MFp4:

Fix reference counting bug, when device unreferenced before then
invalidated. To do it, do not handle validity flag as another
reference, but explicitly modify reference count each time flag is
modified.

Discovered by:	thompsa

1 files changed, 24 insertions, 21 deletions

diff --git a/sys/cam/cam_xpt.c b/sys/cam/cam_xpt.c
index 187683ed8814..700363a1ddac 100644
--- a/sys/cam/cam_xpt.c
+++ b/sys/cam/cam_xpt.c
@@ -217,9 +217,7 @@ static void	 xpt_release_devq_device(struct cam_ed *dev, u_int count,
 					 int run_queue);
 static struct cam_et*
 		 xpt_alloc_target(struct cam_eb *bus, target_id_t target_id);
-static void	 xpt_release_target(struct cam_eb *bus, struct cam_et *target);
-static void	 xpt_release_device(struct cam_eb *bus, struct cam_et *target,
-				    struct cam_ed *device);
+static void	 xpt_release_target(struct cam_et *target);
 static struct cam_eb*
 		 xpt_find_bus(path_id_t path_id);
 static struct cam_et*
@@ -3521,9 +3519,9 @@ xpt_compile_path(struct cam_path *new_path, struct cam_periph *perph,
 		CAM_DEBUG(new_path, CAM_DEBUG_TRACE, ("xpt_compile_path\n"));
 	} else {
 		if (device != NULL)
-			xpt_release_device(bus, target, device);
+			xpt_release_device(device);
 		if (target != NULL)
-			xpt_release_target(bus, target);
+			xpt_release_target(target);
 		if (bus != NULL)
 			xpt_release_bus(bus);
 	}
@@ -3535,11 +3533,11 @@ xpt_release_path(struct cam_path *path)
 {
 	CAM_DEBUG(path, CAM_DEBUG_TRACE, ("xpt_release_path\n"));
 	if (path->device != NULL) {
-		xpt_release_device(path->bus, path->target, path->device);
+		xpt_release_device(path->device);
 		path->device = NULL;
 	}
 	if (path->target != NULL) {
-		xpt_release_target(path->bus, path->target);
+		xpt_release_target(path->target);
 		path->target = NULL;
 	}
 	if (path->bus != NULL) {
@@ -4375,15 +4373,15 @@ xpt_alloc_target(struct cam_eb *bus, target_id_t target_id)
 }
 
 static void
-xpt_release_target(struct cam_eb *bus, struct cam_et *target)
+xpt_release_target(struct cam_et *target)
 {
 
 	if ((--target->refcount == 0)
 	 && (TAILQ_FIRST(&target->ed_entries) == NULL)) {
-		TAILQ_REMOVE(&bus->et_entries, target, links);
-		bus->generation++;
+		TAILQ_REMOVE(&target->bus->et_entries, target, links);
+		target->bus->generation++;
+		xpt_release_bus(target->bus);
 		free(target, M_CAMXPT);
-		xpt_release_bus(bus);
 	}
 }
 
@@ -4470,13 +4468,18 @@ xpt_alloc_device(struct cam_eb *bus, struct cam_et *target, lun_id_t lun_id)
 	return (device);
 }
 
-static void
-xpt_release_device(struct cam_eb *bus, struct cam_et *target,
-		   struct cam_ed *device)
+void
+xpt_acquire_device(struct cam_ed *device)
+{
+
+	device->refcount++;
+}
+
+void
+xpt_release_device(struct cam_ed *device)
 {
 
-	if ((--device->refcount == 0)
-	 && ((device->flags & CAM_DEV_UNCONFIGURED) != 0)) {
+	if (--device->refcount == 0) {
 		struct cam_devq *devq;
 
 		if (device->alloc_ccb_entry.pinfo.index != CAM_UNQUEUED_INDEX
@@ -4486,16 +4489,16 @@ xpt_release_device(struct cam_eb *bus, struct cam_et *target,
 		if ((device->flags & CAM_DEV_REL_TIMEOUT_PENDING) != 0)
 				callout_stop(&device->callout);
 
-		TAILQ_REMOVE(&target->ed_entries, device,links);
-		target->generation++;
-		bus->sim->max_ccbs -= device->ccbq.devq_openings;
+		TAILQ_REMOVE(&device->target->ed_entries, device,links);
+		device->target->generation++;
+		device->target->bus->sim->max_ccbs -= device->ccbq.devq_openings;
 		/* Release our slot in the devq */
-		devq = bus->sim->devq;
+		devq = device->target->bus->sim->devq;
 		cam_devq_resize(devq, devq->alloc_queue.array_size - 1);
 		camq_fini(&device->drvq);
 		cam_ccbq_fini(&device->ccbq);
+		xpt_release_target(device->target);
 		free(device, M_CAMXPT);
-		xpt_release_target(bus, target);
 	}
 }