netfilter: xtables: stackptr should be percpu

commit f3c5c1bfd4 (netfilter: xtables: make ip_tables reentrant)
introduced a performance regression, because stackptr array is shared by
all cpus, adding cache line ping pongs. (16 cpus share a 64 bytes cache
line)

Fix this using alloc_percpu()

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-By: Jan Engelhardt <jengelh@medozas.de>
Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 1 insertions, 1 deletions

diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 63958f3394a5..4b6c5ca610fc 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -336,7 +336,7 @@ ipt_do_table(struct sk_buff *skb,
         cpu        = smp_processor_id();
         table_base = private->entries[cpu];
         jumpstack  = (struct ipt_entry **)private->jumpstack[cpu];
-        stackptr   = &private->stackptr[cpu];
+        stackptr   = per_cpu_ptr(private->stackptr, cpu);
         origptr    = *stackptr;
 
         e = get_entry(table_base, private->hook_entry[hook]);