scsi: iscsi: Delay freeing target_id

If we are doing async removal of the session, we could be doing a
scsi_remove_target from the removal workqueue, and for the offload case we
could be doing a new session addition and scan to the same host. The
add/scan might then end up trying to use the target_id of the target we are
removing.

This patch just has a delay the freeing of the target_id until after the
scsi_remove_target has completed, so we know it's no longer in use.

Link: https://lore.kernel.org/r/1593632868-6808-2-git-send-email-michael.christie@oracle.comReviewed-by: Lee Duncan <lduncan@suse.com>
Signed-off-by: Mike Christie <michael.christie@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_transport_iscsi.c

@@ -2036,11 +2036,11 @@ static void __iscsi_unbind_session(struct work_struct *work)
 	spin_unlock_irqrestore(&session->lock, flags);
 	mutex_unlock(&ihost->mutex);
 
+	scsi_remove_target(&session->dev);
+
 	if (session->ida_used)
 		ida_simple_remove(&iscsi_sess_ida, target_id);
 
-	scsi_remove_target(&session->dev);
-
 unbind_session_exit:
 	iscsi_session_event(session, ISCSI_KEVENT_UNBIND_SESSION);
 	ISCSI_DBG_TRANS_SESSION(session, "Completed target removal\n");