sched,locktorture: Convert to sched_set_fifo()

Because SCHED_FIFO is a broken scheduler model (see previous patches)
take away the priority field, the kernel can't possibly make an
informed decision.

Effectively changes prio from 99 to 50.

Cc: paulmck@kernel.org
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>

kernel/locking/locktorture.c

@@ -436,8 +436,6 @@ static int torture_rtmutex_lock(void) __acquires(torture_rtmutex)
 
 static void torture_rtmutex_boost(struct torture_random_state *trsp)
 {
-	int policy;
-	struct sched_param param;
 	const unsigned int factor = 50000; /* yes, quite arbitrary */
 
 	if (!rt_task(current)) {
@@ -448,8 +446,7 @@ static void torture_rtmutex_boost(struct torture_random_state *trsp)
 		 */
 		if (trsp && !(torture_random(trsp) %
 			      (cxt.nrealwriters_stress * factor))) {
-			policy = SCHED_FIFO;
-			param.sched_priority = MAX_RT_PRIO - 1;
+			sched_set_fifo(current);
 		} else /* common case, do nothing */
 			return;
 	} else {
@@ -462,13 +459,10 @@ static void torture_rtmutex_boost(struct torture_random_state *trsp)
 		 */
 		if (!trsp || !(torture_random(trsp) %
 			       (cxt.nrealwriters_stress * factor * 2))) {
-			policy = SCHED_NORMAL;
-			param.sched_priority = 0;
+			sched_set_normal(current, 0);
 		} else /* common case, do nothing */
 			return;
 	}
-
-	sched_setscheduler_nocheck(current, policy, &param);
 }
 
 static void torture_rtmutex_delay(struct torture_random_state *trsp)