linux-kernel - Re: [PATCH v9 04/16] PCI/AER: Dequeue forwarded CXL error

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Message-ID: <c11c30ae-85d5-4f00-a243-a3b7710b913e@amd.com>
Date: Wed, 4 Jun 2025 09:38:58 -0500
From: "Bowman, Terry" <terry.bowman@....com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: PradeepVineshReddy.Kodamati@....com, 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, bhelgaas@...gle.com, bp@...en8.de,
 ming.li@...omail.com, shiju.jose@...wei.com,
 Smita.KoralahalliChannabasappa@....com, kobayashi.da-06@...itsu.com,
 yanfei.xu@...el.com, rrichter@....com, peterz@...radead.org, colyli@...e.de,
 uaisheng.ye@...el.com, fabio.m.de.francesco@...ux.intel.com,
 ilpo.jarvinen@...ux.intel.com, yazen.ghannam@....com,
 linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-pci@...r.kernel.org
Subject: Re: [PATCH v9 04/16] PCI/AER: Dequeue forwarded CXL error



On 6/4/2025 1:05 AM, Dan Carpenter wrote:
> On Tue, Jun 03, 2025 at 12:22:27PM -0500, Terry Bowman wrote:
>> +static struct pci_dev *sbdf_to_pci(struct cxl_prot_error_info *err_info)
>> +{
>> +	unsigned int devfn = PCI_DEVFN(err_info->device,
>> +				       err_info->function);
>> +	struct pci_dev *pdev __free(pci_dev_put) =
> What?  Why is it freeing the returned pointer?  That should happen in
> the caller, surely?
>
>> +		pci_get_domain_bus_and_slot(err_info->segment,
>> +					    err_info->bus,
>> +					    devfn);
>> +	return pdev;
>> +}
>> +
>> +static void cxl_handle_prot_error(struct cxl_prot_error_info *err_info)
>> +{
>> +	struct pci_dev *pdev __free(pci_dev_put) = pci_dev_get(sbdf_to_pci(err_info));
> Ok, it does happen in the caller, but dropping and then incrementing
> the reference count  like this is racy.
>
> regards,
> dan carpenter

Thanks dan. This was an oversight on my part. I'll change.

-Terry
>> +
>> +	if (!pdev) {
>> +		pr_err("Failed to find the CXL device\n");
>> +		return;
>> +	}
>> +
>> +	/*
>> +	 * Internal errors of an RCEC indicate an AER error in an
>> +	 * RCH's downstream port. Check and handle them in the CXL.mem
>> +	 * device driver.
>> +	 */
>> +	if (pci_pcie_type(pdev) == PCI_EXP_TYPE_RC_EC)
>> +		return pcie_walk_rcec(pdev, cxl_rch_handle_error_iter, err_info);
>> +
>> +	if (err_info->severity == AER_CORRECTABLE) {
>> +		int aer = pdev->aer_cap;
>> +		struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
>> +		struct device *dev __free(put_device) = get_device(&cxlds->cxlmd->dev);
>> +
>> +		if (aer)
>> +			pci_clear_and_set_config_dword(pdev,
>> +						       aer + PCI_ERR_COR_STATUS,
>> +						       0, PCI_ERR_COR_INTERNAL);
>> +
>> +		cxl_cor_error_detected(pdev);
>> +
>> +		pcie_clear_device_status(pdev);
>> +	} else {
>> +		cxl_do_recovery(pdev);
>> +	}
>> +}
>> +