[ofa-general] [RFC] [PATCH 1/3] 2.6.23: IB/CM: add support for paths with hop_limit > 1

[Sean Hefty]

Paths with hop_limit > 1 indicate that the connection will be routed
between IB subnets.  To support routed connections, the ib_cm requires
two paths: one from the active side to the active side router, and
a second from the passive side to the passive side router.

Modify the ib_cm interface to support multiple paths, and format the
CM REQ message with the correct passive side information.

Signed-off-by: Sean Hefty <sean.hefty at intel.com>
---

 drivers/infiniband/core/cm.c |   50 ++++++++++++++++++++++++------------------
 include/rdma/ib_cm.h         |    5 ++++
 2 files changed, 33 insertions(+), 22 deletions(-)

diff --git a/drivers/infiniband/core/cm.c b/drivers/infiniband/core/cm.c
index 842cd0b..1e2010e 100644
--- a/drivers/infiniband/core/cm.c
+++ b/drivers/infiniband/core/cm.c
@@ -877,6 +877,8 @@ static void cm_format_req(struct cm_req_msg *req_msg,
 			  struct cm_id_private *cm_id_priv,
 			  struct ib_cm_req_param *param)
 {
+	struct ib_sa_path_rec *pri_path, *alt_path;
+
 	cm_format_mad_hdr(&req_msg->hdr, CM_REQ_ATTR_ID,
 			  cm_form_tid(cm_id_priv, CM_MSG_SEQUENCE_REQ));
 
@@ -900,33 +902,37 @@ static void cm_format_req(struct cm_req_msg *req_msg,
 	cm_req_set_max_cm_retries(req_msg, param->max_cm_retries);
 	cm_req_set_srq(req_msg, param->srq);
 
-	req_msg->primary_local_lid = param->primary_path->slid;
-	req_msg->primary_remote_lid = param->primary_path->dlid;
-	req_msg->primary_local_gid = param->primary_path->sgid;
-	req_msg->primary_remote_gid = param->primary_path->dgid;
-	cm_req_set_primary_flow_label(req_msg, param->primary_path->flow_label);
-	cm_req_set_primary_packet_rate(req_msg, param->primary_path->rate);
-	req_msg->primary_traffic_class = param->primary_path->traffic_class;
-	req_msg->primary_hop_limit = param->primary_path->hop_limit;
-	cm_req_set_primary_sl(req_msg, param->primary_path->sl);
-	cm_req_set_primary_subnet_local(req_msg, 1); /* local only... */
+	pri_path = (param->primary_path->hop_limit <= 1) ?
+		    param->primary_path : &param->primary_path[1];
+	req_msg->primary_local_lid = pri_path->slid;
+	req_msg->primary_remote_lid = pri_path->dlid;
+	req_msg->primary_local_gid = pri_path->sgid;
+	req_msg->primary_remote_gid = pri_path->dgid;
+	cm_req_set_primary_flow_label(req_msg, pri_path->flow_label);
+	cm_req_set_primary_packet_rate(req_msg, pri_path->rate);
+	req_msg->primary_traffic_class = pri_path->traffic_class;
+	req_msg->primary_hop_limit = pri_path->hop_limit;
+	cm_req_set_primary_sl(req_msg, pri_path->sl);
+	cm_req_set_primary_subnet_local(req_msg, (pri_path->hop_limit <= 1));
 	cm_req_set_primary_local_ack_timeout(req_msg,
-		min(31, param->primary_path->packet_life_time + 1));
+		min(31, pri_path->packet_life_time + 1));
 
 	if (param->alternate_path) {
-		req_msg->alt_local_lid = param->alternate_path->slid;
-		req_msg->alt_remote_lid = param->alternate_path->dlid;
-		req_msg->alt_local_gid = param->alternate_path->sgid;
-		req_msg->alt_remote_gid = param->alternate_path->dgid;
+		alt_path = (param->alternate_path->hop_limit <= 1) ?
+			    param->alternate_path : &param->alternate_path[1];
+		req_msg->alt_local_lid = alt_path->slid;
+		req_msg->alt_remote_lid = alt_path->dlid;
+		req_msg->alt_local_gid = alt_path->sgid;
+		req_msg->alt_remote_gid = alt_path->dgid;
 		cm_req_set_alt_flow_label(req_msg,
-					  param->alternate_path->flow_label);
-		cm_req_set_alt_packet_rate(req_msg, param->alternate_path->rate);
-		req_msg->alt_traffic_class = param->alternate_path->traffic_class;
-		req_msg->alt_hop_limit = param->alternate_path->hop_limit;
-		cm_req_set_alt_sl(req_msg, param->alternate_path->sl);
-		cm_req_set_alt_subnet_local(req_msg, 1); /* local only... */
+					  alt_path->flow_label);
+		cm_req_set_alt_packet_rate(req_msg, alt_path->rate);
+		req_msg->alt_traffic_class = alt_path->traffic_class;
+		req_msg->alt_hop_limit = alt_path->hop_limit;
+		cm_req_set_alt_sl(req_msg, alt_path->sl);
+		cm_req_set_alt_subnet_local(req_msg, (alt_path->hop_limit <= 1));
 		cm_req_set_alt_local_ack_timeout(req_msg,
-			min(31, param->alternate_path->packet_life_time + 1));
+			min(31, alt_path->packet_life_time + 1));
 	}
 
 	if (param->private_data && param->private_data_len)
diff --git a/include/rdma/ib_cm.h b/include/rdma/ib_cm.h
index 5c07017..f715ba5 100644
--- a/include/rdma/ib_cm.h
+++ b/include/rdma/ib_cm.h
@@ -347,6 +347,11 @@ struct ib_cm_compare_data {
 int ib_cm_listen(struct ib_cm_id *cm_id, __be64 service_id, __be64 service_mask,
 		 struct ib_cm_compare_data *compare_data);
 
+/*
+ * If hop_limit > 1 or reversible = 0, then primary/alternate path fields
+ * point to an array of paths.  The first path is relative to the active
+ * side, and the second path is relative to the passive side.
+ */
 struct ib_cm_req_param {
 	struct ib_sa_path_rec	*primary_path;
 	struct ib_sa_path_rec	*alternate_path;