On 2020/7/1 18:15, Mika Westerberg wrote:
> On Wed, Jul 01, 2020 at 09:53:51AM +0800, Yicong Yang wrote:
>>> static inline struct pci_dev *pcie_find_root_port(struct pci_dev *dev)
>>> {
>>> - struct pci_dev *bridge = pci_upstream_bridge(dev);
>>> -
>>> - while (bridge) {
>>> - if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT)
>>> - return bridge;
>>> - bridge = pci_upstream_bridge(bridge);
>>> + while (dev) {
>>> + if (pci_is_pcie(dev) &&
>>> + pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
>>> + return dev;
>>> + dev = pci_upstream_bridge(dev);
>>> }
>>>
>> We may have some problems here, as after pcie_find_root_port() called, *dev will
>> be either root port or NULL but users may want it unchanged. One such usage is
>> in acpi_pci_bridge_d3(), drivers/pci/pci-acpi.c, *dev is used as origin
>> after called this.
>>
>> So we should use a temporary point to *dev rather than directly modify it.
> dev is already a copy of what is passed by the caller so it does not
> matter if it gets changed here. You would need to pass it through struct
> pci_dev **dev in order to modify the passed pointer.
Ah...I must be fuzzy in mind then. Thanks.
> .
>
