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Date: Tue, 13 Oct 2026 00:37:10 +0200
Message-Id: <DM37WR9GUVEO.1ZJWESPXVQ8X5@kernel.org>
From: "Danilo Krummrich" <dakr@kernel.org>
Subject: Re: [PATCH] debugfs: clarify return values when disabled
Cc: <linux-kernel@vger.kernel.org>, "Greg Kroah-Hartman"
 <gregkh@linuxfoundation.org>, "Rafael J. Wysocki" <rafael@kernel.org>,
 <driver-core@lists.linux.dev>, "Jonathan Corbet" <corbet@lwn.net>, "Shuah
 Khan" <skhan@linuxfoundation.org>, <linux-doc@vger.kernel.org>, "Johan
 Hovold" <johan@kernel.org>
To: "Randy Dunlap" <rdunlap@infradead.org>
References: <20261008171547.3084466-1-rdunlap@infradead.org>
In-Reply-To: <20261008171547.3084466-1-rdunlap@infradead.org>

On Thu Oct 8, 2026 at 7:15 PM CEST, Randy Dunlap wrote:
> @@ -820,6 +826,10 @@ EXPORT_SYMBOL_GPL(debugfs_lookup_and_rem
>   *
>   * If debugfs is not enabled in the kernel, the value -%ENODEV will be
>   * returned.
> + * If debugfs is not enabled in the kernel build, the value %-ENODEV
> + * will be returned. If debugfs is enabled in the kernel build but is di=
sabled
> + * by using "debugfs=3Doff" on the kernel command line, the value %-EPER=
M
> + * will be returned.

This keeps the old *and* the new text.

Besides that, when debugfs is disabled via kernel command line
debugfs_change_name() checks

	if (IS_ERR_OR_NULL(dentry))
		return 0;

and if disabled via kernel command line dentry would have been an ERR_PTR a=
nd
hence it would just return 0.

(There may be more functions of this sort, I didn't check all of them.)

Thanks,
Danilo