Re: [ndctl PATCH 13/15] cxl/region: Default to memdev mode for create with no arguments

[Alison Schofield <alison.schofield@intel.com>]

On Sun, Nov 06, 2022 at 03:48:01PM -0800, Dan Williams wrote:
> Allow for:
> 
>    cxl create-region -d decoderX.Y
> 
> ...to assume (-m -w $(count of memdevs beneath decoderX.Y))

I'm not understanding what the change is here. Poked around a bit
and still didn't get it. Help!

Leaving out the -m leads to this:
$ cxl create-region -d decoder3.3 mem0 mem1
cxl region: parse_create_options: must specify option for target object types (-m)
cxl region: cmd_create_region: created 0 regions

Leaving out the the -m and the memdevs fails because the memdev order is
not correct. 
$ cxl create-region -d decoder3.3
cxl region: create_region: region5: failed to set target0 to mem1
cxl region: cmd_create_region: created 0 regions

This still works, where I give the -m and the correct order of memdevs.
cxl create-region -m -d decoder3.3 mem0 mem1

> 
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
>  cxl/region.c |   16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/cxl/region.c b/cxl/region.c
> index aa0735194fa1..c0cf4ab350da 100644
> --- a/cxl/region.c
> +++ b/cxl/region.c
> @@ -227,10 +227,13 @@ static int parse_create_options(struct cxl_ctx *ctx, int count,
>  	}
>  
>  	/*
> -	 * For all practical purposes, -m is the default target type, but
> -	 * hold off on actively making that decision until a second target
> -	 * option is available.
> +	 * For all practical purposes, -m is the default target type, but hold
> +	 * off on actively making that decision until a second target option is
> +	 * available. Unless there are no arguments then just assume memdevs.
>  	 */
> +	if (!count)
> +		param.memdevs = true;
> +
>  	if (!param.memdevs) {
>  		log_err(&rl,
>  			"must specify option for target object types (-m)\n");
> @@ -272,11 +275,8 @@ static int parse_create_options(struct cxl_ctx *ctx, int count,
>  		p->ways = count;
>  		if (!validate_ways(p, count))
>  			return -EINVAL;
> -	} else {
> -		log_err(&rl,
> -			"couldn't determine interleave ways from options or arguments\n");
> -		return -EINVAL;
> -	}
> +	} else
> +		p->ways = p->num_memdevs;
>  
>  	if (param.granularity < INT_MAX) {
>  		if (param.granularity <= 0) {
>