1 files changed, 82 insertions, 6 deletions

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index 5feb886c3392..6828ca305c2a 100644
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -52,6 +52,82 @@ static struct class shost_class = {
 };
 
 /**
+ *      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 @@ static void scsi_host_cancel(struct Scsi_Host *shost, int recovery)
 {
         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 @@ void scsi_remove_host(struct Scsi_Host *shost)
         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 @@ int scsi_add_host(struct Scsi_Host *shost, struct device *dev)
         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 @@ struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 
         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 @@ EXPORT_SYMBOL(scsi_host_lookup);
  **/
 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;