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 A6F8D8635D for ; Sat, 28 Jun 2025 08:19:15 +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=1751098757; cv=none; b=mNmbOzroKQrJPdw+EWmS7aQkdJFnO6KnP+GwaFl9Jw+UKkiWOCjC2tzVT9O5MiY61VnX87w+2f26YwjzyXYWX0eLXbbKLC6/wg7ZjvGQBJ7bPnOA+GRrqWBvltrLsbUfchR2wV6SgZvgrGsxWdL7PyEsoE4m2Ni3kgGmQehH1qo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751098757; c=relaxed/simple; bh=kWeQEBkGz4f2k7+bgpN5NBO5qLlK9Xf3YPzocVL7GKE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aZL46t0IDzYWZ74CnS336rjLgzFfyxFmcl6DlxleXHOaqcVyWfn9K8WlMxHBdkwK8UHWAASilFDM0dfgCU88YOaVCvqKBsUVooM8/6bLZvWPCOS6xlPL9+4hUajI7UMYa810zJO8t8ODdlkA0sc6lJAF0wNspw655SLIAJqi32s= 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=LTCDH8q0; 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="LTCDH8q0" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=weissschuh.net; s=mail; t=1751098748; bh=kWeQEBkGz4f2k7+bgpN5NBO5qLlK9Xf3YPzocVL7GKE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LTCDH8q0oEtiSdXSZpTV0lq16MHxuoZOBdZ57gyrQgWDUvJs5oEQMXiX/Lcczii1y IOrNHK+dWVAaVCvT+a1cV42TL2oMPBYVgjeaVs/opbKHLgUn10QmkYLTv0i0QtiE/X GkmGbPW/4uRjG5s6otFSZC9nkVYzBppFpmqueH+w= Date: Sat, 28 Jun 2025 10:19:07 +0200 From: Thomas =?utf-8?Q?Wei=C3=9Fschuh?= To: Greg Kroah-Hartman Cc: "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, Danilo Krummrich Subject: Re: [PATCH 1/6] sysfs: attribute_group: allow registration of const attribute Message-ID: <3d4c063e-e56d-466c-a3a7-58566bf1da3c@t-8ch.de> References: <20250116-sysfs-const-attr-prep-v1-0-15e72dba4205@weissschuh.net> <20250116-sysfs-const-attr-prep-v1-1-15e72dba4205@weissschuh.net> <2025011714-skeleton-bring-3e77@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: <2025011714-skeleton-bring-3e77@gregkh> Hi Greg, On 2025-01-17 08:01:00+0100, Greg Kroah-Hartman wrote: > On Thu, Jan 16, 2025 at 06:32:27PM +0100, 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 0f2fcd244523f050c5286f19d4fe1846506f9214..f5e25bed777a6a6e717f10973f1abcd12111f5c5 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'm all for the idea, BUT, let's finish up doing this one: > > > union { > > struct bin_attribute **bin_attrs; > > const struct bin_attribute *const *bin_attrs_new; > > first please. > > That way we can see just how "easy" the switch from _new to not-new goes :) I'd like to resend these preparatory patches so they go into v6.17-rc1 and I can work on the follow-up changes. In my opinion the switch from _new will work nicely. There have been no new users of _new in -next at all. Any objections? Thomas