Re: [PATCH] memory: avoid pointless continuation in xenmem_add_to_physmap()

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 04/12/2020 10:43, Jan Beulich wrote:
> Adjust so we uniformly avoid needlessly arranging for a continuation on
> the last iteration.
>
> Fixes: 5777a3742d88 ("IOMMU: hold page ref until after deferred TLB flush")
I view this patch as an optimization because there is nothing wrong with 
the code. So I think "Fixes" is not entirely suitable here.
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Other than my remark about the tag:

Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -854,8 +854,9 @@ int xenmem_add_to_physmap(struct domain
>               ++extra.ppage;
>   
>           /* Check for continuation if it's not the last iteration. */
> -        if ( (++done >= ARRAY_SIZE(pages) && extra.ppage) ||
> -             (xatp->size > done && hypercall_preempt_check()) )
> +        if ( xatp->size > ++done &&
> +             ((done >= ARRAY_SIZE(pages) && extra.ppage) ||
> +              hypercall_preempt_check()) )
>           {
>               rc = start + done;
>               break;
--
Julien Grall