Index: sched_ule.c
===================================================================
--- sched_ule.c	(revision 197110)
+++ sched_ule.c	(working copy)
@@ -1821,19 +1821,17 @@
 	 * not holding either run-queue lock.
 	 */
 	spinlock_enter();
-	thread_block_switch(td);	/* This releases the lock on tdq. */
-	TDQ_LOCK(tdn);
-	tdq_add(tdn, td, flags);
-	tdq_notify(td->td_sched);
-	/*
-	 * After we unlock tdn the new cpu still can't switch into this
-	 * thread until we've unblocked it in cpu_switch().  The lock
-	 * pointers may match in the case of HTT cores.  Don't unlock here
-	 * or we can deadlock when the other CPU runs the IPI handler.
-	 */
-	if (TDQ_LOCKPTR(tdn) != TDQ_LOCKPTR(tdq)) {
-		TDQ_UNLOCK(tdn);
+	thread_block_switch(td);
+
+	if (TDQ_LOCKPTR(tdn) == TDQ_LOCKPTR(tdq)) {
 		TDQ_LOCK(tdq);
+		tdq_add(tdn, td, flags);
+		tdq_notify(td->td_sched);
+	} else {
+		tdq_lock_pair(tdn, tdq);
+		tdq_add(tdn, td, flags);
+		tdq_notify(td->td_sched);
+		TDQ_UNLOCK(tdn);
 	}
 	spinlock_exit();
 #endif