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

Christophe Leroy
2020-09-08T05:19:50Z

Le 07/09/2020 à 20:00, Gerald Schaefer a écrit :
> 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

I think that #define is pointless, usually there is no such #define for
the default case.

> +static inline unsigned long pgd_addr_end(pgd_t pgd, unsigned long addr, unsigned long end)
> +{ unsigned long __boundary = (addr + PGDIR_SIZE) & PGDIR_MASK;
> + return (__boundary - 1 < end - 1) ? __boundary : end;
> +}

Please use the standard layout, ie entry { and exit } alone on their
line, and space between local vars declaration and the rest.

Also remove the leading __ in front of var names as it's not needed once
it is not macros anymore.

f_name()
{
some_local_var;

do_something();
}

> #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
>
> /*
>