Re: [RFC PATCH v2 3/3] mm: make generic pXd_addr_end() macros inline functions

Mike Rapoport
2020-09-07T20:15:47Z

Hi,

Some style comments below.

On Mon, Sep 07, 2020 at 08:00:58PM +0200, Gerald Schaefer wrote:
> From: Alexander Gordeev <agordeev@linux.ibm.com>
>
> Since pXd_addr_end() macros take pXd page-table entry as a
> parameter it makes sense to check the entry type on compile.
> Even though most archs do not make use of page-table entries
> in pXd_addr_end() calls, checking the type in traversal code
> paths could help to avoid subtle bugs.
>
> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
> Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
> ---
> include/linux/pgtable.h | 36 ++++++++++++++++++++----------------
> 1 file changed, 20 insertions(+), 16 deletions(-)
>
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 67ebc22cf83d..d9e7d16c2263 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -656,31 +656,35 @@ static inline int arch_unmap_one(struct mm_struct *mm,
> */
>
> #ifndef pgd_addr_end
> -#define pgd_addr_end(pgd, addr, end) \
> -({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pgd_addr_end pgd_addr_end
> +static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PGDIR_SIZE) & PGDIR_MASK;

The code should be on a separate line from the curly brace.
Besides, since this is not a macro anymore, I think it would be nicer to
use 'boundary' without underscores.
This applies to the changes below as well.

> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> #ifndef p4d_addr_end
> -#define p4d_addr_end(p4d, addr, end) \
> -({ unsigned long __boundary = ((addr) + P4D_SIZE) & P4D_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define p4d_addr_end p4d_addr_end
> +static inline unsigned long p4d_addr_end(p4d_t p4d, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + P4D_SIZE) & P4D_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> #ifndef pud_addr_end
> -#define pud_addr_end(pud, addr, end) \
> -({ unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pud_addr_end pud_addr_end
> +static inline unsigned long pud_addr_end(pud_t pud, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PUD_SIZE) & PUD_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> #ifndef pmd_addr_end
> -#define pmd_addr_end(pmd, addr, end) \
> -({ unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK; \
> - (__boundary - 1 < (end) - 1)? __boundary: (end); \
> -})
> +#define pmd_addr_end pmd_addr_end
> +static inline unsigned long pmd_addr_end(pmd_t pmd, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PMD_SIZE) & PMD_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}
> #endif
>
> /*
> --
> 2.17.1
>

--
Sincerely yours,
Mike.