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

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Message-ID: <a890091b-b28b-4122-a7ae-bbb8d750cd7d@163.com>
Date: Sat, 19 Apr 2025 21:14:05 +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: [RESEND] PCI: cadence: Fix runtime atomic count underflow.



On 2025/4/19 18:05, Manivannan Sadhasivam wrote:
> On Sat, Mar 01, 2025 at 08:44:18PM +0800, Hans Zhang wrote:
>> From: "Hans Zhang" <18255117159@....com>
>>
>> If the pci_host_probe fails to be executed and run one time
>> pm_runtime_put_sync. Run pm_runtime_put_sync or pm_runtime_put again in
>> cdns_plat_pcie_probe or j721e_pcie_probe. Finally, it will print log
>> "runtime PM usage count underflow!".
>>
> 
> Please reword the description as:
> 
> "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 the
> runtime 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."
> 

Hi Mani,

Thank you very much for your reply and suggestions.

>> Signed-off-by: Hans Zhang <18255117159@....com>
> 
> Fixes tag?

Will add.

> 
>> ---
>>   drivers/pci/controller/cadence/pcie-cadence-host.c | 4 +---
>>   1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
>> index 8af95e9da7ce..fe0b8d76005e 100644
>> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
>> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
>> @@ -576,8 +576,6 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
>>   
>>   	return 0;
>>   
>> - err_init:
>> -	pm_runtime_put_sync(dev);
>> -
>> +err_init:
>>   	return ret;
> 
> You can now directly do 'return ret' instead of using label.

Will change.

Best regards,
Hans