linux-kernel - Re: [PATCH 2/8] leds: nic78bx: explicitly unregister LEDs at module's shutdown

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Message-ID: <810346b6-c8a4-8c40-8fe3-242332428313@csgroup.eu>
Date:   Mon, 6 Nov 2023 08:13:19 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     George Stark <gnstark@...utedevices.com>,
        "pavel@....cz" <pavel@....cz>, "lee@...nel.org" <lee@...nel.org>,
        "vadimp@...dia.com" <vadimp@...dia.com>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "npiggin@...il.com" <npiggin@...il.com>
CC:     "linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "kernel@...rdevices.ru" <kernel@...rdevices.ru>
Subject: Re: [PATCH 2/8] leds: nic78bx: explicitly unregister LEDs at module's
 shutdown



Le 25/10/2023 à 15:07, George Stark a écrit :
> LEDs are registered using devm_led_classdev_register() and automatically
> unregistered after module's remove(). led_classdev_unregister() calls
> led_set_brightness() to turn off the LEDs and module's appropriate callback
> uses resources those were destroyed already in module's remove().
> So explicitly unregister LEDs at module shutdown.
> 
> Signed-off-by: George Stark <gnstark@...utedevices.com>
> ---
>   drivers/leds/leds-nic78bx.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/leds/leds-nic78bx.c b/drivers/leds/leds-nic78bx.c
> index f196f52eec1e..12b70fcad37f 100644
> --- a/drivers/leds/leds-nic78bx.c
> +++ b/drivers/leds/leds-nic78bx.c
> @@ -170,6 +170,10 @@ static int nic78bx_probe(struct platform_device *pdev)
>   static int nic78bx_remove(struct platform_device *pdev)
>   {
>   	struct nic78bx_led_data *led_data = platform_get_drvdata(pdev);
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(nic78bx_leds); i++)
> +		devm_led_classdev_unregister(&pdev->dev, &nic78bx_leds[i].cdev);

The whole purpose of devm_ functions is that you don't need to call 
unregister when removing the driver as the dev core will do it for you. 
I understand your problem but I think this is not the solution.

>   
>   	/* Lock LED register */
>   	outb(NIC78BX_LOCK_VALUE,