linux-kernel - Re: [PATCH v3 1/1] cxl/pmem: debug invalid serial number data

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Message-ID: <Z7P4A+3hfRdNnMM3@phytium.com.cn>
Date: Tue, 18 Feb 2025 11:01:23 +0800
From: Yuquan Wang <wangyuquan1236@...tium.com.cn>
To: Fan Ni <nifan.cxl@...il.com>
Cc: dave@...olabs.net, jonathan.cameron@...wei.com, 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 v3 1/1] cxl/pmem: debug invalid serial number data

On Mon, Feb 17, 2025 at 06:20:18PM -0800, Fan Ni wrote:
> On Tue, Feb 18, 2025 at 09:47:46AM +0800, Yuquan Wang 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>
> > ---
> >  drivers/cxl/pmem.c           | 8 ++++++++
> >  tools/testing/cxl/test/mem.c | 2 +-
> >  2 files changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/cxl/pmem.c b/drivers/cxl/pmem.c
> > index f9c95996e937..73787afe1b9d 100644
> > --- a/drivers/cxl/pmem.c
> > +++ b/drivers/cxl/pmem.c
> > @@ -383,6 +383,14 @@ static int cxl_pmem_region_probe(struct device *dev)
> >  			.position = i,
> >  		};
> >  		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 = -ENXIO;
> > +			goto out_nvd;
> > +		}
> 
> Should we do the check earlier in the code? 
> For example, right below if (!nvdimm) {}
> 
> Fan

I agree. This would removes unnecessary struct value assignments
and make the code easier to read. Jonathan, what's your opinion?

Yuquan

> 
> >  		info[i].serial = cxlds->serial;
> >  	}
> >  	ndr_desc.num_mappings = cxlr_pmem->nr_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;
> >  
> > -- 
> > 2.34.1
> >