Use the MI ithread helper functions in the x86 interrupt code.

12 files changed, 402 insertions, 886 deletions

diff --git a/sys/amd64/amd64/legacy.c b/sys/amd64/amd64/legacy.c
index 76c41ae..ce2c9cd 100644
--- a/sys/amd64/amd64/legacy.c
+++ b/sys/amd64/amd64/legacy.c
@@ -560,23 +560,17 @@ nexus_setup_intr(device_t bus, device_t child, struct resource *irq,
 		 int flags, void (*ihand)(void *), void *arg, void **cookiep)
 {
 	driver_t	*driver;
-	int		error, icflags;
-	int 		pri;		/* interrupt thread priority */
+	int		error;
 
 	/* somebody tried to setup an irq that failed to allocate! */
 	if (irq == NULL)
 		panic("nexus_setup_intr: NULL irq resource!");
 
 	*cookiep = 0;
-	if (irq->r_flags & RF_SHAREABLE)
-		icflags = 0;
-	else
-		icflags = INTR_EXCL;
+	if ((irq->r_flags & RF_SHAREABLE) == 0)
+		flags |= INTR_EXCL;
 
 	driver = device_get_driver(child);
-	pri = ithread_priority(flags);
-	if (flags & INTR_FAST)
-		icflags |= INTR_FAST;
 
 	/*
 	 * We depend here on rman_activate_resource() being idempotent.
@@ -585,10 +579,8 @@ nexus_setup_intr(device_t bus, device_t child, struct resource *irq,
 	if (error)
 		return (error);
 
-	*cookiep = inthand_add(device_get_nameunit(child), irq->r_start,
-	    ihand, arg, pri, icflags);
-	if (*cookiep == NULL)
-		error = EINVAL;	/* XXX ??? */
+	error = inthand_add(device_get_nameunit(child), irq->r_start,
+	    ihand, arg, flags, cookiep);
 
 	return (error);
 }
diff --git a/sys/amd64/amd64/nexus.c b/sys/amd64/amd64/nexus.c
index 76c41ae..ce2c9cd 100644
--- a/sys/amd64/amd64/nexus.c
+++ b/sys/amd64/amd64/nexus.c
@@ -560,23 +560,17 @@ nexus_setup_intr(device_t bus, device_t child, struct resource *irq,
 		 int flags, void (*ihand)(void *), void *arg, void **cookiep)
 {
 	driver_t	*driver;
-	int		error, icflags;
-	int 		pri;		/* interrupt thread priority */
+	int		error;
 
 	/* somebody tried to setup an irq that failed to allocate! */
 	if (irq == NULL)
 		panic("nexus_setup_intr: NULL irq resource!");
 
 	*cookiep = 0;
-	if (irq->r_flags & RF_SHAREABLE)
-		icflags = 0;
-	else
-		icflags = INTR_EXCL;
+	if ((irq->r_flags & RF_SHAREABLE) == 0)
+		flags |= INTR_EXCL;
 
 	driver = device_get_driver(child);
-	pri = ithread_priority(flags);
-	if (flags & INTR_FAST)
-		icflags |= INTR_FAST;
 
 	/*
 	 * We depend here on rman_activate_resource() being idempotent.
@@ -585,10 +579,8 @@ nexus_setup_intr(device_t bus, device_t child, struct resource *irq,
 	if (error)
 		return (error);
 
-	*cookiep = inthand_add(device_get_nameunit(child), irq->r_start,
-	    ihand, arg, pri, icflags);
-	if (*cookiep == NULL)
-		error = EINVAL;	/* XXX ??? */
+	error = inthand_add(device_get_nameunit(child), irq->r_start,
+	    ihand, arg, flags, cookiep);
 
 	return (error);
 }
diff --git a/sys/amd64/isa/intr_machdep.c b/sys/amd64/isa/intr_machdep.c
index 70b9378..2dd96d7 100644
--- a/sys/amd64/isa/intr_machdep.c
+++ b/sys/amd64/isa/intr_machdep.c
@@ -93,10 +93,12 @@
  * Per-interrupt data.
  */
 u_long	*intr_countp[ICU_LEN];		/* pointers to interrupt counters */
-driver_intr_t *intr_handler[ICU_LEN];	/* first level interrupt handler */
-struct ithd *ithds[ICU_LEN];		/* real interrupt handler */
+driver_intr_t	*intr_handler[ICU_LEN];	/* first level interrupt handler */
+struct	 ithd *ithds[ICU_LEN];		/* real interrupt handler */
 void	*intr_unit[ICU_LEN];
 
+static struct	mtx ithds_table_lock;	/* protect the ithds table */
+
 static inthand_t *fastintr[ICU_LEN] = {
 	&IDTVEC(fastintr0), &IDTVEC(fastintr1),
 	&IDTVEC(fastintr2), &IDTVEC(fastintr3),
@@ -133,6 +135,10 @@ static inthand_t *slowintr[ICU_LEN] = {
 
 static driver_intr_t isa_strayintr;
 
+static void	ithds_init(void *dummy);
+static void	ithread_enable(int vector);
+static void	ithread_disable(int vector);
+
 #ifdef PC98
 #define NMI_PARITY 0x04
 #define NMI_EPARITY 0x02
@@ -388,7 +394,7 @@ isa_irq_pending()
  * vmstat(8) and the like.
  */
 static void
-update_intrname(int intr, char *name)
+update_intrname(int intr, const char *name)
 {
 	char buf[32];
 	char *cp;
@@ -536,132 +542,90 @@ icu_unset(intr, handler)
 	return (0);
 }
 
-struct intrhand *
+static void
+ithds_init(void *dummy)
+{
+
+	mtx_init(&ithds_table_lock, "ithread table lock", MTX_SPIN);
+}
+SYSINIT(ithds_init, SI_SUB_INTR, SI_ORDER_SECOND, ithds_init, NULL);
+
+static void
+ithread_enable(int vector)
+{
+
+	INTREN(1 << vector);
+}
+
+static void
+ithread_disable(int vector)
+{
+
+	INTRDIS(1 << vector);
+}
+
+int
 inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
-	     int pri, int flags)
+    enum intr_type flags, void **cookiep)
 {
-	struct ithd *ithd = ithds[irq];	/* descriptor for the IRQ */
-	struct intrhand *head;		/* chain of handlers for IRQ */
-	struct intrhand *idesc;		/* descriptor for this handler */
-	struct proc *p;			/* interrupt thread */
+	struct ithd *ithd;		/* descriptor for the IRQ */
 	int errcode = 0;
+	int created_ithd = 0;
 
-	if (name == NULL)		/* no name? */
-		panic ("anonymous interrupt");
-	if (ithd == NULL || ithd->it_ih == NULL) {
-		/* first handler for this irq. */
-		if (ithd == NULL) {
-			ithd = malloc(sizeof (struct ithd), M_DEVBUF,
-			    M_WAITOK | M_ZERO);
-			if (ithd == NULL)
-				return (NULL);
-			ithd->irq = irq;
+	/*
+	 * Work around a race where more than one CPU may be registering
+	 * handlers on the same IRQ at the same time.
+	 */
+	mtx_lock_spin(&ithds_table_lock);
+	ithd = ithds[irq];
+	mtx_unlock_spin(&ithds_table_lock);
+	if (ithd == NULL) {
+		errcode = ithread_create(&ithd, irq, 0, ithread_disable,
+		    ithread_enable, "irq%d:", irq);
+		if (errcode)
+			return (errcode);
+		mtx_lock_spin(&ithds_table_lock);
+		if (ithds[irq] == NULL) {
 			ithds[irq] = ithd;
+			created_ithd++;
+			mtx_unlock_spin(&ithds_table_lock);
+		} else {
+			struct ithd *orphan;
+
+			orphan = ithd;
+			ithd = ithds[irq];
+			mtx_unlock_spin(&ithds_table_lock);
+			ithread_destroy(orphan);
 		}
+	}
+
+	errcode = ithread_add_handler(ithd, name, handler, arg,
+	    ithread_priority(flags), flags, cookiep);
+	
+	if ((flags & INTR_FAST) == 0 || errcode)
 		/*
-		 * If we have a fast interrupt, we need to set the
-		 * handler address directly.  Do that below.  For a
-		 * slow interrupt, we don't need to know more details,
-		 * so do it here because it's tidier.
-		 */
-		if ((flags & INTR_FAST)	== 0) {
-			/*
-			 * Only create a kernel thread if we don't already
-			 * have one.
-			 */
-			if (ithd->it_proc == NULL) {
-				errcode = kthread_create(ithd_loop, NULL, &p,
-				    RFSTOPPED | RFHIGHPID, "irq%d: %s", irq,
-				    name);
-				if (errcode)
-					panic("inthand_add: Can't create "
-					      "interrupt thread");
-				p->p_intr_nesting_level = 1;
-				p->p_rtprio.type = RTP_PRIO_ITHREAD;
-				p->p_stat = SWAIT; /* we're idle */
-
-				/* Put in linkages. */
-				ithd->it_proc = p;
-				p->p_ithd = ithd;
-			} else
-				snprintf(ithd->it_proc->p_comm, MAXCOMLEN,
-				    "irq%d: %s", irq, name);
-			p->p_rtprio.prio = pri;
-
-			/*
-			 * The interrupt process must be in place, but
-			 * not necessarily schedulable, before we
-			 * initialize the ICU, since it may cause an
-			 * immediate interrupt.
-			 */
-			if (icu_setup(irq, &sched_ithd, arg, flags) != 0)
-				panic("inthand_add: Can't initialize ICU");
-		}
-	} else if ((flags & INTR_EXCL) != 0
-		   || (ithd->it_ih->ih_flags & INTR_EXCL) != 0) {
-		/*
-		 * We can't append the new handler if either
-		 * list ithd or new handler do not allow
-		 * interrupts to be shared.
+		 * The interrupt process must be in place, but
+		 * not necessarily schedulable, before we
+		 * initialize the ICU, since it may cause an
+		 * immediate interrupt.
 		 */
-		if (bootverbose)
-			printf("\tdevice combination %s and %s "
-			       "doesn't support shared irq%d\n",
-			       ithd->it_ih->ih_name, name, irq);
-		return(NULL);
-	} else if (flags & INTR_FAST) {
-		 /* We can only have one fast interrupt by itself. */
-		if (bootverbose)
-			printf("\tCan't add fast interrupt %s"
- 			       " to normal interrupt %s on irq%d",
-			       name, ithd->it_ih->ih_name, irq);
-		return (NULL);
-	} else {			/* update p_comm */
-		p = ithd->it_proc;
-		if (strlen(p->p_comm) + strlen(name) < MAXCOMLEN) {
-			strcat(p->p_comm, " ");
-			strcat(p->p_comm, name);
-		} else if (strlen(p->p_comm) == MAXCOMLEN)
-			p->p_comm[MAXCOMLEN - 1] = '+';
-		else
-			strcat(p->p_comm, "+");
-	}
-	idesc = malloc(sizeof (struct intrhand), M_DEVBUF, M_WAITOK | M_ZERO);
-	if (idesc == NULL)
-		return (NULL);
-
-	idesc->ih_handler = handler;
-	idesc->ih_argument = arg;
-	idesc->ih_flags = flags;
-	idesc->ih_ithd = ithd;
-
-	idesc->ih_name = malloc(strlen(name) + 1, M_DEVBUF, M_WAITOK);
-	if (idesc->ih_name == NULL) {
-		free(idesc, M_DEVBUF);
-		return (NULL);
-	}
-	strcpy(idesc->ih_name, name);
+		if (icu_setup(irq, &sched_ithd, arg, flags) != 0)
+			panic("inthand_add: Can't initialize ICU");
 
-	/* Slow interrupts got set up above. */
-	if ((flags & INTR_FAST)
-		&& (icu_setup(irq, idesc->ih_handler, idesc->ih_argument,
-			      idesc->ih_flags) != 0) ) {
-		if (bootverbose)
+	if (errcode)
+		return (errcode);
+	
+	if (flags & INTR_FAST) {
+		errcode = icu_setup(irq, handler, arg, flags);
+		if (errcode && bootverbose)
 			printf("\tinthand_add(irq%d) failed, result=%d\n", 
 			       irq, errcode);
-		free(idesc->ih_name, M_DEVBUF);
-		free(idesc, M_DEVBUF);
-		return NULL;
+		if (errcode)
+			return (errcode);
 	}
-	head = ithd->it_ih;		/* look at chain of handlers */
-	if (head) {
-		while (head->ih_next != NULL)
-			head = head->ih_next; /* find the end */
-		head->ih_next = idesc;	/* hook it in there */
-	} else
-		ithd->it_ih = idesc;	/* put it up front */
-	update_intrname(irq, idesc->ih_name);
-	return (idesc);
+
+	update_intrname(irq, name);
+	return (0);
 }
 
 /*
@@ -673,50 +637,9 @@ inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
  * structure to the system.  First ensure the handler is not actively
  * in use.
  */
-
 int
-inthand_remove(struct intrhand *idesc)
+inthand_remove(void *cookie)
 {
-	struct ithd *ithd;		/* descriptor for the IRQ */
-	struct intrhand *ih;		/* chain of handlers */
 
-	if (idesc == NULL)
-		return (-1);
-	ithd = idesc->ih_ithd;
-	ih = ithd->it_ih;
-
-	if (ih == idesc)		/* first in the chain */
-		ithd->it_ih = idesc->ih_next; /* unhook it */
-	else {
-		while ((ih != NULL)
-			&& (ih->ih_next != idesc) )
-			ih = ih->ih_next;
-		if (ih->ih_next != idesc)
-			return (-1);
-		ih->ih_next = ih->ih_next->ih_next;
-	}
-	
-	if (ithd->it_ih == NULL) {	/* no handlers left, */
-		icu_unset(ithd->irq, idesc->ih_handler);
-		ithds[ithd->irq] = NULL;
-
-		if ((idesc->ih_flags & INTR_FAST) == 0) {
-			mtx_lock_spin(&sched_lock);
-			if (ithd->it_proc->p_stat == SWAIT) {
-				ithd->it_proc->p_intr_nesting_level = 0;
-				ithd->it_proc->p_stat = SRUN;
-				setrunqueue(ithd->it_proc);
-				/*
-				 * We don't do an ast here because we really
-				 * don't care when it runs next.
-				 *
-				 * XXX: should we lower the threads priority?
-				 */
-			}
-			mtx_unlock_spin(&sched_lock);
-		}
-	}
-	free(idesc->ih_name, M_DEVBUF);
-	free(idesc, M_DEVBUF);
-	return (0);
+	return (ithread_remove_handler(cookie));
 }
diff --git a/sys/amd64/isa/intr_machdep.h b/sys/amd64/isa/intr_machdep.h
index 53d782f..b42c348 100644
--- a/sys/amd64/isa/intr_machdep.h
+++ b/sys/amd64/isa/intr_machdep.h
@@ -220,13 +220,10 @@ int	icu_unset __P((int intr, driver_intr_t *handler));
  * WARNING: These are internal functions and not to be used by device drivers!
  * They are subject to change without notice. 
  */
-struct intrhand *inthand_add(const char *name, int irq, driver_intr_t handler,
-			   void *arg, int pri, int flags);
-int inthand_remove(struct intrhand *idesc);
-void sched_ithd(void *);
-void ithd_loop(void *);
-void start_softintr(void *);
-void intr_soft(void *);
+int	inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
+	    enum intr_type flags, void **cookiep);
+int	inthand_remove(void *cookie);
+void	sched_ithd(void *dummy);
 
 #endif /* LOCORE */
 
diff --git a/sys/amd64/isa/ithread.c b/sys/amd64/isa/ithread.c
index 99a1abf..8fb1924 100644
--- a/sys/amd64/isa/ithread.c
+++ b/sys/amd64/isa/ithread.c
@@ -51,6 +51,8 @@
 #include <sys/unistd.h>
 #include <sys/errno.h>
 #include <sys/interrupt.h>
+#include <sys/random.h>
+#include <sys/time.h>
 #include <machine/md_var.h>
 #include <machine/segments.h>
 
@@ -64,6 +66,11 @@
 #include <sys/ktr.h>
 #include <machine/cpu.h>
 
+struct int_entropy {
+	struct proc *p;
+	int irq;
+};
+
 static u_int straycount[NHWI];
 
 #define	MAX_STRAY_LOG	5
@@ -87,6 +94,19 @@ sched_ithd(void *cookie)
 	 */
 	atomic_add_long(intr_countp[irq], 1); /* one more for this IRQ */
 	atomic_add_int(&cnt.v_intr, 1); /* one more global interrupt */
+
+	/*
+	 * If this interrupt is marked as being a source of entropy, use
+	 * the current timestamp to feed entropy to the PRNG.
+	 */
+	if (ir != NULL && (ir->it_flags & IT_ENTROPY)) {
+		struct int_entropy entropy;
+
+		entropy.irq = irq;
+		entropy.p = curproc;
+		random_harvest(&entropy, sizeof(entropy), 2, 0,
+			       RANDOM_INTERRUPT);
+	}
 		
 	/*
 	 * If we don't have an interrupt resource or an interrupt thread for
@@ -121,102 +141,13 @@ sched_ithd(void *cookie)
 /*		membar_lock(); */
 		ir->it_proc->p_stat = SRUN;
 		setrunqueue(ir->it_proc);
-		if (!cold) {
-			if (curproc != PCPU_GET(idleproc))
-				setrunqueue(curproc);
-			mi_switch();
-		}
+		need_resched();
 	}
 	else {
 		CTR3(KTR_INTR, "sched_ithd %d: it_need %d, state %d",
 			ir->it_proc->p_pid,
 		        ir->it_need,
 		        ir->it_proc->p_stat );
-		need_resched();
 	}
 	mtx_unlock_spin(&sched_lock);
 }
-
-/*
- * This is the main code for all interrupt threads.  It gets put on
- * whichkqs by setrunqueue above.
- */
-void
-ithd_loop(void *dummy)
-{
-	struct ithd *me;		/* our thread context */
-	struct intrhand *ih;		/* and our interrupt handler chain */
-
-	me = curproc->p_ithd;		/* point to myself */
-
-	/*
-	 * As long as we have interrupts outstanding, go through the
-	 * list of handlers, giving each one a go at it.
-	 */
-	for (;;) {
-		/*
-		 * If we don't have any handlers, then we are an orphaned
-		 * thread and just need to die.
-		 */
-		if (me->it_ih == NULL) {
-			CTR2(KTR_INTR, "ithd_loop pid %d(%s) exiting",
-			     me->it_proc->p_pid, me->it_proc->p_comm);
-			curproc->p_ithd = NULL;
-			free(me, M_DEVBUF);
-			mtx_lock(&Giant);
-			kthread_exit(0);
-		}
-
-		CTR3(KTR_INTR, "ithd_loop pid %d(%s) need=%d",
-		     me->it_proc->p_pid, me->it_proc->p_comm, me->it_need);
-		while (me->it_need) {
-			/*
-			 * Service interrupts.  If another interrupt
-			 * arrives while we are running, they will set
-			 * it_need to denote that we should make
-			 * another pass.
-			 */
-			me->it_need = 0;
-#if 0
-			membar_unlock(); /* push out "it_need=0" */
-#endif
-			for (ih = me->it_ih; ih != NULL; ih = ih->ih_next) {
-				CTR5(KTR_INTR,
-				    "ithd_loop pid %d ih=%p: %p(%p) flg=%x",
-				    me->it_proc->p_pid, (void *)ih,
-				    (void *)ih->ih_handler, ih->ih_argument,
-				    ih->ih_flags);
-
-				if ((ih->ih_flags & INTR_MPSAFE) == 0)
-					mtx_lock(&Giant);
-				ih->ih_handler(ih->ih_argument);
-				if ((ih->ih_flags & INTR_MPSAFE) == 0)
-					mtx_unlock(&Giant);
-			}
-		}
-
-		/*
-		 * Processed all our interrupts.  Now get the sched
-		 * lock.  This may take a while and it_need may get
-		 * set again, so we have to check it again.
-		 */
-		mtx_assert(&Giant, MA_NOTOWNED);
-		mtx_lock_spin(&sched_lock);
-		if (!me->it_need) {
-
-			INTREN (1 << me->irq); /* reset the mask bit */
-			me->it_proc->p_stat = SWAIT; /* we're idle */
-#ifdef APIC_IO
-			CTR2(KTR_INTR, "ithd_loop pid %d: done, apic_imen=%x",
-				me->it_proc->p_pid, apic_imen);
-#else
-			CTR2(KTR_INTR, "ithd_loop pid %d: done, imen=%x",
-				me->it_proc->p_pid, imen);
-#endif
-			mi_switch();
-			CTR1(KTR_INTR, "ithd_loop pid %d: resumed",
-				me->it_proc->p_pid);
-		}
-		mtx_unlock_spin(&sched_lock);
-	}
-}
diff --git a/sys/amd64/isa/nmi.c b/sys/amd64/isa/nmi.c
index 70b9378..2dd96d7 100644
--- a/sys/amd64/isa/nmi.c
+++ b/sys/amd64/isa/nmi.c
@@ -93,10 +93,12 @@
  * Per-interrupt data.
  */
 u_long	*intr_countp[ICU_LEN];		/* pointers to interrupt counters */
-driver_intr_t *intr_handler[ICU_LEN];	/* first level interrupt handler */
-struct ithd *ithds[ICU_LEN];		/* real interrupt handler */
+driver_intr_t	*intr_handler[ICU_LEN];	/* first level interrupt handler */
+struct	 ithd *ithds[ICU_LEN];		/* real interrupt handler */
 void	*intr_unit[ICU_LEN];
 
+static struct	mtx ithds_table_lock;	/* protect the ithds table */
+
 static inthand_t *fastintr[ICU_LEN] = {
 	&IDTVEC(fastintr0), &IDTVEC(fastintr1),
 	&IDTVEC(fastintr2), &IDTVEC(fastintr3),
@@ -133,6 +135,10 @@ static inthand_t *slowintr[ICU_LEN] = {
 
 static driver_intr_t isa_strayintr;
 
+static void	ithds_init(void *dummy);
+static void	ithread_enable(int vector);
+static void	ithread_disable(int vector);
+
 #ifdef PC98
 #define NMI_PARITY 0x04
 #define NMI_EPARITY 0x02
@@ -388,7 +394,7 @@ isa_irq_pending()
  * vmstat(8) and the like.
  */
 static void
-update_intrname(int intr, char *name)
+update_intrname(int intr, const char *name)
 {
 	char buf[32];
 	char *cp;
@@ -536,132 +542,90 @@ icu_unset(intr, handler)
 	return (0);
 }
 
-struct intrhand *
+static void
+ithds_init(void *dummy)
+{
+
+	mtx_init(&ithds_table_lock, "ithread table lock", MTX_SPIN);
+}
+SYSINIT(ithds_init, SI_SUB_INTR, SI_ORDER_SECOND, ithds_init, NULL);
+
+static void
+ithread_enable(int vector)
+{
+
+	INTREN(1 << vector);
+}
+
+static void
+ithread_disable(int vector)
+{
+
+	INTRDIS(1 << vector);
+}
+
+int
 inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
-	     int pri, int flags)
+    enum intr_type flags, void **cookiep)
 {
-	struct ithd *ithd = ithds[irq];	/* descriptor for the IRQ */
-	struct intrhand *head;		/* chain of handlers for IRQ */
-	struct intrhand *idesc;		/* descriptor for this handler */
-	struct proc *p;			/* interrupt thread */
+	struct ithd *ithd;		/* descriptor for the IRQ */
 	int errcode = 0;
+	int created_ithd = 0;
 
-	if (name == NULL)		/* no name? */
-		panic ("anonymous interrupt");
-	if (ithd == NULL || ithd->it_ih == NULL) {
-		/* first handler for this irq. */
-		if (ithd == NULL) {
-			ithd = malloc(sizeof (struct ithd), M_DEVBUF,
-			    M_WAITOK | M_ZERO);
-			if (ithd == NULL)
-				return (NULL);
-			ithd->irq = irq;
+	/*
+	 * Work around a race where more than one CPU may be registering
+	 * handlers on the same IRQ at the same time.
+	 */
+	mtx_lock_spin(&ithds_table_lock);
+	ithd = ithds[irq];
+	mtx_unlock_spin(&ithds_table_lock);
+	if (ithd == NULL) {
+		errcode = ithread_create(&ithd, irq, 0, ithread_disable,
+		    ithread_enable, "irq%d:", irq);
+		if (errcode)
+			return (errcode);
+		mtx_lock_spin(&ithds_table_lock);
+		if (ithds[irq] == NULL) {
 			ithds[irq] = ithd;
+			created_ithd++;
+			mtx_unlock_spin(&ithds_table_lock);
+		} else {
+			struct ithd *orphan;
+
+			orphan = ithd;
+			ithd = ithds[irq];
+			mtx_unlock_spin(&ithds_table_lock);
+			ithread_destroy(orphan);
 		}
+	}
+
+	errcode = ithread_add_handler(ithd, name, handler, arg,
+	    ithread_priority(flags), flags, cookiep);
+	
+	if ((flags & INTR_FAST) == 0 || errcode)
 		/*
-		 * If we have a fast interrupt, we need to set the
-		 * handler address directly.  Do that below.  For a
-		 * slow interrupt, we don't need to know more details,
-		 * so do it here because it's tidier.
-		 */
-		if ((flags & INTR_FAST)	== 0) {
-			/*
-			 * Only create a kernel thread if we don't already
-			 * have one.
-			 */
-			if (ithd->it_proc == NULL) {
-				errcode = kthread_create(ithd_loop, NULL, &p,
-				    RFSTOPPED | RFHIGHPID, "irq%d: %s", irq,
-				    name);
-				if (errcode)
-					panic("inthand_add: Can't create "
-					      "interrupt thread");
-				p->p_intr_nesting_level = 1;
-				p->p_rtprio.type = RTP_PRIO_ITHREAD;
-				p->p_stat = SWAIT; /* we're idle */
-
-				/* Put in linkages. */
-				ithd->it_proc = p;
-				p->p_ithd = ithd;
-			} else
-				snprintf(ithd->it_proc->p_comm, MAXCOMLEN,
-				    "irq%d: %s", irq, name);
-			p->p_rtprio.prio = pri;
-
-			/*
-			 * The interrupt process must be in place, but
-			 * not necessarily schedulable, before we
-			 * initialize the ICU, since it may cause an
-			 * immediate interrupt.
-			 */
-			if (icu_setup(irq, &sched_ithd, arg, flags) != 0)
-				panic("inthand_add: Can't initialize ICU");
-		}
-	} else if ((flags & INTR_EXCL) != 0
-		   || (ithd->it_ih->ih_flags & INTR_EXCL) != 0) {
-		/*
-		 * We can't append the new handler if either
-		 * list ithd or new handler do not allow
-		 * interrupts to be shared.
+		 * The interrupt process must be in place, but
+		 * not necessarily schedulable, before we
+		 * initialize the ICU, since it may cause an
+		 * immediate interrupt.
 		 */
-		if (bootverbose)
-			printf("\tdevice combination %s and %s "
-			       "doesn't support shared irq%d\n",
-			       ithd->it_ih->ih_name, name, irq);
-		return(NULL);
-	} else if (flags & INTR_FAST) {
-		 /* We can only have one fast interrupt by itself. */
-		if (bootverbose)
-			printf("\tCan't add fast interrupt %s"
- 			       " to normal interrupt %s on irq%d",
-			       name, ithd->it_ih->ih_name, irq);
-		return (NULL);
-	} else {			/* update p_comm */
-		p = ithd->it_proc;
-		if (strlen(p->p_comm) + strlen(name) < MAXCOMLEN) {
-			strcat(p->p_comm, " ");
-			strcat(p->p_comm, name);
-		} else if (strlen(p->p_comm) == MAXCOMLEN)
-			p->p_comm[MAXCOMLEN - 1] = '+';
-		else
-			strcat(p->p_comm, "+");
-	}
-	idesc = malloc(sizeof (struct intrhand), M_DEVBUF, M_WAITOK | M_ZERO);
-	if (idesc == NULL)
-		return (NULL);
-
-	idesc->ih_handler = handler;
-	idesc->ih_argument = arg;
-	idesc->ih_flags = flags;
-	idesc->ih_ithd = ithd;
-
-	idesc->ih_name = malloc(strlen(name) + 1, M_DEVBUF, M_WAITOK);
-	if (idesc->ih_name == NULL) {
-		free(idesc, M_DEVBUF);
-		return (NULL);
-	}
-	strcpy(idesc->ih_name, name);
+		if (icu_setup(irq, &sched_ithd, arg, flags) != 0)
+			panic("inthand_add: Can't initialize ICU");
 
-	/* Slow interrupts got set up above. */
-	if ((flags & INTR_FAST)
-		&& (icu_setup(irq, idesc->ih_handler, idesc->ih_argument,
-			      idesc->ih_flags) != 0) ) {
-		if (bootverbose)
+	if (errcode)
+		return (errcode);
+	
+	if (flags & INTR_FAST) {
+		errcode = icu_setup(irq, handler, arg, flags);
+		if (errcode && bootverbose)
 			printf("\tinthand_add(irq%d) failed, result=%d\n", 
 			       irq, errcode);
-		free(idesc->ih_name, M_DEVBUF);
-		free(idesc, M_DEVBUF);
-		return NULL;
+		if (errcode)
+			return (errcode);
 	}
-	head = ithd->it_ih;		/* look at chain of handlers */
-	if (head) {
-		while (head->ih_next != NULL)
-			head = head->ih_next; /* find the end */
-		head->ih_next = idesc;	/* hook it in there */
-	} else
-		ithd->it_ih = idesc;	/* put it up front */
-	update_intrname(irq, idesc->ih_name);
-	return (idesc);
+
+	update_intrname(irq, name);
+	return (0);
 }
 
 /*
@@ -673,50 +637,9 @@ inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
  * structure to the system.  First ensure the handler is not actively
  * in use.
  */
-
 int
-inthand_remove(struct intrhand *idesc)
+inthand_remove(void *cookie)
 {
-	struct ithd *ithd;		/* descriptor for the IRQ */
-	struct intrhand *ih;		/* chain of handlers */
 
-	if (idesc == NULL)
-		return (-1);
-	ithd = idesc->ih_ithd;
-	ih = ithd->it_ih;
-
-	if (ih == idesc)		/* first in the chain */
-		ithd->it_ih = idesc->ih_next; /* unhook it */
-	else {
-		while ((ih != NULL)
-			&& (ih->ih_next != idesc) )
-			ih = ih->ih_next;
-		if (ih->ih_next != idesc)
-			return (-1);
-		ih->ih_next = ih->ih_next->ih_next;
-	}
-	
-	if (ithd->it_ih == NULL) {	/* no handlers left, */
-		icu_unset(ithd->irq, idesc->ih_handler);
-		ithds[ithd->irq] = NULL;
-
-		if ((idesc->ih_flags & INTR_FAST) == 0) {
-			mtx_lock_spin(&sched_lock);
-			if (ithd->it_proc->p_stat == SWAIT) {
-				ithd->it_proc->p_intr_nesting_level = 0;
-				ithd->it_proc->p_stat = SRUN;
-				setrunqueue(ithd->it_proc);
-				/*
-				 * We don't do an ast here because we really
-				 * don't care when it runs next.
-				 *
-				 * XXX: should we lower the threads priority?
-				 */
-			}
-			mtx_unlock_spin(&sched_lock);
-		}
-	}
-	free(idesc->ih_name, M_DEVBUF);
-	free(idesc, M_DEVBUF);
-	return (0);
+	return (ithread_remove_handler(cookie));
 }
diff --git a/sys/i386/i386/legacy.c b/sys/i386/i386/legacy.c
index 76c41ae..ce2c9cd 100644
--- a/sys/i386/i386/legacy.c
+++ b/sys/i386/i386/legacy.c
@@ -560,23 +560,17 @@ nexus_setup_intr(device_t bus, device_t child, struct resource *irq,
 		 int flags, void (*ihand)(void *), void *arg, void **cookiep)
 {
 	driver_t	*driver;
-	int		error, icflags;
-	int 		pri;		/* interrupt thread priority */
+	int		error;
 
 	/* somebody tried to setup an irq that failed to allocate! */
 	if (irq == NULL)
 		panic("nexus_setup_intr: NULL irq resource!");
 
 	*cookiep = 0;
-	if (irq->r_flags & RF_SHAREABLE)
-		icflags = 0;
-	else
-		icflags = INTR_EXCL;
+	if ((irq->r_flags & RF_SHAREABLE) == 0)
+		flags |= INTR_EXCL;
 
 	driver = device_get_driver(child);
-	pri = ithread_priority(flags);
-	if (flags & INTR_FAST)
-		icflags |= INTR_FAST;
 
 	/*
 	 * We depend here on rman_activate_resource() being idempotent.
@@ -585,10 +579,8 @@ nexus_setup_intr(device_t bus, device_t child, struct resource *irq,
 	if (error)
 		return (error);
 
-	*cookiep = inthand_add(device_get_nameunit(child), irq->r_start,
-	    ihand, arg, pri, icflags);
-	if (*cookiep == NULL)
-		error = EINVAL;	/* XXX ??? */
+	error = inthand_add(device_get_nameunit(child), irq->r_start,
+	    ihand, arg, flags, cookiep);
 
 	return (error);
 }
diff --git a/sys/i386/i386/nexus.c b/sys/i386/i386/nexus.c
index 76c41ae..ce2c9cd 100644
--- a/sys/i386/i386/nexus.c
+++ b/sys/i386/i386/nexus.c
@@ -560,23 +560,17 @@ nexus_setup_intr(device_t bus, device_t child, struct resource *irq,
 		 int flags, void (*ihand)(void *), void *arg, void **cookiep)
 {
 	driver_t	*driver;
-	int		error, icflags;
-	int 		pri;		/* interrupt thread priority */
+	int		error;
 
 	/* somebody tried to setup an irq that failed to allocate! */
 	if (irq == NULL)
 		panic("nexus_setup_intr: NULL irq resource!");
 
 	*cookiep = 0;
-	if (irq->r_flags & RF_SHAREABLE)
-		icflags = 0;
-	else
-		icflags = INTR_EXCL;
+	if ((irq->r_flags & RF_SHAREABLE) == 0)
+		flags |= INTR_EXCL;
 
 	driver = device_get_driver(child);
-	pri = ithread_priority(flags);
-	if (flags & INTR_FAST)
-		icflags |= INTR_FAST;
 
 	/*
 	 * We depend here on rman_activate_resource() being idempotent.
@@ -585,10 +579,8 @@ nexus_setup_intr(device_t bus, device_t child, struct resource *irq,
 	if (error)
 		return (error);
 
-	*cookiep = inthand_add(device_get_nameunit(child), irq->r_start,
-	    ihand, arg, pri, icflags);
-	if (*cookiep == NULL)
-		error = EINVAL;	/* XXX ??? */
+	error = inthand_add(device_get_nameunit(child), irq->r_start,
+	    ihand, arg, flags, cookiep);
 
 	return (error);
 }
diff --git a/sys/i386/isa/intr_machdep.c b/sys/i386/isa/intr_machdep.c
index 70b9378..2dd96d7 100644
--- a/sys/i386/isa/intr_machdep.c
+++ b/sys/i386/isa/intr_machdep.c
@@ -93,10 +93,12 @@
  * Per-interrupt data.
  */
 u_long	*intr_countp[ICU_LEN];		/* pointers to interrupt counters */
-driver_intr_t *intr_handler[ICU_LEN];	/* first level interrupt handler */
-struct ithd *ithds[ICU_LEN];		/* real interrupt handler */
+driver_intr_t	*intr_handler[ICU_LEN];	/* first level interrupt handler */
+struct	 ithd *ithds[ICU_LEN];		/* real interrupt handler */
 void	*intr_unit[ICU_LEN];
 
+static struct	mtx ithds_table_lock;	/* protect the ithds table */
+
 static inthand_t *fastintr[ICU_LEN] = {
 	&IDTVEC(fastintr0), &IDTVEC(fastintr1),
 	&IDTVEC(fastintr2), &IDTVEC(fastintr3),
@@ -133,6 +135,10 @@ static inthand_t *slowintr[ICU_LEN] = {
 
 static driver_intr_t isa_strayintr;
 
+static void	ithds_init(void *dummy);
+static void	ithread_enable(int vector);
+static void	ithread_disable(int vector);
+
 #ifdef PC98
 #define NMI_PARITY 0x04
 #define NMI_EPARITY 0x02
@@ -388,7 +394,7 @@ isa_irq_pending()
  * vmstat(8) and the like.
  */
 static void
-update_intrname(int intr, char *name)
+update_intrname(int intr, const char *name)
 {
 	char buf[32];
 	char *cp;
@@ -536,132 +542,90 @@ icu_unset(intr, handler)
 	return (0);
 }
 
-struct intrhand *
+static void
+ithds_init(void *dummy)
+{
+
+	mtx_init(&ithds_table_lock, "ithread table lock", MTX_SPIN);
+}
+SYSINIT(ithds_init, SI_SUB_INTR, SI_ORDER_SECOND, ithds_init, NULL);
+
+static void
+ithread_enable(int vector)
+{
+
+	INTREN(1 << vector);
+}
+
+static void
+ithread_disable(int vector)
+{
+
+	INTRDIS(1 << vector);
+}
+
+int
 inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
-	     int pri, int flags)
+    enum intr_type flags, void **cookiep)
 {
-	struct ithd *ithd = ithds[irq];	/* descriptor for the IRQ */
-	struct intrhand *head;		/* chain of handlers for IRQ */
-	struct intrhand *idesc;		/* descriptor for this handler */
-	struct proc *p;			/* interrupt thread */
+	struct ithd *ithd;		/* descriptor for the IRQ */
 	int errcode = 0;
+	int created_ithd = 0;
 
-	if (name == NULL)		/* no name? */
-		panic ("anonymous interrupt");
-	if (ithd == NULL || ithd->it_ih == NULL) {
-		/* first handler for this irq. */
-		if (ithd == NULL) {
-			ithd = malloc(sizeof (struct ithd), M_DEVBUF,
-			    M_WAITOK | M_ZERO);
-			if (ithd == NULL)
-				return (NULL);
-			ithd->irq = irq;
+	/*
+	 * Work around a race where more than one CPU may be registering
+	 * handlers on the same IRQ at the same time.
+	 */
+	mtx_lock_spin(&ithds_table_lock);
+	ithd = ithds[irq];
+	mtx_unlock_spin(&ithds_table_lock);
+	if (ithd == NULL) {
+		errcode = ithread_create(&ithd, irq, 0, ithread_disable,
+		    ithread_enable, "irq%d:", irq);
+		if (errcode)
+			return (errcode);
+		mtx_lock_spin(&ithds_table_lock);
+		if (ithds[irq] == NULL) {
 			ithds[irq] = ithd;
+			created_ithd++;
+			mtx_unlock_spin(&ithds_table_lock);
+		} else {
+			struct ithd *orphan;
+
+			orphan = ithd;
+			ithd = ithds[irq];
+			mtx_unlock_spin(&ithds_table_lock);
+			ithread_destroy(orphan);
 		}
+	}
+
+	errcode = ithread_add_handler(ithd, name, handler, arg,
+	    ithread_priority(flags), flags, cookiep);
+	
+	if ((flags & INTR_FAST) == 0 || errcode)
 		/*
-		 * If we have a fast interrupt, we need to set the
-		 * handler address directly.  Do that below.  For a
-		 * slow interrupt, we don't need to know more details,
-		 * so do it here because it's tidier.
-		 */
-		if ((flags & INTR_FAST)	== 0) {
-			/*
-			 * Only create a kernel thread if we don't already
-			 * have one.
-			 */
-			if (ithd->it_proc == NULL) {
-				errcode = kthread_create(ithd_loop, NULL, &p,
-				    RFSTOPPED | RFHIGHPID, "irq%d: %s", irq,
-				    name);
-				if (errcode)
-					panic("inthand_add: Can't create "
-					      "interrupt thread");
-				p->p_intr_nesting_level = 1;
-				p->p_rtprio.type = RTP_PRIO_ITHREAD;
-				p->p_stat = SWAIT; /* we're idle */
-
-				/* Put in linkages. */
-				ithd->it_proc = p;
-				p->p_ithd = ithd;
-			} else
-				snprintf(ithd->it_proc->p_comm, MAXCOMLEN,
-				    "irq%d: %s", irq, name);
-			p->p_rtprio.prio = pri;
-
-			/*
-			 * The interrupt process must be in place, but
-			 * not necessarily schedulable, before we
-			 * initialize the ICU, since it may cause an
-			 * immediate interrupt.
-			 */
-			if (icu_setup(irq, &sched_ithd, arg, flags) != 0)
-				panic("inthand_add: Can't initialize ICU");
-		}
-	} else if ((flags & INTR_EXCL) != 0
-		   || (ithd->it_ih->ih_flags & INTR_EXCL) != 0) {
-		/*
-		 * We can't append the new handler if either
-		 * list ithd or new handler do not allow
-		 * interrupts to be shared.
+		 * The interrupt process must be in place, but
+		 * not necessarily schedulable, before we
+		 * initialize the ICU, since it may cause an
+		 * immediate interrupt.
 		 */
-		if (bootverbose)
-			printf("\tdevice combination %s and %s "
-			       "doesn't support shared irq%d\n",
-			       ithd->it_ih->ih_name, name, irq);
-		return(NULL);
-	} else if (flags & INTR_FAST) {
-		 /* We can only have one fast interrupt by itself. */
-		if (bootverbose)
-			printf("\tCan't add fast interrupt %s"
- 			       " to normal interrupt %s on irq%d",
-			       name, ithd->it_ih->ih_name, irq);
-		return (NULL);
-	} else {			/* update p_comm */
-		p = ithd->it_proc;
-		if (strlen(p->p_comm) + strlen(name) < MAXCOMLEN) {
-			strcat(p->p_comm, " ");
-			strcat(p->p_comm, name);
-		} else if (strlen(p->p_comm) == MAXCOMLEN)
-			p->p_comm[MAXCOMLEN - 1] = '+';
-		else
-			strcat(p->p_comm, "+");
-	}
-	idesc = malloc(sizeof (struct intrhand), M_DEVBUF, M_WAITOK | M_ZERO);
-	if (idesc == NULL)
-		return (NULL);
-
-	idesc->ih_handler = handler;
-	idesc->ih_argument = arg;
-	idesc->ih_flags = flags;
-	idesc->ih_ithd = ithd;
-
-	idesc->ih_name = malloc(strlen(name) + 1, M_DEVBUF, M_WAITOK);
-	if (idesc->ih_name == NULL) {
-		free(idesc, M_DEVBUF);
-		return (NULL);
-	}
-	strcpy(idesc->ih_name, name);
+		if (icu_setup(irq, &sched_ithd, arg, flags) != 0)
+			panic("inthand_add: Can't initialize ICU");
 
-	/* Slow interrupts got set up above. */
-	if ((flags & INTR_FAST)
-		&& (icu_setup(irq, idesc->ih_handler, idesc->ih_argument,
-			      idesc->ih_flags) != 0) ) {
-		if (bootverbose)
+	if (errcode)
+		return (errcode);
+	
+	if (flags & INTR_FAST) {
+		errcode = icu_setup(irq, handler, arg, flags);
+		if (errcode && bootverbose)
 			printf("\tinthand_add(irq%d) failed, result=%d\n", 
 			       irq, errcode);
-		free(idesc->ih_name, M_DEVBUF);
-		free(idesc, M_DEVBUF);
-		return NULL;
+		if (errcode)
+			return (errcode);
 	}
-	head = ithd->it_ih;		/* look at chain of handlers */
-	if (head) {
-		while (head->ih_next != NULL)
-			head = head->ih_next; /* find the end */
-		head->ih_next = idesc;	/* hook it in there */
-	} else
-		ithd->it_ih = idesc;	/* put it up front */
-	update_intrname(irq, idesc->ih_name);
-	return (idesc);
+
+	update_intrname(irq, name);
+	return (0);
 }
 
 /*
@@ -673,50 +637,9 @@ inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
  * structure to the system.  First ensure the handler is not actively
  * in use.
  */
-
 int
-inthand_remove(struct intrhand *idesc)
+inthand_remove(void *cookie)
 {
-	struct ithd *ithd;		/* descriptor for the IRQ */
-	struct intrhand *ih;		/* chain of handlers */
 
-	if (idesc == NULL)
-		return (-1);
-	ithd = idesc->ih_ithd;
-	ih = ithd->it_ih;
-
-	if (ih == idesc)		/* first in the chain */
-		ithd->it_ih = idesc->ih_next; /* unhook it */
-	else {
-		while ((ih != NULL)
-			&& (ih->ih_next != idesc) )
-			ih = ih->ih_next;
-		if (ih->ih_next != idesc)
-			return (-1);
-		ih->ih_next = ih->ih_next->ih_next;
-	}
-	
-	if (ithd->it_ih == NULL) {	/* no handlers left, */
-		icu_unset(ithd->irq, idesc->ih_handler);
-		ithds[ithd->irq] = NULL;
-
-		if ((idesc->ih_flags & INTR_FAST) == 0) {
-			mtx_lock_spin(&sched_lock);
-			if (ithd->it_proc->p_stat == SWAIT) {
-				ithd->it_proc->p_intr_nesting_level = 0;
-				ithd->it_proc->p_stat = SRUN;
-				setrunqueue(ithd->it_proc);
-				/*
-				 * We don't do an ast here because we really
-				 * don't care when it runs next.
-				 *
-				 * XXX: should we lower the threads priority?
-				 */
-			}
-			mtx_unlock_spin(&sched_lock);
-		}
-	}
-	free(idesc->ih_name, M_DEVBUF);
-	free(idesc, M_DEVBUF);
-	return (0);
+	return (ithread_remove_handler(cookie));
 }
diff --git a/sys/i386/isa/intr_machdep.h b/sys/i386/isa/intr_machdep.h
index 53d782f..b42c348 100644
--- a/sys/i386/isa/intr_machdep.h
+++ b/sys/i386/isa/intr_machdep.h
@@ -220,13 +220,10 @@ int	icu_unset __P((int intr, driver_intr_t *handler));
  * WARNING: These are internal functions and not to be used by device drivers!
  * They are subject to change without notice. 
  */
-struct intrhand *inthand_add(const char *name, int irq, driver_intr_t handler,
-			   void *arg, int pri, int flags);
-int inthand_remove(struct intrhand *idesc);
-void sched_ithd(void *);
-void ithd_loop(void *);
-void start_softintr(void *);
-void intr_soft(void *);
+int	inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
+	    enum intr_type flags, void **cookiep);
+int	inthand_remove(void *cookie);
+void	sched_ithd(void *dummy);
 
 #endif /* LOCORE */
 
diff --git a/sys/i386/isa/ithread.c b/sys/i386/isa/ithread.c
index 99a1abf..8fb1924 100644
--- a/sys/i386/isa/ithread.c
+++ b/sys/i386/isa/ithread.c
@@ -51,6 +51,8 @@
 #include <sys/unistd.h>
 #include <sys/errno.h>
 #include <sys/interrupt.h>
+#include <sys/random.h>
+#include <sys/time.h>
 #include <machine/md_var.h>
 #include <machine/segments.h>
 
@@ -64,6 +66,11 @@
 #include <sys/ktr.h>
 #include <machine/cpu.h>
 
+struct int_entropy {
+	struct proc *p;
+	int irq;
+};
+
 static u_int straycount[NHWI];
 
 #define	MAX_STRAY_LOG	5
@@ -87,6 +94,19 @@ sched_ithd(void *cookie)
 	 */
 	atomic_add_long(intr_countp[irq], 1); /* one more for this IRQ */
 	atomic_add_int(&cnt.v_intr, 1); /* one more global interrupt */
+
+	/*
+	 * If this interrupt is marked as being a source of entropy, use
+	 * the current timestamp to feed entropy to the PRNG.
+	 */
+	if (ir != NULL && (ir->it_flags & IT_ENTROPY)) {
+		struct int_entropy entropy;
+
+		entropy.irq = irq;
+		entropy.p = curproc;
+		random_harvest(&entropy, sizeof(entropy), 2, 0,
+			       RANDOM_INTERRUPT);
+	}
 		
 	/*
 	 * If we don't have an interrupt resource or an interrupt thread for
@@ -121,102 +141,13 @@ sched_ithd(void *cookie)
 /*		membar_lock(); */
 		ir->it_proc->p_stat = SRUN;
 		setrunqueue(ir->it_proc);
-		if (!cold) {
-			if (curproc != PCPU_GET(idleproc))
-				setrunqueue(curproc);
-			mi_switch();
-		}
+		need_resched();
 	}
 	else {
 		CTR3(KTR_INTR, "sched_ithd %d: it_need %d, state %d",
 			ir->it_proc->p_pid,
 		        ir->it_need,
 		        ir->it_proc->p_stat );
-		need_resched();
 	}
 	mtx_unlock_spin(&sched_lock);
 }
-
-/*
- * This is the main code for all interrupt threads.  It gets put on
- * whichkqs by setrunqueue above.
- */
-void
-ithd_loop(void *dummy)
-{
-	struct ithd *me;		/* our thread context */
-	struct intrhand *ih;		/* and our interrupt handler chain */
-
-	me = curproc->p_ithd;		/* point to myself */
-
-	/*
-	 * As long as we have interrupts outstanding, go through the
-	 * list of handlers, giving each one a go at it.
-	 */
-	for (;;) {
-		/*
-		 * If we don't have any handlers, then we are an orphaned
-		 * thread and just need to die.
-		 */
-		if (me->it_ih == NULL) {
-			CTR2(KTR_INTR, "ithd_loop pid %d(%s) exiting",
-			     me->it_proc->p_pid, me->it_proc->p_comm);
-			curproc->p_ithd = NULL;
-			free(me, M_DEVBUF);
-			mtx_lock(&Giant);
-			kthread_exit(0);
-		}
-
-		CTR3(KTR_INTR, "ithd_loop pid %d(%s) need=%d",
-		     me->it_proc->p_pid, me->it_proc->p_comm, me->it_need);
-		while (me->it_need) {
-			/*
-			 * Service interrupts.  If another interrupt
-			 * arrives while we are running, they will set
-			 * it_need to denote that we should make
-			 * another pass.
-			 */
-			me->it_need = 0;
-#if 0
-			membar_unlock(); /* push out "it_need=0" */
-#endif
-			for (ih = me->it_ih; ih != NULL; ih = ih->ih_next) {
-				CTR5(KTR_INTR,
-				    "ithd_loop pid %d ih=%p: %p(%p) flg=%x",
-				    me->it_proc->p_pid, (void *)ih,
-				    (void *)ih->ih_handler, ih->ih_argument,
-				    ih->ih_flags);
-
-				if ((ih->ih_flags & INTR_MPSAFE) == 0)
-					mtx_lock(&Giant);
-				ih->ih_handler(ih->ih_argument);
-				if ((ih->ih_flags & INTR_MPSAFE) == 0)
-					mtx_unlock(&Giant);
-			}
-		}
-
-		/*
-		 * Processed all our interrupts.  Now get the sched
-		 * lock.  This may take a while and it_need may get
-		 * set again, so we have to check it again.
-		 */
-		mtx_assert(&Giant, MA_NOTOWNED);
-		mtx_lock_spin(&sched_lock);
-		if (!me->it_need) {
-
-			INTREN (1 << me->irq); /* reset the mask bit */
-			me->it_proc->p_stat = SWAIT; /* we're idle */
-#ifdef APIC_IO
-			CTR2(KTR_INTR, "ithd_loop pid %d: done, apic_imen=%x",
-				me->it_proc->p_pid, apic_imen);
-#else
-			CTR2(KTR_INTR, "ithd_loop pid %d: done, imen=%x",
-				me->it_proc->p_pid, imen);
-#endif
-			mi_switch();
-			CTR1(KTR_INTR, "ithd_loop pid %d: resumed",
-				me->it_proc->p_pid);
-		}
-		mtx_unlock_spin(&sched_lock);
-	}
-}
diff --git a/sys/i386/isa/nmi.c b/sys/i386/isa/nmi.c
index 70b9378..2dd96d7 100644
--- a/sys/i386/isa/nmi.c
+++ b/sys/i386/isa/nmi.c
@@ -93,10 +93,12 @@
  * Per-interrupt data.
  */
 u_long	*intr_countp[ICU_LEN];		/* pointers to interrupt counters */
-driver_intr_t *intr_handler[ICU_LEN];	/* first level interrupt handler */
-struct ithd *ithds[ICU_LEN];		/* real interrupt handler */
+driver_intr_t	*intr_handler[ICU_LEN];	/* first level interrupt handler */
+struct	 ithd *ithds[ICU_LEN];		/* real interrupt handler */
 void	*intr_unit[ICU_LEN];
 
+static struct	mtx ithds_table_lock;	/* protect the ithds table */
+
 static inthand_t *fastintr[ICU_LEN] = {
 	&IDTVEC(fastintr0), &IDTVEC(fastintr1),
 	&IDTVEC(fastintr2), &IDTVEC(fastintr3),
@@ -133,6 +135,10 @@ static inthand_t *slowintr[ICU_LEN] = {
 
 static driver_intr_t isa_strayintr;
 
+static void	ithds_init(void *dummy);
+static void	ithread_enable(int vector);
+static void	ithread_disable(int vector);
+
 #ifdef PC98
 #define NMI_PARITY 0x04
 #define NMI_EPARITY 0x02
@@ -388,7 +394,7 @@ isa_irq_pending()
  * vmstat(8) and the like.
  */
 static void
-update_intrname(int intr, char *name)
+update_intrname(int intr, const char *name)
 {
 	char buf[32];
 	char *cp;
@@ -536,132 +542,90 @@ icu_unset(intr, handler)
 	return (0);
 }
 
-struct intrhand *
+static void
+ithds_init(void *dummy)
+{
+
+	mtx_init(&ithds_table_lock, "ithread table lock", MTX_SPIN);
+}
+SYSINIT(ithds_init, SI_SUB_INTR, SI_ORDER_SECOND, ithds_init, NULL);
+
+static void
+ithread_enable(int vector)
+{
+
+	INTREN(1 << vector);
+}
+
+static void
+ithread_disable(int vector)
+{
+
+	INTRDIS(1 << vector);
+}
+
+int
 inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
-	     int pri, int flags)
+    enum intr_type flags, void **cookiep)
 {
-	struct ithd *ithd = ithds[irq];	/* descriptor for the IRQ */
-	struct intrhand *head;		/* chain of handlers for IRQ */
-	struct intrhand *idesc;		/* descriptor for this handler */
-	struct proc *p;			/* interrupt thread */
+	struct ithd *ithd;		/* descriptor for the IRQ */
 	int errcode = 0;
+	int created_ithd = 0;
 
-	if (name == NULL)		/* no name? */
-		panic ("anonymous interrupt");
-	if (ithd == NULL || ithd->it_ih == NULL) {
-		/* first handler for this irq. */
-		if (ithd == NULL) {
-			ithd = malloc(sizeof (struct ithd), M_DEVBUF,
-			    M_WAITOK | M_ZERO);
-			if (ithd == NULL)
-				return (NULL);
-			ithd->irq = irq;
+	/*
+	 * Work around a race where more than one CPU may be registering
+	 * handlers on the same IRQ at the same time.
+	 */
+	mtx_lock_spin(&ithds_table_lock);
+	ithd = ithds[irq];
+	mtx_unlock_spin(&ithds_table_lock);
+	if (ithd == NULL) {
+		errcode = ithread_create(&ithd, irq, 0, ithread_disable,
+		    ithread_enable, "irq%d:", irq);
+		if (errcode)
+			return (errcode);
+		mtx_lock_spin(&ithds_table_lock);
+		if (ithds[irq] == NULL) {
 			ithds[irq] = ithd;
+			created_ithd++;
+			mtx_unlock_spin(&ithds_table_lock);
+		} else {
+			struct ithd *orphan;
+
+			orphan = ithd;
+			ithd = ithds[irq];
+			mtx_unlock_spin(&ithds_table_lock);
+			ithread_destroy(orphan);
 		}
+	}
+
+	errcode = ithread_add_handler(ithd, name, handler, arg,
+	    ithread_priority(flags), flags, cookiep);
+	
+	if ((flags & INTR_FAST) == 0 || errcode)
 		/*
-		 * If we have a fast interrupt, we need to set the
-		 * handler address directly.  Do that below.  For a
-		 * slow interrupt, we don't need to know more details,
-		 * so do it here because it's tidier.
-		 */
-		if ((flags & INTR_FAST)	== 0) {
-			/*
-			 * Only create a kernel thread if we don't already
-			 * have one.
-			 */
-			if (ithd->it_proc == NULL) {
-				errcode = kthread_create(ithd_loop, NULL, &p,
-				    RFSTOPPED | RFHIGHPID, "irq%d: %s", irq,
-				    name);
-				if (errcode)
-					panic("inthand_add: Can't create "
-					      "interrupt thread");
-				p->p_intr_nesting_level = 1;
-				p->p_rtprio.type = RTP_PRIO_ITHREAD;
-				p->p_stat = SWAIT; /* we're idle */
-
-				/* Put in linkages. */
-				ithd->it_proc = p;
-				p->p_ithd = ithd;
-			} else
-				snprintf(ithd->it_proc->p_comm, MAXCOMLEN,
-				    "irq%d: %s", irq, name);
-			p->p_rtprio.prio = pri;
-
-			/*
-			 * The interrupt process must be in place, but
-			 * not necessarily schedulable, before we
-			 * initialize the ICU, since it may cause an
-			 * immediate interrupt.
-			 */
-			if (icu_setup(irq, &sched_ithd, arg, flags) != 0)
-				panic("inthand_add: Can't initialize ICU");
-		}
-	} else if ((flags & INTR_EXCL) != 0
-		   || (ithd->it_ih->ih_flags & INTR_EXCL) != 0) {
-		/*
-		 * We can't append the new handler if either
-		 * list ithd or new handler do not allow
-		 * interrupts to be shared.
+		 * The interrupt process must be in place, but
+		 * not necessarily schedulable, before we
+		 * initialize the ICU, since it may cause an
+		 * immediate interrupt.
 		 */
-		if (bootverbose)
-			printf("\tdevice combination %s and %s "
-			       "doesn't support shared irq%d\n",
-			       ithd->it_ih->ih_name, name, irq);
-		return(NULL);
-	} else if (flags & INTR_FAST) {
-		 /* We can only have one fast interrupt by itself. */
-		if (bootverbose)
-			printf("\tCan't add fast interrupt %s"
- 			       " to normal interrupt %s on irq%d",
-			       name, ithd->it_ih->ih_name, irq);
-		return (NULL);
-	} else {			/* update p_comm */
-		p = ithd->it_proc;
-		if (strlen(p->p_comm) + strlen(name) < MAXCOMLEN) {
-			strcat(p->p_comm, " ");
-			strcat(p->p_comm, name);
-		} else if (strlen(p->p_comm) == MAXCOMLEN)
-			p->p_comm[MAXCOMLEN - 1] = '+';
-		else
-			strcat(p->p_comm, "+");
-	}
-	idesc = malloc(sizeof (struct intrhand), M_DEVBUF, M_WAITOK | M_ZERO);
-	if (idesc == NULL)
-		return (NULL);
-
-	idesc->ih_handler = handler;
-	idesc->ih_argument = arg;
-	idesc->ih_flags = flags;
-	idesc->ih_ithd = ithd;
-
-	idesc->ih_name = malloc(strlen(name) + 1, M_DEVBUF, M_WAITOK);
-	if (idesc->ih_name == NULL) {
-		free(idesc, M_DEVBUF);
-		return (NULL);
-	}
-	strcpy(idesc->ih_name, name);
+		if (icu_setup(irq, &sched_ithd, arg, flags) != 0)
+			panic("inthand_add: Can't initialize ICU");
 
-	/* Slow interrupts got set up above. */
-	if ((flags & INTR_FAST)
-		&& (icu_setup(irq, idesc->ih_handler, idesc->ih_argument,
-			      idesc->ih_flags) != 0) ) {
-		if (bootverbose)
+	if (errcode)
+		return (errcode);
+	
+	if (flags & INTR_FAST) {
+		errcode = icu_setup(irq, handler, arg, flags);
+		if (errcode && bootverbose)
 			printf("\tinthand_add(irq%d) failed, result=%d\n", 
 			       irq, errcode);
-		free(idesc->ih_name, M_DEVBUF);
-		free(idesc, M_DEVBUF);
-		return NULL;
+		if (errcode)
+			return (errcode);
 	}
-	head = ithd->it_ih;		/* look at chain of handlers */
-	if (head) {
-		while (head->ih_next != NULL)
-			head = head->ih_next; /* find the end */
-		head->ih_next = idesc;	/* hook it in there */
-	} else
-		ithd->it_ih = idesc;	/* put it up front */
-	update_intrname(irq, idesc->ih_name);
-	return (idesc);
+
+	update_intrname(irq, name);
+	return (0);
 }
 
 /*
@@ -673,50 +637,9 @@ inthand_add(const char *name, int irq, driver_intr_t handler, void *arg,
  * structure to the system.  First ensure the handler is not actively
  * in use.
  */
-
 int
-inthand_remove(struct intrhand *idesc)
+inthand_remove(void *cookie)
 {
-	struct ithd *ithd;		/* descriptor for the IRQ */
-	struct intrhand *ih;		/* chain of handlers */
 
-	if (idesc == NULL)
-		return (-1);
-	ithd = idesc->ih_ithd;
-	ih = ithd->it_ih;
-
-	if (ih == idesc)		/* first in the chain */
-		ithd->it_ih = idesc->ih_next; /* unhook it */
-	else {
-		while ((ih != NULL)
-			&& (ih->ih_next != idesc) )
-			ih = ih->ih_next;
-		if (ih->ih_next != idesc)
-			return (-1);
-		ih->ih_next = ih->ih_next->ih_next;
-	}
-	
-	if (ithd->it_ih == NULL) {	/* no handlers left, */
-		icu_unset(ithd->irq, idesc->ih_handler);
-		ithds[ithd->irq] = NULL;
-
-		if ((idesc->ih_flags & INTR_FAST) == 0) {
-			mtx_lock_spin(&sched_lock);
-			if (ithd->it_proc->p_stat == SWAIT) {
-				ithd->it_proc->p_intr_nesting_level = 0;
-				ithd->it_proc->p_stat = SRUN;
-				setrunqueue(ithd->it_proc);
-				/*
-				 * We don't do an ast here because we really
-				 * don't care when it runs next.
-				 *
-				 * XXX: should we lower the threads priority?
-				 */
-			}
-			mtx_unlock_spin(&sched_lock);
-		}
-	}
-	free(idesc->ih_name, M_DEVBUF);
-	free(idesc, M_DEVBUF);
-	return (0);
+	return (ithread_remove_handler(cookie));
 }