Re: [PATCH] compat: remove compat_printk

From: Andreas Dilger <adilger@dilger.ca>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] compat: remove compat_printk
Date: Wed, 22 Jun 2016 11:09:28 -0600	[thread overview]
Message-ID: <98637B71-BE33-431B-8A91-A0F8C335654B@dilger.ca> (raw)
In-Reply-To: <32739965.DkybxvdJlf@wuerfel>

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> On Jun 22, 2016, at 4:15 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> 
> On Tuesday, June 21, 2016 4:38:57 PM CEST Andrew Morton wrote:
>>> @@ -1077,15 +1076,6 @@ static struct ctl_table kern_table[] = {
>>>              .extra1         = &neg_one,
>>>      },
>>> #endif
>>> -#ifdef CONFIG_COMPAT
>>> -     {
>>> -             .procname       = "compat-log",
>>> -             .data           = &compat_log,
>>> -             .maxlen         = sizeof (int),
>>> -             .mode           = 0644,
>>> -             .proc_handler   = proc_dointvec,
>>> -     },
>>> -#endif
>> 
>> How do we know we can simply remove /proc/sys/kernel/compat-log without
>> breaking any userspace?
>> 
> 
> Good point. I guess we can leave this in place just in case (with a comment)
> and just remove the compat_printk function. We could probably have a Kconfig
> symbol for obsolete sysctl files, but if this is the only one controlled
> by it, it's probably not worth the effort.

It probably makes sense to print a deprecation warning containing the current
process name if this /proc file is modified, so that users can update any
scripts/tools using it.

Cheers, Andreas

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