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Date: Mon, 21 Jul 2025 09:20:33 +0200
From: Christoph Hellwig <hch@lst.de>
To: Thomas =?iso-8859-1?Q?Wei=DFschuh?= <thomas.weissschuh@linutronix.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>, Willy Tarreau <w@1wt.eu>,
	Thomas =?iso-8859-1?Q?Wei=DFschuh?= <linux@weissschuh.net>,
	Brendan Higgins <brendan.higgins@linux.dev>,
	David Gow <davidgow@google.com>, Rae Moar <rmoar@google.com>,
	Shuah Khan <shuah@kernel.org>, Jonathan Corbet <corbet@lwn.net>,
	Nicolas Schier <nicolas.schier@linux.dev>,
	Kees Cook <kees@kernel.org>, Christian Brauner <brauner@kernel.org>,
	Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>,
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	Christophe Leroy <christophe.leroy@csgroup.eu>,
	linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org, kunit-dev@googlegroups.com,
	linux-doc@vger.kernel.org, workflows@vger.kernel.org,
	linux-mm@kvack.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v5 06/15] fs,fork,exit: export symbols necessary for
 KUnit UAPI support
Message-ID: <20250721072033.GA30175@lst.de>
References: <20250717-kunit-kselftests-v5-0-442b711cde2e@linutronix.de> <20250717-kunit-kselftests-v5-6-442b711cde2e@linutronix.de> <20250718164412.GD2580412@ZenIV> <20250721075849-b3cf33b6-2516-4707-bab6-53fe95afbffa@linutronix.de>
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On Mon, Jul 21, 2025 at 08:42:40AM +0200, Thomas Weißschuh wrote:
> This would still leave the exports for replace_fd(), create_pipe_files()
> and set_fs_pwd(). Instead of using kernel/umh.c,

Please look into a way to just run your userspace tests from userspace.

It's not that hard, people have done this novel concept for at least
a few decades if you look into it.

> I can also extend
> kernel/usermode_driver.c to provide these in a way that works for me.
> But kernel/usermode_driver.c is dead code, unused since commit
> 98e20e5e13d2 ("bpfilter: remove bpfilter")
> Would it be fine to export those symbols? And delete usermode_driver.c,
> as carrying around an unused generic framework seems pointless.

Unused code should always go away.  Weirdly enough USERMODE_DRIVER is
selected by BPF_PRELOAD despite that not really using any code from
it, though.