ipv6: reduce per device ICMP mib sizes

ipv6 has per device ICMP SNMP counters, taking too much space because
they use percpu storage.

needed size per device is :
(512+4)*sizeof(long)*number_of_possible_cpus*2

On a 32bit kernel, 16 possible cpus, this wastes more than 64kbytes of
memory per ipv6 enabled network device, taken in vmalloc pool.

Since ICMP messages are rare, just use shared counters (atomic_long_t)

Per network space ICMP counters are still using percpu memory, we might
also convert them to shared counters in a future patch.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Denys Fedoryshchenko <denys@visp.net.lb>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 14 insertions, 5 deletions

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index e1c60b43e73b..c033ed00df7d 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -123,6 +123,15 @@ extern struct ctl_path net_ipv6_ctl_path[];
         SNMP_INC_STATS##modifier((net)->mib.statname##_statistics, (field));\
 })
 
+/* per device counters are atomic_long_t */
+#define _DEVINCATOMIC(net, statname, modifier, idev, field)             \
+({                                                                      \
+        struct inet6_dev *_idev = (idev);                               \
+        if (likely(_idev != NULL))                                      \
+                SNMP_INC_STATS_ATOMIC_LONG((_idev)->stats.statname##dev, (field)); \
+        SNMP_INC_STATS##modifier((net)->mib.statname##_statistics, (field));\
+})
+
 #define _DEVADD(net, statname, modifier, idev, field, val)              \
 ({                                                                      \
         struct inet6_dev *_idev = (idev);                               \
@@ -154,16 +163,16 @@ extern struct ctl_path net_ipv6_ctl_path[];
 #define IP6_UPD_PO_STATS_BH(net, idev,field,val)   \
                 _DEVUPD(net, ipv6, 64_BH, idev, field, val)
 #define ICMP6_INC_STATS(net, idev, field)       \
-                _DEVINC(net, icmpv6, , idev, field)
+                _DEVINCATOMIC(net, icmpv6, , idev, field)
 #define ICMP6_INC_STATS_BH(net, idev, field)    \
-                _DEVINC(net, icmpv6, _BH, idev, field)
+                _DEVINCATOMIC(net, icmpv6, _BH, idev, field)
 
 #define ICMP6MSGOUT_INC_STATS(net, idev, field)         \
-        _DEVINC(net, icmpv6msg, , idev, field +256)
+        _DEVINCATOMIC(net, icmpv6msg, , idev, field +256)
 #define ICMP6MSGOUT_INC_STATS_BH(net, idev, field)      \
-        _DEVINC(net, icmpv6msg, _BH, idev, field +256)
+        _DEVINCATOMIC(net, icmpv6msg, _BH, idev, field +256)
 #define ICMP6MSGIN_INC_STATS_BH(net, idev, field)       \
-        _DEVINC(net, icmpv6msg, _BH, idev, field)
+        _DEVINCATOMIC(net, icmpv6msg, _BH, idev, field)
 
 struct ip6_ra_chain {
         struct ip6_ra_chain     *next;