cpuset: limit the input of cpuset.sched_relax_domain_level

We allow the inputs to be [-1 ... SD_LV_MAX), and return -EINVAL
for inputs outside this range.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Acked-by: Paul Jackson <pj@sgi.com>
Acked-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Documentation/cpusets.txt

@@ -542,7 +542,7 @@ otherwise initial value -1 that indicates the cpuset has no request.
    2  : search cores in a package.
    3  : search cpus in a node [= system wide on non-NUMA system]
  ( 4  : search nodes in a chunk of node [on NUMA system] )
- ( 5~ : search system wide [on NUMA system])
+ ( 5  : search system wide [on NUMA system] )
 
 This file is per-cpuset and affect the sched domain where the cpuset
 belongs to.  Therefore if the flag 'sched_load_balance' of a cpuset

kernel/cpuset.c

@@ -1037,8 +1037,8 @@ int current_cpuset_is_being_rebound(void)
 
 static int update_relax_domain_level(struct cpuset *cs, s64 val)
 {
-	if ((int)val < 0)
-		val = -1;
+	if (val < -1 || val >= SD_LV_MAX)
+		return -EINVAL;
 
 	if (val != cs->relax_domain_level) {
 		cs->relax_domain_level = val;

kernel/sched.c

@@ -6877,7 +6877,12 @@ static int default_relax_domain_level = -1;
 
 static int __init setup_relax_domain_level(char *str)
 {
-	default_relax_domain_level = simple_strtoul(str, NULL, 0);
+	unsigned long val;
+
+	val = simple_strtoul(str, NULL, 0);
+	if (val < SD_LV_MAX)
+		default_relax_domain_level = val;
+
 	return 1;
 }
 __setup("relax_domain_level=", setup_relax_domain_level);