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 D0892155326; Mon, 22 Dec 2025 04:40:15 +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=1766378415; cv=none; b=nblPTFgZ+S8yMRess3Bwdin/czoI+QKoCnWuZYvqJmKwob+fhUUEWC0RgQ9ZHlobt0BnUvwUcvNpHKaPCZzDYsyZoxPOPu0XIeQFlm8mNSu71IhtqVozoU8T1/B4dUl3N6snJwhma7hSeq17o86OdQZzGk0k61Avs2Q2qLdrwwY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1766378415; c=relaxed/simple; bh=59RINjXBROtdfqnPC4dtWKuiuAB2h20wNTa080CYBZw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mQe3g5YOjbMTPItjDdpGLTRqjk1Z/TnLzel68jR1kFeYpeGteSxLiJCdlKH+JcaahxSHCyVmAAh1s1dpBxMcLKc0aZXwnynoCKQen51FFTFNS8s/29uYkxW7elhqljQwG9lWWjV52Y2YivrROGcaTilYTl+1ArGLyikwda+w7+c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EEFoCh10; 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="EEFoCh10" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 72D98C4CEF1; Mon, 22 Dec 2025 04:40:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1766378415; bh=59RINjXBROtdfqnPC4dtWKuiuAB2h20wNTa080CYBZw=; h=Date:Reply-To:Subject:To:Cc:References:From:In-Reply-To:From; b=EEFoCh10HKBznipcniS9TErcGHUjR/HWpi2BVyG2coQkvipR5IDSYJUqXr7KTxXLA iZV3Yx8682Kht0cPq1usDVI/Fb7O1or2+pXl0dQqtSyIYVmMabUYU4QrlOFarxddCk Fpl+7YUNS3Xp96QAFDINeU/vyPzFdsTMmyPPX+XBVGqenuZx9LO9mdowgv4DGucppm rfjcCphqd6EymNeyogvW6u2pM4vfaqy9tjLpeUJ0cSpZVntQxYbcQ/nXUgyX4coHwG PKIEITTVnBkTzqFG/bp9QgtxWBVEoyb5Pyq2Q+CbOvY7y3DnZN+Wl9o0QAHFK2Dul2 Ws6Z1C/mGj6Vg== Message-ID: <8a43a502-af65-41d9-9ae0-81f9a27ff45e@kernel.org> Date: Mon, 22 Dec 2025 05:40:10 +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: Sakari Ailus Cc: Andy Shevchenko , Daniel Scally , Heikki Krogerus , Greg Kroah-Hartman , "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> Content-Language: en-US From: Daniel Gomez Organization: kernel.org In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 21/12/2025 22.59, Sakari Ailus wrote: > Hi Daniel, > > Thanks for the patch. > > 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. > > This might not be the only case where -EEXIST may be returned by loading a > module. That is correct. There are 40+ places detected and around 20+ more where the error is returned but at some point ignored and not propagated back to userspace. I have all the series ready for the first case, but I've only sent the first 6. > The patch is fine IMO but I'd just change -EEXIST to -EBUSY in e.g. > do_init_module() to avoid this being an actual bug elsewhere. We are planning to merge that too. Link [2] refers to Lucas's "[PATCH 0/2] module: Tweak return and warning" series, which replaces -EEXIST with -EBUSY at runtime and warns. However, we do not consider that to be the actual fix. I am starting to send these fixes out to avoid "spamming" unnecessarily the kernel log in cases we can already detect. > > I wonder what others think. Please, find the rest of the series sent: 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 FYI, these docs go on top of Lucas' changes with the hope this is clear in the docs. https://lore.kernel.org/all/20251218-dev-module-init-eexists-modules-docs-v1-0-361569aa782a@samsung.com > >> >> 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]