From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from todd.t-8ch.de (todd.t-8ch.de [159.69.126.157]) (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 3770E257AC7 for ; Tue, 19 Aug 2025 13:59:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.69.126.157 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755611949; cv=none; b=Od8uIMKRHJiDE4+QA0cWGdIpYKEU1b+6iryqALoFqm4UqMjzYnIoR2mZKNrzgfNhnmnAXmJAaxUztXa1iMPchLfaDxpbKA3yENg0ofiAjMKHKYKDQKqptmvIPRJzL+j+NrHiqHiaBJwnahS+1fgpzjvgQa/g/5Mfp64psz7yVGw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755611949; c=relaxed/simple; bh=e7m49b60v1bM9iFQgpANqdyWxfp5USjhGn0iqaiCmwY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=J/EKIs3Vr7a0sry5uQdGU/XzEnOl87BSNN6JWwn1bE1ZJ3HIP4TGJ/fK3H25NdTDR6GYyIjxrek3Rd7dPGRSOv8K7WKs/WWrTa08IJFqL95Ki9W05oeZflTSs/Mk1GAyZKDYZlN5PRf/u4eyUhdr4j0pvSFnsVmq5wQgqDd4lyk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=weissschuh.net; spf=pass smtp.mailfrom=weissschuh.net; dkim=pass (1024-bit key) header.d=weissschuh.net header.i=@weissschuh.net header.b=H2RtdW4G; arc=none smtp.client-ip=159.69.126.157 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=weissschuh.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=weissschuh.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=weissschuh.net header.i=@weissschuh.net header.b="H2RtdW4G" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=weissschuh.net; s=mail; t=1755611945; bh=e7m49b60v1bM9iFQgpANqdyWxfp5USjhGn0iqaiCmwY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H2RtdW4G4WD3MDUsmCfSe/j60L1G952CpSrJUxnfPnJfr2CIAmPPtZUAM+J8MPhdU 8v+XXtKuR+RkQCK0ch077KfPGymu/uCDvTN/Xuy/HDuXY0YalwiKloCY+g+DDRBza9 Ej3cIembtvU4o1wHy326TSALutCvpr92InoulRW8= Date: Tue, 19 Aug 2025 15:59:04 +0200 From: Thomas =?utf-8?Q?Wei=C3=9Fschuh?= To: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" , Danilo Krummrich , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/7] sysfs: attribute_group: allow registration of const attribute Message-ID: References: <20250811-sysfs-const-attr-prep-v3-0-0d973ff46afc@weissschuh.net> <20250811-sysfs-const-attr-prep-v3-1-0d973ff46afc@weissschuh.net> <2025081957-refueling-anteater-4720@gregkh> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <2025081957-refueling-anteater-4720@gregkh> On 2025-08-19 13:22:55+0200, Greg Kroah-Hartman wrote: > On Mon, Aug 11, 2025 at 11:14:27AM +0200, Thomas Weißschuh wrote: > > To be able to constify instances of struct attribute it has to be > > possible to add them to struct attribute_group. > > The current type of the attrs member however is not compatible with that. > > Introduce a union that allows registration of both const and non-const > > attributes to enable a piecewise transition. > > As both union member types are compatible no logic needs to be adapted. > > > > Technically it is now possible register a const struct > > attribute and receive it as mutable pointer in the callbacks. > > This is a soundness issue. > > But this same soundness issue already exists today in > > sysfs_create_file(). > > Also the struct definition and callback implementation are always > > closely linked and are meant to be moved to const in lockstep. > > > > Similar to commit 906c508afdca ("sysfs: attribute_group: allow registration of const bin_attribute") > > > > Signed-off-by: Thomas Weißschuh > > --- > > include/linux/sysfs.h | 5 ++++- > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h > > index f418aae4f1134f8126783d9e8eb575ba4278e927..a47092e837d9eb014894d1f7e49f0fd0f9a2e350 100644 > > --- a/include/linux/sysfs.h > > +++ b/include/linux/sysfs.h > > @@ -105,7 +105,10 @@ struct attribute_group { > > size_t (*bin_size)(struct kobject *, > > const struct bin_attribute *, > > int); > > - struct attribute **attrs; > > + union { > > + struct attribute **attrs; > > + const struct attribute *const *attrs_new; > > I know you will drop the "_new" prefix after a while, but "new" is > relative, and not very descriptive. That is somewhat intentional to express that it is a transitional thing. > How about "_const"? At some point the regular variant will be const too, so "_const" would be a bit weird. > > + }; > > union { > > const struct bin_attribute *const *bin_attrs; > > const struct bin_attribute *const *bin_attrs_new; > > There is no bin_attrs_new anymore. Finally. sorry about that... Thanks! No worries. Thomas