Re: [PATCH] mm: hugetlb: replace some macros with inline functions

[Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>]

On Fri, Jun 09, 2017 at 12:25:05PM +0200, Arnd Bergmann wrote:
> All users of dissolve_free_huge_page() that ignore the result cause a warning
> when CONFIG_HUGETLB_PAGE is disabled:
> 
> mm/memory-failure.c: In function 'me_huge_page':
> include/linux/hugetlb.h:556:36: error: statement with no effect [-Werror=unused-value]
>  #define dissolve_free_huge_page(p) 0
> 
> We can avoid this by using an inline function instead of the macro, and I
> decided to do the same change for the related helpers as well.
> 
> Fixes: mmotm ("mm: hugetlb: soft-offline: dissolve source hugepage after successful migration")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Right, thank you for catching this.

Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

> ---
>  include/linux/hugetlb.h | 31 ++++++++++++++++++++++++++-----
>  1 file changed, 26 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index dbb118c566cd..57f700ac127e 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -546,16 +546,37 @@ static inline unsigned int pages_per_huge_page(struct hstate *h)
>  {
>  	return 1;
>  }
> -#define hstate_index_to_shift(index) 0
> -#define hstate_index(h) 0
> +
> +static inline unsigned hstate_index_to_shift(unsigned index)
> +{
> +	return 0;
> +}
> +
> +static inline int hstate_index(struct hstate *h)
> +{
> +	return 0;
> +}
>  
>  static inline pgoff_t basepage_index(struct page *page)
>  {
>  	return page->index;
>  }
> -#define dissolve_free_huge_page(p)	0
> -#define dissolve_free_huge_pages(s, e)	0
> -#define hugepage_migration_supported(h)	false
> +
> +static inline int dissolve_free_huge_page(struct page *page)
> +{
> +	return 0;
> +}
> +
> +static inline int dissolve_free_huge_pages(unsigned long start_pfn,
> +					   unsigned long end_pfn)
> +{
> +	return 0;
> +}
> +
> +static inline bool hugepage_migration_supported(struct hstate *h)
> +{
> +	return false;
> +}
>  
>  static inline spinlock_t *huge_pte_lockptr(struct hstate *h,
>  					   struct mm_struct *mm, pte_t *pte)
> -- 
> 2.9.0
> 
>