Re: [PATCH v5 02/15] vhost: add helpers for packed virtqueues

[Tiwei Bie <tiwei.bie@intel.com>]

On Fri, Jun 22, 2018 at 03:43:14PM +0200, Maxime Coquelin wrote:
> From: Jens Freimann <jfreimann@redhat.com>
> 
> Add some helper functions to check descriptor flags
> and check if a vring is of type packed.
> 
> Signed-off-by: Jens Freimann <jfreimann@redhat.com>
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/librte_vhost/vhost.h         |  6 ++++++
>  lib/librte_vhost/virtio-packed.h | 16 ++++++++++++++++
>  2 files changed, 22 insertions(+)
> 
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index bf2059198..34a614c97 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -319,6 +319,12 @@ struct virtio_net {
>  	struct vhost_user_extern_ops extern_ops;
>  } __rte_cache_aligned;
>  
> +static __rte_always_inline bool
> +vq_is_packed(struct virtio_net *dev)
> +{
> +	return dev->features & (1ull << VIRTIO_F_RING_PACKED);
> +}
> +
>  #define VHOST_LOG_PAGE	4096
>  
>  /*
> diff --git a/lib/librte_vhost/virtio-packed.h b/lib/librte_vhost/virtio-packed.h
> index 744b3991b..21fe5045b 100644
> --- a/lib/librte_vhost/virtio-packed.h
> +++ b/lib/librte_vhost/virtio-packed.h
> @@ -19,4 +19,20 @@ struct vring_desc_packed {
>  	uint16_t flags;
>  };
>  
> +
> +static inline int

Better to return bool.

> +desc_is_avail(struct vring_desc_packed *desc, uint16_t wrap_counter)
> +{
> +	if (wrap_counter == 1) {
> +		if ((desc->flags & VRING_DESC_F_AVAIL) &&
> +				!(desc->flags & VRING_DESC_F_USED))
> +			return 1;
> +	} else {
> +		if (!(desc->flags & VRING_DESC_F_AVAIL) &&
> +				(desc->flags & VRING_DESC_F_USED))
> +			return 1;
> +	}
> +	return 0;

Maybe something like:

return wrap_counter == !!(desc->flags & VRING_DESC_F_AVAIL) &&
	wrap_counter != !!(dsec->flags & VRING_DESC_F_USED);

is better?

Best regards,
Tiwei Bie

> +}
> +
>  #endif /* __VIRTIO_PACKED_H */
> -- 
> 2.14.4
>