Re: [PATCH v5 13/16] cxl/pci: Add error handler for CXL PCIe Port RAS errors

Bowman, Terry
2025-02-07T21:04:28Z

On 2/7/2025 1:41 PM, Gregory Price wrote:
> On Fri, Feb 07, 2025 at 01:23:06PM -0600, Bowman, Terry wrote:
>>
>> On 2/7/2025 2:01 AM, Gregory Price wrote:
>>> On Tue, Jan 07, 2025 at 08:38:49AM -0600, Terry Bowman wrote:
>>>> +static void __iomem *cxl_pci_port_ras(struct pci_dev *pdev)
>>>> +{
>>>> + struct cxl_port *port;
>>>> +
>>>> + if (!pdev)
>>>> + return NULL;
>>>> +
>>>> + if ((pci_pcie_type(pdev) == PCI_EXP_TYPE_ROOT_PORT) ||
>>>> + (pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM)) {
>>>> + struct cxl_dport *dport;
>>>> + void __iomem *ras_base;
>>>> +
>>>> + port = find_cxl_port(&pdev->dev, &dport);
>>>> + ras_base = dport ? dport->regs.ras : NULL;
>>> I'm fairly certain dport can come back here uninitialized, you
>>> probably want to put this inside the `if (port)` block and
>>> pre-initialize dport to NULL.
>> Right, it can. NULL dport check here covers this, no?:
>>
>> ras_base = dport ? dport->regs.ras : NULL;
> dport can be garbage (whatever is on the stack) at this check because
> nothing ever intializes it to NULL.

Got it. Thanks.
>> Terry
>>
>>>> + if (port)
>>>> + put_device(&port->dev);
>>>> + return ras_base;
>>> You can probably even simplify this down to something like
>>>
>>> struct_cxl_dport *dport = NULL;
>>>
>>> port = find_cxl_port(&pdev->dev, &dport);
>>> if (port)
>>> put_device(&port->dev);
>>>
>>> return dport ? dport->regs.ras : NULL;
>>>
>>>
>>> ~Gregory