This patch exchanges the two loop for collecting the percpu statistics
data. This can aggregate the data by going through all the items of each
cpu sequentially. Then snmp_seq_show is split into 2 parts to avoid build
warning "the frame size" larger than 1024.

Signed-off-by: Jia He <hejia...@gmail.com>
---
 net/ipv4/proc.c | 112 ++++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 81 insertions(+), 31 deletions(-)

diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 9f665b6..f413fdc 100644
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -46,6 +46,9 @@
 #include <net/sock.h>
 #include <net/raw.h>
 
+#define MAX(a, b) ((u32)(a) >= (u32)(b) ? (a) : (b))
+#define TCPUDP_MIB_MAX MAX(UDP_MIB_MAX, TCP_MIB_MAX)
+
 /*
  *     Report socket allocation statistics [m...@utu.fi]
  */
@@ -378,13 +381,15 @@ static void icmp_put(struct seq_file *seq)
 /*
  *     Called from the PROCfs module. This outputs /proc/net/snmp.
  */
-static int snmp_seq_show(struct seq_file *seq, void *v)
+static int snmp_seq_show_ipstats(struct seq_file *seq, void *v)
 {
-       int i;
+       int i, c;
+       u64 buff64[IPSTATS_MIB_MAX];
        struct net *net = seq->private;
 
-       seq_puts(seq, "Ip: Forwarding DefaultTTL");
+       memset(buff64, 0, IPSTATS_MIB_MAX * sizeof(u64));
 
+       seq_puts(seq, "Ip: Forwarding DefaultTTL");
        for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
                seq_printf(seq, " %s", snmp4_ipstats_list[i].name);
 
@@ -393,57 +398,92 @@ static int snmp_seq_show(struct seq_file *seq, void *v)
                   net->ipv4.sysctl_ip_default_ttl);
 
        BUILD_BUG_ON(offsetof(struct ipstats_mib, mibs) != 0);
+
+       for_each_possible_cpu(c) {
+               for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
+                       buff64[i] += snmp_get_cpu_field64(
+                                       net->mib.ip_statistics,
+                                       c, snmp4_ipstats_list[i].entry,
+                                       offsetof(struct ipstats_mib, syncp));
+       }
        for (i = 0; snmp4_ipstats_list[i].name != NULL; i++)
-               seq_printf(seq, " %llu",
-                          snmp_fold_field64(net->mib.ip_statistics,
-                                            snmp4_ipstats_list[i].entry,
-                                            offsetof(struct ipstats_mib, 
syncp)));
+               seq_printf(seq, " %llu", buff64[i]);
 
-       icmp_put(seq);  /* RFC 2011 compatibility */
-       icmpmsg_put(seq);
+       return 0;
+}
+
+static int snmp_seq_show_tcp_udp(struct seq_file *seq, void *v)
+{
+       int i, c;
+       unsigned long buff[TCPUDP_MIB_MAX];
+       struct net *net = seq->private;
+
+       memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
 
        seq_puts(seq, "\nTcp:");
        for (i = 0; snmp4_tcp_list[i].name != NULL; i++)
                seq_printf(seq, " %s", snmp4_tcp_list[i].name);
 
        seq_puts(seq, "\nTcp:");
+       for_each_possible_cpu(c) {
+               for (i = 0; snmp4_tcp_list[i].name != NULL; i++)
+                       buff[i] += snmp_get_cpu_field(net->mib.tcp_statistics,
+                                               c, snmp4_tcp_list[i].entry);
+       }
+
        for (i = 0; snmp4_tcp_list[i].name != NULL; i++) {
                /* MaxConn field is signed, RFC 2012 */
                if (snmp4_tcp_list[i].entry == TCP_MIB_MAXCONN)
-                       seq_printf(seq, " %ld",
-                                  snmp_fold_field(net->mib.tcp_statistics,
-                                                  snmp4_tcp_list[i].entry));
+                       seq_printf(seq, " %ld", buff[i]);
                else
-                       seq_printf(seq, " %lu",
-                                  snmp_fold_field(net->mib.tcp_statistics,
-                                                  snmp4_tcp_list[i].entry));
+                       seq_printf(seq, " %lu", buff[i]);
        }
 
+       memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
+
+       for_each_possible_cpu(c) {
+               for (i = 0; snmp4_udp_list[i].name != NULL; i++)
+                       buff[i] += snmp_get_cpu_field(net->mib.udp_statistics,
+                                               c, snmp4_udp_list[i].entry);
+       }
        seq_puts(seq, "\nUdp:");
        for (i = 0; snmp4_udp_list[i].name != NULL; i++)
                seq_printf(seq, " %s", snmp4_udp_list[i].name);
-
        seq_puts(seq, "\nUdp:");
        for (i = 0; snmp4_udp_list[i].name != NULL; i++)
-               seq_printf(seq, " %lu",
-                          snmp_fold_field(net->mib.udp_statistics,
-                                          snmp4_udp_list[i].entry));
+               seq_printf(seq, " %lu", buff[i]);
+
+       memset(buff, 0, TCPUDP_MIB_MAX * sizeof(unsigned long));
 
        /* the UDP and UDP-Lite MIBs are the same */
        seq_puts(seq, "\nUdpLite:");
+       for_each_possible_cpu(c) {
+               for (i = 0; snmp4_udp_list[i].name != NULL; i++)
+                       buff[i] += 
snmp_get_cpu_field(net->mib.udplite_statistics,
+                                               c, snmp4_udp_list[i].entry);
+       }
        for (i = 0; snmp4_udp_list[i].name != NULL; i++)
                seq_printf(seq, " %s", snmp4_udp_list[i].name);
-
        seq_puts(seq, "\nUdpLite:");
        for (i = 0; snmp4_udp_list[i].name != NULL; i++)
-               seq_printf(seq, " %lu",
-                          snmp_fold_field(net->mib.udplite_statistics,
-                                          snmp4_udp_list[i].entry));
+               seq_printf(seq, " %lu", buff[i]);
 
        seq_putc(seq, '\n');
        return 0;
 }
 
+static int snmp_seq_show(struct seq_file *seq, void *v)
+{
+       snmp_seq_show_ipstats(seq, v);
+
+       icmp_put(seq);  /* RFC 2011 compatibility */
+       icmpmsg_put(seq);
+
+       snmp_seq_show_tcp_udp(seq, v);
+
+       return 0;
+}
+
 static int snmp_seq_open(struct inode *inode, struct file *file)
 {
        return single_open_net(inode, file, snmp_seq_show);
@@ -464,29 +504,39 @@ static const struct file_operations snmp_seq_fops = {
  */
 static int netstat_seq_show(struct seq_file *seq, void *v)
 {
-       int i;
+       int i, c;
+       unsigned long buff[LINUX_MIB_MAX];
+       u64 buff64[IPSTATS_MIB_MAX];
        struct net *net = seq->private;
 
+       memset(buff, 0, sizeof(unsigned long) * LINUX_MIB_MAX);
+       memset(buff64, 0, sizeof(u64) * IPSTATS_MIB_MAX);
+
        seq_puts(seq, "TcpExt:");
        for (i = 0; snmp4_net_list[i].name != NULL; i++)
                seq_printf(seq, " %s", snmp4_net_list[i].name);
 
        seq_puts(seq, "\nTcpExt:");
+       for_each_possible_cpu(c)
+               for (i = 0; snmp4_net_list[i].name != NULL; i++)
+                       buff[i] += snmp_get_cpu_field(net->mib.net_statistics,
+                                               c, snmp4_net_list[i].entry);
        for (i = 0; snmp4_net_list[i].name != NULL; i++)
-               seq_printf(seq, " %lu",
-                          snmp_fold_field(net->mib.net_statistics,
-                                          snmp4_net_list[i].entry));
+               seq_printf(seq, " %lu", buff[i]);
 
        seq_puts(seq, "\nIpExt:");
        for (i = 0; snmp4_ipextstats_list[i].name != NULL; i++)
                seq_printf(seq, " %s", snmp4_ipextstats_list[i].name);
 
        seq_puts(seq, "\nIpExt:");
+       for_each_possible_cpu(c)
+               for (i = 0; snmp4_ipextstats_list[i].name != NULL; i++)
+                       buff64[i] += snmp_get_cpu_field64(
+                                       net->mib.ip_statistics,
+                                       c, snmp4_ipextstats_list[i].entry,
+                                       offsetof(struct ipstats_mib, syncp));
        for (i = 0; snmp4_ipextstats_list[i].name != NULL; i++)
-               seq_printf(seq, " %llu",
-                          snmp_fold_field64(net->mib.ip_statistics,
-                                            snmp4_ipextstats_list[i].entry,
-                                            offsetof(struct ipstats_mib, 
syncp)));
+               seq_printf(seq, " %llu", buff64[i]);
 
        seq_putc(seq, '\n');
        return 0;
-- 
1.8.3.1

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