checkpatch: make "return is not a function" test quieter

This test is a bit noisy and opinions seem to agree that it should not
warn in a lot more situations.

It seems people agree that:

	return (foo || bar);
and
	return foo || bar;

are both acceptable style and checkpatch should be silent about them.

For now, it warns on parentheses around a simple constant or a single
function or a ternary.

	return (foo);
	return (foo(bar));
	return (foo ? bar : baz);

The last ternary test may be quieted in the future.

Modify the deparenthesize function to only strip balanced leading and
trailing parentheses.

Signed-off-by: Joe Perches <joe@perches.com>
Cc: Julia Lawall <julia.lawall@lip6.fr>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Cc: Monam Agarwal <monamagarwal123@gmail.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 15 insertions, 7 deletions

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index c624b04d0070..f0ea8a037a6d 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -439,9 +439,14 @@ our $FuncArg = qr{$Typecast{0,1}($LvalOrFunc|$Constant)};
 sub deparenthesize {
         my ($string) = @_;
         return "" if (!defined($string));
-        $string =~ s@^\s*\(\s*@@g;
-        $string =~ s@\s*\)\s*$@@g;
+
+        while ($string =~ /^\s*\(.*\)\s*$/) {
+                $string =~ s@^\s*\(\s*@@;
+                $string =~ s@\s*\)\s*$@@;
+        }
+
         $string =~ s@\s+@ @g;
+
         return $string;
 }
 
@@ -3374,14 +3379,17 @@ sub process {
                         }
                 }
 
-# Return is not a function.
+# return is not a function
                 if (defined($stat) && $stat =~ /^.\s*return(\s*)\(/s) {
                         my $spacing = $1;
                         if ($^V && $^V ge 5.10.0 &&
-                            $stat =~ /^.\s*return\s*$balanced_parens\s*;\s*$/) {
-                                ERROR("RETURN_PARENTHESES",
-                                      "return is not a function, parentheses are not required\n" . $herecurr);
-
+                            $stat =~ /^.\s*return\s*($balanced_parens)\s*;\s*$/) {
+                                my $value = $1;
+                                $value = deparenthesize($value);
+                                if ($value =~ m/^\s*$FuncArg\s*(?:\?|$)/) {
+                                        ERROR("RETURN_PARENTHESES",
+                                              "return is not a function, parentheses are not required\n" . $herecurr);
+                                }
                         } elsif ($spacing !~ /\s+/) {
                                 ERROR("SPACING",
                                       "space required before the open parenthesis '('\n" . $herecurr);