RDMA/srpt: Fix handling of SR-IOV and iWARP ports

Management datagrams (MADs) are not supported by SR-IOV VFs nor by iWARP
ports. Support SR-IOV VFs and iWARP ports by only logging an error message
if MAD handler registration fails.

Link: https://lore.kernel.org/r/20190930231707.48259-10-bvanassche@acm.org
Cc: Honggang LI <honli@redhat.com>
Cc: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/ulp/srpt/ib_srpt.c

@@ -556,24 +556,16 @@ static int srpt_refresh_port(struct srpt_port *sport)
 	struct ib_port_attr port_attr;
 	int ret;
 
-	memset(&port_modify, 0, sizeof(port_modify));
-	port_modify.set_port_cap_mask = IB_PORT_DEVICE_MGMT_SUP;
-	port_modify.clr_port_cap_mask = 0;
-
-	ret = ib_modify_port(sport->sdev->device, sport->port, 0, &port_modify);
-	if (ret)
-		goto err_mod_port;
-
 	ret = ib_query_port(sport->sdev->device, sport->port, &port_attr);
 	if (ret)
-		goto err_query_port;
+		return ret;
 
 	sport->sm_lid = port_attr.sm_lid;
 	sport->lid = port_attr.lid;
 
 	ret = rdma_query_gid(sport->sdev->device, sport->port, 0, &sport->gid);
 	if (ret)
-		goto err_query_port;
+		return ret;
 
 	sport->port_guid_wwn.priv = sport;
 	srpt_format_guid(sport->port_guid, sizeof(sport->port_guid),
@@ -584,6 +576,20 @@ static int srpt_refresh_port(struct srpt_port *sport)
 		 be64_to_cpu(sport->gid.global.subnet_prefix),
 		 be64_to_cpu(sport->gid.global.interface_id));
 
+	if (rdma_protocol_iwarp(sport->sdev->device, sport->port))
+		return 0;
+
+	memset(&port_modify, 0, sizeof(port_modify));
+	port_modify.set_port_cap_mask = IB_PORT_DEVICE_MGMT_SUP;
+	port_modify.clr_port_cap_mask = 0;
+
+	ret = ib_modify_port(sport->sdev->device, sport->port, 0, &port_modify);
+	if (ret) {
+		pr_warn("%s-%d: enabling device management failed (%d). Note: this is expected if SR-IOV is enabled.\n",
+			dev_name(&sport->sdev->device->dev), sport->port, ret);
+		return 0;
+	}
+
 	if (!sport->mad_agent) {
 		memset(&reg_req, 0, sizeof(reg_req));
 		reg_req.mgmt_class = IB_MGMT_CLASS_DEVICE_MGMT;
@@ -599,23 +605,14 @@ static int srpt_refresh_port(struct srpt_port *sport)
 							 srpt_mad_recv_handler,
 							 sport, 0);
 		if (IS_ERR(sport->mad_agent)) {
-			ret = PTR_ERR(sport->mad_agent);
+			pr_err("%s-%d: MAD agent registration failed (%ld). Note: this is expected if SR-IOV is enabled.\n",
+			       dev_name(&sport->sdev->device->dev), sport->port,
+			       PTR_ERR(sport->mad_agent));
 			sport->mad_agent = NULL;
-			goto err_query_port;
 		}
 	}
 
 	return 0;
-
-err_query_port:
-
-	port_modify.set_port_cap_mask = 0;
-	port_modify.clr_port_cap_mask = IB_PORT_DEVICE_MGMT_SUP;
-	ib_modify_port(sport->sdev->device, sport->port, 0, &port_modify);
-
-err_mod_port:
-
-	return ret;
 }
 
 /**