From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-fsdevel-owner@vger.kernel.org>
Received: from zeniv.linux.org.uk ([195.92.253.2]:59645 "EHLO
	ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1757840AbcDACF0 (ORCPT
	<rfc822;linux-fsdevel@vger.kernel.org>);
	Thu, 31 Mar 2016 22:05:26 -0400
Date: Fri, 1 Apr 2016 03:05:24 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Eric Biggers <ebiggers3@gmail.com>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] vfs: constify arguments to utime family of system
 calls
Message-ID: <20160401020524.GA17997@ZenIV.linux.org.uk>
References: <1459475472-13104-1-git-send-email-ebiggers3@gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1459475472-13104-1-git-send-email-ebiggers3@gmail.com>
Sender: linux-fsdevel-owner@vger.kernel.org
List-ID: <linux-fsdevel.vger.kernel.org>

On Thu, Mar 31, 2016 at 08:51:12PM -0500, Eric Biggers wrote:
> The system calls to set file times: utime(), utimes(), futimesat(), and
> utimensat(), all take in pointers to a filename and time information,
> neither of which is modified.  Mark the pointed-to data as 'const' to
> better reflect the semantics.

I'm not sure if there's any point, to be honest.  Anything doing direct
dereferencing of those pointers is completely broken and reads are no
better than writes in that respect.  OTOH... put_user() and friends will
produce an error when you give them const void __user * on most of the
architectures, so it's not entirely useles...

What's the situation with other syscalls?  It doesn't make much sense
to do it piece-by-piece...