[PATCH] checkpatch: suppress false long-line warining

[Yury Norov <ynorov@caviumnetworks.com>]

For DOS-formatted patches, extra ^M symbol at the end of line
increases overall line length by 1.

It triggers unneeded warning if line is exactly 80 chars length.
This patch fixes it.

Discovered in discussion to this patch:
https://lkml.org/lkml/2017/11/25/24

Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
---
 scripts/checkpatch.pl | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 95cda3ecc66b..a14d36f7df13 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -59,6 +59,7 @@ my $conststructsfile = "$D/const_structs.checkpatch";
 my $typedefsfile = "";
 my $color = "auto";
 my $allow_c99_comments = 1;
+my $is_dos_line;
 
 sub help {
 	my ($exitcode) = @_;
@@ -2731,7 +2732,9 @@ sub process {
 		next if (!$hunk_line || $line =~ /^-/);
 
 #trailing whitespace
+		$is_dos_line = 0;
 		if ($line =~ /^\+.*\015/) {
+			$is_dos_line = 1 if (!$fix_inplace);
 			my $herevet = "$here\n" . cat_vet($rawline) . "\n";
 			if (ERROR("DOS_LINE_ENDINGS",
 				  "DOS line endings\n" . $herevet) &&
@@ -2884,7 +2887,12 @@ sub process {
 # if LONG_LINE is ignored, the other 2 types are also ignored
 #
 
-		if ($line =~ /^\+/ && $length > $max_line_length) {
+		# If DOS line detected, additional ^M symbol at the end of
+		# line increases line length, so increase max_line_length
+		# accordingly.
+		my $__max_line_length = $max_line_length + $is_dos_line;
+
+		if ($line =~ /^\+/ && $length > $__max_line_length) {
 			my $msg_type = "LONG_LINE";
 
 			# Check the allowed long line types first
@@ -2892,7 +2900,7 @@ sub process {
 			# logging functions that end in a string that starts
 			# before $max_line_length
 			if ($line =~ /^\+\s*$logFunctions\s*\(\s*(?:(?:KERN_\S+\s*|[^"]*))?($String\s*(?:|,|\)\s*;)\s*)$/ &&
-			    length(expand_tabs(substr($line, 1, length($line) - length($1) - 1))) <= $max_line_length) {
+			    length(expand_tabs(substr($line, 1, length($line) - length($1) - 1))) <= $__max_line_length) {
 				$msg_type = "";
 
 			# lines with only strings (w/ possible termination)
@@ -2910,12 +2918,12 @@ sub process {
 
 			# a comment starts before $max_line_length
 			} elsif ($line =~ /($;[\s$;]*)$/ &&
-				 length(expand_tabs(substr($line, 1, length($line) - length($1) - 1))) <= $max_line_length) {
+				 length(expand_tabs(substr($line, 1, length($line) - length($1) - 1))) <= $__max_line_length) {
 				$msg_type = "LONG_LINE_COMMENT"
 
 			# a quoted string starts before $max_line_length
 			} elsif ($sline =~ /\s*($String(?:\s*(?:\\|,\s*|\)\s*;\s*))?)$/ &&
-				 length(expand_tabs(substr($line, 1, length($line) - length($1) - 1))) <= $max_line_length) {
+				 length(expand_tabs(substr($line, 1, length($line) - length($1) - 1))) <= $__max_line_length) {
 				$msg_type = "LONG_LINE_STRING"
 			}
 
-- 
2.11.0