Messages in this thread | | | Date | Sat, 25 Apr 2020 17:55:11 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 3/3] mm/hugetlb: Introduce HAVE_ARCH_CLEAR_HUGEPAGE_FLAGS |
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On Tue, 14 Apr 2020 17:14:30 +0530 Anshuman Khandual <anshuman.khandual@arm.com> wrote:
> There are multiple similar definitions for arch_clear_hugepage_flags() on > various platforms. This introduces HAVE_ARCH_CLEAR_HUGEPAGE_FLAGS for those > platforms that need to define their own arch_clear_hugepage_flags() while > also providing a generic fallback definition for others to use. This help > reduce code duplication. > > ... > > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -544,6 +544,10 @@ static inline int is_hugepage_only_range(struct mm_struct *mm, > } > #endif > > +#ifndef HAVE_ARCH_CLEAR_HUGEPAGE_FLAGS > +static inline void arch_clear_hugepage_flags(struct page *page) { } > +#endif > + > #ifndef arch_make_huge_pte > static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma, > struct page *page, int writable)
This is the rather old-school way of doing it. The Linus-suggested way is
#ifndef arch_clear_hugepage_flags static inline void arch_clear_hugepage_flags(struct page *page) { } #define arch_clear_hugepage_flags arch_clear_hugepage_flags #endif
And the various arch headers do
static inline void arch_clear_hugepage_flags(struct page *page) { <some implementation> } #define arch_clear_hugepage_flags arch_clear_hugepage_flags
It's a small difference - mainly to avoid adding two variables to the overall namespace where one would do.
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