Merge branch 'snmp-optimizations'

Eric Dumazet says:

====================
net: snmp: minor optimizations

Fetching many SNMP counters on hosts with large number of cpus
takes a lot of time. mptcp still uses the old non-batched
fashion which is not cache friendly.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ip.h

@@ -291,7 +291,11 @@ void ip_send_unicast_reply(struct sock *sk, struct sk_buff *skb,
 #define NET_ADD_STATS(net, field, adnd)	SNMP_ADD_STATS((net)->mib.net_statistics, field, adnd)
 #define __NET_ADD_STATS(net, field, adnd) __SNMP_ADD_STATS((net)->mib.net_statistics, field, adnd)
 
-u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offct);
+static inline u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offt)
+{
+	return  *(((unsigned long *)per_cpu_ptr(mib, cpu)) + offt);
+}
+
 unsigned long snmp_fold_field(void __percpu *mib, int offt);
 #if BITS_PER_LONG==32
 u64 snmp_get_cpu_field64(void __percpu *mib, int cpu, int offct,

net/ipv4/af_inet.c

@@ -1662,12 +1662,6 @@ int inet_ctl_sock_create(struct sock **sk, unsigned short family,
 }
 EXPORT_SYMBOL_GPL(inet_ctl_sock_create);
 
-u64 snmp_get_cpu_field(void __percpu *mib, int cpu, int offt)
-{
-	return  *(((unsigned long *)per_cpu_ptr(mib, cpu)) + offt);
-}
-EXPORT_SYMBOL_GPL(snmp_get_cpu_field);
-
 unsigned long snmp_fold_field(void __percpu *mib, int offt)
 {
 	unsigned long res = 0;

net/mptcp/mib.c

@@ -72,6 +72,7 @@ bool mptcp_mib_alloc(struct net *net)
 
 void mptcp_seq_show(struct seq_file *seq)
 {
+	unsigned long sum[ARRAY_SIZE(mptcp_snmp_list) - 1];
 	struct net *net = seq->private;
 	int i;
 
@@ -81,17 +82,13 @@ void mptcp_seq_show(struct seq_file *seq)
 
 	seq_puts(seq, "\nMPTcpExt:");
 
-	if (!net->mib.mptcp_statistics) {
-		for (i = 0; mptcp_snmp_list[i].name; i++)
-			seq_puts(seq, " 0");
-
-		seq_putc(seq, '\n');
-		return;
-	}
+	memset(sum, 0, sizeof(sum));
+	if (net->mib.mptcp_statistics)
+		snmp_get_cpu_field_batch(sum, mptcp_snmp_list,
+					 net->mib.mptcp_statistics);
 
 	for (i = 0; mptcp_snmp_list[i].name; i++)
-		seq_printf(seq, " %lu",
-			   snmp_fold_field(net->mib.mptcp_statistics,
-					   mptcp_snmp_list[i].entry));
+		seq_printf(seq, " %lu", sum[i]);
+
 	seq_putc(seq, '\n');
 }