RE: [PATCH v2] cxl/region: Add dev_dbg() detail on failure to allocate HPA space

[Dan Williams <dan.j.williams@intel.com>]

alison.schofield@ wrote:
> From: Alison Schofield <alison.schofield@intel.com>
> 
> When the region driver fails while allocating HPA space for a
> new region it can be because the parent resource, the CXL Window,
> has no more available space.
> 
> In that case, the debug user sees this message:
> cxl_core:alloc_hpa:555: cxl region2: failed to allocate HPA: -34
> 
> Expand the message like this:
> cxl_core:alloc_hpa:555: cxl region8: HPA allocation error:-34 for size:0x20000000 in CXL Window 0 [mem 0xf010000000-0xf04fffffff flags 0x200]
> 
> Now the debug user can examine /proc/iomem and consider actions
> like removing other allocations in that space or reducing the
> size of their region request.
> 
> Suggested-by: Dan Williams <dan.j.williams@intel.com>
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>
> Reviewed-by: Dave Jiang <dave.jiang@intel.com>
> Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
> ---
> 
> Changes in v2:
> - Improve the message text (Vishal)
> - Add reviewed by tags (DaveJ, Vishal)
> - Link to v1:
> https://lore.kernel.org/linux-cxl/20231114040147.1124696-1-alison.schofield@intel.com/
> 
> 
>  drivers/cxl/core/region.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 56e575c79bb4..ec792af873c4 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -552,8 +552,9 @@ static int alloc_hpa(struct cxl_region *cxlr, resource_size_t size)
>  	res = alloc_free_mem_region(cxlrd->res, size, SZ_256M,
>  				    dev_name(&cxlr->dev));
>  	if (IS_ERR(res)) {
> -		dev_dbg(&cxlr->dev, "failed to allocate HPA: %ld\n",
> -			PTR_ERR(res));
> +		dev_dbg(&cxlr->dev,
> +			"HPA allocation error:%ld for size:%#llx in %s %pr\n",
> +			PTR_ERR(res), size, cxlrd->res->name, cxlrd->res);

I notice that this did not pick up Vishal's suggested "error (%d) ..."
style for conveying the error code.

   "HPA allocation error (%d) for size: %llx in %s ..."

I prefer that style as well.