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Date: Mon, 23 Mar 2026 07:47:56 -1000
From: Tejun Heo <tj@kernel.org>
To: Cheng-Yang Chou <yphbchou0911@gmail.com>
Cc: sched-ext@lists.linux.dev, David Vernet <void@manifault.com>,
	Andrea Righi <arighi@nvidia.com>,
	Changwoo Min <changwoo@igalia.com>,
	Ching-Chun Huang <jserv@ccns.ncku.edu.tw>,
	Chia-Ping Tsai <chia7712@gmail.com>
Subject: Re: [PATCH v2 sched_ext/for-7.1] sched_ext: Fix invalid kobj cast in
 scx_uevent()
Message-ID: <acF8zKIsBST6Gha_@slm.duckdns.org>
References: <20260323104848.3879920-1-yphbchou0911@gmail.com>
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In-Reply-To: <20260323104848.3879920-1-yphbchou0911@gmail.com>

On Mon, Mar 23, 2026 at 06:48:29PM +0800, Cheng-Yang Chou wrote:
>  static int scx_uevent(const struct kobject *kobj, struct kobj_uevent_env *env)
>  {
> -	const struct scx_sched *sch = container_of(kobj, struct scx_sched, kobj);
> +	const struct scx_sched *sch;
> +
> +	/*
> +	 * scx_uevent() can be reached by both scx_sched kobjects (scx_ktype)
> +	 * and sub-scheduler kset kobjects (kset_ktype) through the parent
> +	 * chain walk. Filter out the latter to avoid invalid casts.
> +	 */
> +	if (kobj->ktype != &scx_ktype)
> +		return 0;
> +
> +	sch = container_of(kobj, struct scx_sched, kobj);

I'll apply as-is but you don't need to move container_of() here. It's just
address calculation, not a dereference.

Thanks.

-- 
tejun