checkstack: sort output by size and function name

Sort output by size and in addition by function name.  This increases
readability for cases where there are many functions with the same stack
usage.

Link: https://lkml.kernel.org/r/20231120183719.2188479-3-hca@linux.ibm.comSigned-off-by: Heiko Carstens <hca@linux.ibm.com>
Cc: Maninder Singh <maninder1.s@samsung.com>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Vaneet Narang <v.narang@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

scripts/checkstack.pl

@@ -189,5 +189,20 @@ if ($total_size > $min_stack) {
 	push @stack, "$intro$total_size\n";
 }
 
-# Sort output by size (last field)
-print sort { ($b =~ /:\t*(\d+)$/)[0] <=> ($a =~ /:\t*(\d+)$/)[0] } @stack;
+# Sort output by size (last field) and function name if size is the same
+sub sort_lines {
+	my ($a, $b) = @_;
+
+	my $num_a = $1 if $a =~ /:\t*(\d+)$/;
+	my $num_b = $1 if $b =~ /:\t*(\d+)$/;
+	my $func_a = $1 if $a =~ / (.*):/;
+	my $func_b = $1 if $b =~ / (.*):/;
+
+	if ($num_a != $num_b) {
+		return $num_b <=> $num_a;
+	} else {
+		return $func_a cmp $func_b;
+	}
+}
+
+print sort { sort_lines($a, $b) } @stack;