Re: [PATCH v4 4/9] cxl/region: Calculate peer distance only for reused targets

[Jonathan Cameron <jic23@kernel.org>]

On Sat, 17 Oct 2026 12:19:49 -0700
Alison Schofield <alison.schofield@intel.com> wrote:

> From: Richard Cheng <icheng@nvidia.com>
> 
> cxl_switch_port_setup_targets() calculates peer distance before
> searching the existing targets. When the endpoint needs a new target,
> the calculated distance is never used.
> 
> Move cxl_port_peer_distance() into the matching-target branch,
> immediately before check_last_peer(). This avoids unnecessary ancestor
> walks and per-port region lookups when adding distinct targets.
> 
> Signed-off-by: Richard Cheng <icheng@nvidia.com>
> Tested-by: Alison Schofield <alison.schofield@intel.com>
> Signed-off-by: Alison Schofield <alison.schofield@intel.com>

Reviewed-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
I'm assuming the commit message change Alison just posted or
something along those lines.

> ---
>  drivers/cxl/core/region.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 4ab5a1d025a9..8bfebe3e1025 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -1485,10 +1485,10 @@ static int cxl_switch_port_setup_targets(struct cxl_switch_decoder *cxlsd,
>  	}
>  
>  	if (cxl_rr->nr_targets_set) {
> -		int distance = cxl_port_peer_distance(port, cxlr);
> -
>  		for (int i = 0; i < cxl_rr->nr_targets_set; i++)
>  			if (ep->dport == cxlsd->target[i]) {
> +				int distance = cxl_port_peer_distance(port, cxlr);
> +
>  				rc = check_last_peer(cxled, ep, cxl_rr,
>  						     distance);
>  				if (rc)