Re: [PATCH v2 5/6] xen/arm: unpopulate memory when domain is static

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.04.2022 14:22, Penny Zheng wrote:
> --- a/xen/arch/arm/include/asm/mm.h
> +++ b/xen/arch/arm/include/asm/mm.h
> @@ -358,6 +358,23 @@ void clear_and_clean_page(struct page_info *page);
>  
>  unsigned int arch_get_dma_bitsize(void);
>  
> +/*
> + * Put free pages on the resv page list after having taken them
> + * off the "normal" page list, when pages from static memory
> + */
> +#ifdef CONFIG_STATIC_MEMORY
> +#define arch_free_heap_page(d, pg) {                    \
> +    if ( (pg)->count_info & PGC_reserved )              \
> +    {                                                   \
> +        page_list_del(pg, page_to_list(d, pg));         \
> +        page_list_add_tail(pg, &(d)->resv_page_list);   \
> +        (d)->resv_pages++;                              \

There's no consumer of this counter, so I'd like to ask that it be
introduced once a consumer appears.

> +    }                                                   \
> +    else                                                \
> +        page_list_del(pg, page_to_list(d, pg));         \

Is there a particular reason to have this page_list_del() twice,
instead of just once ahead of the if()?

> +}

Also this entire construct want to be an expression, not a
(compound) statement. And it probably would better evaluate its
parameters just once.

Jan