livepatch: Replace synchronize_sched() with synchronize_rcu()

Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can be
replaced by synchronize_rcu().  This commit therefore makes this change,
even though it is but a comment.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 5bc3498..304d5eb 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -52,7 +52,7 @@
 
 /*
  * This function is just a stub to implement a hard force
- * of synchronize_sched(). This requires synchronizing
+ * of synchronize_rcu(). This requires synchronizing
  * tasks even in userspace and idle.
  */
 static void klp_sync(struct work_struct *work)
@@ -175,7 +175,7 @@
 void klp_update_patch_state(struct task_struct *task)
 {
 	/*
-	 * A variant of synchronize_sched() is used to allow patching functions
+	 * A variant of synchronize_rcu() is used to allow patching functions
 	 * where RCU is not watching, see klp_synchronize_transition().
 	 */
 	preempt_disable_notrace();