From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1DC942D5436; Mon, 22 Dec 2025 08:48:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766393341; cv=none; b=EUj/gbz/SZ5tlQpH4j6gNcSViOUDsfSQn263xn72BFYF2YLMCzpLkQrXUJNPE63PCH7YDcI63KA/QbChC7XFL9Ss4rGuTE1F++T1Xh0buqmUxYpcFMfizd4a+gKDrHYjo/d9RgEMRQ8h+8ElfzKxDu5MF56iPkol3wy4U1O++00= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766393341; c=relaxed/simple; bh=spqJjYicBNrgBP/Mfp87p1zSBBycDXq8bmczYreW+fU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=RgENf2qVWe9QahkWz7IOHFxEocoiM28DbHC3AGgFiVi27SKQ0sgO4akbCsEbblRv9yoAKGgjyV8UpPPgT8egFEjeWCHrJ5I17KnuZt04mxDzlQ6P6SfC07CB25DYQ+5W1oEcrbG7BMjtw0U9ErShfnUNoSgsk1V6KSCU6K8C+wI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=qHyhpyme; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="qHyhpyme" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D65EAC4CEF1; Mon, 22 Dec 2025 08:48:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766393339; bh=spqJjYicBNrgBP/Mfp87p1zSBBycDXq8bmczYreW+fU=; h=Date:Reply-To:Subject:To:Cc:References:From:In-Reply-To:From; b=qHyhpymegZnLGvnPKZyrC5eD+0PwjtPwXo1Qgo62x5soEOFiy67vPdT2G/pZYpyd2 Dw34fbUPKu4UGBYhjiHPFkJoCwVpOHqU4tpaFjsOKhTwOG3O13kvLOfAPJ99Gpdv/6 WsBl0ddVZS04JpqmEX2XncvWdDQcRCK1CraGk9ebiDc1z60jjz7ClxGXgBPLJ3s8Wk VykrQKNIYgwok4f6VYt/85bReiI16pk3DuwNm4YY2NqrERse8iJ0JdAokfGWU0EgCi 6ex9oVZd4z132RtI8ElMCG+ONTH9PbimfWhzrTdO7aZNP23Gt1RjBawAE64PqubbaC ktt6a1hgHUPDQ== Message-ID: <7ff92075-df6a-45d8-9014-647ae45797ff@kernel.org> Date: Mon, 22 Dec 2025 09:48:54 +0100 Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: Daniel Gomez Subject: Re: [PATCH] software node: replace -EEXIST with -EBUSY To: Greg Kroah-Hartman Cc: Andy Shevchenko , Daniel Scally , Heikki Krogerus , Sakari Ailus , "Rafael J. Wysocki" , Danilo Krummrich , Luis Chamberlain , Petr Pavlu , Sami Tolvanen , Aaron Tomlin , Lucas De Marchi , linux-acpi@vger.kernel.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org, Daniel Gomez References: <20251220-dev-module-init-eexists-linux-acpi-v1-1-af59b1a0e217@samsung.com> <2025122203-purely-huntsman-7987@gregkh> Content-Language: en-US From: Daniel Gomez Organization: kernel.org In-Reply-To: <2025122203-purely-huntsman-7987@gregkh> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 22/12/2025 09.19, Greg Kroah-Hartman wrote: > On Sat, Dec 20, 2025 at 04:55:00AM +0100, Daniel Gomez wrote: >> From: Daniel Gomez >> >> The -EEXIST error code is reserved by the module loading infrastructure >> to indicate that a module is already loaded. When a module's init >> function returns -EEXIST, userspace tools like kmod interpret this as >> "module already loaded" and treat the operation as successful, returning >> 0 to the user even though the module initialization actually failed. >> >> This follows the precedent set by commit 54416fd76770 ("netfilter: >> conntrack: helper: Replace -EEXIST by -EBUSY") which fixed the same >> issue in nf_conntrack_helper_register(). >> >> Affected modules: >> * meraki_mx100 pcengines_apuv2 >> >> Signed-off-by: Daniel Gomez >> --- >> The error code -EEXIST is reserved by the kernel module loader to >> indicate that a module with the same name is already loaded. When a >> module's init function returns -EEXIST, kmod interprets this as "module >> already loaded" and reports success instead of failure [1]. >> >> The kernel module loader will include a safety net that provides -EEXIST >> to -EBUSY with a warning [2], and a documentation patch has been sent to >> prevent future occurrences [3]. >> >> These affected code paths were identified using a static analysis tool >> [4] that traces -EEXIST returns to module_init(). The tool was developed >> with AI assistance and all findings were manually validated. >> >> Link: https://lore.kernel.org/all/aKEVQhJpRdiZSliu@orbyte.nwl.cc/ [1] >> Link: https://lore.kernel.org/all/20251013-module-warn-ret-v1-0-ab65b41af01f@intel.com/ [2] >> Link: https://lore.kernel.org/all/20251218-dev-module-init-eexists-modules-docs-v1-0-361569aa782a@samsung.com/ [3] >> Link: https://gitlab.com/-/snippets/4913469 [4] >> --- >> drivers/base/swnode.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/base/swnode.c b/drivers/base/swnode.c >> index 16a8301c25d6..083593d99a18 100644 >> --- a/drivers/base/swnode.c >> +++ b/drivers/base/swnode.c >> @@ -919,7 +919,7 @@ int software_node_register(const struct software_node *node) >> struct swnode *parent = software_node_to_swnode(node->parent); >> >> if (software_node_to_swnode(node)) >> - return -EEXIST; >> + return -EBUSY; > > While I understand the want for the module loader to be returning > -EBUSY, that doesn't really make sense down here in this layer of the > kernel. > > So why doesn't the module loader turn -EEXIST return values into -EBUSY > if it wishes to pass that value on to userspace? Otherwise you are Indeed, we are planning to do that as well with "[PATCH 0/2] module: Tweak return and warning": https://lore.kernel.org/all/20251013-module-warn-ret-v1-0-ab65b41af01f@intel.com/#t However, we don't consider that as the right fix. > going to be constantly playing "whack-a-mole" here and have really > set things up so that NO api can ever return EEXIST as an error value in > the future. 100%. For that reason, on top of the series from Lucas, we are documenting this to make it clear: https://lore.kernel.org/linux-modules/20251218-dev-module-init-eexists-modules-docs-v1-0-361569aa782a@samsung.com/T/#m2ed6fbffb3f78b9bff53840f6492a198c389cb50 And sending patches where we see modules need fixing. I have already sent 6 out of 20-ish series (that include a total of 40+ fixes): https://lore.kernel.org/all/20251220-dev-module-init-eexists-linux-scsi-v1-0-5379db749d54@samsung.com https://lore.kernel.org/all/20251219-dev-module-init-eexists-netfilter-v1-1-efd3f62412dc@samsung.com https://lore.kernel.org/all/20251220-dev-module-init-eexists-bpf-v1-1-7f186663dbe7@samsung.com https://lore.kernel.org/all/20251220-dev-module-init-eexists-keyring-v1-1-a2f23248c300@samsung.com https://lore.kernel.org/all/20251220-dev-module-init-eexists-dm-devel-v1-1-90ed00444ea0@samsung.com