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>

2 files changed, 43 insertions, 74 deletions

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 8c54870db792..6765d91b8e75 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1476,22 +1476,20 @@ int inet_ctl_sock_create(struct sock **sk, unsigned short family,
 }
 EXPORT_SYMBOL_GPL(inet_ctl_sock_create);
 
-unsigned long snmp_fold_field(void __percpu *mib[], int offt)
+unsigned long snmp_fold_field(void __percpu *mib, int offt)
 {
 	unsigned long res = 0;
-	int i, j;
+	int i;
 
-	for_each_possible_cpu(i) {
-		for (j = 0; j < SNMP_ARRAY_SZ; j++)
-			res += *(((unsigned long *) per_cpu_ptr(mib[j], i)) + offt);
-	}
+	for_each_possible_cpu(i)
+		res += *(((unsigned long *) per_cpu_ptr(mib, i)) + offt);
 	return res;
 }
 EXPORT_SYMBOL_GPL(snmp_fold_field);
 
 #if BITS_PER_LONG==32
 
-u64 snmp_fold_field64(void __percpu *mib[], int offt, size_t syncp_offset)
+u64 snmp_fold_field64(void __percpu *mib, int offt, size_t syncp_offset)
 {
 	u64 res = 0;
 	int cpu;
@@ -1502,7 +1500,7 @@ u64 snmp_fold_field64(void __percpu *mib[], int offt, size_t syncp_offset)
 		u64 v;
 		unsigned int start;
 
-		bhptr = per_cpu_ptr(mib[0], cpu);
+		bhptr = per_cpu_ptr(mib, cpu);
 		syncp = (struct u64_stats_sync *)(bhptr + syncp_offset);
 		do {
 			start = u64_stats_fetch_begin_irq(syncp);
@@ -1516,25 +1514,6 @@ u64 snmp_fold_field64(void __percpu *mib[], int offt, size_t syncp_offset)
 EXPORT_SYMBOL_GPL(snmp_fold_field64);
 #endif
 
-int snmp_mib_init(void __percpu *ptr[2], size_t mibsize, size_t align)
-{
-	BUG_ON(ptr == NULL);
-	ptr[0] = __alloc_percpu(mibsize, align);
-	if (!ptr[0])
-		return -ENOMEM;
-
-#if SNMP_ARRAY_SZ == 2
-	ptr[1] = __alloc_percpu(mibsize, align);
-	if (!ptr[1]) {
-		free_percpu(ptr[0]);
-		ptr[0] = NULL;
-		return -ENOMEM;
-	}
-#endif
-	return 0;
-}
-EXPORT_SYMBOL_GPL(snmp_mib_init);
-
 #ifdef CONFIG_IP_MULTICAST
 static const struct net_protocol igmp_protocol = {
 	.handler =	igmp_rcv,
@@ -1570,40 +1549,30 @@ static __net_init int ipv4_mib_init_net(struct net *net)
 {
 	int i;
 
-	if (snmp_mib_init((void __percpu **)net->mib.tcp_statistics,
-			  sizeof(struct tcp_mib),
-			  __alignof__(struct tcp_mib)) < 0)
+	net->mib.tcp_statistics = alloc_percpu(struct tcp_mib);
+	if (!net->mib.tcp_statistics)
 		goto err_tcp_mib;
-	if (snmp_mib_init((void __percpu **)net->mib.ip_statistics,
-			  sizeof(struct ipstats_mib),
-			  __alignof__(struct ipstats_mib)) < 0)
+	net->mib.ip_statistics = alloc_percpu(struct ipstats_mib);
+	if (!net->mib.ip_statistics)
 		goto err_ip_mib;
 
 	for_each_possible_cpu(i) {
 		struct ipstats_mib *af_inet_stats;
-		af_inet_stats = per_cpu_ptr(net->mib.ip_statistics[0], i);
+		af_inet_stats = per_cpu_ptr(net->mib.ip_statistics, i);
 		u64_stats_init(&af_inet_stats->syncp);
-#if SNMP_ARRAY_SZ == 2
-		af_inet_stats = per_cpu_ptr(net->mib.ip_statistics[1], i);
-		u64_stats_init(&af_inet_stats->syncp);
-#endif
 	}
 
-	if (snmp_mib_init((void __percpu **)net->mib.net_statistics,
-			  sizeof(struct linux_mib),
-			  __alignof__(struct linux_mib)) < 0)
+	net->mib.net_statistics = alloc_percpu(struct linux_mib);
+	if (!net->mib.net_statistics)
 		goto err_net_mib;
-	if (snmp_mib_init((void __percpu **)net->mib.udp_statistics,
-			  sizeof(struct udp_mib),
-			  __alignof__(struct udp_mib)) < 0)
+	net->mib.udp_statistics = alloc_percpu(struct udp_mib);
+	if (!net->mib.udp_statistics)
 		goto err_udp_mib;
-	if (snmp_mib_init((void __percpu **)net->mib.udplite_statistics,
-			  sizeof(struct udp_mib),
-			  __alignof__(struct udp_mib)) < 0)
+	net->mib.udplite_statistics = alloc_percpu(struct udp_mib);
+	if (!net->mib.udplite_statistics)
 		goto err_udplite_mib;
-	if (snmp_mib_init((void __percpu **)net->mib.icmp_statistics,
-			  sizeof(struct icmp_mib),
-			  __alignof__(struct icmp_mib)) < 0)
+	net->mib.icmp_statistics = alloc_percpu(struct icmp_mib);
+	if (!net->mib.icmp_statistics)
 		goto err_icmp_mib;
 	net->mib.icmpmsg_statistics = kzalloc(sizeof(struct icmpmsg_mib),
 					      GFP_KERNEL);
@@ -1614,17 +1583,17 @@ static __net_init int ipv4_mib_init_net(struct net *net)
 	return 0;
 
 err_icmpmsg_mib:
-	snmp_mib_free((void __percpu **)net->mib.icmp_statistics);
+	free_percpu(net->mib.icmp_statistics);
 err_icmp_mib:
-	snmp_mib_free((void __percpu **)net->mib.udplite_statistics);
+	free_percpu(net->mib.udplite_statistics);
 err_udplite_mib:
-	snmp_mib_free((void __percpu **)net->mib.udp_statistics);
+	free_percpu(net->mib.udp_statistics);
 err_udp_mib:
-	snmp_mib_free((void __percpu **)net->mib.net_statistics);
+	free_percpu(net->mib.net_statistics);
 err_net_mib:
-	snmp_mib_free((void __percpu **)net->mib.ip_statistics);
+	free_percpu(net->mib.ip_statistics);
 err_ip_mib:
-	snmp_mib_free((void __percpu **)net->mib.tcp_statistics);
+	free_percpu(net->mib.tcp_statistics);
 err_tcp_mib:
 	return -ENOMEM;
 }
@@ -1632,12 +1601,12 @@ err_tcp_mib:
 static __net_exit void ipv4_mib_exit_net(struct net *net)
 {
 	kfree(net->mib.icmpmsg_statistics);
-	snmp_mib_free((void __percpu **)net->mib.icmp_statistics);
-	snmp_mib_free((void __percpu **)net->mib.udplite_statistics);
-	snmp_mib_free((void __percpu **)net->mib.udp_statistics);
-	snmp_mib_free((void __percpu **)net->mib.net_statistics);
-	snmp_mib_free((void __percpu **)net->mib.ip_statistics);
-	snmp_mib_free((void __percpu **)net->mib.tcp_statistics);
+	free_percpu(net->mib.icmp_statistics);
+	free_percpu(net->mib.udplite_statistics);
+	free_percpu(net->mib.udp_statistics);
+	free_percpu(net->mib.net_statistics);
+	free_percpu(net->mib.ip_statistics);
+	free_percpu(net->mib.tcp_statistics);
 }
 
 static __net_initdata struct pernet_operations ipv4_mib_ops = {
diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index ad737fad6d8b..ae0af9386f7c 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -345,15 +345,15 @@ static void icmp_put(struct seq_file *seq)
 	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 @@ static int snmp_seq_show(struct seq_file *seq, void *v)
 	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 @@ static int snmp_seq_show(struct seq_file *seq, void *v)
 		/* 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 @@ static int snmp_seq_show(struct seq_file *seq, void *v)
 	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 @@ static int snmp_seq_show(struct seq_file *seq, void *v)
 	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 @@ static int netstat_seq_show(struct seq_file *seq, void *v)
 	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 @@ static int netstat_seq_show(struct seq_file *seq, void *v)
 	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)));