checkpatch: look for c99 comments in ctx_locate_comment

Some checks look for comments around a specific function like
read_barrier_depends.

Extend the check to support both c89 and c90 comment styles.

	c89 /* comment */
or
	c99 // comment

For c99 comments, only look a 3 single lines, the line being scanned,
the line above and the line below the line being scanned rather than
the patch diff context.

Signed-off-by: Joe Perches <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Tested-by: Paul E. McKenney <[email protected]>
Cc: Marco Elver <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Alexander Potapenko <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Andy Whitcroft <[email protected]>
Cc: Will Deacon <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

scripts/checkpatch.pl

@@ -1676,8 +1676,16 @@ sub ctx_statement_level {
 sub ctx_locate_comment {
 	my ($first_line, $end_line) = @_;
 
+	# If c99 comment on the current line, or the line before or after
+	my ($current_comment) = ($rawlines[$end_line - 1] =~ m@^\+.*(//.*$)@);
+	return $current_comment if (defined $current_comment);
+	($current_comment) = ($rawlines[$end_line - 2] =~ m@^[\+ ].*(//.*$)@);
+	return $current_comment if (defined $current_comment);
+	($current_comment) = ($rawlines[$end_line] =~ m@^[\+ ].*(//.*$)@);
+	return $current_comment if (defined $current_comment);
+
 	# Catch a comment on the end of the line itself.
-	my ($current_comment) = ($rawlines[$end_line - 1] =~ m@.*(/\*.*\*/)\s*(?:\\\s*)?$@);
+	($current_comment) = ($rawlines[$end_line - 1] =~ m@.*(/\*.*\*/)\s*(?:\\\s*)?$@);
 	return $current_comment if (defined $current_comment);
 
 	# Look through the context and try and figure out if there is a