linux-kernel - Re: [PATCH v3 6/8] cxl/region: Move ready-to-probe state check to a helper

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Message-ID: <20250715163340.00002ddc@huawei.com>
Date: Tue, 15 Jul 2025 16:33:40 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Dan Williams <dan.j.williams@...el.com>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Davidlohr
 Bueso <dave@...olabs.net>, Dave Jiang <dave.jiang@...el.com>, Alison
 Schofield <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, "Ira Weiny" <ira.weiny@...el.com>, "Peter
 Zijlstra (Intel)" <peterz@...radead.org>
Subject: Re: [PATCH v3 6/8] cxl/region: Move ready-to-probe state check to a
 helper

On Fri, 11 Jul 2025 16:49:30 -0700
Dan Williams <dan.j.williams@...el.com> wrote:

> Rather than unlocking the region rwsem in the middle of cxl_region_probe()
> create a helper for determining when the region is ready-to-probe.
I'd maybe mention the odd bit of 
if (rc)
	return rc;

return 0;

Will go away shortly. Or maybe that is overkill for a commit message.

Anyhow, with that in mind LGTM
Reviewed-by: Jonathan Cameron <jonathan.cameron@...wei.com>


> 
> Cc: Davidlohr Bueso <dave@...olabs.net>
> Cc: Jonathan Cameron <jonathan.cameron@...wei.com>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Alison Schofield <alison.schofield@...el.com>
> Cc: Vishal Verma <vishal.l.verma@...el.com>
> Cc: Ira Weiny <ira.weiny@...el.com>
> Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>  drivers/cxl/core/region.c | 24 ++++++++++++++++++------
>  1 file changed, 18 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
> index 3a77aec2c447..2a97fa9a394f 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -3572,9 +3572,8 @@ static void shutdown_notifiers(void *_cxlr)
>  	unregister_mt_adistance_algorithm(&cxlr->adist_notifier);
>  }
>  
> -static int cxl_region_probe(struct device *dev)
> +static int cxl_region_can_probe(struct cxl_region *cxlr)
>  {
> -	struct cxl_region *cxlr = to_cxl_region(dev);
>  	struct cxl_region_params *p = &cxlr->params;
>  	int rc;
>  
> @@ -3597,15 +3596,28 @@ static int cxl_region_probe(struct device *dev)
>  		goto out;
>  	}
>  
> -	/*
> -	 * From this point on any path that changes the region's state away from
> -	 * CXL_CONFIG_COMMIT is also responsible for releasing the driver.
> -	 */
>  out:
>  	up_read(&cxl_region_rwsem);
>  
>  	if (rc)
>  		return rc;
> +	return 0;

This is an odd bit of code now.  Why not just

	return rc;

Ah. Patch 8 drops the if (rc) return rc bit.



> +}
> +
> +static int cxl_region_probe(struct device *dev)
> +{
> +	struct cxl_region *cxlr = to_cxl_region(dev);
> +	struct cxl_region_params *p = &cxlr->params;
> +	int rc;
> +
> +	rc = cxl_region_can_probe(cxlr);
> +	if (rc)
> +		return rc;
> +
> +	/*
> +	 * From this point on any path that changes the region's state away from
> +	 * CXL_CONFIG_COMMIT is also responsible for releasing the driver.
> +	 */
>  
>  	cxlr->memory_notifier.notifier_call = cxl_region_perf_attrs_callback;
>  	cxlr->memory_notifier.priority = CXL_CALLBACK_PRI;