sched: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE

Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/bd80780f19b4f9b4a765acc353c8dbc130274dd6.1392103744.git.yangds.fnst@cn.fujitsu.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/auto_group.c

@@ -203,7 +203,7 @@ int proc_sched_autogroup_set_nice(struct task_struct *p, int nice)
 	struct autogroup *ag;
 	int err;
 
-	if (nice < -20 || nice > 19)
+	if (nice < MIN_NICE || nice > MAX_NICE)
 		return -EINVAL;
 
 	err = security_task_setnice(current, nice);

kernel/sched/core.c

@@ -2993,7 +2993,7 @@ void set_user_nice(struct task_struct *p, long nice)
 	unsigned long flags;
 	struct rq *rq;
 
-	if (task_nice(p) == nice || nice < -20 || nice > 19)
+	if (task_nice(p) == nice || nice < MIN_NICE || nice > MAX_NICE)
 		return;
 	/*
 	 * We have to be careful, if called from sys_setpriority(),
@@ -3072,10 +3072,10 @@ SYSCALL_DEFINE1(nice, int, increment)
 		increment = 40;
 
 	nice = task_nice(current) + increment;
-	if (nice < -20)
-		nice = -20;
-	if (nice > 19)
-		nice = 19;
+	if (nice < MIN_NICE)
+		nice = MIN_NICE;
+	if (nice > MAX_NICE)
+		nice = MAX_NICE;
 
 	if (increment < 0 && !can_nice(current, nice))
 		return -EPERM;
@@ -3623,7 +3623,7 @@ static int sched_copy_attr(struct sched_attr __user *uattr,
 	 * XXX: do we want to be lenient like existing syscalls; or do we want
 	 * to be strict and return an error on out-of-bounds values?
 	 */
-	attr->sched_nice = clamp(attr->sched_nice, -20, 19);
+	attr->sched_nice = clamp(attr->sched_nice, MIN_NICE, MAX_NICE);
 
 out:
 	return ret;