rcu: The rcu_gp_cleanup() function does not need cpu_needs_another_gp()

All of the cpu_needs_another_gp() function's checks (except for
newly arrived callbacks) have been subsumed into the rcu_gp_cleanup()
function's scan of the rcu_node tree.  This commit therefore drops the
call to cpu_needs_another_gp().  The check for newly arrived callbacks
is supplied by rcu_accelerate_cbs().  Any needed advancing (as in the
earlier rcu_advance_cbs() call) will be supplied when the corresponding
CPU becomes aware of the end of the now-completed grace period.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>

kernel/rcu/tree.c

@@ -2150,11 +2150,9 @@ static void rcu_gp_cleanup(struct rcu_state *rsp)
 		needgp = true;
 	}
 	/* Advance CBs to reduce false positives below. */
-	needgp = rcu_advance_cbs(rsp, rnp, rdp) || needgp;
-	if (needgp || cpu_needs_another_gp(rsp, rdp)) {
+	if (!rcu_accelerate_cbs(rsp, rnp, rdp) && needgp) {
 		WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT);
-		trace_rcu_grace_period(rsp->name,
-				       READ_ONCE(rsp->gpnum),
+		trace_rcu_grace_period(rsp->name, READ_ONCE(rsp->gpnum),
 				       TPS("newreq"));
 	}
 	WRITE_ONCE(rsp->gp_flags, rsp->gp_flags & RCU_GP_FLAG_INIT);