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From:   Miles Chen <miles.chen@mediatek.com>
To:     Andy Whitcroft <apw@canonical.com>, Joe Perches <joe@perches.com>
CC:     <linux-kernel@vger.kernel.org>,
        <linux-mediatek@lists.infradead.org>, <wsd_upstream@mediatek.com>,
        Miles Chen <miles.chen@mediatek.com>,
        Yingjoe Chen <yingjoe.chen@mediatek.com>
Subject: [PATCH v3] checkpatch: add several Kconfig default value tests
Date:   Wed, 31 Jul 2019 23:13:09 +0800
Message-ID: <20190731151309.1167-1-miles.chen@mediatek.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This change adds 3 Kconfig default value tests.
Repost patch v3 (Follow Joe's suggestion in v2)

1. discourage default n cases:
e.g.,
default n

2. discourage default "[ynm]" cases:
e.g.,
arch/powerpc/Kconfig:   default "y" if PPC_POWERNV
arch/powerpc/Kconfig:   default "y" if PPC_POWERNV
arch/powerpc/Kconfig:   default "n"
drivers/auxdisplay/Kconfig:     default "n"
drivers/crypto/Kconfig: default "m"
drivers/rapidio/devices/Kconfig:        default "n"

3. discourage default EXPERT or default !EXPERT cases:
e.g.,
drivers/hid/Kconfig:    default !EXPERT

tested cases:
default m
default n if ALPHA_EV5 || ALPHA_EV56 || (ALPHA_EV4 && !ALPHA_LCA)
default y if ALPHA_QEMU
default n if PPC_POWERNV
default n
default EXPERT
default !EXPERT
default "m"
default "n"
default "y" if EXPERT
default "y" if PPC_POWERNV

test result:
WARNING: 'default n' is the default value, no need to write it explicitly
+       default n

WARNING: Avoid using default EXPERT
+       default EXPERT

WARNING: Avoid using default EXPERT
+       default !EXPERT

WARNING: Use 'default m' not 'default "m"'
+       default "m"

WARNING: Use 'default n' not 'default "n"'
+       default "n"

WARNING: Use 'default y' not 'default "y"'
+       default "y" if EXPERT

WARNING: Use 'default y' not 'default "y"'
+       default "y" if PPC_POWERNV

test --fix capability:
default n => delete line
default "m" => default m
default "n" => default n
default "y" if EXPERT => default y if EXPERT
default "y" if PPC_POWERNV => default y if PPC_POWERNV
default !EXPERT => no change
default EXPERT => no change

Change since v1:
discourage default n$
discourage default "[ynm]"
discourage default \!?EXPERT

Change since v2:
test Kconfig in a single block
print precise message such as 'default "m"', not 'default "[ynm]"'
provide --fix capability

Cc: Joe Perches <joe@perches.com>
Cc: Yingjoe Chen <yingjoe.chen@mediatek.com>
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
---
 scripts/checkpatch.pl | 139 ++++++++++++++++++++++++++----------------
 1 file changed, 85 insertions(+), 54 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 93a7edfe0f05..b080eea68cf6 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2932,60 +2932,98 @@ sub process {
 				      "Do not include the paragraph about writing to the Free Software Foundation's mailing address from the sample GPL notice. The FSF has changed addresses in the past, and may do so again. Linux already includes a copy of the GPL.\n" . $herevet)
 		}
 
-# check for Kconfig help text having a real description
-# Only applies when adding the entry originally, after that we do not have
-# sufficient context to determine whether it is indeed long enough.
-		if ($realfile =~ /Kconfig/ &&
-		    # 'choice' is usually the last thing on the line (though
-		    # Kconfig supports named choices), so use a word boundary
-		    # (\b) rather than a whitespace character (\s)
-		    $line =~ /^\+\s*(?:config|menuconfig|choice)\b/) {
-			my $length = 0;
-			my $cnt = $realcnt;
-			my $ln = $linenr + 1;
-			my $f;
-			my $is_start = 0;
-			my $is_end = 0;
-			for (; $cnt > 0 && defined $lines[$ln - 1]; $ln++) {
-				$f = $lines[$ln - 1];
-				$cnt-- if ($lines[$ln - 1] !~ /^-/);
-				$is_end = $lines[$ln - 1] =~ /^\+/;
-
-				next if ($f =~ /^-/);
-				last if (!$file && $f =~ /^\@\@/);
-
-				if ($lines[$ln - 1] =~ /^\+\s*(?:bool|tristate|prompt)\s*["']/) {
-					$is_start = 1;
-				} elsif ($lines[$ln - 1] =~ /^\+\s*(?:help|---help---)\s*$/) {
-					if ($lines[$ln - 1] =~ "---help---") {
-						WARN("CONFIG_DESCRIPTION",
-						     "prefer 'help' over '---help---' for new help texts\n" . $herecurr);
+# Kconfig tests
+		if ($realfile =~ /Kconfig/) {
+			# check for Kconfig help text having a real description
+			# Only applies when adding the entry originally, after
+			# that we do not have sufficient context to determine
+			# whether it is indeed long enough.
+			# 'choice' is usually the last thing on the line (though
+			# Kconfig supports named choices), so use a word
+			# boundary (\b) rather than a whitespace character (\s)
+			if ($line =~ /^\+\s*(?:config|menuconfig|choice)\b/) {
+				my $length = 0;
+				my $cnt = $realcnt;
+				my $ln = $linenr + 1;
+				my $f;
+				my $is_start = 0;
+				my $is_end = 0;
+				for (; $cnt > 0 && defined $lines[$ln - 1]; $ln++) {
+					$f = $lines[$ln - 1];
+					$cnt-- if ($lines[$ln - 1] !~ /^-/);
+					$is_end = $lines[$ln - 1] =~ /^\+/;
+
+					next if ($f =~ /^-/);
+					last if (!$file && $f =~ /^\@\@/);
+
+					if ($lines[$ln - 1] =~ /^\+\s*(?:bool|tristate|prompt)\s*["']/) {
+						$is_start = 1;
+					} elsif ($lines[$ln - 1] =~ /^\+\s*(?:help|---help---)\s*$/) {
+						if ($lines[$ln - 1] =~ "---help---") {
+							WARN("CONFIG_DESCRIPTION",
+							     "prefer 'help' over '---help---' for new help texts\n" . $herecurr);
+						}
+						$length = -1;
+					}
+
+					$f =~ s/^.//;
+					$f =~ s/#.*//;
+					$f =~ s/^\s+//;
+					next if ($f =~ /^$/);
+
+					# This only checks context lines in the patch
+					# and so hopefully shouldn't trigger false
+					# positives, even though some of these are
+					# common words in help texts
+					if ($f =~ /^\s*(?:config|menuconfig|choice|endchoice|
+							   if|endif|menu|endmenu|source)\b/x) {
+						$is_end = 1;
+						last;
 					}
-					$length = -1;
+					$length++;
+				}
+				if ($is_start && $is_end && $length < $min_conf_desc_length) {
+					WARN("CONFIG_DESCRIPTION",
+					     "please write a paragraph that describes the config symbol fully\n" . $herecurr);
 				}
+				#print "is_start<$is_start> is_end<$is_end> length<$length>\n";
+			}
 
-				$f =~ s/^.//;
-				$f =~ s/#.*//;
-				$f =~ s/^\s+//;
-				next if ($f =~ /^$/);
-
-				# This only checks context lines in the patch
-				# and so hopefully shouldn't trigger false
-				# positives, even though some of these are
-				# common words in help texts
-				if ($f =~ /^\s*(?:config|menuconfig|choice|endchoice|
-						  if|endif|menu|endmenu|source)\b/x) {
-					$is_end = 1;
-					last;
+# discourage the use of boolean for type definition attributes
+			if ($line =~ /^\+\s*\bboolean\b/) {
+				if (WARN("CONFIG_TYPE_BOOLEAN",
+					 "Use of boolean is deprecated, please use bool instead\n" . $herecurr) &&
+				    $fix) {
+					$fixed[$fixlinenr] =~ s/\bboolean\b/bool/;
+				}
+			}
+
+# Kconfig: discourage redundant 'default n'
+			if ($line =~ /^\+\s*default\s+n$/) {
+				if (WARN("CONFIG_DEFAULT_VALUE_STYLE",
+					 "'default n' is the default value, no need to write it explicitly\n" . $herecurr) &&
+				    $fix) {
+					fix_delete_line($fixlinenr, $rawline);
 				}
-				$length++;
 			}
-			if ($is_start && $is_end && $length < $min_conf_desc_length) {
-				WARN("CONFIG_DESCRIPTION",
-				     "please write a paragraph that describes the config symbol fully\n" . $herecurr);
+
+# Kconfig: discourage quoted defaults: use default [ynm], not default "[ynm]"
+			if ($rawline =~ /^\+\s*default\s+"([ynm])"/) {
+				if (WARN("CONFIG_DEFAULT_VALUE_STYLE",
+					 "Use 'default $1' not 'default \"$1\"'\n" . $herecurr) &&
+				    $fix) {
+					$fixed[$fixlinenr] =~ s/\b(default\s+)"(.)"/$1$2/;
+				}
+			}
+
+# Kconfig: discourage using default EXPERT or !EXPERT
+			if ($line =~ /^\+\s*default\s+\!?\s*EXPERT\b/) {
+				WARN("CONFIG_DEFAULT_VALUE_STYLE",
+				     "Avoid using default EXPERT\n" . $herecurr);
 			}
-			#print "is_start<$is_start> is_end<$is_end> length<$length>\n";
 		}
+# End of Kconfig tests
+
 
 # check for MAINTAINERS entries that don't have the right form
 		if ($realfile =~ /^MAINTAINERS$/ &&
@@ -2998,13 +3036,6 @@ sub process {
 			}
 		}
 
-# discourage the use of boolean for type definition attributes of Kconfig options
-		if ($realfile =~ /Kconfig/ &&
-		    $line =~ /^\+\s*\bboolean\b/) {
-			WARN("CONFIG_TYPE_BOOLEAN",
-			     "Use of boolean is deprecated, please use bool instead.\n" . $herecurr);
-		}
-
 		if (($realfile =~ /Makefile.*/ || $realfile =~ /Kbuild.*/) &&
 		    ($line =~ /\+(EXTRA_[A-Z]+FLAGS).*/)) {
 			my $flag = $1;
-- 
2.18.0