linux-kernel - Re: [RFC PATCH v3 06/16] cxl/mem: Find device capabilities

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Date:   Tue, 12 Jan 2021 19:17:44 +0000
From:   Jonathan Cameron <Jonathan.Cameron@...wei.com>
To:     Ben Widawsky <ben.widawsky@...el.com>
CC:     <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-pci@...r.kernel.org>,
        "linux-acpi@...r.kernel.org, Ira Weiny" <ira.weiny@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        "Vishal Verma" <vishal.l.verma@...el.com>,
        "Kelley, Sean V" <sean.v.kelley@...el.com>,
        Rafael Wysocki <rafael.j.wysocki@...el.com>,
        "Bjorn Helgaas" <helgaas@...nel.org>,
        Jon Masters <jcm@...masters.org>,
        Chris Browy <cbrowy@...ry-design.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        "Christoph Hellwig" <hch@...radead.org>,
        <daniel.lll@...baba-inc.com>
Subject: Re: [RFC PATCH v3 06/16] cxl/mem: Find device capabilities

On Mon, 11 Jan 2021 14:51:10 -0800
Ben Widawsky <ben.widawsky@...el.com> wrote:

> CXL devices contain an array of capabilities that describe the
> interactions software can have with the device or firmware running on
> the device. A CXL compliant device must implement the device status and
> the mailbox capability. A CXL compliant memory device must implement the
> memory device capability.
> 
> Each of the capabilities can [will] provide an offset within the MMIO
> region for interacting with the CXL device.
> 
> For more details see 8.2.8 of the CXL 2.0 specification.
> 
> Link: Link: https://www.computeexpresslink.org/download-the-specification
> Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>


...

>  /**
>   * cxl_mem_create() - Create a new &struct cxl_mem.
>   * @pdev: The pci device associated with the new &struct cxl_mem.
> @@ -129,8 +214,20 @@ static int cxl_mem_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	if (rc)
>  		return rc;
>  
> +	rc = cxl_mem_setup_regs(cxlm);
> +	if (rc)
> +		goto err;
> +
> +	rc = cxl_mem_setup_mailbox(cxlm);
> +	if (rc)
> +		goto err;
> +
>  	pci_set_drvdata(pdev, cxlm);
>  	return 0;
> +
> +err:
> +	kfree(cxlm);

>From previous patch that was created using devm_kzalloc in which case
this free just introduced a double free if you hit this error path.
Having go rid of that you can do direct returns instead of goto.


> +	return rc;
>  }
>  
>  static void cxl_mem_remove(struct pci_dev *pdev)