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 B45BA28690; Mon, 22 Dec 2025 08:19:45 +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=1766391585; cv=none; b=PReYO5Qkb4Cy8ByYYR8fBc3xHWs9D8GQMtG8y5BMPk0lP655wrZAMgeJaE0OwZFHeV3egULCoc2oEuZ77nuReCPy2VClJM3RHxlbmwgXYFt9Zeugmgmp4odq7+Hmi31UZg2k4nPiS1RpeStooYA9lTei734yhf/1sUxkv3SP5uA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766391585; c=relaxed/simple; bh=E1A7PNNWRR+k5MTnKO7m1Fvt91vOM0psW3gAF0DO/y8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ki+NknWwG2rBPfwkZnoiGWb0EkolYRlvU7ifm49nmaDdOFK9VufGI/JI4EqDjwVq4ecRFhUnD2pLeiqW7dIFOfGFWf0cpDIOb07VbCN5VSSJ2hTzoGFoqxq/XtbNGKzzCCu5ILresYnKG7WPFrnS6h9wB8pRNGNXDDtBkNuQDxw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h4NjSzd+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="h4NjSzd+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CB840C4CEF1; Mon, 22 Dec 2025 08:19:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1766391585; bh=E1A7PNNWRR+k5MTnKO7m1Fvt91vOM0psW3gAF0DO/y8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=h4NjSzd+BLW6sliXM63tt7Ns5GoMuzm7PazLMEuCaPzp7To3T1bGJC9Q6hS/DRmcO i4LwnKjZSerz/bRoOU2KzJjSgu+tQuFLWYJatsCenJpd/cSE4y5EnkhEEMsFRvSgOI Ba6PIhCQ+2DmR2L45Y8BVqX+LfTaXGcLMlKeNSGA= Date: Mon, 22 Dec 2025 09:19:42 +0100 From: Greg Kroah-Hartman To: Daniel Gomez 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 Subject: Re: [PATCH] software node: replace -EEXIST with -EBUSY Message-ID: <2025122203-purely-huntsman-7987@gregkh> References: <20251220-dev-module-init-eexists-linux-acpi-v1-1-af59b1a0e217@samsung.com> Precedence: bulk X-Mailing-List: linux-modules@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251220-dev-module-init-eexists-linux-acpi-v1-1-af59b1a0e217@samsung.com> 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 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. thanks, greg k-h