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 93C7D44E037; Thu, 8 Jan 2026 11:55:18 +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=1767873318; cv=none; b=M2wX5lj4eUZYvGcEyP4KHk2x0nySn865NdR88X60HHO19TfHFZ9C5htqqUy+/bhefH/KRNLpVNGUnz369v1qcpC8M/+jei/uKK5zfTuKyzlkgqM3kzYSxOUpooERm/rnqxHzzfukT7oDPmhYlKQdPUu7bT8xxAXcvpxguViEGcI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767873318; c=relaxed/simple; bh=z382ACtlBmY2CwY2em31mfcaAQGcR3eXb0toDDOrjT0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=On9bTViQEgCOjnwU7qHyemQ+nVGqEcltxWsLYuK2e8PvzaYZkTo7IpdOck+TYsZm3ipANSfbmUNAc1nvhpy5T2vllMXwCqV75jzxPlFBXGwPPjl1xvue92+awleLUer8pau6vp4x0E4dwI1Zw43WTQGn0Y0zN1YJOIZYhZ/aSio= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YO1FLDaO; 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="YO1FLDaO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B5382C116C6; Thu, 8 Jan 2026 11:55:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1767873317; bh=z382ACtlBmY2CwY2em31mfcaAQGcR3eXb0toDDOrjT0=; h=Date:Reply-To:Subject:To:Cc:References:From:In-Reply-To:From; b=YO1FLDaOrpGpFDT1/kPBU/A82GB8FX+OmJQfSzwSwIdF6yfUWpgKM3exfzezC3OO1 eJyG5uYjgAl7JxGENXD5YTB1Tkiw7eJGr2LCazWv0fa/5jJdncq97XQkqNM8JF4oDB EJslAsQaIJPsCByka+SgnloKHtnYx/H1+ETXiXcx90JP0AQpPzJAO5rS3Ultan+Se0 8dFsBoqdY7jN8XavmB9de0e1G+12oH33aRI4nxAdE63cCiTD0dhZmQ5iAlSlsXW5nl sfY7MP9+V5Wle+TB1QmLX5VRdfGCbamHwZ3Pilw5Pwq/wdJcZv1JetEs8vdyvBv4sc n2Ftvx5RpYoxA== Message-ID: <3bb8cbf5-9f9e-4f50-a6de-b9b79e097c20@kernel.org> Date: Thu, 8 Jan 2026 12:55:13 +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: Lucas De Marchi , 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 , 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> <7ff92075-df6a-45d8-9014-647ae45797ff@kernel.org> <2025122212-fiction-setback-ede5@gregkh> <4zatcu4izel7yijmkinxy6wq6owktwsyxkazb5ufc4vua54ojx@3vq4dgtydgia> Content-Language: en-US From: Daniel Gomez Organization: kernel.org In-Reply-To: <4zatcu4izel7yijmkinxy6wq6owktwsyxkazb5ufc4vua54ojx@3vq4dgtydgia> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 06/01/2026 15.24, Lucas De Marchi wrote: > On Mon, Dec 22, 2025 at 12:56:38PM +0100, Greg Kroah-Hartman wrote: >> On Mon, Dec 22, 2025 at 09:48:54AM +0100, Daniel Gomez wrote: >>> 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 >> >> Wait, no, that's not what I mean at all :) >> >>> 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 >> >> Please no, let us keep using -EEXIST in the kernel source, and if your >> usage is going to map this to userspace somehow, do the translation >> there, in the module code, as your original patch above said. >> >> Otherwise, again, this is never going to work, let the subsystems use >> this error code how ever they feel they need to. > > Ok. When I added the warning I was more following what the other error > handling was doing for positive values. Happy to change that to simply > map the error code before returning from do_init_module(). > > Daniel, do you want me to resend that with the warning removed? Yes please, I think we should do that and explain the agreement in this thread in the commit message so others can understand the why.