Re: [RFC PATCH 1/4] cxl/mem: Add support to cleanly continue after attach

[Cheatham, Benjamin]

On 4/3/2026 4:00 PM, Dan Williams wrote:
> For drivers that want to fallback to PCI-only operation, immediately
> cleanup on attach failure. Otherwise vestigial topology objects are left
> until driver unload.
> 

The usage of "attach" here is somewhat ambiguous. Does this mean the attach callback,
or cxl_mem attach? Also, I know that providing the attach callback is probably what
indicates a driver wants to fallback to PCIe operation, but it's not evident based on
the description or contents of the patch.

> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
> ---
>  drivers/cxl/mem.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index ff858318091f..5e7fa378dd66 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -201,7 +201,19 @@ static int cxl_mem_probe(struct device *dev)
>  struct cxl_memdev *devm_cxl_add_memdev(struct cxl_dev_state *cxlds,
>  				       const struct cxl_memdev_attach *attach)
>  {
> -	return __devm_cxl_add_memdev(cxlds, attach);
> +	struct cxl_memdev *cxlmd;
> +	void *group;
> +
> +	group = devres_open_group(cxlds->dev, NULL, GFP_KERNEL);
> +	if (!group)
> +		return ERR_PTR(-ENOMEM);
> +
> +	cxlmd = __devm_cxl_add_memdev(cxlds, attach);
> +	if (IS_ERR(cxlmd))
> +		devres_release_group(cxlds->dev, group);
> +	else
> +		devres_remove_group(cxlds->dev, group);
> +	return cxlmd;
>  }
>  EXPORT_SYMBOL_NS_GPL(devm_cxl_add_memdev, "CXL");
>  

I'm having trouble figuring out how exactly this is supposed to work. I guess I have two questions:
1) What is this devres group doing? There aren't any actions added to it (afaik), so it seems to do nothing? Maybe there's some magic
going on here I don't know about?

2) Isn't the memdev already cleaned up if cxl_mem probe fails and attach is provided? What's the extra cleanup happening here?