Initial import

1 files changed, 838 insertions, 0 deletions

diff --git a/net/rds/ib_cm.c b/net/rds/ib_cm.c
new file mode 100644
index 000000000..8a09ee7db
--- /dev/null
+++ b/net/rds/ib_cm.c
@@ -0,0 +1,838 @@
+/*
+ * Copyright (c) 2006 Oracle.  All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/in.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/ratelimit.h>
+
+#include "rds.h"
+#include "ib.h"
+
+static char *rds_ib_event_type_strings[] = {
+#define RDS_IB_EVENT_STRING(foo) \
+		[IB_EVENT_##foo] = __stringify(IB_EVENT_##foo)
+	RDS_IB_EVENT_STRING(CQ_ERR),
+	RDS_IB_EVENT_STRING(QP_FATAL),
+	RDS_IB_EVENT_STRING(QP_REQ_ERR),
+	RDS_IB_EVENT_STRING(QP_ACCESS_ERR),
+	RDS_IB_EVENT_STRING(COMM_EST),
+	RDS_IB_EVENT_STRING(SQ_DRAINED),
+	RDS_IB_EVENT_STRING(PATH_MIG),
+	RDS_IB_EVENT_STRING(PATH_MIG_ERR),
+	RDS_IB_EVENT_STRING(DEVICE_FATAL),
+	RDS_IB_EVENT_STRING(PORT_ACTIVE),
+	RDS_IB_EVENT_STRING(PORT_ERR),
+	RDS_IB_EVENT_STRING(LID_CHANGE),
+	RDS_IB_EVENT_STRING(PKEY_CHANGE),
+	RDS_IB_EVENT_STRING(SM_CHANGE),
+	RDS_IB_EVENT_STRING(SRQ_ERR),
+	RDS_IB_EVENT_STRING(SRQ_LIMIT_REACHED),
+	RDS_IB_EVENT_STRING(QP_LAST_WQE_REACHED),
+	RDS_IB_EVENT_STRING(CLIENT_REREGISTER),
+#undef RDS_IB_EVENT_STRING
+};
+
+static char *rds_ib_event_str(enum ib_event_type type)
+{
+	return rds_str_array(rds_ib_event_type_strings,
+			     ARRAY_SIZE(rds_ib_event_type_strings), type);
+};
+
+/*
+ * Set the selected protocol version
+ */
+static void rds_ib_set_protocol(struct rds_connection *conn, unsigned int version)
+{
+	conn->c_version = version;
+}
+
+/*
+ * Set up flow control
+ */
+static void rds_ib_set_flow_control(struct rds_connection *conn, u32 credits)
+{
+	struct rds_ib_connection *ic = conn->c_transport_data;
+
+	if (rds_ib_sysctl_flow_control && credits != 0) {
+		/* We're doing flow control */
+		ic->i_flowctl = 1;
+		rds_ib_send_add_credits(conn, credits);
+	} else {
+		ic->i_flowctl = 0;
+	}
+}
+
+/*
+ * Tune RNR behavior. Without flow control, we use a rather
+ * low timeout, but not the absolute minimum - this should
+ * be tunable.
+ *
+ * We already set the RNR retry count to 7 (which is the
+ * smallest infinite number :-) above.
+ * If flow control is off, we want to change this back to 0
+ * so that we learn quickly when our credit accounting is
+ * buggy.
+ *
+ * Caller passes in a qp_attr pointer - don't waste stack spacv
+ * by allocation this twice.
+ */
+static void
+rds_ib_tune_rnr(struct rds_ib_connection *ic, struct ib_qp_attr *attr)
+{
+	int ret;
+
+	attr->min_rnr_timer = IB_RNR_TIMER_000_32;
+	ret = ib_modify_qp(ic->i_cm_id->qp, attr, IB_QP_MIN_RNR_TIMER);
+	if (ret)
+		printk(KERN_NOTICE "ib_modify_qp(IB_QP_MIN_RNR_TIMER): err=%d\n", -ret);
+}
+
+/*
+ * Connection established.
+ * We get here for both outgoing and incoming connection.
+ */
+void rds_ib_cm_connect_complete(struct rds_connection *conn, struct rdma_cm_event *event)
+{
+	const struct rds_ib_connect_private *dp = NULL;
+	struct rds_ib_connection *ic = conn->c_transport_data;
+	struct ib_qp_attr qp_attr;
+	int err;
+
+	if (event->param.conn.private_data_len >= sizeof(*dp)) {
+		dp = event->param.conn.private_data;
+
+		/* make sure it isn't empty data */
+		if (dp->dp_protocol_major) {
+			rds_ib_set_protocol(conn,
+				RDS_PROTOCOL(dp->dp_protocol_major,
+				dp->dp_protocol_minor));
+			rds_ib_set_flow_control(conn, be32_to_cpu(dp->dp_credit));
+		}
+	}
+
+	if (conn->c_version < RDS_PROTOCOL(3,1)) {
+		printk(KERN_NOTICE "RDS/IB: Connection to %pI4 version %u.%u failed,"
+		       " no longer supported\n",
+		       &conn->c_faddr,
+		       RDS_PROTOCOL_MAJOR(conn->c_version),
+		       RDS_PROTOCOL_MINOR(conn->c_version));
+		rds_conn_destroy(conn);
+		return;
+	} else {
+		printk(KERN_NOTICE "RDS/IB: connected to %pI4 version %u.%u%s\n",
+		       &conn->c_faddr,
+		       RDS_PROTOCOL_MAJOR(conn->c_version),
+		       RDS_PROTOCOL_MINOR(conn->c_version),
+		       ic->i_flowctl ? ", flow control" : "");
+	}
+
+	/*
+	 * Init rings and fill recv. this needs to wait until protocol negotiation
+	 * is complete, since ring layout is different from 3.0 to 3.1.
+	 */
+	rds_ib_send_init_ring(ic);
+	rds_ib_recv_init_ring(ic);
+	/* Post receive buffers - as a side effect, this will update
+	 * the posted credit count. */
+	rds_ib_recv_refill(conn, 1);
+
+	/* Tune RNR behavior */
+	rds_ib_tune_rnr(ic, &qp_attr);
+
+	qp_attr.qp_state = IB_QPS_RTS;
+	err = ib_modify_qp(ic->i_cm_id->qp, &qp_attr, IB_QP_STATE);
+	if (err)
+		printk(KERN_NOTICE "ib_modify_qp(IB_QP_STATE, RTS): err=%d\n", err);
+
+	/* update ib_device with this local ipaddr */
+	err = rds_ib_update_ipaddr(ic->rds_ibdev, conn->c_laddr);
+	if (err)
+		printk(KERN_ERR "rds_ib_update_ipaddr failed (%d)\n",
+			err);
+
+	/* If the peer gave us the last packet it saw, process this as if
+	 * we had received a regular ACK. */
+	if (dp) {
+		/* dp structure start is not guaranteed to be 8 bytes aligned.
+		 * Since dp_ack_seq is 64-bit extended load operations can be
+		 * used so go through get_unaligned to avoid unaligned errors.
+		 */
+		__be64 dp_ack_seq = get_unaligned(&dp->dp_ack_seq);
+
+		if (dp_ack_seq)
+			rds_send_drop_acked(conn, be64_to_cpu(dp_ack_seq),
+					    NULL);
+	}
+
+	rds_connect_complete(conn);
+}
+
+static void rds_ib_cm_fill_conn_param(struct rds_connection *conn,
+			struct rdma_conn_param *conn_param,
+			struct rds_ib_connect_private *dp,
+			u32 protocol_version,
+			u32 max_responder_resources,
+			u32 max_initiator_depth)
+{
+	struct rds_ib_connection *ic = conn->c_transport_data;
+	struct rds_ib_device *rds_ibdev = ic->rds_ibdev;
+
+	memset(conn_param, 0, sizeof(struct rdma_conn_param));
+
+	conn_param->responder_resources =
+		min_t(u32, rds_ibdev->max_responder_resources, max_responder_resources);
+	conn_param->initiator_depth =
+		min_t(u32, rds_ibdev->max_initiator_depth, max_initiator_depth);
+	conn_param->retry_count = min_t(unsigned int, rds_ib_retry_count, 7);
+	conn_param->rnr_retry_count = 7;
+
+	if (dp) {
+		memset(dp, 0, sizeof(*dp));
+		dp->dp_saddr = conn->c_laddr;
+		dp->dp_daddr = conn->c_faddr;
+		dp->dp_protocol_major = RDS_PROTOCOL_MAJOR(protocol_version);
+		dp->dp_protocol_minor = RDS_PROTOCOL_MINOR(protocol_version);
+		dp->dp_protocol_minor_mask = cpu_to_be16(RDS_IB_SUPPORTED_PROTOCOLS);
+		dp->dp_ack_seq = rds_ib_piggyb_ack(ic);
+
+		/* Advertise flow control */
+		if (ic->i_flowctl) {
+			unsigned int credits;
+
+			credits = IB_GET_POST_CREDITS(atomic_read(&ic->i_credits));
+			dp->dp_credit = cpu_to_be32(credits);
+			atomic_sub(IB_SET_POST_CREDITS(credits), &ic->i_credits);
+		}
+
+		conn_param->private_data = dp;
+		conn_param->private_data_len = sizeof(*dp);
+	}
+}
+
+static void rds_ib_cq_event_handler(struct ib_event *event, void *data)
+{
+	rdsdebug("event %u (%s) data %p\n",
+		 event->event, rds_ib_event_str(event->event), data);
+}
+
+static void rds_ib_qp_event_handler(struct ib_event *event, void *data)
+{
+	struct rds_connection *conn = data;
+	struct rds_ib_connection *ic = conn->c_transport_data;
+
+	rdsdebug("conn %p ic %p event %u (%s)\n", conn, ic, event->event,
+		 rds_ib_event_str(event->event));
+
+	switch (event->event) {
+	case IB_EVENT_COMM_EST:
+		rdma_notify(ic->i_cm_id, IB_EVENT_COMM_EST);
+		break;
+	default:
+		rdsdebug("Fatal QP Event %u (%s) "
+			"- connection %pI4->%pI4, reconnecting\n",
+			event->event, rds_ib_event_str(event->event),
+			&conn->c_laddr, &conn->c_faddr);
+		rds_conn_drop(conn);
+		break;
+	}
+}
+
+/*
+ * This needs to be very careful to not leave IS_ERR pointers around for
+ * cleanup to trip over.
+ */
+static int rds_ib_setup_qp(struct rds_connection *conn)
+{
+	struct rds_ib_connection *ic = conn->c_transport_data;
+	struct ib_device *dev = ic->i_cm_id->device;
+	struct ib_qp_init_attr attr;
+	struct rds_ib_device *rds_ibdev;
+	int ret;
+
+	/*
+	 * It's normal to see a null device if an incoming connection races
+	 * with device removal, so we don't print a warning.
+	 */
+	rds_ibdev = rds_ib_get_client_data(dev);
+	if (!rds_ibdev)
+		return -EOPNOTSUPP;
+
+	/* add the conn now so that connection establishment has the dev */
+	rds_ib_add_conn(rds_ibdev, conn);
+
+	if (rds_ibdev->max_wrs < ic->i_send_ring.w_nr + 1)
+		rds_ib_ring_resize(&ic->i_send_ring, rds_ibdev->max_wrs - 1);
+	if (rds_ibdev->max_wrs < ic->i_recv_ring.w_nr + 1)
+		rds_ib_ring_resize(&ic->i_recv_ring, rds_ibdev->max_wrs - 1);
+
+	/* Protection domain and memory range */
+	ic->i_pd = rds_ibdev->pd;
+	ic->i_mr = rds_ibdev->mr;
+
+	ic->i_send_cq = ib_create_cq(dev, rds_ib_send_cq_comp_handler,
+				     rds_ib_cq_event_handler, conn,
+				     ic->i_send_ring.w_nr + 1, 0);
+	if (IS_ERR(ic->i_send_cq)) {
+		ret = PTR_ERR(ic->i_send_cq);
+		ic->i_send_cq = NULL;
+		rdsdebug("ib_create_cq send failed: %d\n", ret);
+		goto out;
+	}
+
+	ic->i_recv_cq = ib_create_cq(dev, rds_ib_recv_cq_comp_handler,
+				     rds_ib_cq_event_handler, conn,
+				     ic->i_recv_ring.w_nr, 0);
+	if (IS_ERR(ic->i_recv_cq)) {
+		ret = PTR_ERR(ic->i_recv_cq);
+		ic->i_recv_cq = NULL;
+		rdsdebug("ib_create_cq recv failed: %d\n", ret);
+		goto out;
+	}
+
+	ret = ib_req_notify_cq(ic->i_send_cq, IB_CQ_NEXT_COMP);
+	if (ret) {
+		rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
+		goto out;
+	}
+
+	ret = ib_req_notify_cq(ic->i_recv_cq, IB_CQ_SOLICITED);
+	if (ret) {
+		rdsdebug("ib_req_notify_cq recv failed: %d\n", ret);
+		goto out;
+	}
+
+	/* XXX negotiate max send/recv with remote? */
+	memset(&attr, 0, sizeof(attr));
+	attr.event_handler = rds_ib_qp_event_handler;
+	attr.qp_context = conn;
+	/* + 1 to allow for the single ack message */
+	attr.cap.max_send_wr = ic->i_send_ring.w_nr + 1;
+	attr.cap.max_recv_wr = ic->i_recv_ring.w_nr + 1;
+	attr.cap.max_send_sge = rds_ibdev->max_sge;
+	attr.cap.max_recv_sge = RDS_IB_RECV_SGE;
+	attr.sq_sig_type = IB_SIGNAL_REQ_WR;
+	attr.qp_type = IB_QPT_RC;
+	attr.send_cq = ic->i_send_cq;
+	attr.recv_cq = ic->i_recv_cq;
+
+	/*
+	 * XXX this can fail if max_*_wr is too large?  Are we supposed
+	 * to back off until we get a value that the hardware can support?
+	 */
+	ret = rdma_create_qp(ic->i_cm_id, ic->i_pd, &attr);
+	if (ret) {
+		rdsdebug("rdma_create_qp failed: %d\n", ret);
+		goto out;
+	}
+
+	ic->i_send_hdrs = ib_dma_alloc_coherent(dev,
+					   ic->i_send_ring.w_nr *
+						sizeof(struct rds_header),
+					   &ic->i_send_hdrs_dma, GFP_KERNEL);
+	if (!ic->i_send_hdrs) {
+		ret = -ENOMEM;
+		rdsdebug("ib_dma_alloc_coherent send failed\n");
+		goto out;
+	}
+
+	ic->i_recv_hdrs = ib_dma_alloc_coherent(dev,
+					   ic->i_recv_ring.w_nr *
+						sizeof(struct rds_header),
+					   &ic->i_recv_hdrs_dma, GFP_KERNEL);
+	if (!ic->i_recv_hdrs) {
+		ret = -ENOMEM;
+		rdsdebug("ib_dma_alloc_coherent recv failed\n");
+		goto out;
+	}
+
+	ic->i_ack = ib_dma_alloc_coherent(dev, sizeof(struct rds_header),
+				       &ic->i_ack_dma, GFP_KERNEL);
+	if (!ic->i_ack) {
+		ret = -ENOMEM;
+		rdsdebug("ib_dma_alloc_coherent ack failed\n");
+		goto out;
+	}
+
+	ic->i_sends = vzalloc_node(ic->i_send_ring.w_nr * sizeof(struct rds_ib_send_work),
+				   ibdev_to_node(dev));
+	if (!ic->i_sends) {
+		ret = -ENOMEM;
+		rdsdebug("send allocation failed\n");
+		goto out;
+	}
+
+	ic->i_recvs = vzalloc_node(ic->i_recv_ring.w_nr * sizeof(struct rds_ib_recv_work),
+				   ibdev_to_node(dev));
+	if (!ic->i_recvs) {
+		ret = -ENOMEM;
+		rdsdebug("recv allocation failed\n");
+		goto out;
+	}
+
+	rds_ib_recv_init_ack(ic);
+
+	rdsdebug("conn %p pd %p mr %p cq %p %p\n", conn, ic->i_pd, ic->i_mr,
+		 ic->i_send_cq, ic->i_recv_cq);
+
+out:
+	rds_ib_dev_put(rds_ibdev);
+	return ret;
+}
+
+static u32 rds_ib_protocol_compatible(struct rdma_cm_event *event)
+{
+	const struct rds_ib_connect_private *dp = event->param.conn.private_data;
+	u16 common;
+	u32 version = 0;
+
+	/*
+	 * rdma_cm private data is odd - when there is any private data in the
+	 * request, we will be given a pretty large buffer without telling us the
+	 * original size. The only way to tell the difference is by looking at
+	 * the contents, which are initialized to zero.
+	 * If the protocol version fields aren't set, this is a connection attempt
+	 * from an older version. This could could be 3.0 or 2.0 - we can't tell.
+	 * We really should have changed this for OFED 1.3 :-(
+	 */
+
+	/* Be paranoid. RDS always has privdata */
+	if (!event->param.conn.private_data_len) {
+		printk(KERN_NOTICE "RDS incoming connection has no private data, "
+			"rejecting\n");
+		return 0;
+	}
+
+	/* Even if len is crap *now* I still want to check it. -ASG */
+	if (event->param.conn.private_data_len < sizeof (*dp) ||
+	    dp->dp_protocol_major == 0)
+		return RDS_PROTOCOL_3_0;
+
+	common = be16_to_cpu(dp->dp_protocol_minor_mask) & RDS_IB_SUPPORTED_PROTOCOLS;
+	if (dp->dp_protocol_major == 3 && common) {
+		version = RDS_PROTOCOL_3_0;
+		while ((common >>= 1) != 0)
+			version++;
+	} else
+		printk_ratelimited(KERN_NOTICE "RDS: Connection from %pI4 using incompatible protocol version %u.%u\n",
+				&dp->dp_saddr,
+				dp->dp_protocol_major,
+				dp->dp_protocol_minor);
+	return version;
+}
+
+int rds_ib_cm_handle_connect(struct rdma_cm_id *cm_id,
+				    struct rdma_cm_event *event)
+{
+	__be64 lguid = cm_id->route.path_rec->sgid.global.interface_id;
+	__be64 fguid = cm_id->route.path_rec->dgid.global.interface_id;
+	const struct rds_ib_connect_private *dp = event->param.conn.private_data;
+	struct rds_ib_connect_private dp_rep;
+	struct rds_connection *conn = NULL;
+	struct rds_ib_connection *ic = NULL;
+	struct rdma_conn_param conn_param;
+	u32 version;
+	int err = 1, destroy = 1;
+
+	/* Check whether the remote protocol version matches ours. */
+	version = rds_ib_protocol_compatible(event);
+	if (!version)
+		goto out;
+
+	rdsdebug("saddr %pI4 daddr %pI4 RDSv%u.%u lguid 0x%llx fguid "
+		 "0x%llx\n", &dp->dp_saddr, &dp->dp_daddr,
+		 RDS_PROTOCOL_MAJOR(version), RDS_PROTOCOL_MINOR(version),
+		 (unsigned long long)be64_to_cpu(lguid),
+		 (unsigned long long)be64_to_cpu(fguid));
+
+	conn = rds_conn_create(dp->dp_daddr, dp->dp_saddr, &rds_ib_transport,
+			       GFP_KERNEL);
+	if (IS_ERR(conn)) {
+		rdsdebug("rds_conn_create failed (%ld)\n", PTR_ERR(conn));
+		conn = NULL;
+		goto out;
+	}
+
+	/*
+	 * The connection request may occur while the
+	 * previous connection exist, e.g. in case of failover.
+	 * But as connections may be initiated simultaneously
+	 * by both hosts, we have a random backoff mechanism -
+	 * see the comment above rds_queue_reconnect()
+	 */
+	mutex_lock(&conn->c_cm_lock);
+	if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_CONNECTING)) {
+		if (rds_conn_state(conn) == RDS_CONN_UP) {
+			rdsdebug("incoming connect while connecting\n");
+			rds_conn_drop(conn);
+			rds_ib_stats_inc(s_ib_listen_closed_stale);
+		} else
+		if (rds_conn_state(conn) == RDS_CONN_CONNECTING) {
+			/* Wait and see - our connect may still be succeeding */
+			rds_ib_stats_inc(s_ib_connect_raced);
+		}
+		goto out;
+	}
+
+	ic = conn->c_transport_data;
+
+	rds_ib_set_protocol(conn, version);
+	rds_ib_set_flow_control(conn, be32_to_cpu(dp->dp_credit));
+
+	/* If the peer gave us the last packet it saw, process this as if
+	 * we had received a regular ACK. */
+	if (dp->dp_ack_seq)
+		rds_send_drop_acked(conn, be64_to_cpu(dp->dp_ack_seq), NULL);
+
+	BUG_ON(cm_id->context);
+	BUG_ON(ic->i_cm_id);
+
+	ic->i_cm_id = cm_id;
+	cm_id->context = conn;
+
+	/* We got halfway through setting up the ib_connection, if we
+	 * fail now, we have to take the long route out of this mess. */
+	destroy = 0;
+
+	err = rds_ib_setup_qp(conn);
+	if (err) {
+		rds_ib_conn_error(conn, "rds_ib_setup_qp failed (%d)\n", err);
+		goto out;
+	}
+
+	rds_ib_cm_fill_conn_param(conn, &conn_param, &dp_rep, version,
+		event->param.conn.responder_resources,
+		event->param.conn.initiator_depth);
+
+	/* rdma_accept() calls rdma_reject() internally if it fails */
+	err = rdma_accept(cm_id, &conn_param);
+	if (err)
+		rds_ib_conn_error(conn, "rdma_accept failed (%d)\n", err);
+
+out:
+	if (conn)
+		mutex_unlock(&conn->c_cm_lock);
+	if (err)
+		rdma_reject(cm_id, NULL, 0);
+	return destroy;
+}
+
+
+int rds_ib_cm_initiate_connect(struct rdma_cm_id *cm_id)
+{
+	struct rds_connection *conn = cm_id->context;
+	struct rds_ib_connection *ic = conn->c_transport_data;
+	struct rdma_conn_param conn_param;
+	struct rds_ib_connect_private dp;
+	int ret;
+
+	/* If the peer doesn't do protocol negotiation, we must
+	 * default to RDSv3.0 */
+	rds_ib_set_protocol(conn, RDS_PROTOCOL_3_0);
+	ic->i_flowctl = rds_ib_sysctl_flow_control;	/* advertise flow control */
+
+	ret = rds_ib_setup_qp(conn);
+	if (ret) {
+		rds_ib_conn_error(conn, "rds_ib_setup_qp failed (%d)\n", ret);
+		goto out;
+	}
+
+	rds_ib_cm_fill_conn_param(conn, &conn_param, &dp, RDS_PROTOCOL_VERSION,
+		UINT_MAX, UINT_MAX);
+	ret = rdma_connect(cm_id, &conn_param);
+	if (ret)
+		rds_ib_conn_error(conn, "rdma_connect failed (%d)\n", ret);
+
+out:
+	/* Beware - returning non-zero tells the rdma_cm to destroy
+	 * the cm_id. We should certainly not do it as long as we still
+	 * "own" the cm_id. */
+	if (ret) {
+		if (ic->i_cm_id == cm_id)
+			ret = 0;
+	}
+	return ret;
+}
+
+int rds_ib_conn_connect(struct rds_connection *conn)
+{
+	struct rds_ib_connection *ic = conn->c_transport_data;
+	struct sockaddr_in src, dest;
+	int ret;
+
+	/* XXX I wonder what affect the port space has */
+	/* delegate cm event handler to rdma_transport */
+	ic->i_cm_id = rdma_create_id(rds_rdma_cm_event_handler, conn,
+				     RDMA_PS_TCP, IB_QPT_RC);
+	if (IS_ERR(ic->i_cm_id)) {
+		ret = PTR_ERR(ic->i_cm_id);
+		ic->i_cm_id = NULL;
+		rdsdebug("rdma_create_id() failed: %d\n", ret);
+		goto out;
+	}
+
+	rdsdebug("created cm id %p for conn %p\n", ic->i_cm_id, conn);
+
+	src.sin_family = AF_INET;
+	src.sin_addr.s_addr = (__force u32)conn->c_laddr;
+	src.sin_port = (__force u16)htons(0);
+
+	dest.sin_family = AF_INET;
+	dest.sin_addr.s_addr = (__force u32)conn->c_faddr;
+	dest.sin_port = (__force u16)htons(RDS_PORT);
+
+	ret = rdma_resolve_addr(ic->i_cm_id, (struct sockaddr *)&src,
+				(struct sockaddr *)&dest,
+				RDS_RDMA_RESOLVE_TIMEOUT_MS);
+	if (ret) {
+		rdsdebug("addr resolve failed for cm id %p: %d\n", ic->i_cm_id,
+			 ret);
+		rdma_destroy_id(ic->i_cm_id);
+		ic->i_cm_id = NULL;
+	}
+
+out:
+	return ret;
+}
+
+/*
+ * This is so careful about only cleaning up resources that were built up
+ * so that it can be called at any point during startup.  In fact it
+ * can be called multiple times for a given connection.
+ */
+void rds_ib_conn_shutdown(struct rds_connection *conn)
+{
+	struct rds_ib_connection *ic = conn->c_transport_data;
+	int err = 0;
+
+	rdsdebug("cm %p pd %p cq %p %p qp %p\n", ic->i_cm_id,
+		 ic->i_pd, ic->i_send_cq, ic->i_recv_cq,
+		 ic->i_cm_id ? ic->i_cm_id->qp : NULL);
+
+	if (ic->i_cm_id) {
+		struct ib_device *dev = ic->i_cm_id->device;
+
+		rdsdebug("disconnecting cm %p\n", ic->i_cm_id);
+		err = rdma_disconnect(ic->i_cm_id);
+		if (err) {
+			/* Actually this may happen quite frequently, when
+			 * an outgoing connect raced with an incoming connect.
+			 */
+			rdsdebug("failed to disconnect, cm: %p err %d\n",
+				ic->i_cm_id, err);
+		}
+
+		/*
+		 * We want to wait for tx and rx completion to finish
+		 * before we tear down the connection, but we have to be
+		 * careful not to get stuck waiting on a send ring that
+		 * only has unsignaled sends in it.  We've shutdown new
+		 * sends before getting here so by waiting for signaled
+		 * sends to complete we're ensured that there will be no
+		 * more tx processing.
+		 */
+		wait_event(rds_ib_ring_empty_wait,
+			   rds_ib_ring_empty(&ic->i_recv_ring) &&
+			   (atomic_read(&ic->i_signaled_sends) == 0));
+		tasklet_kill(&ic->i_recv_tasklet);
+
+		if (ic->i_send_hdrs)
+			ib_dma_free_coherent(dev,
+					   ic->i_send_ring.w_nr *
+						sizeof(struct rds_header),
+					   ic->i_send_hdrs,
+					   ic->i_send_hdrs_dma);
+
+		if (ic->i_recv_hdrs)
+			ib_dma_free_coherent(dev,
+					   ic->i_recv_ring.w_nr *
+						sizeof(struct rds_header),
+					   ic->i_recv_hdrs,
+					   ic->i_recv_hdrs_dma);
+
+		if (ic->i_ack)
+			ib_dma_free_coherent(dev, sizeof(struct rds_header),
+					     ic->i_ack, ic->i_ack_dma);
+
+		if (ic->i_sends)
+			rds_ib_send_clear_ring(ic);
+		if (ic->i_recvs)
+			rds_ib_recv_clear_ring(ic);
+
+		if (ic->i_cm_id->qp)
+			rdma_destroy_qp(ic->i_cm_id);
+		if (ic->i_send_cq)
+			ib_destroy_cq(ic->i_send_cq);
+		if (ic->i_recv_cq)
+			ib_destroy_cq(ic->i_recv_cq);
+		rdma_destroy_id(ic->i_cm_id);
+
+		/*
+		 * Move connection back to the nodev list.
+		 */
+		if (ic->rds_ibdev)
+			rds_ib_remove_conn(ic->rds_ibdev, conn);
+
+		ic->i_cm_id = NULL;
+		ic->i_pd = NULL;
+		ic->i_mr = NULL;
+		ic->i_send_cq = NULL;
+		ic->i_recv_cq = NULL;
+		ic->i_send_hdrs = NULL;
+		ic->i_recv_hdrs = NULL;
+		ic->i_ack = NULL;
+	}
+	BUG_ON(ic->rds_ibdev);
+
+	/* Clear pending transmit */
+	if (ic->i_data_op) {
+		struct rds_message *rm;
+
+		rm = container_of(ic->i_data_op, struct rds_message, data);
+		rds_message_put(rm);
+		ic->i_data_op = NULL;
+	}
+
+	/* Clear the ACK state */
+	clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
+#ifdef KERNEL_HAS_ATOMIC64
+	atomic64_set(&ic->i_ack_next, 0);
+#else
+	ic->i_ack_next = 0;
+#endif
+	ic->i_ack_recv = 0;
+
+	/* Clear flow control state */
+	ic->i_flowctl = 0;
+	atomic_set(&ic->i_credits, 0);
+
+	rds_ib_ring_init(&ic->i_send_ring, rds_ib_sysctl_max_send_wr);
+	rds_ib_ring_init(&ic->i_recv_ring, rds_ib_sysctl_max_recv_wr);
+
+	if (ic->i_ibinc) {
+		rds_inc_put(&ic->i_ibinc->ii_inc);
+		ic->i_ibinc = NULL;
+	}
+
+	vfree(ic->i_sends);
+	ic->i_sends = NULL;
+	vfree(ic->i_recvs);
+	ic->i_recvs = NULL;
+}
+
+int rds_ib_conn_alloc(struct rds_connection *conn, gfp_t gfp)
+{
+	struct rds_ib_connection *ic;
+	unsigned long flags;
+	int ret;
+
+	/* XXX too lazy? */
+	ic = kzalloc(sizeof(struct rds_ib_connection), gfp);
+	if (!ic)
+		return -ENOMEM;
+
+	ret = rds_ib_recv_alloc_caches(ic);
+	if (ret) {
+		kfree(ic);
+		return ret;
+	}
+
+	INIT_LIST_HEAD(&ic->ib_node);
+	tasklet_init(&ic->i_recv_tasklet, rds_ib_recv_tasklet_fn,
+		     (unsigned long) ic);
+	mutex_init(&ic->i_recv_mutex);
+#ifndef KERNEL_HAS_ATOMIC64
+	spin_lock_init(&ic->i_ack_lock);
+#endif
+	atomic_set(&ic->i_signaled_sends, 0);
+
+	/*
+	 * rds_ib_conn_shutdown() waits for these to be emptied so they
+	 * must be initialized before it can be called.
+	 */
+	rds_ib_ring_init(&ic->i_send_ring, rds_ib_sysctl_max_send_wr);
+	rds_ib_ring_init(&ic->i_recv_ring, rds_ib_sysctl_max_recv_wr);
+
+	ic->conn = conn;
+	conn->c_transport_data = ic;
+
+	spin_lock_irqsave(&ib_nodev_conns_lock, flags);
+	list_add_tail(&ic->ib_node, &ib_nodev_conns);
+	spin_unlock_irqrestore(&ib_nodev_conns_lock, flags);
+
+
+	rdsdebug("conn %p conn ic %p\n", conn, conn->c_transport_data);
+	return 0;
+}
+
+/*
+ * Free a connection. Connection must be shut down and not set for reconnect.
+ */
+void rds_ib_conn_free(void *arg)
+{
+	struct rds_ib_connection *ic = arg;
+	spinlock_t	*lock_ptr;
+
+	rdsdebug("ic %p\n", ic);
+
+	/*
+	 * Conn is either on a dev's list or on the nodev list.
+	 * A race with shutdown() or connect() would cause problems
+	 * (since rds_ibdev would change) but that should never happen.
+	 */
+	lock_ptr = ic->rds_ibdev ? &ic->rds_ibdev->spinlock : &ib_nodev_conns_lock;
+
+	spin_lock_irq(lock_ptr);
+	list_del(&ic->ib_node);
+	spin_unlock_irq(lock_ptr);
+
+	rds_ib_recv_free_caches(ic);
+
+	kfree(ic);
+}
+
+
+/*
+ * An error occurred on the connection
+ */
+void
+__rds_ib_conn_error(struct rds_connection *conn, const char *fmt, ...)
+{
+	va_list ap;
+
+	rds_conn_drop(conn);
+
+	va_start(ap, fmt);
+	vprintk(fmt, ap);
+	va_end(ap);
+}