IB/cm: Fix stale connection detection

The ib_cm can incorrectly detect a stale connection (a new connection
request for a QPN that is already connected) as a duplicate connection
request.  Separate the handling of potential duplicate REQs from stale
connections.
Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

drivers/infiniband/core/cm.c

@@ -1297,26 +1297,29 @@ static struct cm_id_private * cm_match_req(struct cm_work *work,
 
 	req_msg = (struct cm_req_msg *)work->mad_recv_wc->recv_buf.mad;
 
-	/* Check for duplicate REQ and stale connections. */
+	/* Check for possible duplicate REQ. */
 	spin_lock_irqsave(&cm.lock, flags);
 	timewait_info = cm_insert_remote_id(cm_id_priv->timewait_info);
-	if (!timewait_info)
-		timewait_info = cm_insert_remote_qpn(cm_id_priv->timewait_info);
-
 	if (timewait_info) {
 		cur_cm_id_priv = cm_get_id(timewait_info->work.local_id,
 					   timewait_info->work.remote_id);
-		cm_cleanup_timewait(cm_id_priv->timewait_info);
 		spin_unlock_irqrestore(&cm.lock, flags);
 		if (cur_cm_id_priv) {
 			cm_dup_req_handler(work, cur_cm_id_priv);
 			cm_deref_id(cur_cm_id_priv);
-		} else
+		}
+		return NULL;
+	}
+
+	/* Check for stale connections. */
+	timewait_info = cm_insert_remote_qpn(cm_id_priv->timewait_info);
+	if (timewait_info) {
+		cm_cleanup_timewait(cm_id_priv->timewait_info);
+		spin_unlock_irqrestore(&cm.lock, flags);
 		cm_issue_rej(work->port, work->mad_recv_wc,
 			     IB_CM_REJ_STALE_CONN, CM_MSG_RESPONSE_REQ,
 			     NULL, 0);
-		listen_cm_id_priv = NULL;
-		goto out;
+		return NULL;
 	}
 
 	/* Find matching listen request. */