Index: kern_switch.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_switch.c,v
retrieving revision 1.136
diff -p -u -r1.136 kern_switch.c
--- kern_switch.c	20 Sep 2007 20:38:43 -0000	1.136
+++ kern_switch.c	2 Oct 2007 21:41:10 -0000
@@ -133,16 +133,6 @@ choosethread(void)
 {
 	struct thread *td;
 
-#if defined(SMP) && (defined(__i386__) || defined(__amd64__))
-	if (smp_active == 0 && PCPU_GET(cpuid) != 0) {
-		/* Shutting down, run idlethread on AP's */
-		td = PCPU_GET(idlethread);
-		CTR1(KTR_RUNQ, "choosethread: td=%p (idle)", td);
-		TD_SET_RUNNING(td);
-		return (td);
-	}
-#endif
-
 retry:
 	td = sched_choose();
 
@@ -184,7 +174,7 @@ critical_exit(void)
 	td = curthread;
 	KASSERT(td->td_critnest != 0,
 	    ("critical_exit: td_critnest == 0"));
-#ifdef PREEMPTION
+
 	if (td->td_critnest == 1) {
 		td->td_critnest = 0;
 		if (td->td_owepreempt) {
@@ -196,7 +186,6 @@ critical_exit(void)
 			thread_unlock(td);
 		}
 	} else
-#endif
 		td->td_critnest--;
 
 	CTR4(KTR_CRITICAL, "critical_exit by thread %p (%ld, %s) to %d", td,
Index: kern_synch.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_synch.c,v
retrieving revision 1.301
diff -p -u -r1.301 kern_synch.c
--- kern_synch.c	17 Sep 2007 05:27:20 -0000	1.301
+++ kern_synch.c	2 Oct 2007 08:18:19 -0000
@@ -553,8 +553,11 @@ synch_setup(dummy)
 int
 yield(struct thread *td, struct yield_args *uap)
 {
-	mtx_assert(&Giant, MA_NOTOWNED);
-	(void)uap;
-	sched_relinquish(td);
+
+	thread_lock(td);
+	sched_prio(td, PRI_MAX_TIMESHARE);
+	mi_switch(SW_VOL, NULL);
+	thread_unlock(td);
+	td->td_retval[0] = 0;
 	return (0);
 }
Index: p1003_1b.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/p1003_1b.c,v
retrieving revision 1.35
diff -p -u -r1.35 p1003_1b.c
--- p1003_1b.c	5 Mar 2007 13:10:57 -0000	1.35
+++ p1003_1b.c	2 Oct 2007 21:55:48 -0000
@@ -241,7 +241,8 @@ int
 sched_yield(struct thread *td, struct sched_yield_args *uap)
 {
 
-	return (ksched_yield(ksched));
+	sched_relinquish(curthread);
+	return 0;
 }
 
 int
Index: sched_4bsd.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/sched_4bsd.c,v
retrieving revision 1.105
diff -p -u -r1.105 sched_4bsd.c
--- sched_4bsd.c	21 Sep 2007 04:10:23 -0000	1.105
+++ sched_4bsd.c	2 Oct 2007 08:08:36 -0000
@@ -1324,8 +1324,6 @@ void
 sched_relinquish(struct thread *td)
 {
 	thread_lock(td);
-	if (td->td_pri_class == PRI_TIMESHARE)
-		sched_prio(td, PRI_MAX_TIMESHARE);
 	SCHED_STAT_INC(switch_relinquish);
 	mi_switch(SW_VOL, NULL);
 	thread_unlock(td);
Index: sched_ule.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/sched_ule.c,v
retrieving revision 1.209
diff -p -u -r1.209 sched_ule.c
--- sched_ule.c	24 Sep 2007 00:28:54 -0000	1.209
+++ sched_ule.c	2 Oct 2007 22:26:14 -0000
@@ -2502,8 +2515,6 @@ void
 sched_relinquish(struct thread *td)
 {
 	thread_lock(td);
-	if (td->td_pri_class == PRI_TIMESHARE)
-		sched_prio(td, PRI_MAX_TIMESHARE);
 	SCHED_STAT_INC(switch_relinquish);
 	mi_switch(SW_VOL, NULL);
 	thread_unlock(td);