linux-kernel - Re: [PATCH] ALSA: control led: fix memory leak in snd_ctl_led

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Message-Id: <A622EB84-DC4A-47A4-A828-CE6D25DC92EB@gmail.com>
Date:   Sat, 29 May 2021 05:35:22 +0800
From:   慕冬亮 <mudongliangabcd@...il.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     perex@...ex.cz, tiwai@...e.com, alsa-devel@...a-project.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        syzbot+08a7d8b51ea048a74ffb@...kaller.appspotmail.com
Subject: Re: [PATCH] ALSA: control led: fix memory leak in
 snd_ctl_led_register



> On May 28, 2021, at 10:05 PM, Dan Carpenter <dan.carpenter@...cle.com> wrote:
> 
> On Fri, May 28, 2021 at 09:50:49PM +0800, Dongliang Mu wrote:
>> 
>> Can you please give some advise on how to fix this WARN issue?
> 
> But it feels like it spoils the fun if I write the commit...  Anyway:

It’s fine. I am still in the learning process. It’s also good to learn experience by comparing your patch and my patch.

> 
> regards,
> dan carpenter
> 
> diff --git a/sound/core/control_led.c b/sound/core/control_led.c
> index 25f57c14f294..dd357abc1b58 100644
> --- a/sound/core/control_led.c
> +++ b/sound/core/control_led.c
> @@ -740,6 +740,7 @@ static int __init snd_ctl_led_init(void)
> 			for (; group > 0; group--) {
> 				led = &snd_ctl_leds[group - 1];
> 				device_del(&led->dev);
> +				device_put(&led->dev);
> 			}
> 			device_del(&snd_ctl_led_dev);
> 			return -ENOMEM;
> @@ -768,6 +769,7 @@ static void __exit snd_ctl_led_exit(void)
> 	for (group = 0; group < MAX_LED; group++) {
> 		led = &snd_ctl_leds[group];
> 		device_del(&led->dev);
> +		device_put(&led->dev);
> 	}
> 	device_del(&snd_ctl_led_dev);
> 	snd_ctl_led_clean(NULL);

Does this patch mean I should add device_put in the init and exit function other than snd_ctl_led_sysfs_remove? This will cause device_release bypass the release method checking?