Re: [PATCH v4 2/7] mm/swap: Comment all the ifdef in swapops.h

[Alistair Popple <apopple@nvidia.com>]

Looks good:

Reviewed-by: Alistair Popple <apopple@nvidia.com>

Peter Xu <peterx@redhat.com> writes:

> swapops.h contains quite a few layers of ifdef, some of the "else" and
> "endif" doesn't get proper comment on the macro so it's hard to follow on
> what are they referring to.  Add the comments.
>
> Suggested-by: Nadav Amit <nadav.amit@gmail.com>
> Reviewed-by: Huang Ying <ying.huang@intel.com>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  include/linux/swapops.h | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/swapops.h b/include/linux/swapops.h
> index a3d435bf9f97..3a2901ff4f1e 100644
> --- a/include/linux/swapops.h
> +++ b/include/linux/swapops.h
> @@ -247,8 +247,8 @@ extern void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
>  #ifdef CONFIG_HUGETLB_PAGE
>  extern void __migration_entry_wait_huge(pte_t *ptep, spinlock_t *ptl);
>  extern void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte);
> -#endif
> -#else
> +#endif	/* CONFIG_HUGETLB_PAGE */
> +#else  /* CONFIG_MIGRATION */
>  static inline swp_entry_t make_readable_migration_entry(pgoff_t offset)
>  {
>  	return swp_entry(0, 0);
> @@ -276,7 +276,7 @@ static inline void migration_entry_wait(struct mm_struct *mm, pmd_t *pmd,
>  #ifdef CONFIG_HUGETLB_PAGE
>  static inline void __migration_entry_wait_huge(pte_t *ptep, spinlock_t *ptl) { }
>  static inline void migration_entry_wait_huge(struct vm_area_struct *vma, pte_t *pte) { }
> -#endif
> +#endif	/* CONFIG_HUGETLB_PAGE */
>  static inline int is_writable_migration_entry(swp_entry_t entry)
>  {
>  	return 0;
> @@ -286,7 +286,7 @@ static inline int is_readable_migration_entry(swp_entry_t entry)
>  	return 0;
>  }
>
> -#endif
> +#endif	/* CONFIG_MIGRATION */
>
>  typedef unsigned long pte_marker;
>
> @@ -426,7 +426,7 @@ static inline int is_pmd_migration_entry(pmd_t pmd)
>  {
>  	return is_swap_pmd(pmd) && is_migration_entry(pmd_to_swp_entry(pmd));
>  }
> -#else
> +#else  /* CONFIG_ARCH_ENABLE_THP_MIGRATION */
>  static inline int set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
>  		struct page *page)
>  {
> @@ -455,7 +455,7 @@ static inline int is_pmd_migration_entry(pmd_t pmd)
>  {
>  	return 0;
>  }
> -#endif
> +#endif  /* CONFIG_ARCH_ENABLE_THP_MIGRATION */
>
>  #ifdef CONFIG_MEMORY_FAILURE
>
> @@ -495,7 +495,7 @@ static inline void num_poisoned_pages_sub(long i)
>  	atomic_long_sub(i, &num_poisoned_pages);
>  }
>
> -#else
> +#else  /* CONFIG_MEMORY_FAILURE */
>
>  static inline swp_entry_t make_hwpoison_entry(struct page *page)
>  {
> @@ -514,7 +514,7 @@ static inline void num_poisoned_pages_inc(void)
>  static inline void num_poisoned_pages_sub(long i)
>  {
>  }
> -#endif
> +#endif  /* CONFIG_MEMORY_FAILURE */
>
>  static inline int non_swap_entry(swp_entry_t entry)
>  {