linux-kernel - Re: [RFC PATCH v2 3/3] mm: make generic pXd_addr

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Date:   Tue, 8 Sep 2020 07:19:38 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        John Hubbard <jhubbard@...dia.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-mm <linux-mm@...ck.org>, Paul Mackerras <paulus@...ba.org>,
        linux-sparc <sparclinux@...r.kernel.org>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        Will Deacon <will@...nel.org>,
        linux-arch <linux-arch@...r.kernel.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Richard Weinberger <richard@....at>,
        linux-x86 <x86@...nel.org>, Russell King <linux@...linux.org.uk>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Ingo Molnar <mingo@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Arnd Bergmann <arnd@...db.de>, Jeff Dike <jdike@...toit.com>,
        linux-um <linux-um@...ts.infradead.org>,
        Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-arm <linux-arm-kernel@...ts.infradead.org>,
        linux-power <linuxppc-dev@...ts.ozlabs.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Rapoport <rppt@...nel.org>
Subject: Re: [RFC PATCH v2 3/3] mm: make generic pXd_addr_end() macros inline
 functions



Le 07/09/2020 à 20:00, Gerald Schaefer a écrit :
> From: Alexander Gordeev <agordeev@...ux.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@...ux.ibm.com>
> Signed-off-by: Gerald Schaefer <gerald.schaefer@...ux.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
>   
>   /*
>