linux-kernel - Re: [PATCH v21 1/5] kdump: return -ENOENT if required cmdline option does not exist

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Message-ID: <06dce01e-3587-11c8-3bc1-fa8cf7359176@huawei.com>
Date:   Wed, 16 Mar 2022 14:15:03 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Baoquan He <bhe@...hat.com>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        <x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>,
        <linux-kernel@...r.kernel.org>, Dave Young <dyoung@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        <kexec@...ts.infradead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        Frank Rowand <frowand.list@...il.com>,
        <devicetree@...r.kernel.org>, "Jonathan Corbet" <corbet@....net>,
        <linux-doc@...r.kernel.org>, Randy Dunlap <rdunlap@...radead.org>,
        Feng Zhou <zhoufeng.zf@...edance.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Chen Zhou <dingguo.cz@...group.com>,
        "John Donnelly" <John.p.donnelly@...cle.com>,
        Dave Kleikamp <dave.kleikamp@...cle.com>
Subject: Re: [PATCH v21 1/5] kdump: return -ENOENT if required cmdline option
 does not exist



On 2022/3/16 13:39, Baoquan He wrote:
> On 02/27/22 at 11:07am, Zhen Lei wrote:
>> The crashkernel=Y,low is an optional command-line option. When it doesn't
>> exist, kernel will try to allocate minimum required memory below 4G
>> automatically. Give it a unique error code to distinguish it from other
>> error scenarios.
> 
> This log is a little confusing. __parse_crashkernel() has three callers. 
>  - parse_crashkernel()
>  - parse_crashkernel_high()
>  - parse_crashkernel_low()
> 
> How about tuning the git log as below:

Sure. Your description is much clearer than mine.

> 
> ==================
> According to the current crashkernel=Y,low support in other ARCHes, it's
> an optional command-line option. When it doesn't exist, kernel will try
> to allocate minimum required memory below 4G automatically. 
> 
> However, __parse_crashkernel() returns '-EINVAL' for all error cases. It
> can't distinguish the nonexistent option from invalid option. 
> 
> Change __parse_crashkernel() to return '-ENOENT' for the nonexistent option
> case. With this change, crashkernel,low memory will take the default
> value if crashkernel=,low is not specified; while crashkernel reservation
> will fail and bail out if an invalid option is specified.
> ==================
> 
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
>> ---
>>  kernel/crash_core.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>>
>> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
>> ---
>>  kernel/crash_core.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
>> index 256cf6db573cd09..4d57c03714f4e13 100644
>> --- a/kernel/crash_core.c
>> +++ b/kernel/crash_core.c
>> @@ -243,9 +243,8 @@ static int __init __parse_crashkernel(char *cmdline,
>>  	*crash_base = 0;
>>  
>>  	ck_cmdline = get_last_crashkernel(cmdline, name, suffix);
>> -
>>  	if (!ck_cmdline)
>> -		return -EINVAL;
>> +		return -ENOENT;
>>  
>>  	ck_cmdline += strlen(name);
>>  
>> -- 
>> 2.25.1
>>
> 
> .
> 

-- 
Regards,
  Zhen Lei