rcu: Use the BITS_PER_LONG macro

sizeof(unsigned long) * 8 is the number of bits in an unsigned long
variable, replace it with BITS_PER_LONG macro to make it simpler.

Signed-off-by: Jinjie Ruan <[email protected]>
Reviewed-by: "Paul E. McKenney" <[email protected]>
Signed-off-by: Neeraj Upadhyay <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>

Author: Jinjie Ruan

kernel/rcu/tree.c

@@ -5580,8 +5580,7 @@ void rcu_init_geometry(void)
 	 * Complain and fall back to the compile-time values if this
 	 * limit is exceeded.
 	 */
-	if (rcu_fanout_leaf < 2 ||
-	    rcu_fanout_leaf > sizeof(unsigned long) * 8) {
+	if (rcu_fanout_leaf < 2 || rcu_fanout_leaf > BITS_PER_LONG) {
 		rcu_fanout_leaf = RCU_FANOUT_LEAF;
 		WARN_ON(1);
 		return;