linux-kernel - Re: [PATCH] cxl/region: Clarify pointers in unregister

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Date:   Wed, 30 Aug 2023 10:36:58 -0700
From:   Dave Jiang <dave.jiang@...el.com>
To:     Ira Weiny <ira.weiny@...el.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Jonathan Cameron <jonathan.cameron@...wei.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        "Dan Williams" <dan.j.williams@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Ben Widawsky <bwidawsk@...nel.org>
Subject: Re: [PATCH] cxl/region: Clarify pointers in unregister_region()



On 8/29/23 14:47, Ira Weiny wrote:
> devm_add_action_or_reset() passes a void * data parameter to the
> callback.  In the case of CXL regions, unregister_region() is passed a
> struct cxl_region *.
> 
> unregister_region() incorrectly interprets this as a struct device
> pointer.  Fortunately the device structure was the first member of
> cxl_region.  Therefore the code still works.  However, should struct
> cxl_region change the bug could be subtle.
> 
> Use the proper types in unregister_region() and extract the device
> pointer correctly.
> 
> Fixes: 779dd20cfb56 ("cxl/region: Add region creation support")
> Cc: Ben Widawsky <bwidawsk@...nel.org>
> Signed-off-by: Ira Weiny <ira.weiny@...el.com>

Great catch!
Reviewed-by: Dave Jiang <dave.jiang@...el.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 e115ba382e04..471d305ef675 100644
> --- a/drivers/cxl/core/region.c
> +++ b/drivers/cxl/core/region.c
> @@ -2018,10 +2018,11 @@ static struct cxl_region *to_cxl_region(struct device *dev)
>   	return container_of(dev, struct cxl_region, dev);
>   }
>   
> -static void unregister_region(void *dev)
> +static void unregister_region(void *_cxlr)
>   {
> -	struct cxl_region *cxlr = to_cxl_region(dev);
> +	struct cxl_region *cxlr = _cxlr;
>   	struct cxl_region_params *p = &cxlr->params;
> +	struct device *dev = &cxlr->dev;
>   	int i;
>   
>   	device_del(dev);
> 
> ---
> base-commit: 1c59d383390f970b891b503b7f79b63a02db2ec5
> change-id: 20230829-cxl-clarify-ptrs-f38255b7e52b
> 
> Best regards,