s390/numa: correct early_param handling

When command line options are used without specifying values
(e.g. "emu_size" instead of "emu_size="), the value is NULL. Check that
before performing string operations and further processing.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/numa/mode_emu.c

@@ -558,9 +558,7 @@ static int __init early_parse_emu_nodes(char *p)
 {
 	int count;
 
-	if (kstrtoint(p, 0, &count) != 0 || count <= 0)
-		return 0;
-	if (count <= 0)
+	if (!p || kstrtoint(p, 0, &count) != 0 || count <= 0)
 		return 0;
 	emu_nodes = min(count, MAX_NUMNODES);
 	return 0;
@@ -572,6 +570,7 @@ early_param("emu_nodes", early_parse_emu_nodes);
  */
 static int __init early_parse_emu_size(char *p)
 {
+	if (p)
 		emu_size = memparse(p, NULL);
 	return 0;
 }

arch/s390/numa/numa.c

@@ -158,6 +158,8 @@ early_param("numa_debug", parse_debug);
 
 static int __init parse_numa(char *parm)
 {
+	if (!parm)
+		return 1;
 	if (strcmp(parm, numa_mode_plain.name) == 0)
 		mode = &numa_mode_plain;
 #ifdef CONFIG_NUMA_EMU