Re: [PATCH v5 09/13] gpio: mxc: use cleanup guard for pm_runtime_get_noresume() balance

[Peng Fan]

On Fri, Oct 09, 2026 at 01:51:11PM -0500, Frank Li wrote:
>On Sat, Oct 10, 2026 at 02:05:30AM +0800, Peng Fan (OSS) wrote:
>> From: Peng Fan <peng.fan@xxxxxxx>
>>
>> pm_runtime_get_noresume() in probe must be balanced by
>> pm_runtime_put_noidle() on error paths, or pm_runtime_put_autosuspend()
>> on success. devm_pm_runtime_get_noresume() cannot be used here because
>> its devres action (pm_runtime_put_noidle()) would fire on unbind in
>> addition to the success-path pm_runtime_put_autosuspend(), causing a
>> usage counter underflow.
>>
>> Use a __free guard to automatically call pm_runtime_put_noidle() on
>> error paths, and disarm it with no_free_ptr() before the success-path
>> pm_runtime_put_autosuspend().
>>
>> Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
>> ---
>>  drivers/gpio/gpio-mxc.c | 8 +++++++-
>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpio/gpio-mxc.c b/drivers/gpio/gpio-mxc.c
>> index 5ae9cdee6424..3d5a6566d3f4 100644
>> --- a/drivers/gpio/gpio-mxc.c
>> +++ b/drivers/gpio/gpio-mxc.c
>> @@ -445,6 +445,8 @@ static void mxc_update_irq_chained_handler(struct mxc_gpio_port *port, bool enab
>>  	}
>>  }
>>
>> +DEFINE_FREE(pm_runtime_put_noidle, struct device *, if (_T) pm_runtime_put_noidle(_T))
>> +
>
>This change need put into common runtime_pm.h and like pm maintainer to
>review it. Other system may use it, like DMA engine, CSI, ...
>
>And if someone add to common file later, it will cause build error.

I agree it would be useful there, but that needs a separate patch with
linux-pm@ review. I would keep it local for this series to avoid the
cross-subsystem dependency, and it can be moved to pm_runtime.h as a
follow-up.

Thanks
Peng

>
>>  static int mxc_gpio_probe(struct platform_device *pdev)
>>  {
>>  	struct gpio_generic_chip_config config = { };
>> @@ -486,6 +488,9 @@ static int mxc_gpio_probe(struct platform_device *pdev)
>>  		return PTR_ERR(port->clk);
>>
>>  	pm_runtime_get_noresume(dev);
>> +
>> +	struct device *pm_guard __free(pm_runtime_put_noidle) = dev;
>> +
>>  	pm_runtime_set_active(dev);
>>  	pm_runtime_enable(dev);
>>
>> @@ -556,6 +561,8 @@ static int mxc_gpio_probe(struct platform_device *pdev)
>>  	mxc_update_irq_chained_handler(port, true);
>>
>>  	platform_set_drvdata(pdev, port);
>> +
>> +	pm_guard = no_free_ptr(pm_guard);
>
>use retain_and_null_ptr();
>
>Frank
>
>>  	pm_runtime_put_autosuspend(dev);
>>
>>  	return 0;
>> @@ -564,7 +571,6 @@ static int mxc_gpio_probe(struct platform_device *pdev)
>>  	irq_domain_remove(port->domain);
>>  out_bgio:
>>  	pm_runtime_disable(dev);
>> -	pm_runtime_put_noidle(dev);
>>  	dev_info(dev, "%s failed with errno %d\n", __func__, err);
>>  	return err;
>>  }
>>
>> --
>> 2.51.0
>>
>>
>