--- //depot/vendor/freebsd/src/sys/i386/i386/machdep.c	2004/07/19 02:50:39
+++ //depot/projects/smpng/sys/i386/i386/machdep.c	2004/07/28 18:25:59
@@ -1103,8 +1103,11 @@
 	pcb->pcb_gs = _udatasel;
 	load_gs(_udatasel);
 
+	mtx_lock_spin(&sched_lock);
 	if (td->td_proc->p_md.md_ldt)
 		user_ldt_free(td);
+	else
+		mtx_unlock_spin(&sched_lock);
   
 	bzero((char *)regs, sizeof(struct trapframe));
 	regs->tf_eip = entry;
--- //depot/vendor/freebsd/src/sys/i386/i386/sys_machdep.c	2004/04/07 20:52:05
+++ //depot/projects/smpng/sys/i386/i386/sys_machdep.c	2004/04/16 18:42:25
@@ -292,7 +292,7 @@
 #endif
 
 /*
- * Must be called with either sched_lock free or held but not recursed.
+ * Must be called with sched_lock held but not recursed.
  * If it does not return NULL, it will return with it owned.
  */
 struct proc_ldt *
@@ -300,9 +300,8 @@
 {
 	struct proc_ldt *pldt, *new_ldt;
 
-	if (mtx_owned(&sched_lock))
-		mtx_unlock_spin(&sched_lock);
-	mtx_assert(&sched_lock, MA_NOTOWNED);
+	mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
+	mtx_unlock_spin(&sched_lock);
 	MALLOC(new_ldt, struct proc_ldt *, sizeof(struct proc_ldt),
 		M_SUBPROC, M_WAITOK);
 
@@ -333,7 +332,7 @@
 }
 
 /*
- * Must be called either with sched_lock free or held but not recursed.
+ * Must be called with sched_lock held but not recursed.
  * If md_ldt is not NULL, it will return with sched_lock released.
  */
 void
@@ -345,8 +344,6 @@
 	if (pldt == NULL)
 		return;
 
-	if (!mtx_owned(&sched_lock))
-		mtx_lock_spin(&sched_lock);
 	mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
 	if (td == PCPU_GET(curthread)) {
 		lldt(_default_ldt);
@@ -416,7 +413,7 @@
 	int error = 0, i;
 	int largest_ld;
 	struct mdproc *mdp = &td->td_proc->p_md;
-	struct proc_ldt *pldt = 0;
+	struct proc_ldt *pldt;
 	struct i386_ldt_args ua, *uap = &ua;
 	union descriptor *descs, *dp;
 	int descs_size;
@@ -630,16 +627,19 @@
 
 	if (len > MAX_LD)
 		return (ENOMEM);
-	if (len < NLDT+1)
-		len = NLDT+1;
+	if (len < NLDT + 1)
+		len = NLDT + 1;
+
+	/* allocate user ldt */
+	mtx_lock_spin(&sched_lock);
 	pldt = mdp->md_ldt;
-	/* allocate user ldt */
 	if (!pldt || len > pldt->ldt_len) {
-		struct proc_ldt *new_ldt = user_ldt_alloc(mdp, len);
+		struct proc_ldt *new_ldt;
+
+		new_ldt = user_ldt_alloc(mdp, len);
 		if (new_ldt == NULL)
 			return (ENOMEM);
 		pldt = mdp->md_ldt;
-		/* sched_lock was held by user_ldt_alloc */
 		if (pldt) {
 			if (new_ldt->ldt_len > pldt->ldt_len) {
 				old_ldt_base = pldt->ldt_base;
@@ -676,6 +676,7 @@
 		set_user_ldt(mdp);
 		mtx_unlock_spin(&sched_lock);
 #endif
-	}
+	} else
+		mtx_unlock_spin(&sched_lock);
 	return (0);
 }
--- //depot/vendor/freebsd/src/sys/i386/i386/vm_machdep.c	2004/07/20 01:40:31
+++ //depot/projects/smpng/sys/i386/i386/vm_machdep.c	2004/07/28 18:25:59
@@ -152,7 +152,10 @@
 		if ((flags & RFMEM) == 0) {
 			/* unshare user LDT */
 			struct mdproc *mdp1 = &p1->p_md;
-			struct proc_ldt *pldt = mdp1->md_ldt;
+			struct proc_ldt *pldt;
+
+			mtx_lock_spin(&sched_lock);
+			pldt = mdp1->md_ldt;
 			if (pldt && pldt->ldt_refcnt > 1) {
 				pldt = user_ldt_alloc(mdp1, pldt->ldt_len);
 				if (pldt == NULL)
@@ -160,7 +163,8 @@
 				mdp1->md_ldt = pldt;
 				set_user_ldt(mdp1);
 				user_ldt_free(td1);
-			}
+			} else
+				mtx_unlock_spin(&sched_lock);
 		}
 		return;
 	}
@@ -233,7 +237,7 @@
 
         /* Copy the LDT, if necessary. */
 	mtx_lock_spin(&sched_lock);
-        if (mdp2->md_ldt != 0) {
+        if (mdp2->md_ldt != NULL) {
 		if (flags & RFMEM) {
 			mdp2->md_ldt->ldt_refcnt++;
 		} else {
@@ -285,11 +289,14 @@
 
 	/* Reset pc->pcb_gs and %gs before possibly invalidating it. */
 	mdp = &td->td_proc->p_md;
+	mtx_lock_spin(&sched_lock);
 	if (mdp->md_ldt) {
 		td->td_pcb->pcb_gs = _udatasel;
 		load_gs(_udatasel);
 		user_ldt_free(td);
-	}
+	} else
+		mtx_unlock_spin(&sched_lock);
+
 	if (pcb->pcb_flags & PCB_DBREGS) {
 		/* disable all hardware breakpoints */
 		reset_dbregs();