[SCSI] iscsi class: fix lock dep warning on logout

We never should hit the lock up that is spit out when
lock dep is on and we logout. But we have been using the
shost work queue in a odd way. This patch has us use the
work queue for scanning instead of creating our own,
and this ends up also killing the lock dep warnings.
Signed-off-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/scsi_transport_iscsi.c

@@ -246,30 +246,13 @@ static int iscsi_setup_host(struct transport_container *tc, struct device *dev,
 	memset(ihost, 0, sizeof(*ihost));
 	atomic_set(&ihost->nr_scans, 0);
 	mutex_init(&ihost->mutex);
-
-	snprintf(ihost->scan_workq_name, sizeof(ihost->scan_workq_name),
-		 "iscsi_scan_%d", shost->host_no);
-	ihost->scan_workq = create_singlethread_workqueue(
-						ihost->scan_workq_name);
-	if (!ihost->scan_workq)
-		return -ENOMEM;
-	return 0;
-}
-
-static int iscsi_remove_host(struct transport_container *tc, struct device *dev,
-			     struct device *cdev)
-{
-	struct Scsi_Host *shost = dev_to_shost(dev);
-	struct iscsi_cls_host *ihost = shost->shost_data;
-
-	destroy_workqueue(ihost->scan_workq);
 	return 0;
 }
 
 static DECLARE_TRANSPORT_CLASS(iscsi_host_class,
 			       "iscsi_host",
 			       iscsi_setup_host,
-			       iscsi_remove_host,
+			       NULL,
 			       NULL);
 
 static DECLARE_TRANSPORT_CLASS(iscsi_session_class,
@@ -568,7 +551,7 @@ static void __iscsi_unblock_session(struct work_struct *work)
 	 * scanning from userspace).
 	 */
 	if (shost->hostt->scan_finished) {
-		if (queue_work(ihost->scan_workq, &session->scan_work))
+		if (scsi_queue_work(shost, &session->scan_work))
 			atomic_inc(&ihost->nr_scans);
 	}
 }
@@ -636,14 +619,6 @@ static void __iscsi_unbind_session(struct work_struct *work)
 	iscsi_session_event(session, ISCSI_KEVENT_UNBIND_SESSION);
 }
 
-static int iscsi_unbind_session(struct iscsi_cls_session *session)
-{
-	struct Scsi_Host *shost = iscsi_session_to_shost(session);
-	struct iscsi_cls_host *ihost = shost->shost_data;
-
-	return queue_work(ihost->scan_workq, &session->unbind_work);
-}
-
 struct iscsi_cls_session *
 iscsi_alloc_session(struct Scsi_Host *shost, struct iscsi_transport *transport,
 		    int dd_size)
@@ -796,7 +771,6 @@ static int iscsi_iter_destroy_conn_fn(struct device *dev, void *data)
 void iscsi_remove_session(struct iscsi_cls_session *session)
 {
 	struct Scsi_Host *shost = iscsi_session_to_shost(session);
-	struct iscsi_cls_host *ihost = shost->shost_data;
 	unsigned long flags;
 	int err;
 
@@ -821,7 +795,7 @@ void iscsi_remove_session(struct iscsi_cls_session *session)
 
 	scsi_target_unblock(&session->dev);
 	/* flush running scans then delete devices */
-	flush_workqueue(ihost->scan_workq);
+	scsi_flush_work(shost);
 	__iscsi_unbind_session(&session->unbind_work);
 
 	/* hw iscsi may not have removed all connections from session */
@@ -1447,7 +1421,8 @@ iscsi_if_recv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 	case ISCSI_UEVENT_UNBIND_SESSION:
 		session = iscsi_session_lookup(ev->u.d_session.sid);
 		if (session)
-			iscsi_unbind_session(session);
+			scsi_queue_work(iscsi_session_to_shost(session),
+					&session->unbind_work);
 		else
 			err = -EINVAL;
 		break;
@@ -1809,8 +1784,7 @@ iscsi_register_transport(struct iscsi_transport *tt)
 	priv->daemon_pid = -1;
 	priv->iscsi_transport = tt;
 	priv->t.user_scan = iscsi_user_scan;
-	if (!(tt->caps & CAP_DATA_PATH_OFFLOAD))
-		priv->t.create_work_queue = 1;
+	priv->t.create_work_queue = 1;
 
 	priv->dev.class = &iscsi_transport_class;
 	dev_set_name(&priv->dev, "%s", tt->name);

include/scsi/scsi_transport_iscsi.h

@@ -206,8 +206,6 @@ struct iscsi_cls_session {
 struct iscsi_cls_host {
 	atomic_t nr_scans;
 	struct mutex mutex;
-	struct workqueue_struct *scan_workq;
-	char scan_workq_name[20];
 };
 
 extern void iscsi_host_for_each_session(struct Scsi_Host *shost,