Re: [NDCTL PATCH 2/2] cxl: Add check for regions before disabling memdev

["Cao, Quanquan/曹 全全" <caoqq@fujitsu.com>]

> Add a check for memdev disable to see if there are active regions present
> before disabling the device. This is necessary now regions are present to
> fulfill the TODO that was left there. The best way to determine if a
> region is active is to see if there are decoders enabled for the mem
> device. This is also best effort as the state is only a snapshot the
> kernel provides and is not atomic WRT the memdev disable operation. The
> expectation is the admin issuing the command has full control of the mem
> device and there are no other agents also attempt to control the device.
> 
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
> ---
>   cxl/memdev.c |   14 ++++++++++++--
>   1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/cxl/memdev.c b/cxl/memdev.c
> index f6a2d3f1fdca..314bac082719 100644
> --- a/cxl/memdev.c
> +++ b/cxl/memdev.c
> @@ -373,11 +373,21 @@ static int action_free_dpa(struct cxl_memdev *memdev,
>   
>   static int action_disable(struct cxl_memdev *memdev, struct action_context *actx)
>   {
> +	struct cxl_endpoint *ep;
> +	struct cxl_port *port;
> +
>   	if (!cxl_memdev_is_enabled(memdev))
>   		return 0;
>   
> -	if (!param.force) {
> -		/* TODO: actually detect rather than assume active */
> +	ep = cxl_memdev_get_endpoint(memdev);
> +	if (!ep)
> +		return -ENODEV;
> +
> +	port = cxl_endpoint_get_port(ep);
> +	if (!port)
> +		return -ENODEV;
> +
> +	if (cxl_port_decoders_committed(port) && !param.force) {
>   		log_err(&ml, "%s is part of an active region\n",
>   			cxl_memdev_get_devname(memdev));
>   		return -EBUSY;
> 
> 
Hi Dave,

Based on my understanding of the logic in the "disable_region" and 
"destroy_region" code, in the code logic of 'disable-region -f,' after 
the check, it proceeds with the offline operation. In the code logic of 
'destroy-region -f,' after the check, it performs a disable operation on 
the region. For the 'disable-memdev -f' operation, after completing the 
check, is it also necessary to perform corresponding operations on the 
region(such as disabling region/destroying region) before disabling memdev?