diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 5feb886..6828ca3 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -52,6 +52,82 @@
 };
 
 /**
+ *	scsi_host_set_state - Take the given host through the host
+ *		state model.
+ *	@shost:	scsi host to change the state of.
+ *	@state:	state to change to.
+ *
+ *	Returns zero if unsuccessful or an error if the requested
+ *	transition is illegal.
+ **/
+int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
+{
+	enum scsi_host_state oldstate = shost->shost_state;
+
+	if (state == oldstate)
+		return 0;
+
+	switch (state) {
+	case SHOST_CREATED:
+		/* There are no legal states that come back to
+		 * created.  This is the manually initialised start
+		 * state */
+		goto illegal;
+
+	case SHOST_RUNNING:
+		switch (oldstate) {
+		case SHOST_CREATED:
+		case SHOST_RECOVERY:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SHOST_RECOVERY:
+		switch (oldstate) {
+		case SHOST_RUNNING:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SHOST_CANCEL:
+		switch (oldstate) {
+		case SHOST_CREATED:
+		case SHOST_RUNNING:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	case SHOST_DEL:
+		switch (oldstate) {
+		case SHOST_CANCEL:
+			break;
+		default:
+			goto illegal;
+		}
+		break;
+
+	}
+	shost->shost_state = state;
+	return 0;
+
+ illegal:
+	SCSI_LOG_ERROR_RECOVERY(1,
+				dev_printk(KERN_ERR, &shost->shost_gendev,
+					   "Illegal host state transition"
+					   "%s->%s\n",
+					   scsi_host_state_name(oldstate),
+					   scsi_host_state_name(state)));
+	return -EINVAL;
+}
+EXPORT_SYMBOL(scsi_host_set_state);
+
+/**
  * scsi_host_cancel - cancel outstanding IO to this host
  * @shost:	pointer to struct Scsi_Host
  * recovery:	recovery requested to run.
@@ -60,12 +136,11 @@
 {
 	struct scsi_device *sdev;
 
-	set_bit(SHOST_CANCEL, &shost->shost_state);
+	scsi_host_set_state(shost, SHOST_CANCEL);
 	shost_for_each_device(sdev, shost) {
 		scsi_device_cancel(sdev, recovery);
 	}
-	wait_event(shost->host_wait, (!test_bit(SHOST_RECOVERY,
-						&shost->shost_state)));
+	wait_event(shost->host_wait, (shost->shost_state != SHOST_RECOVERY));
 }
 
 /**
@@ -78,7 +153,7 @@
 	scsi_host_cancel(shost, 0);
 	scsi_proc_host_rm(shost);
 
-	set_bit(SHOST_DEL, &shost->shost_state);
+	scsi_host_set_state(shost, SHOST_DEL);
 
 	transport_unregister_device(&shost->shost_gendev);
 	class_device_unregister(&shost->shost_classdev);
@@ -115,7 +190,7 @@
 	if (error)
 		goto out;
 
-	set_bit(SHOST_ADD, &shost->shost_state);
+	scsi_host_set_state(shost, SHOST_RUNNING);
 	get_device(shost->shost_gendev.parent);
 
 	error = class_device_add(&shost->shost_classdev);
@@ -226,6 +301,7 @@
 
 	spin_lock_init(&shost->default_lock);
 	scsi_assign_lock(shost, &shost->default_lock);
+	shost->shost_state = SHOST_CREATED;
 	INIT_LIST_HEAD(&shost->__devices);
 	INIT_LIST_HEAD(&shost->__targets);
 	INIT_LIST_HEAD(&shost->eh_cmd_q);
@@ -382,7 +458,7 @@
  **/
 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
 {
-	if (test_bit(SHOST_DEL, &shost->shost_state) ||
+	if ((shost->shost_state == SHOST_DEL) ||
 		!get_device(&shost->shost_gendev))
 		return NULL;
 	return shost;
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index d14523d..fb85b3c 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -627,7 +627,7 @@
 	spin_lock_irqsave(host->host_lock, flags);
 	scsi_cmd_get_serial(host, cmd); 
 
-	if (unlikely(test_bit(SHOST_CANCEL, &host->shost_state))) {
+	if (unlikely(host->shost_state == SHOST_CANCEL)) {
 		cmd->result = (DID_NO_CONNECT << 16);
 		scsi_done(cmd);
 	} else {
diff --git a/drivers/scsi/scsi_error.c b/drivers/scsi/scsi_error.c
index 0fc8b48..e9c451b 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -75,7 +75,7 @@
 
 	scmd->eh_eflags |= eh_flag;
 	list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
-	set_bit(SHOST_RECOVERY, &shost->shost_state);
+	scsi_host_set_state(shost, SHOST_RECOVERY);
 	shost->host_failed++;
 	scsi_eh_wakeup(shost);
 	spin_unlock_irqrestore(shost->host_lock, flags);
@@ -197,7 +197,8 @@
 {
 	int online;
 
-	wait_event(sdev->host->host_wait, (!test_bit(SHOST_RECOVERY, &sdev->host->shost_state)));
+	wait_event(sdev->host->host_wait, (sdev->host->shost_state !=
+					   SHOST_RECOVERY));
 
 	online = scsi_device_online(sdev);
 
@@ -1458,7 +1459,7 @@
 	SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
 					  __FUNCTION__));
 
-	clear_bit(SHOST_RECOVERY, &shost->shost_state);
+	scsi_host_set_state(shost, SHOST_RUNNING);
 
 	wake_up(&shost->host_wait);
 
diff --git a/drivers/scsi/scsi_ioctl.c b/drivers/scsi/scsi_ioctl.c
index 7a6b530..f5bf5c0 100644
--- a/drivers/scsi/scsi_ioctl.c
+++ b/drivers/scsi/scsi_ioctl.c
@@ -475,8 +475,7 @@
 	 * error processing, as long as the device was opened
 	 * non-blocking */
 	if (filp && filp->f_flags & O_NONBLOCK) {
-		if (test_bit(SHOST_RECOVERY,
-			     &sdev->host->shost_state))
+		if (sdev->host->shost_state == SHOST_RECOVERY)
 			return -ENODEV;
 	} else if (!scsi_block_when_processing_errors(sdev))
 		return -ENODEV;
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 7a91ca3..060010b 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -348,7 +348,7 @@
 
 	spin_lock_irqsave(shost->host_lock, flags);
 	shost->host_busy--;
-	if (unlikely(test_bit(SHOST_RECOVERY, &shost->shost_state) &&
+	if (unlikely((shost->shost_state == SHOST_RECOVERY) &&
 		     shost->host_failed))
 		scsi_eh_wakeup(shost);
 	spin_unlock(shost->host_lock);
@@ -1207,7 +1207,7 @@
 				   struct Scsi_Host *shost,
 				   struct scsi_device *sdev)
 {
-	if (test_bit(SHOST_RECOVERY, &shost->shost_state))
+	if (shost->shost_state == SHOST_RECOVERY)
 		return 0;
 	if (shost->host_busy == 0 && shost->host_blocked) {
 		/*
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index beed7fb..dae59d1 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -48,6 +48,30 @@
 	return name;
 }
 
+static struct {
+	enum scsi_host_state	value;
+	char			*name;
+} shost_states[] = {
+	{ SHOST_CREATED, "created" },
+	{ SHOST_RUNNING, "running" },
+	{ SHOST_CANCEL, "cancel" },
+	{ SHOST_DEL, "deleted" },
+	{ SHOST_RECOVERY, "recovery" },
+};
+const char *scsi_host_state_name(enum scsi_host_state state)
+{
+	int i;
+	char *name = NULL;
+
+	for (i = 0; i < sizeof(shost_states)/sizeof(shost_states[0]); i++) {
+		if (shost_states[i].value == state) {
+			name = shost_states[i].name;
+			break;
+		}
+	}
+	return name;
+}
+
 static int check_set(unsigned int *val, char *src)
 {
 	char *last;
@@ -124,6 +148,43 @@
 };
 static CLASS_DEVICE_ATTR(scan, S_IWUSR, NULL, store_scan);
 
+static ssize_t
+store_shost_state(struct class_device *class_dev, const char *buf, size_t count)
+{
+	int i;
+	struct Scsi_Host *shost = class_to_shost(class_dev);
+	enum scsi_host_state state = 0;
+
+	for (i = 0; i < sizeof(shost_states)/sizeof(shost_states[0]); i++) {
+		const int len = strlen(shost_states[i].name);
+		if (strncmp(shost_states[i].name, buf, len) == 0 &&
+		   buf[len] == '\n') {
+			state = shost_states[i].value;
+			break;
+		}
+	}
+	if (!state)
+		return -EINVAL;
+
+	if (scsi_host_set_state(shost, state))
+		return -EINVAL;
+	return count;
+}
+
+static ssize_t
+show_shost_state(struct class_device *class_dev, char *buf)
+{
+	struct Scsi_Host *shost = class_to_shost(class_dev);
+	const char *name = scsi_host_state_name(shost->shost_state);
+
+	if (!name)
+		return -EINVAL;
+
+	return snprintf(buf, 20, "%s\n", name);
+}
+
+static CLASS_DEVICE_ATTR(state, S_IRUGO | S_IWUSR, show_shost_state, store_shost_state);
+
 shost_rd_attr(unique_id, "%u\n");
 shost_rd_attr(host_busy, "%hu\n");
 shost_rd_attr(cmd_per_lun, "%hd\n");
@@ -139,6 +200,7 @@
 	&class_device_attr_unchecked_isa_dma,
 	&class_device_attr_proc_name,
 	&class_device_attr_scan,
+	&class_device_attr_state,
 	NULL
 };
 
diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 51292f2..14fb179 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1027,8 +1027,7 @@
 		if (sdp->detached)
 			return -ENODEV;
 		if (filp->f_flags & O_NONBLOCK) {
-			if (test_bit(SHOST_RECOVERY,
-				     &sdp->device->host->shost_state))
+			if (sdp->device->host->shost_state == SHOST_RECOVERY)
 				return -EBUSY;
 		} else if (!scsi_block_when_processing_errors(sdp->device))
 			return -EBUSY;
diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 81d5234..0b1e275 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -429,12 +429,15 @@
 };
 
 /*
- * shost states
+ * shost state: If you alter this, you also need to alter scsi_sysfs.c
+ * (for the ascii descriptions) and the state model enforcer:
+ * scsi_host_set_state()
  */
-enum {
-	SHOST_ADD,
-	SHOST_DEL,
+enum scsi_host_state {
+	SHOST_CREATED = 1,
+	SHOST_RUNNING,
 	SHOST_CANCEL,
+	SHOST_DEL,
 	SHOST_RECOVERY,
 };
 
@@ -575,7 +578,7 @@
 	unsigned int  irq;
 	
 
-	unsigned long shost_state;
+	enum scsi_host_state shost_state;
 
 	/* ldm bits */
 	struct device		shost_gendev;
@@ -633,6 +636,7 @@
 extern struct Scsi_Host *scsi_host_get(struct Scsi_Host *);
 extern void scsi_host_put(struct Scsi_Host *t);
 extern struct Scsi_Host *scsi_host_lookup(unsigned short);
+extern const char *scsi_host_state_name(enum scsi_host_state);
 
 extern u64 scsi_calculate_bounce_limit(struct Scsi_Host *);