8 files changed, 162 insertions, 21 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;
diff --git a/drivers/scsi/scsi.c b/drivers/scsi/scsi.c
index d14523d7e449..fb85b3ced7b5 100644
--- a/drivers/scsi/scsi.c
+++ b/drivers/scsi/scsi.c
@@ -627,7 +627,7 @@ int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
         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 0fc8b48f052b..e9c451ba71fc 100644
--- a/drivers/scsi/scsi_error.c
+++ b/drivers/scsi/scsi_error.c
@@ -75,7 +75,7 @@ int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
 
         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 scsi_block_when_processing_errors(struct scsi_device *sdev)
 {
         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 @@ static void scsi_restart_operations(struct Scsi_Host *shost)
         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 7a6b530115ac..f5bf5c07be91 100644
--- a/drivers/scsi/scsi_ioctl.c
+++ b/drivers/scsi/scsi_ioctl.c
@@ -475,8 +475,7 @@ int scsi_nonblockable_ioctl(struct scsi_device *sdev, int cmd,
          * 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 7a91ca3d32a6..060010bccabc 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -348,7 +348,7 @@ void scsi_device_unbusy(struct scsi_device *sdev)
 
         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 @@ static inline int scsi_host_queue_ready(struct request_queue *q,
                                    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 beed7fbe1cbe..dae59d1da07a 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -48,6 +48,30 @@ const char *scsi_device_state_name(enum scsi_device_state state)
         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 ssize_t store_scan(struct class_device *class_dev, const char *buf,
 };
 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 @@ static struct class_device_attribute *scsi_sysfs_shost_attrs[] = {
         &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 51292f269ce5..14fb179b3842 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1027,8 +1027,7 @@ sg_ioctl(struct inode *inode, struct file *filp,
                 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 81d5234f6771..0b1e275b2699 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -429,12 +429,15 @@ struct scsi_host_template {
 };
 
 /*
- * 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 @@ struct Scsi_Host {
         unsigned int  irq;
         
 
-        unsigned long shost_state;
+        enum scsi_host_state shost_state;
 
         /* ldm bits */
         struct device           shost_gendev;
@@ -633,6 +636,7 @@ extern void scsi_remove_host(struct Scsi_Host *);
 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 *);