ib_cm.c

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/*
 * 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->dp_ack_seq)
        rds_send_drop_acked(conn, be64_to_cpu(dp->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++;
    }
    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);
}