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 96BC91D6DBF for ; Fri, 17 Jan 2025 07:01:54 +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=1737097314; cv=none; b=ciVq9lZZZ4/GRYj2wbV35QZ2EH0g9mXeV7eZ1pgjLhZwQhdFtSZgVUuIVpsPWibjD+WX8EZNdAVQi1fqW+AivZf3kQnjR61Wq51jbFg8AFT2p2uOpHlI97CyPZak0fi4ufsQj7CO10wWiHILtCYp7Ai+PF4PJ8tdaCUfjERQrrk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737097314; c=relaxed/simple; bh=Mgx0wkhZNCYz1RBEpq+4yT87winLy561Us5sAZzmTWQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=RCosWlFpbGVYW0NyIMqfGYRhyzeAkrmMpu/7V899IDHIU4KHRuB8ipG22Pb7a/Tf5JHgPnje2ln1hYKPsq7up65vcN/CONmRABxOxw+M0xc+NbE4xjuS3O59J3aK4jIQPdnZNfN7ZsAJDBDZsd8mPhk08TmeNM6YLECYDpAydIc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=VHZ/+ecm; 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="VHZ/+ecm" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8AEAC4CEE0; Fri, 17 Jan 2025 07:01:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1737097314; bh=Mgx0wkhZNCYz1RBEpq+4yT87winLy561Us5sAZzmTWQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=VHZ/+ecmYm7UT1yza5KVSjcrdJf7pIeXFMArqfPr6NrZUBt0Rm5rfV1qwYQLKJ6oi aAsc2ZqleWPf1NFjHzKXN1CR49Z1cnvBHRLj64LyARjUzqchKpRM0mFXkwFTW1DhAo YGhJdOBXOdSdAbVlkYKKRjOj7YhzPIZBxtjgnBX8= Date: Fri, 17 Jan 2025 08:01:00 +0100 From: Greg Kroah-Hartman To: Thomas =?iso-8859-1?Q?Wei=DFschuh?= Cc: "Rafael J. Wysocki" , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/6] sysfs: attribute_group: allow registration of const attribute Message-ID: <2025011714-skeleton-bring-3e77@gregkh> References: <20250116-sysfs-const-attr-prep-v1-0-15e72dba4205@weissschuh.net> <20250116-sysfs-const-attr-prep-v1-1-15e72dba4205@weissschuh.net> 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20250116-sysfs-const-attr-prep-v1-1-15e72dba4205@weissschuh.net> 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 :) thanks, greg k-h