Re: [PATCH v2 5/7] hwmon: (pwm-fan) Remove redundant dev_err()

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Unbalanced regulator enable count during devres cleanup if fan-shutdown-percent is set.
--

--- Patch [5]: [PATCH v2 5/7] hwmon: (pwm-fan) Remove redundant dev_err() ---
commit 1f579d7c79ca89d1d4a39ad9aa36221339e0a01b
Author: Pan Chuang <panchuang@vivo.com>

hwmon: (pwm-fan) Remove redundant dev_err()

Since devm_request_irq() automatically logs error messages on failure,
this commit removes the redundant driver-specific dev_err() call in the
probe function.

> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 37f37813ea511..3b87f65bae058 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -628,12 +628,8 @@ static int pwm_fan_probe(struct platform_device *pdev)
>  		if (tach->irq > 0) {
>  			ret = devm_request_irq(dev, tach->irq, pulse_handler,
>  					       IRQF_NO_THREAD, pdev->name, tach);
> -			if (ret) {
> -				dev_err(dev,
> -					"Failed to request interrupt: %d\n",
> -					ret);
> +			if (ret)
>  				return ret;

[Severity: High]
This isn't a bug introduced by this patch, but does this error path trigger
an unbalanced regulator enable count if fan-shutdown-percent is set?

If devm_request_irq() fails here, devres teardown executes in reverse order.
First, pwm_fan_cleanup() runs and explicitly enables the regulator to shut
down the fan:

drivers/hwmon/pwm-fan.c:pwm_fan_cleanup() {
    ...
    if (ctx->pwm_shutdown) {
        ctx->enable_mode = pwm_enable_reg_enable;
        __set_pwm(ctx, ctx->pwm_shutdown);
    } else {
    ...
}

Later in the devres unwind, devm_regulator_release() calls regulator_put().
Because pwm_fan_cleanup() left the regulator enabled, does regulator_put()
detect a non-zero enable count and trigger a kernel warning stack trace while
leaking the reference?

>  		}
>  
>  		if (!ctx->pulses_per_revolution[i]) {

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260720063745.309331-1-panchuang@vivo.com?part=5