Re: [PATCH] PM: hibernate: add sanity check on power_kobj

From: Pavel Machek <pavel@ucw.cz>
To: Abel Wu <abel.w@icloud.com>
Cc: rjw@rjwysocki.net, linux-pm@vger.kernel.org,
	linux-kernel@vger.kernel.org, hewenliang4@huawei.com,
	wuyun.wu@huawei.com
Subject: Re: [PATCH] PM: hibernate: add sanity check on power_kobj
Date: Mon, 1 Feb 2021 11:52:43 +0100	[thread overview]
Message-ID: <20210201105243.GA23135@duo.ucw.cz> (raw)
In-Reply-To: <20210201075041.1201-1-abel.w@icloud.com>

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On Mon 2021-02-01 02:50:41, Abel Wu wrote:
> The @power_kobj is initialized in pm_init() which is the same
> initcall level as pm_disk_init(). Although this dependency is
> guaranteed based on the current initcall serial execution model,
> it would still be better do a cost-less sanity check to avoid
> oops once the dependency is broken.

I don't believe this is good idea. If the dependency is ever broken,
this will make failure more subtle and harder to debug.

> Signed-off-by: Abel Wu <abel.w@icloud.com>
> ---
>  kernel/power/hibernate.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index da0b41914177..060089cc261d 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -1262,6 +1262,9 @@ static const struct attribute_group attr_group = {
>  
>  static int __init pm_disk_init(void)
>  {
> +	if (!power_kobj)
> +		return -EINVAL;
> +
>  	return sysfs_create_group(power_kobj, &attr_group);
>  }
>  
> -- 
> 2.27.0

-- 
http://www.livejournal.com/~pavelmachek

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