snmp: 64bit ipstats_mib for all arches

/proc/net/snmp and /proc/net/netstat expose SNMP counters.

Width of these counters is either 32 or 64 bits, depending on the size
of "unsigned long" in kernel.

This means user program parsing these files must already be prepared to
deal with 64bit values, regardless of user program being 32 or 64 bit.

This patch introduces 64bit snmp values for IPSTAT mib, where some
counters can wrap pretty fast if they are 32bit wide.

# netstat -s|egrep "InOctets|OutOctets"
    InOctets: 244068329096
    OutOctets: 244069348848

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index e320ca6..4ae1f20 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -343,10 +343,12 @@
 		   IPV4_DEVCONF_ALL(net, FORWARDING) ? 1 : 2,
 		   sysctl_ip_default_ttl);
 
+	BUILD_BUG_ON(offsetof(struct ipstats_mib, mibs) != 0);
 	for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
-		seq_printf(seq, " %lu",
-			   snmp_fold_field((void __percpu **)net->mib.ip_statistics,
-					   snmp4_ipstats_list[i].entry));
+		seq_printf(seq, " %llu",
+			   snmp_fold_field64((void __percpu **)net->mib.ip_statistics,
+					     snmp4_ipstats_list[i].entry,
+					     offsetof(struct ipstats_mib, syncp)));
 
 	icmp_put(seq);	/* RFC 2011 compatibility */
 	icmpmsg_put(seq);
@@ -432,9 +434,10 @@
 
 	seq_puts(seq, "\nIpExt:");
 	for (i = 0; snmp4_ipextstats_list[i].name != NULL; i++)
-		seq_printf(seq, " %lu",
-			   snmp_fold_field((void __percpu **)net->mib.ip_statistics,
-					   snmp4_ipextstats_list[i].entry));
+		seq_printf(seq, " %llu",
+			   snmp_fold_field64((void __percpu **)net->mib.ip_statistics,
+					     snmp4_ipextstats_list[i].entry,
+					     offsetof(struct ipstats_mib, syncp)));
 
 	seq_putc(seq, '\n');
 	return 0;