IB/srpt: Add RDMA/CM support

Add a parameter for configuring the port on which the ib_srpt driver
listens for incoming RDMA/CM connections, namely
/sys/kernel/config/target/srpt/discovery_auth/rdma_cm_port. The default
value for this parameter is 0 which means "do not listen for incoming
RDMA/CM connections". Add RDMA/CM support to all code that handles
connection state changes. Modify srpt_init_nodeacl() such that ACLs can
be configured for IPv4 and IPv6 addresses.

Note: incoming connection requests are only accepted for ports that
have been enabled. See also the "if (!sport->enabled)" code in the
connection request handler. See also the following configfs attribute:
/sys/kernel/config/target/srpt/$port/$port/enable.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 318 insertions, 62 deletions

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
index 33454309a98b..8956d4621273 100644
--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -41,6 +41,7 @@
 #include <linux/string.h>
 #include <linux/delay.h>
 #include <linux/atomic.h>
+#include <linux/inet.h>
 #include <rdma/ib_cache.h>
 #include <scsi/scsi_proto.h>
 #include <scsi/scsi_tcq.h>
@@ -92,6 +93,11 @@ MODULE_PARM_DESC(srpt_service_guid,
 		 " instead of using the node_guid of the first HCA.");
 
 static struct ib_client srpt_client;
+/* Protects both rdma_cm_port and rdma_cm_id. */
+static DEFINE_MUTEX(rdma_cm_mutex);
+/* Port number RDMA/CM will bind to. */
+static u16 rdma_cm_port;
+static struct rdma_cm_id *rdma_cm_id;
 static void srpt_release_cmd(struct se_cmd *se_cmd);
 static void srpt_free_ch(struct kref *kref);
 static int srpt_queue_status(struct se_cmd *cmd);
@@ -220,7 +226,10 @@ static void srpt_qp_event(struct ib_event *event, struct srpt_rdma_ch *ch)
 
 	switch (event->event) {
 	case IB_EVENT_COMM_EST:
-		ib_cm_notify(ch->ib_cm.cm_id, event->event);
+		if (ch->using_rdma_cm)
+			rdma_notify(ch->rdma_cm.cm_id, event->event);
+		else
+			ib_cm_notify(ch->ib_cm.cm_id, event->event);
 		break;
 	case IB_EVENT_QP_LAST_WQE_REACHED:
 		pr_debug("%s-%d, state %s: received Last WQE event.\n",
@@ -1060,6 +1069,8 @@ static int srpt_init_ch_qp(struct srpt_rdma_ch *ch, struct ib_qp *qp)
 	struct ib_qp_attr *attr;
 	int ret;
 
+	WARN_ON_ONCE(ch->using_rdma_cm);
+
 	attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 	if (!attr)
 		return -ENOMEM;
@@ -1099,6 +1110,8 @@ static int srpt_ch_qp_rtr(struct srpt_rdma_ch *ch, struct ib_qp *qp)
 	int attr_mask;
 	int ret;
 
+	WARN_ON_ONCE(ch->using_rdma_cm);
+
 	qp_attr.qp_state = IB_QPS_RTR;
 	ret = ib_cm_init_qp_attr(ch->ib_cm.cm_id, &qp_attr, &attr_mask);
 	if (ret)
@@ -1749,18 +1762,33 @@ retry:
 		qp_init->cap.max_recv_sge = qp_init->cap.max_send_sge;
 	}
 
-	ch->qp = ib_create_qp(sdev->pd, qp_init);
-	if (IS_ERR(ch->qp)) {
-		ret = PTR_ERR(ch->qp);
-		if (ret == -ENOMEM) {
-			sq_size /= 2;
-			if (sq_size >= MIN_SRPT_SQ_SIZE) {
-				ib_destroy_cq(ch->cq);
-				goto retry;
-			}
+	if (ch->using_rdma_cm) {
+		ret = rdma_create_qp(ch->rdma_cm.cm_id, sdev->pd, qp_init);
+		ch->qp = ch->rdma_cm.cm_id->qp;
+	} else {
+		ch->qp = ib_create_qp(sdev->pd, qp_init);
+		if (!IS_ERR(ch->qp)) {
+			ret = srpt_init_ch_qp(ch, ch->qp);
+			if (ret)
+				ib_destroy_qp(ch->qp);
+		} else {
+			ret = PTR_ERR(ch->qp);
+		}
+	}
+	if (ret) {
+		bool retry = sq_size > MIN_SRPT_SQ_SIZE;
+
+		if (retry) {
+			pr_debug("failed to create queue pair with sq_size = %d (%d) - retrying\n",
+				 sq_size, ret);
+			ib_free_cq(ch->cq);
+			sq_size = max(sq_size / 2, MIN_SRPT_SQ_SIZE);
+			goto retry;
+		} else {
+			pr_err("failed to create queue pair with sq_size = %d (%d)\n",
+			       sq_size, ret);
+			goto err_destroy_cq;
 		}
-		pr_err("failed to create_qp ret= %d\n", ret);
-		goto err_destroy_cq;
 	}
 
 	atomic_set(&ch->sq_wr_avail, qp_init->cap.max_send_wr);
@@ -1769,10 +1797,6 @@ retry:
 		 __func__, ch->cq->cqe, qp_init->cap.max_send_sge,
 		 qp_init->cap.max_send_wr, ch);
 
-	ret = srpt_init_ch_qp(ch, ch->qp);
-	if (ret)
-		goto err_destroy_qp;
-
 	if (!sdev->use_srq)
 		for (i = 0; i < ch->rq_size; i++)
 			srpt_post_recv(sdev, ch, ch->ioctx_recv_ring[i]);
@@ -1781,9 +1805,8 @@ out:
 	kfree(qp_init);
 	return ret;
 
-err_destroy_qp:
-	ib_destroy_qp(ch->qp);
 err_destroy_cq:
+	ch->qp = NULL;
 	ib_free_cq(ch->cq);
 	goto out;
 }
@@ -1852,9 +1875,13 @@ static int srpt_disconnect_ch(struct srpt_rdma_ch *ch)
 	if (!srpt_set_ch_state(ch, CH_DISCONNECTING))
 		return -ENOTCONN;
 
-	ret = ib_send_cm_dreq(ch->ib_cm.cm_id, NULL, 0);
-	if (ret < 0)
-		ret = ib_send_cm_drep(ch->ib_cm.cm_id, NULL, 0);
+	if (ch->using_rdma_cm) {
+		ret = rdma_disconnect(ch->rdma_cm.cm_id);
+	} else {
+		ret = ib_send_cm_dreq(ch->ib_cm.cm_id, NULL, 0);
+		if (ret < 0)
+			ret = ib_send_cm_drep(ch->ib_cm.cm_id, NULL, 0);
+	}
 
 	if (ret < 0 && srpt_close_ch(ch))
 		ret = 0;
@@ -2005,7 +2032,10 @@ static void srpt_release_channel_work(struct work_struct *w)
 	transport_deregister_session(se_sess);
 	ch->sess = NULL;
 
-	ib_destroy_cm_id(ch->ib_cm.cm_id);
+	if (ch->using_rdma_cm)
+		rdma_destroy_id(ch->rdma_cm.cm_id);
+	else
+		ib_destroy_cm_id(ch->ib_cm.cm_id);
 
 	srpt_destroy_ch_ib(ch);
 
@@ -2029,26 +2059,33 @@ static void srpt_release_channel_work(struct work_struct *w)
 
 /**
  * srpt_cm_req_recv - process the event IB_CM_REQ_RECEIVED
- * @cm_id: IB/CM connection identifier.
- * @port_num: Port through which the IB/CM REQ message was received.
+ * @sdev: HCA through which the login request was received.
+ * @ib_cm_id: IB/CM connection identifier in case of IB/CM.
+ * @rdma_cm_id: RDMA/CM connection identifier in case of RDMA/CM.
+ * @port_num: Port through which the REQ message was received.
  * @pkey: P_Key of the incoming connection.
  * @req: SRP login request.
- * @src_addr: GID of the port that submitted the login request.
+ * @src_addr: GID (IB/CM) or IP address (RDMA/CM) of the port that submitted
+ * the login request.
  *
  * Ownership of the cm_id is transferred to the target session if this
- * functions returns zero. Otherwise the caller remains the owner of cm_id.
+ * function returns zero. Otherwise the caller remains the owner of cm_id.
  */
-static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
+static int srpt_cm_req_recv(struct srpt_device *const sdev,
+			    struct ib_cm_id *ib_cm_id,
+			    struct rdma_cm_id *rdma_cm_id,
 			    u8 port_num, __be16 pkey,
 			    const struct srp_login_req *req,
 			    const char *src_addr)
 {
-	struct srpt_device *sdev = cm_id->context;
 	struct srpt_port *sport = &sdev->port[port_num - 1];
 	struct srpt_nexus *nexus;
 	struct srp_login_rsp *rsp = NULL;
 	struct srp_login_rej *rej = NULL;
-	struct ib_cm_rep_param *rep_param = NULL;
+	union {
+		struct rdma_conn_param rdma_cm;
+		struct ib_cm_rep_param ib_cm;
+	} *rep_param = NULL;
 	struct srpt_rdma_ch *ch;
 	char i_port_id[36];
 	u32 it_iu_len;
@@ -2118,8 +2155,14 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
 	ch->zw_cqe.done = srpt_zerolength_write_done;
 	INIT_WORK(&ch->release_work, srpt_release_channel_work);
 	ch->sport = sport;
-	ch->ib_cm.cm_id = cm_id;
-	cm_id->context = ch;
+	if (ib_cm_id) {
+		ch->ib_cm.cm_id = ib_cm_id;
+		ib_cm_id->context = ch;
+	} else {
+		ch->using_rdma_cm = true;
+		ch->rdma_cm.cm_id = rdma_cm_id;
+		rdma_cm_id->context = ch;
+	}
 	/*
 	 * ch->rq_size should be at least as large as the initiator queue
 	 * depth to avoid that the initiator driver has to report QUEUE_FULL
@@ -2230,7 +2273,7 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
 
 	mutex_unlock(&sport->mutex);
 
-	ret = srpt_ch_qp_rtr(ch, ch->qp);
+	ret = ch->using_rdma_cm ? 0 : srpt_ch_qp_rtr(ch, ch->qp);
 	if (ret) {
 		rej->reason = cpu_to_be32(SRP_LOGIN_REJ_INSUFFICIENT_RESOURCES);
 		pr_err("rejected SRP_LOGIN_REQ because enabling RTR failed (error code = %d)\n",
@@ -2254,25 +2297,38 @@ static int srpt_cm_req_recv(struct ib_cm_id *cm_id,
 	atomic_set(&ch->req_lim_delta, 0);
 
 	/* create cm reply */
-	rep_param->qp_num = ch->qp->qp_num;
-	rep_param->private_data = (void *)rsp;
-	rep_param->private_data_len = sizeof(*rsp);
-	rep_param->rnr_retry_count = 7;
-	rep_param->flow_control = 1;
-	rep_param->failover_accepted = 0;
-	rep_param->srq = 1;
-	rep_param->responder_resources = 4;
-	rep_param->initiator_depth = 4;
+	if (ch->using_rdma_cm) {
+		rep_param->rdma_cm.private_data = (void *)rsp;
+		rep_param->rdma_cm.private_data_len = sizeof(*rsp);
+		rep_param->rdma_cm.rnr_retry_count = 7;
+		rep_param->rdma_cm.flow_control = 1;
+		rep_param->rdma_cm.responder_resources = 4;
+		rep_param->rdma_cm.initiator_depth = 4;
+	} else {
+		rep_param->ib_cm.qp_num = ch->qp->qp_num;
+		rep_param->ib_cm.private_data = (void *)rsp;
+		rep_param->ib_cm.private_data_len = sizeof(*rsp);
+		rep_param->ib_cm.rnr_retry_count = 7;
+		rep_param->ib_cm.flow_control = 1;
+		rep_param->ib_cm.failover_accepted = 0;
+		rep_param->ib_cm.srq = 1;
+		rep_param->ib_cm.responder_resources = 4;
+		rep_param->ib_cm.initiator_depth = 4;
+	}
 
 	/*
 	 * Hold the sport mutex while accepting a connection to avoid that
 	 * srpt_disconnect_ch() is invoked concurrently with this code.
 	 */
 	mutex_lock(&sport->mutex);
-	if (sport->enabled && ch->state == CH_CONNECTING)
-		ret = ib_send_cm_rep(cm_id, rep_param);
-	else
+	if (sport->enabled && ch->state == CH_CONNECTING) {
+		if (ch->using_rdma_cm)
+			ret = rdma_accept(rdma_cm_id, &rep_param->rdma_cm);
+		else
+			ret = ib_send_cm_rep(ib_cm_id, &rep_param->ib_cm);
+	} else {
 		ret = -EINVAL;
+	}
 	mutex_unlock(&sport->mutex);
 
 	switch (ret) {
@@ -2302,7 +2358,8 @@ free_ring:
 			     ch->sport->sdev, ch->rq_size,
 			     ch->max_rsp_size, DMA_TO_DEVICE);
 free_ch:
-	cm_id->context = NULL;
+	if (ib_cm_id)
+		ib_cm_id->context = NULL;
 	kfree(ch);
 	ch = NULL;
 
@@ -2315,8 +2372,11 @@ reject:
 	rej->buf_fmt = cpu_to_be16(SRP_BUF_FORMAT_DIRECT |
 				   SRP_BUF_FORMAT_INDIRECT);
 
-	ib_send_cm_rej(cm_id, IB_CM_REJ_CONSUMER_DEFINED, NULL, 0,
-			     (void *)rej, sizeof(*rej));
+	if (rdma_cm_id)
+		rdma_reject(rdma_cm_id, rej, sizeof(*rej));
+	else
+		ib_send_cm_rej(ib_cm_id, IB_CM_REJ_CONSUMER_DEFINED, NULL, 0,
+			       rej, sizeof(*rej));
 
 out:
 	kfree(rep_param);
@@ -2335,10 +2395,44 @@ static int srpt_ib_cm_req_recv(struct ib_cm_id *cm_id,
 	srpt_format_guid(sguid, sizeof(sguid),
 			 &param->primary_path->dgid.global.interface_id);
 
-	return srpt_cm_req_recv(cm_id, param->port, param->primary_path->pkey,
+	return srpt_cm_req_recv(cm_id->context, cm_id, NULL, param->port,
+				param->primary_path->pkey,
 				private_data, sguid);
 }
 
+static int srpt_rdma_cm_req_recv(struct rdma_cm_id *cm_id,
+				 struct rdma_cm_event *event)
+{
+	struct srpt_device *sdev;
+	struct srp_login_req req;
+	const struct srp_login_req_rdma *req_rdma;
+	char src_addr[40];
+
+	sdev = ib_get_client_data(cm_id->device, &srpt_client);
+	if (!sdev)
+		return -ECONNREFUSED;
+
+	if (event->param.conn.private_data_len < sizeof(*req_rdma))
+		return -EINVAL;
+
+	/* Transform srp_login_req_rdma into srp_login_req. */
+	req_rdma = event->param.conn.private_data;
+	memset(&req, 0, sizeof(req));
+	req.opcode		= req_rdma->opcode;
+	req.tag			= req_rdma->tag;
+	req.req_it_iu_len	= req_rdma->req_it_iu_len;
+	req.req_buf_fmt		= req_rdma->req_buf_fmt;
+	req.req_flags		= req_rdma->req_flags;
+	memcpy(req.initiator_port_id, req_rdma->initiator_port_id, 16);
+	memcpy(req.target_port_id, req_rdma->target_port_id, 16);
+
+	snprintf(src_addr, sizeof(src_addr), "%pIS",
+		 &cm_id->route.addr.src_addr);
+
+	return srpt_cm_req_recv(sdev, NULL, cm_id, cm_id->port_num,
+				cm_id->route.path_rec->pkey, &req, src_addr);
+}
+
 static void srpt_cm_rej_recv(struct srpt_rdma_ch *ch,
 			     enum ib_cm_rej_reason reason,
 			     const u8 *private_data,
@@ -2362,14 +2456,14 @@ static void srpt_cm_rej_recv(struct srpt_rdma_ch *ch,
  * srpt_cm_rtu_recv - process an IB_CM_RTU_RECEIVED or USER_ESTABLISHED event
  * @ch: SRPT RDMA channel.
  *
- * An IB_CM_RTU_RECEIVED message indicates that the connection is established
- * and that the recipient may begin transmitting (RTU = ready to use).
+ * An RTU (ready to use) message indicates that the connection has been
+ * established and that the recipient may begin transmitting.
  */
 static void srpt_cm_rtu_recv(struct srpt_rdma_ch *ch)
 {
 	int ret;
 
-	ret = srpt_ch_qp_rts(ch, ch->qp);
+	ret = ch->using_rdma_cm ? 0 : srpt_ch_qp_rts(ch, ch->qp);
 	if (ret < 0) {
 		pr_err("%s-%d: QP transition to RTS failed\n", ch->sess_name,
 		       ch->qp->qp_num);
@@ -2456,6 +2550,49 @@ static int srpt_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
 	return ret;
 }
 
+static int srpt_rdma_cm_handler(struct rdma_cm_id *cm_id,
+				struct rdma_cm_event *event)
+{
+	struct srpt_rdma_ch *ch = cm_id->context;
+	int ret = 0;
+
+	switch (event->event) {
+	case RDMA_CM_EVENT_CONNECT_REQUEST:
+		ret = srpt_rdma_cm_req_recv(cm_id, event);
+		break;
+	case RDMA_CM_EVENT_REJECTED:
+		srpt_cm_rej_recv(ch, event->status,
+				 event->param.conn.private_data,
+				 event->param.conn.private_data_len);
+		break;
+	case RDMA_CM_EVENT_ESTABLISHED:
+		srpt_cm_rtu_recv(ch);
+		break;
+	case RDMA_CM_EVENT_DISCONNECTED:
+		if (ch->state < CH_DISCONNECTING)
+			srpt_disconnect_ch(ch);
+		else
+			srpt_close_ch(ch);
+		break;
+	case RDMA_CM_EVENT_TIMEWAIT_EXIT:
+		srpt_close_ch(ch);
+		break;
+	case RDMA_CM_EVENT_UNREACHABLE:
+		pr_info("Received CM REP error for ch %s-%d.\n", ch->sess_name,
+			ch->qp->qp_num);
+		break;
+	case RDMA_CM_EVENT_DEVICE_REMOVAL:
+	case RDMA_CM_EVENT_ADDR_CHANGE:
+		break;
+	default:
+		pr_err("received unrecognized RDMA CM event %d\n",
+		       event->event);
+		break;
+	}
+
+	return ret;
+}
+
 static int srpt_write_pending_status(struct se_cmd *se_cmd)
 {
 	struct srpt_send_ioctx *ioctx;
@@ -2827,7 +2964,7 @@ static void srpt_add_one(struct ib_device *device)
 {
 	struct srpt_device *sdev;
 	struct srpt_port *sport;
-	int i;
+	int i, ret;
 
 	pr_debug("device = %p\n", device);
 
@@ -2851,9 +2988,15 @@ static void srpt_add_one(struct ib_device *device)
 	if (!srpt_service_guid)
 		srpt_service_guid = be64_to_cpu(device->node_guid);
 
-	sdev->cm_id = ib_create_cm_id(device, srpt_cm_handler, sdev);
-	if (IS_ERR(sdev->cm_id))
-		goto err_ring;
+	if (rdma_port_get_link_layer(device, 1) == IB_LINK_LAYER_INFINIBAND)
+		sdev->cm_id = ib_create_cm_id(device, srpt_cm_handler, sdev);
+	if (IS_ERR(sdev->cm_id)) {
+		pr_info("ib_create_cm_id() failed: %ld\n",
+			PTR_ERR(sdev->cm_id));
+		sdev->cm_id = NULL;
+		if (!rdma_cm_id)
+			goto err_ring;
+	}
 
 	/* print out target login information */
 	pr_debug("Target login info: id_ext=%016llx,ioc_guid=%016llx,"
@@ -2866,8 +3009,14 @@ static void srpt_add_one(struct ib_device *device)
 	 * in the system as service_id; therefore, the target_id will change
 	 * if this HCA is gone bad and replaced by different HCA
 	 */
-	if (ib_cm_listen(sdev->cm_id, cpu_to_be64(srpt_service_guid), 0))
+	ret = sdev->cm_id ?
+		ib_cm_listen(sdev->cm_id, cpu_to_be64(srpt_service_guid), 0) :
+		0;
+	if (ret < 0) {
+		pr_err("ib_cm_listen() failed: %d (cm_id state = %d)\n", ret,
+		       sdev->cm_id->state);
 		goto err_cm;
+	}
 
 	INIT_IB_EVENT_HANDLER(&sdev->event_handler, sdev->device,
 			      srpt_event_handler);
@@ -2907,7 +3056,8 @@ out:
 err_event:
 	ib_unregister_event_handler(&sdev->event_handler);
 err_cm:
-	ib_destroy_cm_id(sdev->cm_id);
+	if (sdev->cm_id)
+		ib_destroy_cm_id(sdev->cm_id);
 err_ring:
 	srpt_free_srq(sdev);
 	ib_dealloc_pd(sdev->pd);
@@ -2942,7 +3092,10 @@ static void srpt_remove_one(struct ib_device *device, void *client_data)
 	for (i = 0; i < sdev->device->phys_port_cnt; i++)
 		cancel_work_sync(&sdev->port[i].work);
 
-	ib_destroy_cm_id(sdev->cm_id);
+	if (sdev->cm_id)
+		ib_destroy_cm_id(sdev->cm_id);
+
+	ib_set_client_data(device, &srpt_client, NULL);
 
 	/*
 	 * Unregistering a target must happen after destroying sdev->cm_id
@@ -3106,18 +3259,26 @@ static int srpt_parse_i_port_id(u8 i_port_id[16], const char *name)
 	leading_zero_bytes = 16 - count;
 	memset(i_port_id, 0, leading_zero_bytes);
 	ret = hex2bin(i_port_id + leading_zero_bytes, p, count);
-	if (ret < 0)
-		pr_debug("hex2bin failed for srpt_parse_i_port_id: %d\n", ret);
+
 out:
 	return ret;
 }
 
 /*
- * configfs callback function invoked for
- * mkdir /sys/kernel/config/target/$driver/$port/$tpg/acls/$i_port_id
+ * configfs callback function invoked for mkdir
+ * /sys/kernel/config/target/$driver/$port/$tpg/acls/$i_port_id
+ *
+ * i_port_id must be an initiator port GUID, GID or IP address. See also the
+ * target_alloc_session() calls in this driver. Examples of valid initiator
+ * port IDs:
+ * 0x0000000000000000505400fffe4a0b7b
+ * 0000000000000000505400fffe4a0b7b
+ * 5054:00ff:fe4a:0b7b
+ * 192.168.122.76
  */
 static int srpt_init_nodeacl(struct se_node_acl *se_nacl, const char *name)
 {
+	struct sockaddr_storage sa;
 	u64 guid;
 	u8 i_port_id[16];
 	int ret;
@@ -3126,6 +3287,9 @@ static int srpt_init_nodeacl(struct se_node_acl *se_nacl, const char *name)
 	if (ret < 0)
 		ret = srpt_parse_i_port_id(i_port_id, name);
 	if (ret < 0)
+		ret = inet_pton_with_scope(&init_net, AF_UNSPEC, name, NULL,
+					   &sa);
+	if (ret < 0)
 		pr_err("invalid initiator port ID %s\n", name);
 	return ret;
 }
@@ -3299,6 +3463,95 @@ static struct configfs_attribute *srpt_tpg_attrib_attrs[] = {
 	NULL,
 };
 
+static struct rdma_cm_id *srpt_create_rdma_id(struct sockaddr *listen_addr)
+{
+	struct rdma_cm_id *rdma_cm_id;
+	int ret;
+
+	rdma_cm_id = rdma_create_id(&init_net, srpt_rdma_cm_handler,
+				    NULL, RDMA_PS_TCP, IB_QPT_RC);
+	if (IS_ERR(rdma_cm_id)) {
+		pr_err("RDMA/CM ID creation failed: %ld\n",
+		       PTR_ERR(rdma_cm_id));
+		goto out;
+	}
+
+	ret = rdma_bind_addr(rdma_cm_id, listen_addr);
+	if (ret) {
+		char addr_str[64];
+
+		snprintf(addr_str, sizeof(addr_str), "%pISp", listen_addr);
+		pr_err("Binding RDMA/CM ID to address %s failed: %d\n",
+		       addr_str, ret);
+		rdma_destroy_id(rdma_cm_id);
+		rdma_cm_id = ERR_PTR(ret);
+		goto out;
+	}
+
+	ret = rdma_listen(rdma_cm_id, 128);
+	if (ret) {
+		pr_err("rdma_listen() failed: %d\n", ret);
+		rdma_destroy_id(rdma_cm_id);
+		rdma_cm_id = ERR_PTR(ret);
+	}
+
+out:
+	return rdma_cm_id;
+}
+
+static ssize_t srpt_rdma_cm_port_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%d\n", rdma_cm_port);
+}
+
+static ssize_t srpt_rdma_cm_port_store(struct config_item *item,
+				       const char *page, size_t count)
+{
+	struct sockaddr_in  addr4 = { .sin_family  = AF_INET  };
+	struct sockaddr_in6 addr6 = { .sin6_family = AF_INET6 };
+	struct rdma_cm_id *new_id = NULL;
+	u16 val;
+	int ret;
+
+	ret = kstrtou16(page, 0, &val);
+	if (ret < 0)
+		return ret;
+	ret = count;
+	if (rdma_cm_port == val)
+		goto out;
+
+	if (val) {
+		addr6.sin6_port = cpu_to_be16(val);
+		new_id = srpt_create_rdma_id((struct sockaddr *)&addr6);
+		if (IS_ERR(new_id)) {
+			addr4.sin_port = cpu_to_be16(val);
+			new_id = srpt_create_rdma_id((struct sockaddr *)&addr4);
+			if (IS_ERR(new_id)) {
+				ret = PTR_ERR(new_id);
+				goto out;
+			}
+		}
+	}
+
+	mutex_lock(&rdma_cm_mutex);
+	rdma_cm_port = val;
+	swap(rdma_cm_id, new_id);
+	mutex_unlock(&rdma_cm_mutex);
+
+	if (new_id)
+		rdma_destroy_id(new_id);
+	ret = count;
+out:
+	return ret;
+}
+
+CONFIGFS_ATTR(srpt_, rdma_cm_port);
+
+static struct configfs_attribute *srpt_da_attrs[] = {
+	&srpt_attr_rdma_cm_port,
+	NULL,
+};
+
 static ssize_t srpt_tpg_enable_show(struct config_item *item, char *page)
 {
 	struct se_portal_group *se_tpg = to_tpg(item);
@@ -3444,6 +3697,7 @@ static const struct target_core_fabric_ops srpt_template = {
 	.fabric_drop_tpg		= srpt_drop_tpg,
 	.fabric_init_nodeacl		= srpt_init_nodeacl,
 
+	.tfc_discovery_attrs		= srpt_da_attrs,
 	.tfc_wwn_attrs			= srpt_wwn_attrs,
 	.tfc_tpg_base_attrs		= srpt_tpg_attrs,
 	.tfc_tpg_attrib_attrs		= srpt_tpg_attrib_attrs,
@@ -3497,6 +3751,8 @@ out:
 
 static void __exit srpt_cleanup_module(void)
 {
+	if (rdma_cm_id)
+		rdma_destroy_id(rdma_cm_id);
 	ib_unregister_client(&srpt_client);
 	target_unregister_template(&srpt_template);
 }