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

[Baoquan He]

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:

==================
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@xxxxxxxxxx>
> ---
>  kernel/crash_core.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> 
> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>
> ---
>  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
>