percpu: add __percpu sparse annotations to net

Add __percpu sparse annotations to net.

These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors.  This patch doesn't affect normal builds.

The macro and type tricks around snmp stats make things a bit
interesting.  DEFINE/DECLARE_SNMP_STAT() macros mark the target field
as __percpu and SNMP_UPD_PO_STATS() macro is updated accordingly.  All
snmp_mib_*() users which used to cast the argument to (void **) are
updated to cast it to (void __percpu **).

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Vlad Yasevich <vladislav.yasevich@hp.com>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index e29160f..37d14e7 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -971,41 +971,41 @@
 
 static int __net_init ipv6_init_mibs(struct net *net)
 {
-	if (snmp_mib_init((void **)net->mib.udp_stats_in6,
+	if (snmp_mib_init((void __percpu **)net->mib.udp_stats_in6,
 			  sizeof (struct udp_mib)) < 0)
 		return -ENOMEM;
-	if (snmp_mib_init((void **)net->mib.udplite_stats_in6,
+	if (snmp_mib_init((void __percpu **)net->mib.udplite_stats_in6,
 			  sizeof (struct udp_mib)) < 0)
 		goto err_udplite_mib;
-	if (snmp_mib_init((void **)net->mib.ipv6_statistics,
+	if (snmp_mib_init((void __percpu **)net->mib.ipv6_statistics,
 			  sizeof(struct ipstats_mib)) < 0)
 		goto err_ip_mib;
-	if (snmp_mib_init((void **)net->mib.icmpv6_statistics,
+	if (snmp_mib_init((void __percpu **)net->mib.icmpv6_statistics,
 			  sizeof(struct icmpv6_mib)) < 0)
 		goto err_icmp_mib;
-	if (snmp_mib_init((void **)net->mib.icmpv6msg_statistics,
+	if (snmp_mib_init((void __percpu **)net->mib.icmpv6msg_statistics,
 			  sizeof(struct icmpv6msg_mib)) < 0)
 		goto err_icmpmsg_mib;
 	return 0;
 
 err_icmpmsg_mib:
-	snmp_mib_free((void **)net->mib.icmpv6_statistics);
+	snmp_mib_free((void __percpu **)net->mib.icmpv6_statistics);
 err_icmp_mib:
-	snmp_mib_free((void **)net->mib.ipv6_statistics);
+	snmp_mib_free((void __percpu **)net->mib.ipv6_statistics);
 err_ip_mib:
-	snmp_mib_free((void **)net->mib.udplite_stats_in6);
+	snmp_mib_free((void __percpu **)net->mib.udplite_stats_in6);
 err_udplite_mib:
-	snmp_mib_free((void **)net->mib.udp_stats_in6);
+	snmp_mib_free((void __percpu **)net->mib.udp_stats_in6);
 	return -ENOMEM;
 }
 
 static void ipv6_cleanup_mibs(struct net *net)
 {
-	snmp_mib_free((void **)net->mib.udp_stats_in6);
-	snmp_mib_free((void **)net->mib.udplite_stats_in6);
-	snmp_mib_free((void **)net->mib.ipv6_statistics);
-	snmp_mib_free((void **)net->mib.icmpv6_statistics);
-	snmp_mib_free((void **)net->mib.icmpv6msg_statistics);
+	snmp_mib_free((void __percpu **)net->mib.udp_stats_in6);
+	snmp_mib_free((void __percpu **)net->mib.udplite_stats_in6);
+	snmp_mib_free((void __percpu **)net->mib.ipv6_statistics);
+	snmp_mib_free((void __percpu **)net->mib.icmpv6_statistics);
+	snmp_mib_free((void __percpu **)net->mib.icmpv6msg_statistics);
 }
 
 static int __net_init inet6_net_init(struct net *net)