Re: [PATCH v4 4/6] drivers: leds: Add the iEi WT61P803 PUZZLE LED driver

[Luka Kovacic]

On Wed, Oct 7, 2020 at 1:27 PM Pavel Machek <pavel@xxxxxx> wrote:
>
> Hi!
>
> > Add support for the iEi WT61P803 PUZZLE LED driver.
> > Currently only the front panel power LED is supported.
> >
> > This driver depends on the iEi WT61P803 PUZZLE MFD driver.
>
> > +static int iei_wt61p803_puzzle_led_brightness_set_blocking(struct led_classdev *cdev,
> > +                                                        enum led_brightness brightness)
> > +{
> > +     struct iei_wt61p803_puzzle_led *priv = cdev_to_iei_wt61p803_puzzle_led(cdev);
> > +     unsigned char *resp_buf = priv->response_buffer;
> > +     unsigned char led_power_cmd[5] = {
> > +             IEI_WT61P803_PUZZLE_CMD_HEADER_START,
> > +             IEI_WT61P803_PUZZLE_CMD_LED,
> > +             IEI_WT61P803_PUZZLE_CMD_LED_POWER,
> > +             (char)IEI_LED_OFF
> > +     };
> > +     size_t reply_size;
> > +
> > +     mutex_lock(&priv->lock);
> > +     if (brightness == LED_OFF) {
> > +             led_power_cmd[3] = (char)IEI_LED_OFF;
> > +             priv->led_power_state = LED_OFF;
> > +     } else {
> > +             led_power_cmd[3] = (char)IEI_LED_ON;
> > +             priv->led_power_state = LED_ON;
> > +     }
> > +     mutex_unlock(&priv->lock);
>
> Are you sure you need the mutex?
>
> > +     ret = devm_led_classdev_register_ext(dev, &priv->cdev, &init_data);
> > +     if (ret) {
> > +             dev_err(dev, "Could not register LED\n");
> > +             goto err_child_node;
> > +     }
> > +     return 0;
> > +err_child_node:
> > +     fwnode_handle_put(child);
> > +     return ret;
> > +}
>
> Is the fwnode_handle_put(child); missing in non-error path somewhere?
>
> > +MODULE_LICENSE("GPL");
>
> Make sure this is consistent with file header. GPLv2+, if you can.
>
> Best regards,
>
>                                                                         Pavel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Hi Pavel,

The mutex is locked in
iei_wt61p803_puzzle_led_brightness_set_blocking(), as concurrent
access to the same private structure member should be possible, when
reading the state
from iei_wt61p803_puzzle_led_brightness_get().

It does look like I missed the final fwnode_handle_put(child) here.

My understanding regarding the license is that when
MODULE_LICENSE("GPL") is used
the SPDX identifier can either be GPL-2.0-only or GPL-2.0-or-later.

Kind regards,
Luka