linux-kernel - Re: [PATCH RESEND] checkpatch: remove obsolete CONFIG

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Date:   Thu, 9 Mar 2017 23:57:09 +0200
From:   Ruslan Bilovol <ruslan.bilovol@...il.com>
To:     Joe Perches <joe@...ches.com>
Cc:     Robo Bot <apw@...onical.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH RESEND] checkpatch: remove obsolete CONFIG_EXPERIMENTAL checks

On Tue, Feb 28, 2017 at 1:04 AM, Joe Perches <joe@...ches.com> wrote:
> On Tue, 2017-02-28 at 00:21 +0200, Ruslan Bilovol wrote:
>> Config EXPERIMENTAL has been removed from kernel in 2013
>> (see 3d374d0: "final removal of CONFIG_EXPERIMENTAL"),
>> there is no any reason to do these checks now.
>
>> Signed-off-by: Ruslan Bilovol <ruslan.bilovol@...il.com>
>
> While I think all the defconfigs that have CONFIG_EXPERIMENTAL
> should have those lines removed, this seems sensible enough.
>
> $ git grep -w CONFIG_EXPERIMENTAL -- "*defconfig*" | wc -l
> 216
>
> Acked-by: Joe Perches <joe@...ches.com>
>
> Here's a little script to remove the CONFIG_EXPERIMENTAL
> lines from all the defconfigs too:
>
> $ git grep -w --name-only CONFIG_EXPERIMENTAL -- "*defconfig*" | \
>   xargs sed -i -e '/CONFIG_EXPERIMENTAL=[yn]/d'

While I originally wanted to remove CONFIG_EXPERIMENTAL from
all defconfigs by similar script, then automatically create patch, get
mainteiner for each defcofnig and send the patch to it, after doing
some investigation here I don't think it make sense.

First of all, I checked if there are any other non-existent config options
used in defconfigs (scripts/checkkconfigsymbols.py is very helpful
here) and I found there are many of them.

Below are just few of them (for kernel 4.10):

- RCU_CPU_STALL_DETECTOR: removed in 2011 by a00e0d71: "rcu:
  Remove conditional compilation for RCU CPU stall warnings", still
  present in *106* defconfigs

- NET_ETHERNET: removed in 2011 by f860b05: "drivers/net: Kconfig
  and Makefile cleanup", still present in *145* defconfigs

- MTD_CHAR: removed in 2013 by 660685d "mtd: merge mtdchar
  module with mtdcore", still present in *98* defconfigs

- INET_LRO removed in 2016 by 7bbf3ca "ipv4: Remove
  inet_lro library", still present in *192* defconfigs

- NETDEV_10000, NETDEV_1000, MTD_PARTITIONS,
  MISC_DEVICES, HID_SUPPORT, and more and more....

It seems nobody cares about presence of such non-existent
config symbols in defconfig files. Such defcifngs are
outdated and at least should be regenerated (instead of
sed-ding for each such config option)

Also presence of old non-existent config options in defconfigs
may be a good indication of systems that nobody uses
or supports, so it will be easy to indentify and remove them
from kernel at some time in the future.

So let's keep it as-is.

--
Ruslan

>
>> ---
>>  scripts/checkpatch.pl | 13 -------------
>>  1 file changed, 13 deletions(-)
>>
>> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
>> index 982c52c..e0a34e6 100755
>> --- a/scripts/checkpatch.pl
>> +++ b/scripts/checkpatch.pl
>> @@ -2746,13 +2746,6 @@ sub process {
>>                       #print "is_start<$is_start> is_end<$is_end> length<$length>\n";
>>               }
>>
>> -# discourage the addition of CONFIG_EXPERIMENTAL in Kconfig.
>> -             if ($realfile =~ /Kconfig/ &&
>> -                 $line =~ /.\s*depends on\s+.*\bEXPERIMENTAL\b/) {
>> -                     WARN("CONFIG_EXPERIMENTAL",
>> -                          "Use of CONFIG_EXPERIMENTAL is deprecated. For alternatives, see https://lkml.org/lkml/2012/10/23/580\n");
>> -             }
>> -
>>  # discourage the use of boolean for type definition attributes of Kconfig options
>>               if ($realfile =~ /Kconfig/ &&
>>                   $line =~ /^\+\s*\bboolean\b/) {
>> @@ -3146,12 +3139,6 @@ sub process {
>>                       }
>>               }
>>
>> -# discourage the addition of CONFIG_EXPERIMENTAL in #if(def).
>> -             if ($line =~ /^\+\s*\#\s*if.*\bCONFIG_EXPERIMENTAL\b/) {
>> -                     WARN("CONFIG_EXPERIMENTAL",
>> -                          "Use of CONFIG_EXPERIMENTAL is deprecated. For alternatives, see https://lkml.org/lkml/2012/10/23/580\n");
>> -             }
>> -
>>  # check for RCS/CVS revision markers
>>               if ($rawline =~ /^\+.*\$(Revision|Log|Id)(?:\$|)/) {
>>                       WARN("CVS_KEYWORD",