rcu: Use MAX_NICE to replace hardcoding of 19

Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Dongsheng Yang <yangds.fnst@cn.fujitsu.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/5b3bf232f41b33ab703a1595e94671b303e2d1fc.1392103744.git.yangds.fnst@cn.fujitsu.comSigned-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/rcu/torture.c

@@ -805,7 +805,7 @@ rcu_torture_writer(void *arg)
 	static DEFINE_RCU_RANDOM(rand);
 
 	VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
-	set_user_nice(current, 19);
+	set_user_nice(current, MAX_NICE);
 
 	do {
 		schedule_timeout_uninterruptible(1);
@@ -871,7 +871,7 @@ rcu_torture_fakewriter(void *arg)
 	DEFINE_RCU_RANDOM(rand);
 
 	VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
-	set_user_nice(current, 19);
+	set_user_nice(current, MAX_NICE);
 
 	do {
 		schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
@@ -987,7 +987,7 @@ rcu_torture_reader(void *arg)
 	unsigned long long ts;
 
 	VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
-	set_user_nice(current, 19);
+	set_user_nice(current, MAX_NICE);
 	if (irqreader && cur_ops->irq_capable)
 		setup_timer_on_stack(&t, rcu_torture_timer, 0);
 
@@ -1584,7 +1584,7 @@ static int rcu_torture_barrier_cbs(void *arg)
 
 	init_rcu_head_on_stack(&rcu);
 	VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
-	set_user_nice(current, 19);
+	set_user_nice(current, MAX_NICE);
 	do {
 		wait_event(barrier_cbs_wq[myid],
 			   (newphase =