linux-kernel - Re: [PATCH v2] PCI: cadence: Fix runtime atomic count underflow.

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Message-ID: <348fd943-3ada-4688-bafc-3b6095e86b61@163.com>
Date: Sun, 20 Apr 2025 09:24:35 +0800
From: Hans Zhang <18255117159@....com>
To: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: lpieralisi@...nel.org, kw@...ux.com, robh@...nel.org,
 bhelgaas@...gle.com, s-vadapalli@...com, thomas.richard@...tlin.com,
 linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org, rockswang7@...il.com
Subject: Re: [PATCH v2] PCI: cadence: Fix runtime atomic count underflow.



On 2025/4/20 00:51, Manivannan Sadhasivam wrote:
> On Sat, Apr 19, 2025 at 09:30:58PM +0800, Hans Zhang wrote:
>> If the call to pci_host_probe() in cdns_pcie_host_setup()
>> fails, PM runtime count is decremented in the error path using
>> pm_runtime_put_sync().But the runtime count is not incremented by this
>> driver, but only by the callers (cdns_plat_pcie_probe/j721e_pcie_probe).
>> And the callers also decrement theruntime PM count in their error path.
>> So this leads to the below warning from the PM core:
>>
>> runtime PM usage count underflow!
>>
>> So fix it by getting rid of pm_runtime_put_sync() in the error path and
>> directly return the errno.
>>
>> Fixes: 1b79c5284439 ("PCI: cadence: Add host driver for Cadence PCIe controller")
>>
> 
> This is not the correct Fixes commit. In fact it took me a while to find the
> correct one. This exact same issue was already fixed by commit, 19abcd790b51
> ("PCI: cadence: Fix cdns_pcie_{host|ep}_setup() error path").
> 
> But then, this bug got reintroduced while fixing the merge conflict in:
> 49e427e6bdd1 ("Merge branch 'pci/host-probe-refactor'")
> 
> I will change the tag while applying.
> 

Hi Mani,

Thank you very much.

Best regards,
Hans

> - Mani
> 
>> Signed-off-by: Hans Zhang <18255117159@....com>
>> ---
>>   drivers/pci/controller/cadence/pcie-cadence-host.c | 11 +----------
>>   1 file changed, 1 insertion(+), 10 deletions(-)
>>
>> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
>> index 8af95e9da7ce..741e10a575ec 100644
>> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
>> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
>> @@ -570,14 +570,5 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
>>   	if (!bridge->ops)
>>   		bridge->ops = &cdns_pcie_host_ops;
>>   
>> -	ret = pci_host_probe(bridge);
>> -	if (ret < 0)
>> -		goto err_init;
>> -
>> -	return 0;
>> -
>> - err_init:
>> -	pm_runtime_put_sync(dev);
>> -
>> -	return ret;
>> +	return pci_host_probe(bridge);
>>   }
>>
>> base-commit: a24588245776dafc227243a01bfbeb8a59bafba9
>> -- 
>> 2.25.1
>>
>