net: clean up snmp stats code

commit 8f0ea0fe3a036a47767f9c80e (snmp: reduce percpu needs by 50%)
reduced snmp array size to 1, so technically it doesn't have to be
an array any more. What's more, after the following commit:

	commit 933393f58fef9963eac61db8093689544e29a600
	Date:   Thu Dec 22 11:58:51 2011 -0600

	    percpu: Remove irqsafe_cpu_xxx variants

	    We simply say that regular this_cpu use must be safe regardless of
	    preemption and interrupt state.  That has no material change for x86
	    and s390 implementations of this_cpu operations.  However, arches that
	    do not provide their own implementation for this_cpu operations will
	    now get code generated that disables interrupts instead of preemption.

probably no arch wants to have SNMP_ARRAY_SZ == 2. At least after
almost 3 years, no one complains.

So, just convert the array to a single pointer and remove snmp_mib_init()
and snmp_mib_free() as well.

Cc: Christoph Lameter <cl@linux.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index ad737fa..ae0af93 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -345,15 +345,15 @@
 	for (i = 0; icmpmibmap[i].name != NULL; i++)
 		seq_printf(seq, " Out%s", icmpmibmap[i].name);
 	seq_printf(seq, "\nIcmp: %lu %lu %lu",
-		snmp_fold_field((void __percpu **) net->mib.icmp_statistics, ICMP_MIB_INMSGS),
-		snmp_fold_field((void __percpu **) net->mib.icmp_statistics, ICMP_MIB_INERRORS),
-		snmp_fold_field((void __percpu **) net->mib.icmp_statistics, ICMP_MIB_CSUMERRORS));
+		snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_INMSGS),
+		snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_INERRORS),
+		snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_CSUMERRORS));
 	for (i = 0; icmpmibmap[i].name != NULL; i++)
 		seq_printf(seq, " %lu",
 			   atomic_long_read(ptr + icmpmibmap[i].index));
 	seq_printf(seq, " %lu %lu",
-		snmp_fold_field((void __percpu **) net->mib.icmp_statistics, ICMP_MIB_OUTMSGS),
-		snmp_fold_field((void __percpu **) net->mib.icmp_statistics, ICMP_MIB_OUTERRORS));
+		snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_OUTMSGS),
+		snmp_fold_field(net->mib.icmp_statistics, ICMP_MIB_OUTERRORS));
 	for (i = 0; icmpmibmap[i].name != NULL; i++)
 		seq_printf(seq, " %lu",
 			   atomic_long_read(ptr + (icmpmibmap[i].index | 0x100)));
@@ -379,7 +379,7 @@
 	BUILD_BUG_ON(offsetof(struct ipstats_mib, mibs) != 0);
 	for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
 		seq_printf(seq, " %llu",
-			   snmp_fold_field64((void __percpu **)net->mib.ip_statistics,
+			   snmp_fold_field64(net->mib.ip_statistics,
 					     snmp4_ipstats_list[i].entry,
 					     offsetof(struct ipstats_mib, syncp)));
 
@@ -395,11 +395,11 @@
 		/* MaxConn field is signed, RFC 2012 */
 		if (snmp4_tcp_list[i].entry == TCP_MIB_MAXCONN)
 			seq_printf(seq, " %ld",
-				   snmp_fold_field((void __percpu **)net->mib.tcp_statistics,
+				   snmp_fold_field(net->mib.tcp_statistics,
 						   snmp4_tcp_list[i].entry));
 		else
 			seq_printf(seq, " %lu",
-				   snmp_fold_field((void __percpu **)net->mib.tcp_statistics,
+				   snmp_fold_field(net->mib.tcp_statistics,
 						   snmp4_tcp_list[i].entry));
 	}
 
@@ -410,7 +410,7 @@
 	seq_puts(seq, "\nUdp:");
 	for (i = 0; snmp4_udp_list[i].name != NULL; i++)
 		seq_printf(seq, " %lu",
-			   snmp_fold_field((void __percpu **)net->mib.udp_statistics,
+			   snmp_fold_field(net->mib.udp_statistics,
 					   snmp4_udp_list[i].entry));
 
 	/* the UDP and UDP-Lite MIBs are the same */
@@ -421,7 +421,7 @@
 	seq_puts(seq, "\nUdpLite:");
 	for (i = 0; snmp4_udp_list[i].name != NULL; i++)
 		seq_printf(seq, " %lu",
-			   snmp_fold_field((void __percpu **)net->mib.udplite_statistics,
+			   snmp_fold_field(net->mib.udplite_statistics,
 					   snmp4_udp_list[i].entry));
 
 	seq_putc(seq, '\n');
@@ -458,7 +458,7 @@
 	seq_puts(seq, "\nTcpExt:");
 	for (i = 0; snmp4_net_list[i].name != NULL; i++)
 		seq_printf(seq, " %lu",
-			   snmp_fold_field((void __percpu **)net->mib.net_statistics,
+			   snmp_fold_field(net->mib.net_statistics,
 					   snmp4_net_list[i].entry));
 
 	seq_puts(seq, "\nIpExt:");
@@ -468,7 +468,7 @@
 	seq_puts(seq, "\nIpExt:");
 	for (i = 0; snmp4_ipextstats_list[i].name != NULL; i++)
 		seq_printf(seq, " %llu",
-			   snmp_fold_field64((void __percpu **)net->mib.ip_statistics,
+			   snmp_fold_field64(net->mib.ip_statistics,
 					     snmp4_ipextstats_list[i].entry,
 					     offsetof(struct ipstats_mib, syncp)));