Re: [PATCH v3 2/2] cxl: Add decoders_committed sysfs attribute to cxl_port

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Mon, 16 Oct 2023 10:57:54 -0700
Dave Jiang <dave.jiang@intel.com> wrote:

> This attribute allows cxl-cli to determine whether there are decoders
> committed to a memdev.  This is only a snapshot of the state, and
> doesn't offer any protection or serialization against a concurrent
> disable-region operation.
> 
> Reviewed-by: Jim Harris <jim.harris@samsung.com>
> Suggested-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Seems reasonable, but it is adding ABI so the docs are missing.
Documentation/ABI/testing/sysfs-bus-cxl



> ---
> v2:
> - Use cxl_region_rwsem to protect reading of decoder info. (Dan)
> ---
>  drivers/cxl/core/port.c |   25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/cxl/core/port.c b/drivers/cxl/core/port.c
> index d0ed98a6bade..0adee1e406ec 100644
> --- a/drivers/cxl/core/port.c
> +++ b/drivers/cxl/core/port.c
> @@ -534,8 +534,33 @@ static void cxl_port_release(struct device *dev)
>  	kfree(port);
>  }
>  
> +static ssize_t decoders_committed_show(struct device *dev,
> +				       struct device_attribute *attr, char *buf)
> +{
> +	struct cxl_port *port = to_cxl_port(dev);
> +	int rc;
> +
> +	down_read(&cxl_region_rwsem);
> +	rc = sysfs_emit(buf, "%d\n", cxl_num_decoders_committed(port));
> +	up_read(&cxl_region_rwsem);
> +
> +	return rc;
> +}
> +
> +static DEVICE_ATTR_RO(decoders_committed);
> +
> +static struct attribute *cxl_port_attrs[] = {
> +	&dev_attr_decoders_committed.attr,
> +	NULL,
> +};
> +
> +static struct attribute_group cxl_port_attribute_group = {
> +	.attrs = cxl_port_attrs,
> +};
> +
>  static const struct attribute_group *cxl_port_attribute_groups[] = {
>  	&cxl_base_attribute_group,
> +	&cxl_port_attribute_group,
>  	NULL,
>  };
>  
> 
> 
>