[openib-general] [PATCH 4/7 v2] for 2.6.20 rdma/cma: add rdma_establish to force connection if RTU is lost

[Sean Hefty]

Allow ULPs to transition to RTS before sending a REP.  This allows the
ULP to respond to a received message if it arrives before the RTU or
communication established event.

Modify the RDMA CM to transition to RTS when sending a REP over IB, and
expose a new rdma_establish interface that a user can invoke to force a
connection into the established state if it polls a receive completion
before an RTU arrives.

Signed-off-by: Sean Hefty <sean.hefty at intel.com>
---
diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index 1cf0d42..492d4ce 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -3242,6 +3242,10 @@ static int cm_init_qp_rts_attr(struct cm
 
 	spin_lock_irqsave(&cm_id_priv->lock, flags);
 	switch (cm_id_priv->id.state) {
+	/* Allow transition to RTS before sending REP */
+	case IB_CM_REQ_RCVD:
+	case IB_CM_MRA_REQ_SENT:
+
 	case IB_CM_REP_RCVD:
 	case IB_CM_MRA_REP_SENT:
 	case IB_CM_REP_SENT:
diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 622c8f9..416fee8 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -759,22 +759,6 @@ static int cma_verify_rep(struct rdma_id
 	return 0;
 }
 
-static int cma_rtu_recv(struct rdma_id_private *id_priv)
-{
-	int ret;
-
-	ret = cma_modify_qp_rts(&id_priv->id);
-	if (ret)
-		goto reject;
-
-	return 0;
-reject:
-	cma_modify_qp_err(&id_priv->id);
-	ib_send_cm_rej(id_priv->cm_id.ib, IB_CM_REJ_CONSUMER_DEFINED,
-		       NULL, 0, NULL, 0);
-	return ret;
-}
-
 static void cma_set_rep_event_data(struct rdma_cm_event *event,
 				   struct ib_cm_rep_event_param *rep_data,
 				   void *private_data)
@@ -820,9 +804,8 @@ static int cma_ib_handler(struct ib_cm_i
 				       ib_event->private_data);
 		break;
 	case IB_CM_RTU_RECEIVED:
-		event.status = cma_rtu_recv(id_priv);
-		event.event = event.status ? RDMA_CM_EVENT_CONNECT_ERROR :
-					     RDMA_CM_EVENT_ESTABLISHED;
+	case IB_CM_USER_ESTABLISHED:
+		event.event = RDMA_CM_EVENT_ESTABLISHED;
 		break;
 	case IB_CM_DREQ_ERROR:
 		event.status = -ETIMEDOUT; /* fall through */
@@ -1990,11 +1973,25 @@ static int cma_accept_ib(struct rdma_id_
 			 struct rdma_conn_param *conn_param)
 {
 	struct ib_cm_rep_param rep;
-	int ret;
+	struct ib_qp_attr qp_attr;
+	int qp_attr_mask, ret;
 
-	ret = cma_modify_qp_rtr(&id_priv->id);
-	if (ret)
-		return ret;
+	if (id_priv->id.qp) {
+		ret = cma_modify_qp_rtr(&id_priv->id);
+		if (ret)
+			goto out;
+
+		qp_attr.qp_state = IB_QPS_RTS;
+		ret = ib_cm_init_qp_attr(id_priv->cm_id.ib, &qp_attr,
+					 &qp_attr_mask);
+		if (ret)
+			goto out;
+
+		qp_attr.max_rd_atomic = conn_param->initiator_depth;
+		ret = ib_modify_qp(id_priv->id.qp, &qp_attr, qp_attr_mask);
+		if (ret)
+			goto out;
+	}
 
 	memset(&rep, 0, sizeof rep);
 	rep.qp_num = id_priv->qp_num;
@@ -2009,7 +2006,9 @@ static int cma_accept_ib(struct rdma_id_
 	rep.rnr_retry_count = conn_param->rnr_retry_count;
 	rep.srq = id_priv->srq ? 1 : 0;
 
-	return ib_send_cm_rep(id_priv->cm_id.ib, &rep);
+	ret = ib_send_cm_rep(id_priv->cm_id.ib, &rep);
+out:
+	return ret;
 }
 
 static int cma_accept_iw(struct rdma_id_private *id_priv,
@@ -2074,6 +2073,27 @@ reject:
 }
 EXPORT_SYMBOL(rdma_accept);
 
+int rdma_establish(struct rdma_cm_id *id)
+{
+	struct rdma_id_private *id_priv;
+	int ret;
+
+	id_priv = container_of(id, struct rdma_id_private, id);
+	if (!cma_comp(id_priv, CMA_CONNECT))
+		return -EINVAL;
+
+	switch (id->device->node_type) {
+	case RDMA_NODE_IB_CA:
+		ret = ib_cm_establish(id_priv->cm_id.ib);
+		break;
+	default:
+		ret = 0;
+		break;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(rdma_establish);
+
 int rdma_reject(struct rdma_cm_id *id, const void *private_data,
 		u8 private_data_len)
 {
diff --git a/include/rdma/rdma_cm.h b/include/rdma/rdma_cm.h
index aa6ce47..dbc7c56 100644
--- a/include/rdma/rdma_cm.h
+++ b/include/rdma/rdma_cm.h
@@ -253,6 +253,16 @@ int rdma_listen(struct rdma_cm_id *id, i
 int rdma_accept(struct rdma_cm_id *id, struct rdma_conn_param *conn_param);
 
 /**
+ * rdma_establish - Forces a connection state to established.
+ * @id: Connection identifier to transition to established.
+ *
+ * This routine should be invoked by users who receive messages on a
+ * QP before being notified that the connection has been established by the
+ * RDMA CM.
+ */
+int rdma_establish(struct rdma_cm_id *id);
+
+/**
  * rdma_reject - Called to reject a connection request or response.
  */
 int rdma_reject(struct rdma_cm_id *id, const void *private_data,