mpt2sas: delay scsi_add_host call to work with scsi-mq

In _scsih_probe, delay the call to scsi_add_host until the host has been
fully set up.

Otherwise, the default .can_queue value of 1 causes scsi-mq to set the block
layer request queue size to its minimum size, resulting in awful performance.

In _scsih_probe error handling, call mpt3sas_base_detach rather than
scsi_remove_host to properly clean up in reverse order.

In _scsih_remove, call scsi_remove_host earlier to clean up in reverse order.

Signed-off-by: Robert Elliott <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Nagalakshmi Nandigama <[e-mail]>
Signed-off-by: Sreekanth Reddy <[e-mail]>
Signed-off-by: Christoph Hellwig <[e-mail]>

drivers/scsi/mpt2sas/mpt2sas_base.c

···
 	ioc->fault_reset_work_q = NULL;
 	spin_unlock_irqrestore(&ioc->ioc_reset_in_progress_lock, flags);
 	if (wq) {
-		if (!cancel_delayed_work(&ioc->fault_reset_work))
+		if (!cancel_delayed_work_sync(&ioc->fault_reset_work))
 			flush_workqueue(wq);
 		destroy_workqueue(wq);
 	}

drivers/scsi/mpt2sas/mpt2sas_scsih.c

···
 		return;
 
 	list_for_each_entry_safe(fw_event, next, &ioc->fw_event_list, list) {
-		if (cancel_delayed_work(&fw_event->delayed_work)) {
+		if (cancel_delayed_work_sync(&fw_event->delayed_work)) {
 			_scsih_fw_event_free(ioc, fw_event);
 			continue;
 		}
-		fw_event->cancel_pending_work = 1;
 	}
 }
 
···
 	struct MPT2SAS_ADAPTER *ioc = fw_event->ioc;
 
 	/* the queue is being flushed so ignore this event */
-	if (ioc->remove_host || fw_event->cancel_pending_work ||
+	if (ioc->remove_host ||
 	    ioc->pci_error_recovery) {
 		_scsih_fw_event_free(ioc, fw_event);
 		return;
···
 	}
 
 	sas_remove_host(shost);
+	scsi_remove_host(shost);
 	mpt2sas_base_detach(ioc);
 	list_del(&ioc->list);
-	scsi_remove_host(shost);
 	scsi_host_put(shost);
 }
 
···
 		}
 	}
 
-	if ((scsi_add_host(shost, &pdev->dev))) {
-		printk(MPT2SAS_ERR_FMT "failure at %s:%d/%s()!\n",
-		    ioc->name, __FILE__, __LINE__, __func__);
-		list_del(&ioc->list);
-		goto out_add_shost_fail;
-	}
-
 	/* register EEDP capabilities with SCSI layer */
 	if (prot_mask)
 		scsi_host_set_prot(shost, prot_mask);
···
 		}
 	} else
 		ioc->hide_drives = 0;
+
+	if ((scsi_add_host(shost, &pdev->dev))) {
+		printk(MPT2SAS_ERR_FMT "failure at %s:%d/%s()!\n",
+		    ioc->name, __FILE__, __LINE__, __func__);
+		goto out_add_shost_fail;
+	}
+
 	scsi_scan_host(shost);
 
 	return 0;
 
+ out_add_shost_fail:
+	mpt2sas_base_detach(ioc);
  out_attach_fail:
 	destroy_workqueue(ioc->firmware_event_thread);
  out_thread_fail:
 	list_del(&ioc->list);
-	scsi_remove_host(shost);
- out_add_shost_fail:
 	scsi_host_put(shost);
 	return -ENODEV;
 }