Re: [dpdk-dev] [PATCH] vdpa/mlx5: use master core Id for vhost thread

[David Marchand <david.marchand@redhat.com>]

On Tue, Jul 28, 2020 at 8:11 AM Xueming Li <xuemingl@mellanox.com> wrote:
>
> With latest rte api, vdpa example failed on vq setup, the api to get
> event queue of specified core failed.
>
> The api to get event queue needs core id as input, but after
> commit 67ae5936c4fc36 ("eal: fix lcore accessors for non-EAL threads"),
> code of "vhost-event" thread to get current core returns -1, an invalid
> core id.
>
> As vhost thread created on same core of eal master core, this patch uses
> master core ID as a workaround.

rte_lcore_to_cpu_id(-1) is supposed to return the current lcore id.
As explained in the commitlog of 67ae5936c4fc36, for a non-EAL thread
(which has no associated lcore by default) calling this function means
lcore_config[-1].core_id.

Did I miss something?
If not, this is not a workaround but a fix.


>
> Signed-off-by: Xueming Li <xuemingl@mellanox.com>
> Acked-by: Matan Azrad <matan@mellanox.com>
> ---
>  drivers/vdpa/mlx5/mlx5_vdpa_event.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vdpa/mlx5/mlx5_vdpa_event.c b/drivers/vdpa/mlx5/mlx5_vdpa_event.c
> index 13ad43611e..ff6db8e345 100644
> --- a/drivers/vdpa/mlx5/mlx5_vdpa_event.c
> +++ b/drivers/vdpa/mlx5/mlx5_vdpa_event.c
> @@ -55,7 +55,7 @@ mlx5_vdpa_event_qp_global_prepare(struct mlx5_vdpa_priv *priv)
>
>         if (priv->eventc)
>                 return 0;
> -       lcore = (uint32_t)rte_lcore_to_cpu_id(-1);
> +       lcore = (uint32_t)rte_get_master_lcore();
>         if (mlx5_glue->devx_query_eqn(priv->ctx, lcore, &priv->eqn)) {
>                 rte_errno = errno;
>                 DRV_LOG(ERR, "Failed to query EQ number %d.", rte_errno);
> --
> 2.17.1
>


-- 
David Marchand