[SCSI] host state model update: mediate host add/remove race

[safe/jmp/linux-2.6] / drivers / scsi / hosts.c

diff --git a/drivers/scsi/hosts.c b/drivers/scsi/hosts.c
index ba34757..8640ad1 100644 (file)
--- a/drivers/scsi/hosts.c
+++ b/drivers/scsi/hosts.c
@@ -52,21 +52,80 @@ static struct class shost_class = {
 };
 
 /**
- * scsi_host_cancel - cancel outstanding IO to this host
- * @shost:     pointer to struct Scsi_Host
- * recovery:   recovery requested to run.
+ *     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.
  **/
-void scsi_host_cancel(struct Scsi_Host *shost, int recovery)
+int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
 {
-       struct scsi_device *sdev;
+       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;
 
-       set_bit(SHOST_CANCEL, &shost->shost_state);
-       shost_for_each_device(sdev, shost) {
-               scsi_device_cancel(sdev, recovery);
        }
-       wait_event(shost->host_wait, (!test_bit(SHOST_RECOVERY,
-                                               &shost->shost_state)));
+       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_remove_host - remove a scsi host
@@ -74,11 +133,13 @@ void scsi_host_cancel(struct Scsi_Host *shost, int recovery)
  **/
 void scsi_remove_host(struct Scsi_Host *shost)
 {
+       down(&shost->scan_mutex);
+       scsi_host_set_state(shost, SHOST_CANCEL);
+       up(&shost->scan_mutex);
        scsi_forget_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 +176,7 @@ 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);
@@ -180,11 +241,6 @@ static void scsi_host_dev_release(struct device *dev)
        scsi_destroy_command_freelist(shost);
        kfree(shost->shost_data);
 
-       /*
-        * Some drivers (eg aha1542) do scsi_register()/scsi_unregister()
-        * during probing without performing a scsi_set_device() in between.
-        * In this case dev->parent is NULL.
-        */
        if (parent)
                put_device(parent);
        kfree(shost);
@@ -231,6 +287,7 @@ 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);
@@ -387,7 +444,7 @@ 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;