--- /home/rookie/perforce/smpng/attilio_smpng/i386/i386/intr_machdep.c	Thu Jun  7 23:33:08 2007
+++ intr_machdep.c	Mon Sep 24 23:49:41 2007
@@ -61,6 +61,8 @@
 
 typedef void (*mask_fn)(void *);
 
+extern struct mtx intr_wait_lock;
+
 static int intrcnt_index;
 static struct intsrc *interrupt_sources[NUM_IO_INTS];
 static struct sx intr_table_lock;
@@ -481,6 +483,7 @@
 	STAILQ_INIT(&pics);
 	sx_init(&intr_table_lock, "intr sources");
 	mtx_init(&intrcnt_lock, "intrcnt", NULL, MTX_SPIN);
+	mtx_init(&intr_wait_lock, "intr wait state", NULL, MTX_SPIN);
 }
 SYSINIT(intr_init, SI_SUB_INTR, SI_ORDER_FIRST, intr_init, NULL)
 
--- /home/rookie/perforce/smpng/attilio_smpng/kern/kern_intr.c	Thu Jun  7 23:33:11 2007
+++ kern_intr.c	Mon Sep 24 23:48:02 2007
@@ -76,6 +76,7 @@
 	uintptr_t event;
 };
 
+struct	mtx intr_wait_lock;
 struct	intr_event *clk_intr_event;
 struct	intr_event *tty_intr_event;
 void	*softclock_ih;
@@ -342,7 +343,9 @@
 	if (error)
 		panic("kthread_create() failed with %d", error);
 	td = FIRST_THREAD_IN_PROC(p);	/* XXXKSE */
+	mtx_lock_spin(&intr_wait_lock);
 	thread_lock(td);
+	thread_lock_set(td, &intr_wait_lock);
 	sched_class(td, PRI_ITHD);
 	TD_SET_IWAIT(td);
 	thread_unlock(td);
@@ -367,7 +370,9 @@
 	if (error)
 		panic("kthread_create() failed with %d", error);
 	td = FIRST_THREAD_IN_PROC(p);	/* XXXKSE */
+	mtx_lock_spin(&intr_wait_lock);
 	thread_lock(td);
+	thread_lock_set(td, &intr_wait_lock);
 	sched_class(td, PRI_ITHD);
 	TD_SET_IWAIT(td);
 	thread_unlock(td);
@@ -1128,12 +1133,15 @@
 		 * lock.  This may take a while and it_need may get
 		 * set again, so we have to check it again.
 		 */
+		mtx_lock_spin(&intr_wait_lock);
 		thread_lock(td);
 		if (!ithd->it_need && !(ithd->it_flags & IT_DEAD)) {
+			thread_lock_set(td, &intr_wait_lock);
 			TD_SET_IWAIT(td);
 			ie->ie_count = 0;
 			mi_switch(SW_VOL, NULL);
-		}
+		} else
+			mtx_unlock_spin(&intr_wait_lock);
 		thread_unlock(td);
 	}
 }
@@ -1202,12 +1210,15 @@
 		 * lock.  This may take a while and it_need may get
 		 * set again, so we have to check it again.
 		 */
+		mtx_lock_spin(&intr_wait_lock);
 		thread_lock(td);
 		if (!ithd->it_need && !(ithd->it_flags & IT_DEAD)) {
+			thread_lock_set(td, &intr_wait_lock);
 			TD_SET_IWAIT(td);
 			ie->ie_count = 0;
 			mi_switch(SW_VOL, NULL);
-		}
+		} else
+			mtx_unlock_spin(&intr_wait_lock);
 		thread_unlock(td);
 	}
 }