linux-kernel - Re: [PATCH v2 1/1] cxl/pmem: debug invalid serial number data

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Message-ID: <20250214133109.00006249@huawei.com>
Date: Fri, 14 Feb 2025 13:31:09 +0000
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: Yuquan Wang <wangyuquan1236@...tium.com.cn>
CC: <dave@...olabs.net>, <dave.jiang@...el.com>, <alison.schofield@...el.com>,
	<vishal.l.verma@...el.com>, <ira.weiny@...el.com>,
	<dan.j.williams@...el.com>, <linux-cxl@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <chenbaozi@...tium.com.cn>
Subject: Re: [PATCH v2 1/1] cxl/pmem: debug invalid serial number data

On Fri, 14 Feb 2025 11:09:52 +0800
Yuquan Wang <wangyuquan1236@...tium.com.cn> wrote:

> In a nvdimm interleave-set each device with an invalid or zero
> serial number may cause pmem region initialization to fail, but in
> cxl case such device could still set cookies of nd_interleave_set
> and create a nvdimm pmem region.
> 
> This adds the validation of serial number in cxl pmem region creation.
> The event of no serial number would cause to fail to set the cookie
> and pmem region.
> 
> For cxl-test to work properly, always +1 on mock device's serial
> number.
> 
> Signed-off-by: Yuquan Wang <wangyuquan1236@...tium.com.cn>
A minor comment inline.  Thanks for sorting this out.

Jonathan

> ---
>  drivers/cxl/pmem.c           | 7 +++++++
>  tools/testing/cxl/test/mem.c | 2 +-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
> index f9c95996e937..cc854169e50b 100644
> --- a/drivers/cxl/pmem.c
> +++ b/drivers/cxl/pmem.c
> @@ -384,6 +384,13 @@ static int cxl_pmem_region_probe(struct device *dev)
>  		};
>  		info[i].offset = m->start;
>  		info[i].serial = cxlds->serial;
> +
Even though it's error path, it seems odd to check the serial
number is valid just after 'using' it.

I would do
		info[i].offset = m->start;

		if (cxlds->serial == 0) {
			//include missing alongside invalid in this error message.
			dev_err(dev, "%s: invalid or missing serial number\n",
				dev_name(&cxlmd->dev));
			rc = -NEXIO;
			goto out_nvd;
		}
		info[i].serial = cxlds->serial;

> +		if (info[i].serial == 0) {
> +			dev_err(dev, "%s: invalid serial number\n",
> +				dev_name(&cxlmd->dev));
> +			rc = -ENXIO;
> +			goto out_nvd;
> +		}
>  	}
>  	ndr_desc.num_mappings = cxlr_pmem->nr_mappings;
>  	ndr_desc.mapping = mappings;
> diff --git a/tools/testing/cxl/test/mem.c b/tools/testing/cxl/test/mem.c
> index 8d731bd63988..9e098cf06603 100644
> --- a/tools/testing/cxl/test/mem.c
> +++ b/tools/testing/cxl/test/mem.c
> @@ -1533,7 +1533,7 @@ static int cxl_mock_mem_probe(struct platform_device *pdev)
>  	mds->event.buf = (struct cxl_get_event_payload *) mdata->event_buf;
>  	INIT_DELAYED_WORK(&mds->security.poll_dwork, cxl_mockmem_sanitize_work);
>  
> -	cxlds->serial = pdev->id;
> +	cxlds->serial = pdev->id + 1;
>  	if (is_rcd(pdev))
>  		cxlds->rcd = true;
>