Re: [PATCH v3 15/18] cxl/region: Add a dev_warn() on registration failure

[Jonathan Cameron]

On Tue, 11 Feb 2025 10:53:45 +0100
Robert Richter <rrichter@xxxxxxx> wrote:

> Esp. in complex system configurations with multiple endpoints and
> interleaving setups it is hard to detect region setup failures as its
> registration may silently fail. Add messages to show registration
> failures.
> 
> Example log message:
> 
>   cxl region5: region sort successful
>   cxl region5: mem0:endpoint5 decoder5.0 add: mem0:decoder5.0 @ 0 next: none nr_eps: 1 nr_targets: 1
>   cxl_port endpoint5: decoder5.0: range: 0x22350000000-0x2634fffffff iw: 1 ig: 256
>   cxl region5: pci0000:e0:port1 decoder1.2 add: mem0:decoder5.0 @ 0 next: mem0 nr_eps: 1 nr_targets: 1
>   cxl region5: pci0000:e0:port1 iw: 1 ig: 256
>   cxl region5: pci0000:e0:port1: decoder1.2 expected 0000:e0:01.2 at 0
>   cxl endpoint5: failed to attach decoder5.0 to region5: -6
>   cxl_port endpoint5: probe: 0
> 
> Signed-off-by: Robert Richter <rrichter@xxxxxxx>
> Reviewed-by: Gregory Price <gourry@xxxxxxxxxx>
> Tested-by: Gregory Price <gourry@xxxxxxxxxx>
I'm in general fine with this, but we have previously been reluctant in
some cases to go above dev_dbg.  Hence would like input from more
people on this one.

From me though
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

> ---
>  drivers/cxl/core/region.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index ebcfbfe9eafc..3031d4773274 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -2147,6 +2147,12 @@ static int attach_target(struct cxl_region *cxlr,
>  	rc = cxl_region_attach(cxlr, cxled, pos);
>  	up_read(&cxl_dpa_rwsem);
>  	up_write(&cxl_region_rwsem);
> +
> +	if (rc)
> +		dev_warn(cxled->cxld.dev.parent,
> +			"failed to attach %s to %s: %d\n",
> +			dev_name(&cxled->cxld.dev), dev_name(&cxlr->dev), rc);
> +
>  	return rc;
>  }
>