percpu-refcount: Replace call_rcu_sched() with call_rcu()

Now that call_rcu()'s callback is not invoked until after all
preempt-disable regions of code have completed (in addition to explicitly
marked RCU read-side critical sections), call_rcu() can be used in place
of call_rcu_sched().  This commit therefore makes that change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>
Acked-by: Tejun Heo <tj@kernel.org>

lib/percpu-refcount.c

@@ -181,7 +181,7 @@ static void __percpu_ref_switch_to_atomic(struct percpu_ref *ref,
 	ref->confirm_switch = confirm_switch ?: percpu_ref_noop_confirm_switch;
 
 	percpu_ref_get(ref);	/* put after confirmation */
-	call_rcu_sched(&ref->rcu, percpu_ref_switch_to_atomic_rcu);
+	call_rcu(&ref->rcu, percpu_ref_switch_to_atomic_rcu);
 }
 
 static void __percpu_ref_switch_to_percpu(struct percpu_ref *ref)