From a1a56aaa0735c7821e85c37268a7c12e132415cb Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Mon, 15 Jun 2015 18:10:13 -0700 Subject: [PATCH] netfilter: x_tables: align per cpu xt_counter Let's force a 16 bytes alignment on xt_counter percpu allocations, so that bytes and packets sit in same cache line. xt_counter being exported to user space, we cannot add __align(16) on the structure itself. Signed-off-by: Eric Dumazet Cc: Florian Westphal Acked-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/x_tables.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/include/linux/netfilter/x_tables.h b/include/linux/netfilter/x_tables.h index 95693c4cebdd..1c97a2204379 100644 --- a/include/linux/netfilter/x_tables.h +++ b/include/linux/netfilter/x_tables.h @@ -356,7 +356,8 @@ static inline unsigned long ifname_compare_aligned(const char *_a, * so nothing needs to be done there. * * xt_percpu_counter_alloc returns the address of the percpu - * counter, or 0 on !SMP. + * counter, or 0 on !SMP. We force an alignment of 16 bytes + * so that bytes/packets share a common cache line. * * Hence caller must use IS_ERR_VALUE to check for error, this * allows us to return 0 for single core systems without forcing @@ -365,7 +366,8 @@ static inline unsigned long ifname_compare_aligned(const char *_a, static inline u64 xt_percpu_counter_alloc(void) { if (nr_cpu_ids > 1) { - void __percpu *res = alloc_percpu(struct xt_counters); + void __percpu *res = __alloc_percpu(sizeof(struct xt_counters), + sizeof(struct xt_counters)); if (res == NULL) return (u64) -ENOMEM; -- 2.20.1