Re: [PATCH v3 10/21] xen/shbuf: switch xen-front-pgdir-shbuf to use INVALID_GRANT_REF

Oleksandr
2022-05-09T08:57:17Z

On 05.05.22 11:16, Juergen Gross wrote:

Hello Juergen

> Instead of using a private macro for an invalid grant reference use
> the common one.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> V3:
> - terminate grant ref list with 0 (Oleksandr Tyshchenko)

Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

> ---
> drivers/xen/xen-front-pgdir-shbuf.c | 18 +++++-------------
> 1 file changed, 5 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/xen/xen-front-pgdir-shbuf.c b/drivers/xen/xen-front-pgdir-shbuf.c
> index a959dee21134..b6433761d42c 100644
> --- a/drivers/xen/xen-front-pgdir-shbuf.c
> +++ b/drivers/xen/xen-front-pgdir-shbuf.c
> @@ -21,15 +21,6 @@
>
> #include <xen/xen-front-pgdir-shbuf.h>
>
> -#ifndef GRANT_INVALID_REF
> -/*
> - * FIXME: usage of grant reference 0 as invalid grant reference:
> - * grant reference 0 is valid, but never exposed to a PV driver,
> - * because of the fact it is already in use/reserved by the PV console.
> - */
> -#define GRANT_INVALID_REF 0
> -#endif
> -
> /**
> * This structure represents the structure of a shared page
> * that contains grant references to the pages of the shared
> @@ -38,6 +29,7 @@
> */
> struct xen_page_directory {
> grant_ref_t gref_dir_next_page;
> +#define XEN_GREF_LIST_END 0
> grant_ref_t gref[1]; /* Variable length */
> };
>
> @@ -83,7 +75,7 @@ grant_ref_t
> xen_front_pgdir_shbuf_get_dir_start(struct xen_front_pgdir_shbuf *buf)
> {
> if (!buf->grefs)
> - return GRANT_INVALID_REF;
> + return INVALID_GRANT_REF;
>
> return buf->grefs[0];
> }
> @@ -142,7 +134,7 @@ void xen_front_pgdir_shbuf_free(struct xen_front_pgdir_shbuf *buf)
> int i;
>
> for (i = 0; i < buf->num_grefs; i++)
> - if (buf->grefs[i] != GRANT_INVALID_REF)
> + if (buf->grefs[i] != INVALID_GRANT_REF)
> gnttab_end_foreign_access(buf->grefs[i], 0UL);
> }
> kfree(buf->grefs);
> @@ -355,7 +347,7 @@ static void backend_fill_page_dir(struct xen_front_pgdir_shbuf *buf)
> }
> /* Last page must say there is no more pages. */
> page_dir = (struct xen_page_directory *)ptr;
> - page_dir->gref_dir_next_page = GRANT_INVALID_REF;
> + page_dir->gref_dir_next_page = XEN_GREF_LIST_END;
> }
>
> /**
> @@ -384,7 +376,7 @@ static void guest_fill_page_dir(struct xen_front_pgdir_shbuf *buf)
>
> if (grefs_left <= XEN_NUM_GREFS_PER_PAGE) {
> to_copy = grefs_left;
> - page_dir->gref_dir_next_page = GRANT_INVALID_REF;
> + page_dir->gref_dir_next_page = XEN_GREF_LIST_END;
> } else {
> to_copy = XEN_NUM_GREFS_PER_PAGE;
> page_dir->gref_dir_next_page = buf->grefs[i + 1];

--
Regards,

Oleksandr Tyshchenko