linux-kernel - Re: [PATCH v14 30/34] PCI/AER: Dequeue forwarded CXL error

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Message-ID: <20260115160107.000019d3@huawei.com>
Date: Thu, 15 Jan 2026 16:01:07 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Terry Bowman <terry.bowman@....com>
CC: <dave@...olabs.net>, <dave.jiang@...el.com>, <alison.schofield@...el.com>,
	<dan.j.williams@...el.com>, <bhelgaas@...gle.com>, <shiju.jose@...wei.com>,
	<ming.li@...omail.com>, <Smita.KoralahalliChannabasappa@....com>,
	<rrichter@....com>, <dan.carpenter@...aro.org>,
	<PradeepVineshReddy.Kodamati@....com>, <lukas@...ner.de>,
	<Benjamin.Cheatham@....com>, <sathyanarayanan.kuppuswamy@...ux.intel.com>,
	<linux-cxl@...r.kernel.org>, <vishal.l.verma@...el.com>, <alucerop@....com>,
	<ira.weiny@...el.com>, <linux-kernel@...r.kernel.org>,
	<linux-pci@...r.kernel.org>
Subject: Re: [PATCH v14 30/34] PCI/AER: Dequeue forwarded CXL error

On Wed, 14 Jan 2026 12:20:51 -0600
Terry Bowman <terry.bowman@....com> wrote:

> The AER driver now forwards CXL protocol errors to the CXL driver via a
> kfifo. The CXL driver must consume these work items and initiate protocol
> error handling while ensuring the device's RAS mappings remain valid
> throughout processing.
> 
> Implement cxl_proto_err_work_fn() to dequeue work items forwarded by the
> AER service driver. Lock the parent CXL Port device to ensure the CXL
> device's RAS registers are accessible during handling. Add pdev reference-put
> to match reference-get in AER driver. This will ensure pdev access after
> kfifo dequeue. These changes apply to CXL Ports and CXL Endpoints.
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>

Few things inline.
Thanks,

Jonathan

> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index bf82880e19b4..0c640b84ad70 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> @@ -117,17 +117,6 @@ static void cxl_cper_prot_err_work_fn(struct work_struct *work)

> +/*
> + * Return 'struct cxl_port *' parent CXL Port of dev
> + *
> + * Reference count increments returned port on success
> + *
> + * @pdev: Find the parent CXL Port of this device

This is a non standard type of a comment. I'd make it formal
kernel-doc.



> +
> +static void cxl_proto_err_work_fn(struct work_struct *work)
> +{
> +	struct cxl_proto_err_work_data wd;
> +
> +	while (cxl_proto_err_kfifo_get(&wd)) {

I'm probably being slow today but where does that helper come from?

> +		struct pci_dev *pdev __free(pci_dev_put) = wd.pdev;
> +
> +		if (!pdev) {
> +			pr_err_ratelimited("NULL PCI device passed in AER-CXL KFIFO\n");
> +			continue;
> +		}
> +
> +		struct cxl_port *port __free(put_cxl_port) = get_cxl_port(pdev);
> +		if (!port) {
> +			pr_err_ratelimited("Failed to find parent Port device in CXL topology.\n");
> +			continue;
> +		}
> +		guard(device)(&port->dev);
> +
> +		cxl_handle_proto_error(&wd);
> +	}
> +}