Re: [PATCH v3] iio: light: isl29028: fix runtime PM reference leak on error paths

[Joshua Crofts <joshua.crofts1@gmail.com>]

On Thu, 10 Sep 2026 08:24:35 +0200
Fabio Cesari <fabio.cesari@gmail.com> wrote:

> isl29028_read_raw() and isl29028_write_raw() take a runtime PM reference
> with pm_runtime_resume_and_get() but return directly on their error
> paths without dropping it. The usage count never balances again and the
> device stops entering autosuspend for good. In isl29028_read_raw() this
> needs a regmap access to fail; in isl29028_write_raw() one rejected
> sysfs write is enough, for example
> 
>   echo 200 > in_proximity_sampling_frequency
> 
> which is outside the [1:100] range and returns -EINVAL with the
> reference still held.
> 
> Take the reference with PM_RUNTIME_ACQUIRE_AUTOSUSPEND() instead, so it
> is released on every return path.
> 
> This also stops the return value of pm_runtime_put_autosuspend() from
> reaching userspace. That value only says whether the device could be
> suspended right away, so -EAGAIN or -EPERM turns a successful access
> into a failure, and with CONFIG_PM=n the stub returns -ENOSYS on every
> access.
> 
> PM_RUNTIME_ACQUIRE_AUTOSUSPEND() exists since v6.19. Older trees need
> the manual form instead: keep pm_runtime_resume_and_get() and drop the
> reference on all paths with an unchecked pm_runtime_put_autosuspend().
> 
> Fixes: 2db5054ac28d ("staging: iio: isl29028: add runtime power management support")
> Suggested-by: Joshua Crofts <joshua.crofts1@gmail.com>
> Cc: <stable@vger.kernel.org> # see patch description, needs adjustments for < 6.19
> Assisted-by: LLM coccinelle
> Signed-off-by: Fabio Cesari <fabio.cesari@gmail.com>
> ---

LGTM now.

Reviewed-by: Joshua Crofts <joshua.crofts1@gmail.com>

-- 
Kind regards,
Joshua Crofts