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[PATCH v3 1/2] checkpatch: add Kconfig 'default n' test

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  [PATCH v3 1/2] checkpatch: add Kconfig 'default n' test Yingjoe Chen <yingjoe.chen@mediatek.com> - 2016-06-04 07:20 +0200
    [PATCH v3 2/2] checkpatch: testing more config for Kconfig help text Yingjoe Chen <yingjoe.chen@mediatek.com> - 2016-06-04 07:20 +0200
    Re: [PATCH v3 1/2] checkpatch: add Kconfig 'default n' test Joe Perches <joe@perches.com> - 2016-06-06 18:50 +0200
      Re: [PATCH v3 1/2] checkpatch: add Kconfig 'default n' test Andy Whitcroft <apw@canonical.com> - 2016-06-06 21:20 +0200
        Re: [PATCH v3 1/2] checkpatch: add Kconfig 'default n' test Yingjoe Chen <yingjoe.chen@mediatek.com> - 2016-06-07 15:20 +0200
          Re: [PATCH v3 1/2] checkpatch: add Kconfig 'default n' test Paul Bolle <pebolle@tiscali.nl> - 2016-06-08 21:50 +0200

#1413647 — [PATCH v3 1/2] checkpatch: add Kconfig 'default n' test

If a Kconfig config option doesn't specify 'default', the default
will be n. Adding 'default n' is unnecessary.

Add a test to warn about this.

Signed-off-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
---
For this series, rebase to v4.7-rc1 and dropped 'relax Kconfig help text
line number threshold' patch.

Let me know what you think. Thanks.


Change in v3:
- Rebase to v4.7-rc1

Change in v2:
- Change according to Joe Perches' suggesti

 scripts/checkpatch.pl | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 6750595..f5ce804 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2683,6 +2683,13 @@ sub process {
 			     "Use of boolean is deprecated, please use bool instead.\n" . $herecurr);
 		}
 
+# discourage the use of default n
+		if ($realfile =~ /Kconfig/ &&
+		    $line =~ /^\+\s*default\s*n\s*(#.*|$)/i) {
+			WARN("CONFIG_DEFAULT_N",
+			     "Use of default n is unnecessary, default is n when omitted.\n" . $herecurr);
+		}
+
 		if (($realfile =~ /Makefile.*/ || $realfile =~ /Kbuild.*/) &&
 		    ($line =~ /\+(EXTRA_[A-Z]+FLAGS).*/)) {
 			my $flag = $1;
-- 
1.9.1

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#1413650 — [PATCH v3 2/2] checkpatch: testing more config for Kconfig help text

Current help text check only check a config option if it is followed
by another config.
Adding check for help text if the next entry is menuconfig, choice/
endchoice, comment, menu/endmenu, if/endif, source or end of file.

Signed-off-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
---
 scripts/checkpatch.pl | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index f5ce804..8e17593 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2646,6 +2646,12 @@ sub process {
 				next if ($f =~ /^-/);
 				last if (!$file && $f =~ /^\@\@/);
 
+				if ($f !~ /^[+\- ]/) {
+					# End of file
+					$is_end = 1;
+					last;
+				}
+
 				if ($lines[$ln - 1] =~ /^\+\s*(?:bool|tristate)\s*\"/) {
 					$is_start = 1;
 				} elsif ($lines[$ln - 1] =~ /^\+\s*(?:---)?help(?:---)?$/) {
@@ -2656,7 +2662,7 @@ sub process {
 				$f =~ s/#.*//;
 				$f =~ s/^\s+//;
 				next if ($f =~ /^$/);
-				if ($f =~ /^\s*config\s/) {
+				if ($f =~ /^(?:config\s|menuconfig\s|choice\s|endchoice\s*$|comment\s|menu\s|endmenu\s*$|if\s|endif\s*$|source\s)/) {
 					$is_end = 1;
 					last;
 				}
-- 
1.9.1

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#1415284

On Sat, 2016-06-04 at 13:10 +0800, Yingjoe Chen wrote:
> If a Kconfig config option doesn't specify 'default', the default
> will be n. Adding 'default n' is unnecessary.
> Add a test to warn about this.

Is it obvious that a Kconfig has "default n" ?
This seems to work, but is this useful?

> Signed-off-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
> ---
> For this series, rebase to v4.7-rc1 and dropped 'relax Kconfig help text
> line number threshold' patch.
> 
> Let me know what you think. Thanks.
> 
> 
> Change in v3:
> - Rebase to v4.7-rc1
> 
> Change in v2:
> - Change according to Joe Perches' suggesti
> 
>  scripts/checkpatch.pl | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
> index 6750595..f5ce804 100755
> --- a/scripts/checkpatch.pl
> +++ b/scripts/checkpatch.pl
> @@ -2683,6 +2683,13 @@ sub process {
>  			     "Use of boolean is deprecated, please use bool instead.\n" . $herecurr);
>  		}
>  
> +# discourage the use of default n
> +		if ($realfile =~ /Kconfig/ &&
> +		    $line =~ /^\+\s*default\s*n\s*(#.*|$)/i) {
> +			WARN("CONFIG_DEFAULT_N",
> +			     "Use of default n is unnecessary, default is n when omitted.\n" . $herecurr);
> +		}
> +
>  		if (($realfile =~ /Makefile.*/ || $realfile =~ /Kbuild.*/) &&
>  		    ($line =~ /\+(EXTRA_[A-Z]+FLAGS).*/)) {
>  			my $flag = $1;

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#1415384

On Mon, Jun 06, 2016 at 09:43:15AM -0700, Joe Perches wrote:
> On Sat, 2016-06-04 at 13:10 +0800, Yingjoe Chen wrote:
> > If a Kconfig config option doesn't specify 'default', the default
> > will be n. Adding 'default n' is unnecessary.
> > Add a test to warn about this.
> 
> Is it obvious that a Kconfig has "default n" ?
> This seems to work, but is this useful?

> > +		if ($realfile =~ /Kconfig/ &&
> > +		    $line =~ /^\+\s*default\s*n\s*(#.*|$)/i) {

I wonder particually when the submitter has supplied a comment, presumably
to tell us why it defaults to 'n'.  I feel more accepting of rejecting
uncommented ones than those with.

> > +			WARN("CONFIG_DEFAULT_N",
> > +			     "Use of default n is unnecessary, default is n when omitted.\n" . $herecurr);
> > +		}
> > +
> >  		if (($realfile =~ /Makefile.*/ || $realfile =~ /Kbuild.*/) &&
> >  		    ($line =~ /\+(EXTRA_[A-Z]+FLAGS).*/)) {
> >  			my $flag = $1;

-apw

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#1416157

Hi,

Thanks for the review.


On Mon, 2016-06-06 at 20:10 +0100, Andy Whitcroft wrote:
> On Mon, Jun 06, 2016 at 09:43:15AM -0700, Joe Perches wrote:
> > On Sat, 2016-06-04 at 13:10 +0800, Yingjoe Chen wrote:
> > > If a Kconfig config option doesn't specify 'default', the default
> > > will be n. Adding 'default n' is unnecessary.
> > > Add a test to warn about this.
> > 
> > Is it obvious that a Kconfig has "default n" ?
> > This seems to work, but is this useful?


While sending patch for upstream, I saw maintainers request it to be
removed. So I think it might worth adding check to it.
Some examples from google:

http://lists.infradead.org/pipermail/linux-arm-kernel/2012-September/120733.html
https://lkml.org/lkml/2013/3/16/153
https://lkml.org/lkml/2016/5/23/657


> 
> > > +		if ($realfile =~ /Kconfig/ &&
> > > +		    $line =~ /^\+\s*default\s*n\s*(#.*|$)/i) {
> 
> I wonder particually when the submitter has supplied a comment, presumably
> to tell us why it defaults to 'n'.  I feel more accepting of rejecting
> uncommented ones than those with.


How about change this to /^\+\s*default\s*n$/i ?

Joe.C

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#1417802

On di, 2016-06-07 at 21:16 +0800, Yingjoe Chen wrote:
> On Mon, 2016-06-06 at 20:10 +0100, Andy Whitcroft wrote:
> > > Is it obvious that a Kconfig has "default n" ?
> > > This seems to work, but is this useful?
>
> While sending patch for upstream, I saw maintainers request it to be
> removed. So I think it might worth adding check to it.
> Some examples from google:
> 
> http://lists.infradead.org/pipermail/linux-arm-kernel/2012-September/1
> 20733.html
> https://lkml.org/lkml/2013/3/16/153
> https://lkml.org/lkml/2016/5/23/657

There's one rather subtle case where setting "default n" is, sort of,
useful. See lkml.kernel.org/r/<178407860.0zoJnDfCo1@tacticalops> . 

(I seem to remember disagreeing here. Ie, in my view setting defaults
for a specific Kconfig symbol at two different places is confusing at
best. People probably weren't convinced by my objections. I also
remember diving into this by looking at the various places where a
Kconfig symbol was being set twice. I must have ended that endeavor when
it became clear to me I was't making any progress.)

Even though there's  a corner case where "default n" is useful, it could
still be worth to add a checkpatch check that warns about it. But I
can't say I feel strongly about this either way.


Paul Bolle

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