[PATCH V2] checkpatch: Categorize some long line length checks

Joe Perches
2015-05-24T02:49:46Z

Many lines of code extend beyond the maximum line length.
Some of these are possibly justified by use type.

For instance:

structure definitions where comments are added per member like:
struct foo {
type member; /* some long description */

And lines that don't fit the typical logging message style
where a string constant is used like:

SOME_MACRO(args, "Some long string");

Categorize these long line types so that checkpatch can use a
command-line --ignore=<type> option to avoid emitting some long
line warnings.

One of the existing checkpatch exclusions allowed kernel-doc
argument documentation to exceed 80 columns because old versions
of kernel-doc required single line documentation. The requirement
was removed in 2009 so remove that exclusion.

Add documentation to make the test a bit clearer.

Signed-off-by: Joe Perches <joe@perches.com>
---
scripts/checkpatch.pl | 60 ++++++++++++++++++++++++++++++++++++++++++---------
1 file changed, 50 insertions(+), 10 deletions(-)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 89b1df4..a5d2d11 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2510,16 +2510,56 @@ sub process {
# check we are in a valid source file if not then ignore this hunk
next if ($realfile !~ /\.(h|c|s|S|pl|sh|dtsi|dts)$/);

-#line length limit
- if ($line =~ /^\+/ && $prevrawline !~ /\/\*\*/ &&
- $rawline !~ /^.\s*\*\s*\@$Ident\s/ &&
- !($line =~ /^\+\s*$logFunctions\s*\(\s*(?:(KERN_\S+\s*|[^"]*))?$String\s*(?:|,|\)\s*;)\s*$/ ||
- $line =~ /^\+\s*$String\s*(?:\s*|,|\)\s*;)\s*$/ ||
- $line =~ /^\+\s*#\s*define\s+\w+\s+$String$/) &&
- $length > $max_line_length)
- {
- WARN("LONG_LINE",
- "line over $max_line_length characters\n" . $herecurr);
+# line length limit (with some exclusions)
+#
+# There are a few types of lines that may extend beyond $max_line_length:
+# logging functions like pr_info that end in a string
+# lines with a single string
+# #defines that are a single string
+#
+# There are 3 different line length message types:
+# LONG_LINE_COMMENT a comment starts before but extends beyond $max_linelength
+# LONG_LINE_STRING a string starts before but extends beyond $max_line_length
+# LONG_LINE all other lines longer than $max_line_length
+#
+# if LONG_LINE is ignored, the other 2 types are also ignored
+#
+
+ if ($length > $max_line_length) {
+ my $msg_type = "LONG_LINE";
+
+ # Check the allowed long line types first
+
+ # 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) {
+ $msg_type = "";
+
+ # lines with only strings (w/ possible termination)
+ # #defines with only strings
+ } elsif ($line =~ /^\+\s*$String\s*(?:\s*|,|\)\s*;)\s*$/ ||
+ $line =~ /^\+\s*#\s*define\s+\w+\s+$String$/) {
+ $msg_type = "";
+
+ # Otherwise set the alternate message types
+
+ # a comment starts before $max_line_length
+ } elsif ($line =~ /($;[\s$;]*)$/ &&
+ length(expand_tabs(substr($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) {
+ $msg_type = "LONG_LINE_STRING"
+ }
+
+ if ($msg_type ne "" &&
+ (show_type("LONG_LINE") || show_type($msg_type))) {
+ WARN($msg_type,
+ "line over $max_line_length characters\n" . $herecurr);
+ }
}

# check for adding lines without a newline.