checkpatch: additional MAINTAINER section entry ordering checks

There is a preferred order for the entries in MAINTAINERS sections.

See commits 3b50142d ("MAINTAINERS: sort field names for all
entries") and 6680125e ("MAINTAINERS: list the section entries in
the preferred order")

Add checkpatch tests to try to keep that ordering.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: http://lkml.kernel.org/r/17677130b3ca62d79817e6a22546bad39d7e81b4.camel@perches.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -3062,9 +3062,10 @@ sub process {
 			#print "is_start<$is_start> is_end<$is_end> length<$length>\n";
 		}
 
-# check for MAINTAINERS entries that don't have the right form
-		if ($realfile =~ /^MAINTAINERS$/ &&
-		    $rawline =~ /^\+[A-Z]:/ &&
+# check MAINTAINERS entries
+		if ($realfile =~ /^MAINTAINERS$/) {
+# check MAINTAINERS entries for the right form
+			if ($rawline =~ /^\+[A-Z]:/ &&
 			    $rawline !~ /^\+[A-Z]:\t\S/) {
 				if (WARN("MAINTAINERS_STYLE",
 					 "MAINTAINERS entries use one tab after TYPE:\n" . $herecurr) &&
@@ -3072,6 +3073,34 @@ sub process {
 					$fixed[$fixlinenr] =~ s/^(\+[A-Z]):\s*/$1:\t/;
 				}
 			}
+# check MAINTAINERS entries for the right ordering too
+			my $preferred_order = 'MRLSWQBCPTFXNK';
+			if ($rawline =~ /^\+[A-Z]:/ &&
+			    $prevrawline =~ /^[\+ ][A-Z]:/) {
+				$rawline =~ /^\+([A-Z]):\s*(.*)/;
+				my $cur = $1;
+				my $curval = $2;
+				$prevrawline =~ /^[\+ ]([A-Z]):\s*(.*)/;
+				my $prev = $1;
+				my $prevval = $2;
+				my $curindex = index($preferred_order, $cur);
+				my $previndex = index($preferred_order, $prev);
+				if ($curindex < 0) {
+					WARN("MAINTAINERS_STYLE",
+					     "Unknown MAINTAINERS entry type: '$cur'\n" . $herecurr);
+				} else {
+					if ($previndex >= 0 && $curindex < $previndex) {
+						WARN("MAINTAINERS_STYLE",
+						     "Misordered MAINTAINERS entry - list '$cur:' before '$prev:'\n" . $hereprev);
+					} elsif ((($prev eq 'F' && $cur eq 'F') ||
+						  ($prev eq 'X' && $cur eq 'X')) &&
+						 ($prevval cmp $curval) > 0) {
+						WARN("MAINTAINERS_STYLE",
+						     "Misordered MAINTAINERS entry - list file patterns in alphabetic order\n" . $hereprev);
+					}
+				}
+			}
+		}
 
 # discourage the use of boolean for type definition attributes of Kconfig options
 		if ($realfile =~ /Kconfig/ &&