scsi: ufs: fix race between clock gating and devfreq scaling work

[linux/fpc-iii.git] / net / rds / ib_cm.c

/*
 * 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_single_path.h"
#include "rds.h"
#include "ib.h"

/*
 * 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, GFP_KERNEL);

        /* 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 = cpu_to_be64(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, ib_event_msg(event->event), data);
}

/* Plucking the oldest entry from the ring can be done concurrently with
 * the thread refilling the ring.  Each ring operation is protected by
 * spinlocks and the transient state of refilling doesn't change the
 * recording of which entry is oldest.
 *
 * This relies on IB only calling one cq comp_handler for each cq so that
 * there will only be one caller of rds_recv_incoming() per RDS connection.
 */
static void rds_ib_cq_comp_handler_recv(struct ib_cq *cq, void *context)
{
        struct rds_connection *conn = context;
        struct rds_ib_connection *ic = conn->c_transport_data;

        rdsdebug("conn %p cq %p\n", conn, cq);

        rds_ib_stats_inc(s_ib_evt_handler_call);

        tasklet_schedule(&ic->i_recv_tasklet);
}

static void poll_scq(struct rds_ib_connection *ic, struct ib_cq *cq,
                     struct ib_wc *wcs)
{
        int nr, i;
        struct ib_wc *wc;

        while ((nr = ib_poll_cq(cq, RDS_IB_WC_MAX, wcs)) > 0) {
                for (i = 0; i < nr; i++) {
                        wc = wcs + i;
                        rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
                                 (unsigned long long)wc->wr_id, wc->status,
                                 wc->byte_len, be32_to_cpu(wc->ex.imm_data));

                        if (wc->wr_id <= ic->i_send_ring.w_nr ||
                            wc->wr_id == RDS_IB_ACK_WR_ID)
                                rds_ib_send_cqe_handler(ic, wc);
                        else
                                rds_ib_mr_cqe_handler(ic, wc);

                }
        }
}

static void rds_ib_tasklet_fn_send(unsigned long data)
{
        struct rds_ib_connection *ic = (struct rds_ib_connection *)data;
        struct rds_connection *conn = ic->conn;

        rds_ib_stats_inc(s_ib_tasklet_call);

        poll_scq(ic, ic->i_send_cq, ic->i_send_wc);
        ib_req_notify_cq(ic->i_send_cq, IB_CQ_NEXT_COMP);
        poll_scq(ic, ic->i_send_cq, ic->i_send_wc);

        if (rds_conn_up(conn) &&
            (!test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
            test_bit(0, &conn->c_map_queued)))
                rds_send_xmit(&ic->conn->c_path[0]);
}

static void poll_rcq(struct rds_ib_connection *ic, struct ib_cq *cq,
                     struct ib_wc *wcs,
                     struct rds_ib_ack_state *ack_state)
{
        int nr, i;
        struct ib_wc *wc;

        while ((nr = ib_poll_cq(cq, RDS_IB_WC_MAX, wcs)) > 0) {
                for (i = 0; i < nr; i++) {
                        wc = wcs + i;
                        rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
                                 (unsigned long long)wc->wr_id, wc->status,
                                 wc->byte_len, be32_to_cpu(wc->ex.imm_data));

                        rds_ib_recv_cqe_handler(ic, wc, ack_state);
                }
        }
}

static void rds_ib_tasklet_fn_recv(unsigned long data)
{
        struct rds_ib_connection *ic = (struct rds_ib_connection *)data;
        struct rds_connection *conn = ic->conn;
        struct rds_ib_device *rds_ibdev = ic->rds_ibdev;
        struct rds_ib_ack_state state;

        if (!rds_ibdev)
                rds_conn_drop(conn);

        rds_ib_stats_inc(s_ib_tasklet_call);

        memset(&state, 0, sizeof(state));
        poll_rcq(ic, ic->i_recv_cq, ic->i_recv_wc, &state);
        ib_req_notify_cq(ic->i_recv_cq, IB_CQ_SOLICITED);
        poll_rcq(ic, ic->i_recv_cq, ic->i_recv_wc, &state);

        if (state.ack_next_valid)
                rds_ib_set_ack(ic, state.ack_next, state.ack_required);
        if (state.ack_recv_valid && state.ack_recv > ic->i_ack_recv) {
                rds_send_drop_acked(conn, state.ack_recv, NULL);
                ic->i_ack_recv = state.ack_recv;
        }

        if (rds_conn_up(conn))
                rds_ib_attempt_ack(ic);
}

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,
                 ib_event_msg(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, ib_event_msg(event->event),
                        &conn->c_laddr, &conn->c_faddr);
                rds_conn_drop(conn);
                break;
        }
}

static void rds_ib_cq_comp_handler_send(struct ib_cq *cq, void *context)
{
        struct rds_connection *conn = context;
        struct rds_ib_connection *ic = conn->c_transport_data;

        rdsdebug("conn %p cq %p\n", conn, cq);

        rds_ib_stats_inc(s_ib_evt_handler_call);

        tasklet_schedule(&ic->i_send_tasklet);
}

/*
 * 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 ib_cq_init_attr cq_attr = {};
        struct rds_ib_device *rds_ibdev;
        int ret, fr_queue_space;

        /*
         * 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;

        /* The fr_queue_space is currently set to 512, to add extra space on
         * completion queue and send queue. This extra space is used for FRMR
         * registration and invalidation work requests
         */
        fr_queue_space = (rds_ibdev->use_fastreg ? RDS_IB_DEFAULT_FR_WR : 0);

        /* 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;

        cq_attr.cqe = ic->i_send_ring.w_nr + fr_queue_space + 1;

        ic->i_send_cq = ib_create_cq(dev, rds_ib_cq_comp_handler_send,
                                     rds_ib_cq_event_handler, conn,
                                     &cq_attr);
        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 rds_ibdev_out;
        }

        cq_attr.cqe = ic->i_recv_ring.w_nr;
        ic->i_recv_cq = ib_create_cq(dev, rds_ib_cq_comp_handler_recv,
                                     rds_ib_cq_event_handler, conn,
                                     &cq_attr);
        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 send_cq_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 recv_cq_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 recv_cq_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 + fr_queue_space + 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;
        atomic_set(&ic->i_fastreg_wrs, RDS_IB_DEFAULT_FR_WR);

        /*
         * 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 recv_cq_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 qp_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 send_hdrs_dma_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 recv_hdrs_dma_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 ack_dma_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 sends_out;
        }

        rds_ib_recv_init_ack(ic);

        rdsdebug("conn %p pd %p cq %p %p\n", conn, ic->i_pd,
                 ic->i_send_cq, ic->i_recv_cq);

        goto out;

sends_out:
        vfree(ic->i_sends);
ack_dma_out:
        ib_dma_free_coherent(dev, sizeof(struct rds_header),
                             ic->i_ack, ic->i_ack_dma);
recv_hdrs_dma_out:
        ib_dma_free_coherent(dev, ic->i_recv_ring.w_nr *
                                        sizeof(struct rds_header),
                                        ic->i_recv_hdrs, ic->i_recv_hdrs_dma);
send_hdrs_dma_out:
        ib_dma_free_coherent(dev, ic->i_send_ring.w_nr *
                                        sizeof(struct rds_header),
                                        ic->i_send_hdrs, ic->i_send_hdrs_dma);
qp_out:
        rdma_destroy_qp(ic->i_cm_id);
recv_cq_out:
        if (!ib_destroy_cq(ic->i_recv_cq))
                ic->i_recv_cq = NULL;
send_cq_out:
        if (!ib_destroy_cq(ic->i_send_cq))
                ic->i_send_cq = NULL;
rds_ibdev_out:
        rds_ib_remove_conn(rds_ibdev, conn);
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));

        /* RDS/IB is not currently netns aware, thus init_net */
        conn = rds_conn_create(&init_net, 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_path_connect(struct rds_conn_path *cp)
{
        struct rds_connection *conn = cp->cp_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(&init_net, 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_path_shutdown(struct rds_conn_path *cp)
{
        struct rds_connection *conn = cp->cp_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) &&
                           (atomic_read(&ic->i_fastreg_wrs) == RDS_IB_DEFAULT_FR_WR));
                tasklet_kill(&ic->i_send_tasklet);
                tasklet_kill(&ic->i_recv_tasklet);

                /* first destroy the ib state that generates callbacks */
                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);

                /* then free the resources that ib callbacks use */
                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);

                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_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_send_tasklet, rds_ib_tasklet_fn_send,
                     (unsigned long)ic);
        tasklet_init(&ic->i_recv_tasklet, rds_ib_tasklet_fn_recv,
                     (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);
}