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

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Message-ID: <YjB/QILintgvo1AL@MiWiFi-R3L-srv>
Date:   Tue, 15 Mar 2022 19:57:52 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Zhen Lei <thunder.leizhen@...wei.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 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.
> 
> 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;

Firstly, I am not sure if '-ENOENT' is a right value to return. From the
code comment of ENOENT, it's used for file or dir?
#define ENOENT           2      /* No such file or directory */

Secondly, we ever discussed the case including
 - no crashkernel=,low is provided;
 - messy code is provied, e.g crashkernel=aaaaaabbbb,low

The 2nd one is not handled in this patchset. How about taking the
handling into another round of patches. This patchset just adds
crashkernel=,high purely.

>  
>  	ck_cmdline += strlen(name);
>  
> -- 
> 2.25.1
>