Re: [PATCH v2 2/4] xen: introduce grant_map_exists

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 03/10/14 15:50, Stefano Stabellini wrote:
> Check whether an mfn has been granted to a given domain on a target
> grant table.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
>
> ---
>
> Changes in v2:
> - make the function static;
> - remove the spin_lock.
> ---
>  xen/common/grant_table.c |   30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
>
> diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
> index 23266c3..7a6399b 100644
> --- a/xen/common/grant_table.c
> +++ b/xen/common/grant_table.c
> @@ -484,6 +484,36 @@ static int _set_status(unsigned gt_version,
>          return _set_status_v2(domid, readonly, mapflag, shah, act, status);
>  }
>  
> +static bool_t grant_map_exists(struct domain *ld,
> +                        struct grant_table *rgt,
> +                        unsigned long mfn)
> +{
> +    struct active_grant_entry *act;
> +    grant_ref_t ref;
> +    bool_t ret = 0;
> +
> +    ASSERT(&rgt->lock);

I presume you mean spin_is_locked()?  This assertion is currently a
tautology.

~Andrew

> +
> +    for ( ref = 0; ref != nr_grant_entries(rgt); ref++ )
> +    {
> +        act = &active_entry(rgt, ref);
> +
> +        if ( !act->pin )
> +            continue;
> +
> +        if ( act->domid != ld->domain_id )
> +            continue;
> +
> +        if ( act->frame != mfn )
> +            continue;
> +        
> +        ret = 1;
> +        break;
> +    }
> +
> +    return ret;
> +}
> +
>  static void mapcount(
>      struct grant_table *lgt, struct domain *rd, unsigned long mfn,
>      unsigned int *wrc, unsigned int *rdc)