Index: cam_xpt.c
===================================================================
RCS file: /dump/FreeBSD-CVS/src/sys/cam/cam_xpt.c,v
retrieving revision 1.156
diff -u -r1.156 cam_xpt.c
--- cam_xpt.c	16 Sep 2005 01:26:17 -0000	1.156
+++ cam_xpt.c	6 Jan 2006 01:33:52 -0000
@@ -682,6 +682,18 @@
 
 static struct intr_config_hook *xpt_config_hook;
 
+static void dead_sim_action(struct cam_sim *sim, union ccb *ccb);
+static void dead_sim_poll(struct cam_sim *sim);
+
+/* Dummy SIM that is used when the real one has gone. */
+static struct cam_sim cam_dead_sim = {
+	.sim_action =	dead_sim_action,
+	.sim_poll =	dead_sim_poll,
+	.sim_name =	"dead_sim",
+};
+
+#define SIM_DEAD(sim)	((sim) == &cam_dead_sim)
+
 /* Registered busses */
 static TAILQ_HEAD(,cam_eb) xpt_busses;
 static u_int bus_generation;
@@ -3055,12 +3067,22 @@
 	case XPT_ENG_EXEC:
 	{
 		struct cam_path *path;
+		struct cam_sim *ccbsim;
 		int s;
 		int runq;
 
 		path = start_ccb->ccb_h.path;
 		s = splsoftcam();
 
+		if (SIM_DEAD(path->bus->sim)) {
+			/* The SIM has gone; just execute the CCB directly. */
+			cam_ccbq_send_ccb(&path->device->ccbq, start_ccb);
+			ccbsim = start_ccb->ccb_h.path->bus->sim;
+			(*(ccbsim->sim_action))(ccbsim, start_ccb);
+			splx(s);
+			break;
+		}
+
 		cam_ccbq_insert_ccb(&path->device->ccbq, start_ccb);
 		if (path->device->qfrozen_cnt == 0)
 			runq = xpt_schedule_dev_sendq(path->bus, path->device);
@@ -3641,8 +3663,8 @@
 	dev->ccbq.devq_openings--;
 	dev->ccbq.dev_openings--;	
 	
-	while((devq->send_openings <= 0 || dev->ccbq.dev_openings < 0)
-	   && (--timeout > 0)) {
+	while(((devq != NULL && devq->send_openings <= 0) ||
+	   dev->ccbq.dev_openings < 0) && (--timeout > 0)) {
 		DELAY(1000);
 		(*(sim->sim_poll))(sim);
 		camisr(&cam_bioq);
@@ -3684,6 +3706,7 @@
 xpt_schedule(struct cam_periph *perph, u_int32_t new_priority)
 {
 	struct cam_ed *device;
+	union ccb *work_ccb;
 	int s;
 	int runq;
 
@@ -3702,6 +3725,16 @@
 					     new_priority);
 		}
 		runq = 0;
+	} else if (SIM_DEAD(perph->path->bus->sim)) {
+		/* The SIM is gone so just call periph_start directly. */
+		work_ccb = xpt_get_ccb(perph->path->device);
+		splx(s);
+		if (work_ccb == NULL)
+			return; /* XXX */
+		xpt_setup_ccb(&work_ccb->ccb_h, perph->path, new_priority);
+		perph->pinfo.priority = new_priority;
+		perph->periph_start(perph, work_ccb);
+		return;
 	} else {
 		/* New entry on the queue */
 		CAM_DEBUG(perph->path, CAM_DEBUG_SUBTRACE,
@@ -4337,6 +4370,10 @@
 	} else {
 		SLIST_INSERT_HEAD(&ccb_freeq, &free_ccb->ccb_h, xpt_links.sle);
 	}
+	if (bus->sim->devq == NULL) {
+		splx(s);
+		return;
+	}
 	bus->sim->devq->alloc_openings++;
 	bus->sim->devq->alloc_active--;
 	/* XXX Turn this into an inline function - xpt_run_device?? */
@@ -4422,6 +4459,12 @@
 xpt_bus_deregister(path_id_t pathid)
 {
 	struct cam_path bus_path;
+	struct cam_ed *device;
+	struct cam_ed_qinfo *qinfo;
+	struct cam_devq *devq;
+	struct cam_periph *periph;
+	struct cam_sim *ccbsim;
+	union ccb *work_ccb;
 	cam_status status;
 
 	GIANT_REQUIRED;
@@ -4433,11 +4476,51 @@
 
 	xpt_async(AC_LOST_DEVICE, &bus_path, NULL);
 	xpt_async(AC_PATH_DEREGISTERED, &bus_path, NULL);
-	
+
+	/* The SIM may be gone, so use a dummy SIM for any stray operations. */
+	devq = bus_path.bus->sim->devq;
+	bus_path.bus->sim = &cam_dead_sim;
+
+	/* Execute any pending operations now. */
+	while ((qinfo = (struct cam_ed_qinfo *)camq_remove(&devq->send_queue,
+	    CAMQ_HEAD)) != NULL ||
+	    (qinfo = (struct cam_ed_qinfo *)camq_remove(&devq->alloc_queue,
+	    CAMQ_HEAD)) != NULL) {
+		do {
+			device = qinfo->device;
+			work_ccb = cam_ccbq_peek_ccb(&device->ccbq, CAMQ_HEAD);
+			if (work_ccb != NULL) {
+				devq->active_dev = device;
+				cam_ccbq_remove_ccb(&device->ccbq, work_ccb);
+				cam_ccbq_send_ccb(&device->ccbq, work_ccb);
+				ccbsim = work_ccb->ccb_h.path->bus->sim;
+				(*(ccbsim->sim_action))(ccbsim, work_ccb);
+			}
+
+			periph = (struct cam_periph *)camq_remove(&device->drvq,
+			    CAMQ_HEAD);
+			if (periph != NULL)
+				xpt_schedule(periph, periph->pinfo.priority);
+		} while (work_ccb != NULL || periph != NULL);
+	}
+
+	/* Make sure all completed CCBs are processed. */
+	while (!TAILQ_EMPTY(&cam_bioq)) {
+		camisr(&cam_bioq);
+
+		/* Repeat the async's for the benefit of any new devices. */
+		xpt_async(AC_LOST_DEVICE, &bus_path, NULL);
+		xpt_async(AC_PATH_DEREGISTERED, &bus_path, NULL);
+	}
+
 	/* Release the reference count held while registered. */
 	xpt_release_bus(bus_path.bus);
 	xpt_release_path(&bus_path);
 
+	/* Recheck for more completed CCBs. */
+	while (!TAILQ_EMPTY(&cam_bioq))
+		camisr(&cam_bioq);
+
 	return (CAM_REQ_CMP);
 }
 
@@ -5021,6 +5104,9 @@
 	struct	   cam_devq *devq;
 	cam_status status;
 
+	if (SIM_DEAD(bus->sim))
+		return (NULL);
+
 	/* Make space for us in the device queue on our bus */
 	devq = bus->sim->devq;
 	status = cam_devq_resize(devq, devq->alloc_queue.array_size + 1);
@@ -5131,9 +5217,11 @@
 		TAILQ_REMOVE(&target->ed_entries, device,links);
 		target->generation++;
 		xpt_max_ccbs -= device->ccbq.devq_openings;
-		/* Release our slot in the devq */
-		devq = bus->sim->devq;
-		cam_devq_resize(devq, devq->alloc_queue.array_size - 1);
+		if (!SIM_DEAD(bus->sim)) {
+			/* Release our slot in the devq */
+			devq = bus->sim->devq;
+			cam_devq_resize(devq, devq->alloc_queue.array_size - 1);
+		}
 		splx(s);
 		camq_fini(&device->drvq);
 		camq_fini(&device->ccbq.queue);
@@ -7096,8 +7184,10 @@
 			s = splcam();
 			cam_ccbq_ccb_done(&dev->ccbq, (union ccb *)ccb_h);
 
-			ccb_h->path->bus->sim->devq->send_active--;
-			ccb_h->path->bus->sim->devq->send_openings++;
+			if (!SIM_DEAD(ccb_h->path->bus->sim)) {
+				ccb_h->path->bus->sim->devq->send_active--;
+				ccb_h->path->bus->sim->devq->send_openings++;
+			}
 			splx(s);
 			
 			if (((dev->flags & CAM_DEV_REL_ON_COMPLETE) != 0
@@ -7145,3 +7235,16 @@
 	}
 	splx(s);
 }
+
+static void
+dead_sim_action(struct cam_sim *sim, union ccb *ccb)
+{
+
+	ccb->ccb_h.status = CAM_DEV_NOT_THERE;
+	xpt_done(ccb);
+}
+ 
+static void
+dead_sim_poll(struct cam_sim *sim)
+{
+}