linux-kernel - Re: [PATCH v2 11/19] mm/mmap: Make vm_special

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Message-ID: <a5a9a165-11ea-29d0-46e7-cd6ea0028fec@csgroup.eu>
Date:   Tue, 24 Nov 2020 07:25:22 +0100
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Dmitry Safonov <dima@...sta.com>, linux-kernel@...r.kernel.org
Cc:     Dmitry Safonov <0x7f454c46@...il.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, Borislav Petkov <bp@...en8.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Guo Ren <guoren@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Ingo Molnar <mingo@...hat.com>,
        Oleg Nesterov <oleg@...hat.com>,
        Russell King <linux@...linux.org.uk>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Will Deacon <will@...nel.org>, x86@...nel.org
Subject: Re: [PATCH v2 11/19] mm/mmap: Make vm_special_mapping::mremap return
 void



Le 24/11/2020 à 01:29, Dmitry Safonov a écrit :
> Previously .mremap() callback needed (int) return to provide way to
> restrict resizing of a special mapping. Now it's restricted by
> providing .may_split = special_mapping_split.
> 
> Removing (int) return simplifies further changes to
> special_mapping_mremap() as it won't need save ret code from the
> callback. Also, it removes needless `return 0` from callbacks.
> 
> Signed-off-by: Dmitry Safonov <dima@...sta.com>
> ---
>   arch/arm/kernel/process.c | 3 +--
>   arch/arm64/kernel/vdso.c  | 4 +---
>   arch/mips/vdso/genvdso.c  | 3 +--
>   arch/x86/entry/vdso/vma.c | 4 +---
>   include/linux/mm_types.h  | 2 +-
>   mm/mmap.c                 | 2 +-
>   6 files changed, 6 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 65df8abd90bd..95a257927dae 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -780,7 +780,7 @@ struct vm_special_mapping {
>   				struct vm_area_struct *vma,
>   				struct vm_fault *vmf);
>   
> -	int (*mremap)(const struct vm_special_mapping *sm,
> +	void (*mremap)(const struct vm_special_mapping *sm,
>   		     struct vm_area_struct *new_vma);

Second line should be aligned to first line's parenthesis I think.

>   };
>   
> diff --git a/mm/mmap.c b/mm/mmap.c
> index d0d458632c1b..17fe59a9780b 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -3433,7 +3433,7 @@ static int special_mapping_mremap(struct vm_area_struct *new_vma,
>   		return -EFAULT;
>   
>   	if (sm->mremap)
> -		return sm->mremap(sm, new_vma);
> +		sm->mremap(sm, new_vma);
>   
>   	return 0;
>   }
>