Re: [PATCH] PCI: Stop waiting for link status after config read failure

["Yury M." <yurypm@arista.com>]

what to you think about this check:
if ((pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta) ||  
PCI_POSSIBLE_ERROR(lnksta)) && pci_dev_is_disconnected(pdev))
     return -ENODEV;

On 9/4/26 13:20, Lukas Wunner wrote:
> On Fri, Sep 04, 2026 at 11:13:18AM +0000, Yury Murashka wrote:
>> With a nested PCIe topology with multiple layers of hotplug, a link can go
>> down near the bottom of the topology shortly before a link above it goes
>> down. In that case, pcie_wait_for_link_status() can wait for the full
>> timeout while every read of the link status register fails because the
>> device has disappeared.
>>
>> Return immediately when reading the link status fails so event processing
>> can continue.
> [...]
>> +++ b/drivers/pci/pci.c
>> @@ -4580,7 +4581,8 @@ static int pcie_wait_for_link_status(struct pci_dev *pdev,
>>   
>>   	end_jiffies = jiffies + msecs_to_jiffies(PCIE_LINK_RETRAIN_TIMEOUT_MS);
>>   	do {
>> -		pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta);
>> +		if (pcie_capability_read_word(pdev, PCI_EXP_LNKSTA, &lnksta))
>> +			return -ENODEV;
>>   		if ((lnksta & lnksta_mask) == lnksta_match)
>>   			return 0;
>>   		msleep(1);
> It might be clearer if you check for pci_dev_is_disconnected() directly
> instead of relying on a PCIBIOS_DEVICE_NOT_FOUND return value which is
> generated as a side effect of the device being gone.
>
> Thanks,
>
> Lukas