linux-kernel - Re: [PATCH] x86/mce: remove unused mce

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Date:   Sat, 3 Jun 2023 11:17:08 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     Alison Schofield <alison.schofield@...el.com>
CC:     <tony.luck@...el.com>, <bp@...en8.de>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <dave.hansen@...ux.intel.com>, <hpa@...or.com>,
        <x86@...nel.org>, <linux-edac@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/mce: remove unused mce_vaddr

On 2023/5/31 3:16, Alison Schofield wrote:
> On Sun, May 28, 2023 at 07:35:45PM +0800, Miaohe Lin wrote:
>> Since commit a6e3cf70b772 ("x86/mce: Change to not send SIGBUS error during
>> copy from user"), mce_vaddr is not used anymore. Remove it and clean up the
>> relevant code.
> 
> Hi Miaohe,
> 
> Not so sure that the 'clean up' part is useful. See below.
> 
> 
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
>> ---
>>  arch/x86/kernel/cpu/mce/severity.c | 7 +------
>>  include/linux/sched.h              | 1 -
>>  2 files changed, 1 insertion(+), 7 deletions(-)
>>
>> diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
>> index c4477162c07d..0acc0039de81 100644
>> --- a/arch/x86/kernel/cpu/mce/severity.c
>> +++ b/arch/x86/kernel/cpu/mce/severity.c
>> @@ -252,12 +252,7 @@ static bool is_copy_from_user(struct pt_regs *regs)
>>  		return false;
>>  	}
>>  
>> -	if (fault_in_kernel_space(addr))
>> -		return false;
>> -
>> -	current->mce_vaddr = (void __user *)addr;
>> -
>> -	return true;
>> +	return !fault_in_kernel_space(addr);
>>  }
> 
> 
> Refactoring the return is unnecessary and seems less readable.
> How about removing the assignment, and leaving the rest, as is:
> 
> diff --git a/arch/x86/kernel/cpu/mce/severity.c b/arch/x86/kernel/cpu/mce/severity.c
> index c4477162c07d..1c03221ddcb1 100644
> --- a/arch/x86/kernel/cpu/mce/severity.c
> +++ b/arch/x86/kernel/cpu/mce/severity.c
> @@ -255,8 +255,6 @@ static bool is_copy_from_user(struct pt_regs *regs)
>         if (fault_in_kernel_space(addr))
>                 return false;
>  
> -       current->mce_vaddr = (void __user *)addr;
> -
>         return true;
>  }
> 

Sounds good to me. Will do it in v2. Thanks for your advice.