Re: [dpdk-dev] [PATCH] lib: change rte_ring dequeue to guarantee ordering before tail update

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> 
> Consumer queue dequeuing must be guaranteed to be done fully before the tail is updated. This is not guaranteed with a read barrier,
> changed to a write barrier just before tail update which in practice guarantees correct order of reads and writes.
> 
> Signed-off-by: Juhamatti Kuusisaari <juhamatti.kuusisaari@coriant.com>
> ---
>  lib/librte_ring/rte_ring.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_ring/rte_ring.h b/lib/librte_ring/rte_ring.h index 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 **obj_table,
> 
>         /* copy in table */
>         DEQUEUE_PTRS();
> -       rte_smp_rmb();
> +       rte_smp_wmb();
> 
>         __RING_STAT_ADD(r, deq_success, n);
>         r->cons.tail = cons_next;
> --

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

> 2.9.0
>