
···
 	}
 
 	net->ipv4.ipv4_hdr = register_net_sysctl_sz(net, "net/ipv4", table,
-						    ARRAY_SIZE(ipv4_net_table));
+						    table_size);
 	if (!net->ipv4.ipv4_hdr)
 		goto err_reg;
 

net/ipv4/xfrm4_policy.c

···
 		.mode           = 0644,
 		.proc_handler   = proc_dointvec,
 	},
-	{ }
 };
 
 static __net_init int xfrm4_net_sysctl_init(struct net *net)

net/ipv6/addrconf.c

···
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_TWO,
 	},
-	{
-		/* sentinel */
-	}
 };
 
 static int __addrconf_sysctl_register(struct net *net, char *dev_name,
 		struct inet6_dev *idev, struct ipv6_devconf *p)
 {
+	size_t table_size = ARRAY_SIZE(addrconf_sysctl);
 	int i, ifindex;
 	struct ctl_table *table;
 	char path[sizeof("net/ipv6/conf/") + IFNAMSIZ];
···
 	if (!table)
 		goto out;
 
-	for (i = 0; table[i].data; i++) {
+	for (i = 0; i < table_size; i++) {
 		table[i].data += (char *)p - (char *)&ipv6_devconf;
 		/* If one of these is already set, then it is not safe to
 		 * overwrite either of them: this makes proc_dointvec_minmax
···
 	snprintf(path, sizeof(path), "net/ipv6/conf/%s", dev_name);
 
 	p->sysctl_header = register_net_sysctl_sz(net, path, table,
-						  ARRAY_SIZE(addrconf_sysctl));
+						  table_size);
 	if (!p->sysctl_header)
 		goto free;
 

net/ipv6/icmp.c

···
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
 	},
-	{ },
 };
 
 struct ctl_table * __net_init ipv6_icmp_sysctl_init(struct net *net)

net/ipv6/reassembly.c

···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 
 /* secret interval has been deprecated */
···
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec_jiffies,
 	},
-	{ }
 };
 
 static int __net_init ip6_frags_ns_sysctl_register(struct net *net)

net/ipv6/route.c

···
 		.extra1		=	SYSCTL_ZERO,
 		.extra2		=	SYSCTL_ONE,
 	},
-	{ }
 };
 
 struct ctl_table * __net_init ipv6_route_sysctl_init(struct net *net)
···
 		table[8].data = &net->ipv6.sysctl.ip6_rt_min_advmss;
 		table[9].data = &net->ipv6.sysctl.ip6_rt_gc_min_interval;
 		table[10].data = &net->ipv6.sysctl.skip_notify_on_dev_down;
-
-		/* Don't export sysctls to unprivileged users */
-		if (net->user_ns != &init_user_ns)
-			table[1].procname = NULL;
 	}
 
 	return table;

net/ipv6/sysctl_net_ipv6.c

···
 		.proc_handler	= proc_doulongvec_minmax,
 		.extra2		= &ioam6_id_wide_max,
 	},
-	{ }
 };
 
 static struct ctl_table ipv6_rotable[] = {
···
 		.proc_handler	= proc_dointvec,
 	},
 #endif /* CONFIG_NETLABEL */
-	{ }
 };
 
 static int __net_init ipv6_sysctl_net_init(struct net *net)
 {
+	size_t table_size = ARRAY_SIZE(ipv6_table_template);
 	struct ctl_table *ipv6_table;
 	struct ctl_table *ipv6_route_table;
 	struct ctl_table *ipv6_icmp_table;
···
 	if (!ipv6_table)
 		goto out;
 	/* Update the variables to point into the current struct net */
-	for (i = 0; i < ARRAY_SIZE(ipv6_table_template) - 1; i++)
+	for (i = 0; i < table_size; i++)
 		ipv6_table[i].data += (void *)net - (void *)&init_net;
 
 	ipv6_route_table = ipv6_route_sysctl_init(net);
···
 		goto out_ipv6_route_table;
 
 	net->ipv6.sysctl.hdr = register_net_sysctl_sz(net, "net/ipv6",
-						      ipv6_table,
-						      ARRAY_SIZE(ipv6_table_template));
+						      ipv6_table, table_size);
 	if (!net->ipv6.sysctl.hdr)
 		goto out_ipv6_icmp_table;
 

net/ipv6/xfrm6_policy.c

···
 		.mode		= 0644,
 		.proc_handler   = proc_dointvec,
 	},
-	{ }
 };
 
 static int __net_init xfrm6_net_sysctl_init(struct net *net)