checkpatch: improve "return is not a function" test

Find a few more cases where parentheses are used around the value of a
return statement.

This now uses the "$balanced_parens" test and also makes the test depend
on perl v5.10 and higher.

This now finds return with parenthesis uses the old code did not find
like:

ERROR: return is not a function, parentheses are not required
torvalds#211: FILE: arch/m68k/include/asm/sun3xflop.h:211:
+		return ((error == 0) ? 0 : -1);

Signed-off-by: Joe Perches <[email protected]>
Tested-by: David Cohen <[email protected]>
Acked-by: David Cohen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

scripts/checkpatch.pl

@@ -3233,21 +3233,10 @@ sub process {
 		}
 
 # Return is not a function.
-		if (defined($stat) && $stat =~ /^.\s*return(\s*)(\(.*);/s) {
+		if (defined($stat) && $stat =~ /^.\s*return(\s*)\(/s) {
 			my $spacing = $1;
-			my $value = $2;
-
-			# Flatten any parentheses
-			$value =~ s/\(/ \(/g;
-			$value =~ s/\)/\) /g;
-			while ($value =~ s/\[[^\[\]]*\]/1/ ||
-			       $value !~ /(?:$Ident|-?$Constant)\s*
-					     $Compare\s*
-					     (?:$Ident|-?$Constant)/x &&
-			       $value =~ s/\([^\(\)]*\)/1/) {
-			}
-#print "value<$value>\n";
-			if ($value =~ /^\s*(?:$Ident|-?$Constant)\s*$/) {
+			if ($^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);
 
@@ -3256,6 +3245,7 @@ sub process {
 				      "space required before the open parenthesis '('\n" . $herecurr);
 			}
 		}
+
 # Return of what appears to be an errno should normally be -'ve
 		if ($line =~ /^.\s*return\s*(E[A-Z]*)\s*;/) {
 			my $name = $1;