[dpdk-dev] [PATCH v1 1/4] net/virtio: remove unnecessary rmb barrier

[Maxime Coquelin]

On 12/21/20 3:23 PM, Joyce Kong wrote:
> As desc_is_used has a load-acquire or rte_io_rmb inside
> and wait for used desc in virtqueue, it is ok to remove
> virtio_rmb behind it.
> 
> Signed-off-by: Joyce Kong <joyce.kong at arm.com>
> Reviewed-by: Ruifeng Wang <ruifeng.wang at arm.com>
> ---
>  drivers/net/virtio/virtio_ethdev.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index 6c233b75b..0d91f7a50 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -209,12 +209,12 @@ virtio_send_command_packed(struct virtnet_ctl *cvq,
>  	virtio_wmb(vq->hw->weak_barriers);
>  	virtqueue_notify(vq);
>  
> -	/* wait for used descriptors in virtqueue */
> +	/* wait for used desc in virtqueue
> +	 * desc_is_used has a load-acquire or rte_io_rmb inside
> +	 */
>  	while (!desc_is_used(&desc[head], vq))
>  		usleep(100);
>  
> -	virtio_rmb(vq->hw->weak_barriers);
> -
>  	/* now get used descriptors */
>  	vq->vq_free_cnt += nb_descs;
>  	vq->vq_used_cons_idx += nb_descs;
> 

Reviewed-by: Maxime Coquelin <maxime.coquelin at redhat.com>

Thanks,
Maxime