linux-kernel - Re: [PATCH v3 3/4] x86, kdump: Change crashkernel

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Date:	Tue, 9 Apr 2013 09:45:44 -0400
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	"H. Peter Anvin" <hpa@...or.com>, WANG Chao <chaowang@...hat.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 3/4] x86, kdump: Change crashkernel_high/low= to
 crashkernel=;high/low

On Thu, Apr 04, 2013 at 03:17:01PM -0700, Yinghai Lu wrote:

[..]
> @@ -1360,37 +1369,80 @@ static int __init parse_crashkernel_simp
>  
>  	if (*cur == '@')
>  		*crash_base = memparse(cur+1, &cur);
> -	else if (*cur != ' ' && *cur != '\0') {
> -		pr_warning("crashkernel: unrecognized char\n");
> -		return -EINVAL;
> +	else {
> +		int i;
> +
> +		/* check with known suffix */
> +		for (i = 0; suffix_tbl[i]; i++)
> +			if (!strncmp(cur, suffix_tbl[i], strlen(suffix_tbl[i])))
> +				return 0;
> +

So crashkernel=X@Y;high is a valid syntax? Looks like we will reserve
X amount of RAM at base Y and ignore "high" or "low".

[..]
>  static int __init __parse_crashkernel(char *cmdline,
>  			     unsigned long long system_ram,
>  			     unsigned long long *crash_size,
>  			     unsigned long long *crash_base,
> -				const char *name)
> +			     const char *name,
> +			     const char *suffix,
> +			     bool simple_only)
>  {
> -	char 	*p = cmdline, *ck_cmdline = NULL;
>  	char	*first_colon, *first_space;
> +	char	*ck_cmdline;
>  
>  	BUG_ON(!crash_size || !crash_base);
>  	*crash_size = 0;
>  	*crash_base = 0;
>  
> -	/* find crashkernel and use the last one if there are more */
> -	p = strstr(p, name);
> -	while (p) {
> -		ck_cmdline = p;
> -		p = strstr(p+1, name);
> -	}
> +	ck_cmdline = get_last_crashkernel(cmdline, name, suffix);
>  
>  	if (!ck_cmdline)
>  		return -EINVAL;
> @@ -1403,23 +1455,30 @@ static int __init __parse_crashkernel(ch
>  	 */
>  	first_colon = strchr(ck_cmdline, ':');
>  	first_space = strchr(ck_cmdline, ' ');
> -	if (first_colon && (!first_space || first_colon < first_space))
> -		return parse_crashkernel_mem(ck_cmdline, system_ram,
> -				crash_size, crash_base);
> -	else
> +	if (first_colon && (!first_space || first_colon < first_space)) {
> +		if (simple_only)
> +			return -EINVAL;
> +		else
> +			return parse_crashkernel_mem(ck_cmdline, system_ram,
> +					crash_size, crash_base);
> +	} else
>  		return parse_crashkernel_simple(ck_cmdline, crash_size,
>  				crash_base);

Why don't we structure it little differently. Now we seem to have 3 
categories of crashkernel= parameters.

- crashkernel_simple (crashkernel=X or crashkernel=X@Y)
- crashkernel_mem (crashkernel=range:size,.....)
- crashkerenl_high_low_suffix (crashkernel=X;high or crashkernel=Y;low)

if (suffix) {
	parse_crashkernel_high_low_suffix()
} else {
	if (first_colon.....)
		parse_crashkernel_mem()
	else
		parse_crashkernel_simple();
}

And now you should not require "simple_only" function parameter and you
can also do strict syntax checking for each type of crashkernel=
parameter.

Thanks
Vivek
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