Virtualization - Mar 2021 - [PATCH v4 06/14] vringh: add vringh_kiov_length() helper

This new helper returns the total number of bytes covered by
a vringh_kiov.

Suggested-by: Jason Wang <jasowang at redhat.com>
Acked-by: Jason Wang <jasowang at redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare at redhat.com>
---
 include/linux/vringh.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/vringh.h b/include/linux/vringh.h
index 755211ebd195..84db7b8f912f 100644
--- a/include/linux/vringh.h
+++ b/include/linux/vringh.h
@@ -199,6 +199,17 @@ static inline void vringh_kiov_cleanup(struct vringh_kiov
*kiov)
 	kiov->iov = NULL;
 }
 
+static inline size_t vringh_kiov_length(struct vringh_kiov *kiov)
+{
+	size_t len = 0;
+	int i;
+
+	for (i = kiov->i; i < kiov->used; i++)
+		len += kiov->iov[i].iov_len;
+
+	return len;
+}
+
 void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len);
 
 int vringh_getdesc_kern(struct vringh *vrh,
-- 
2.30.2

On 15/03/2021 17:34, Stefano Garzarella wrote:
> This new helper returns the total number of bytes covered by
> a vringh_kiov.
> 
> Suggested-by: Jason Wang <jasowang at redhat.com>
> Acked-by: Jason Wang <jasowang at redhat.com>
> Signed-off-by: Stefano Garzarella <sgarzare at redhat.com>
> ---
>  include/linux/vringh.h | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/include/linux/vringh.h b/include/linux/vringh.h
> index 755211ebd195..84db7b8f912f 100644
> --- a/include/linux/vringh.h
> +++ b/include/linux/vringh.h
> @@ -199,6 +199,17 @@ static inline void vringh_kiov_cleanup(struct
vringh_kiov *kiov)
>  	kiov->iov = NULL;
>  }
>  
> +static inline size_t vringh_kiov_length(struct vringh_kiov *kiov)
> +{
> +	size_t len = 0;
> +	int i;
> +
> +	for (i = kiov->i; i < kiov->used; i++)
> +		len += kiov->iov[i].iov_len;
> +
> +	return len;
> +}
Do we really need an helper?

For instance, we can use:

len = iov_length((struct iovec *)kiov->iov, kiov->used);

Or do we want to avoid the cast?

Thanks,
Laurent