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From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: Juhamatti Kuusisaari <juhamatti.kuusisaari@coriant.com>, "dev@dpdk.org"
 <dev@dpdk.org>
Thread-Topic: [dpdk-dev] [PATCH] lib: change rte_ring dequeue to guarantee
 ordering before tail update
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Date: Fri, 15 Jul 2016 12:22:29 +0000
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References: <20160715043951.32040-1-juhamatti.kuusisaari@coriant.com>
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Subject: Re: [dpdk-dev] [PATCH] lib: change rte_ring dequeue to
	guarantee	ordering before tail update
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>=20
> Consumer queue dequeuing must be guaranteed to be done fully before the t=
ail is updated. This is not guaranteed with a read barrier,
> changed to a write barrier just before tail update which in practice guar=
antees correct order of reads and writes.
>=20
> Signed-off-by: Juhamatti Kuusisaari <juhamatti.kuusisaari@coriant.com>
> ---
>  lib/librte_ring/rte_ring.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>=20
> diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h inde=
x eb45e41..14920af 100644
> --- a/lib/librte_ring/rte_ring.h
> +++ b/lib/librte_ring/rte_ring.h
> @@ -748,7 +748,7 @@ __rte_ring_sc_do_dequeue(struct rte_ring *r, void **o=
bj_table,
>=20
>         /* copy in table */
>         DEQUEUE_PTRS();
> -       rte_smp_rmb();
> +       rte_smp_wmb();
>=20
>         __RING_STAT_ADD(r, deq_success, n);
>         r->cons.tail =3D cons_next;
> --

Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

> 2.9.0
>=20