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Commit a1a56aaa authored by Eric Dumazet's avatar Eric Dumazet Committed by Pablo Neira Ayuso
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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: default avatarEric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Acked-by: default avatarFlorian Westphal <fw@strlen.de>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 01555e74

include/linux/netfilter/x_tables.h

+4 −2
Original line number Diff line number Diff line
@@ -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;