ipoib_cm.c

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/*
 * Copyright (c) 2006 Mellanox Technologies. 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 <rdma/ib_cm.h>
#include <net/dst.h>
#include <net/icmp.h>
#include <linux/icmpv6.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/moduleparam.h>

#include "ipoib.h"

int ipoib_max_conn_qp = 128;

module_param_named(max_nonsrq_conn_qp, ipoib_max_conn_qp, int, 0444);
MODULE_PARM_DESC(max_nonsrq_conn_qp,
         "Max number of connected-mode QPs per interface "
         "(applied only if shared receive queue is not available)");

#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG_DATA
static int data_debug_level;

module_param_named(cm_data_debug_level, data_debug_level, int, 0644);
MODULE_PARM_DESC(cm_data_debug_level,
         "Enable data path debug tracing for connected mode if > 0");
#endif

#define IPOIB_CM_IETF_ID 0x1000000000000000ULL

#define IPOIB_CM_RX_UPDATE_TIME (256 * HZ)
#define IPOIB_CM_RX_TIMEOUT     (2 * 256 * HZ)
#define IPOIB_CM_RX_DELAY       (3 * 256 * HZ)
#define IPOIB_CM_RX_UPDATE_MASK (0x3)

static struct ib_qp_attr ipoib_cm_err_attr = {
    .qp_state = IB_QPS_ERR
};

#define IPOIB_CM_RX_DRAIN_WRID 0xffffffff

static struct ib_send_wr ipoib_cm_rx_drain_wr = {
    .wr_id = IPOIB_CM_RX_DRAIN_WRID,
    .opcode = IB_WR_SEND,
};

static int ipoib_cm_tx_handler(struct ib_cm_id *cm_id,
                   struct ib_cm_event *event);

static void ipoib_cm_dma_unmap_rx(struct ipoib_dev_priv *priv, int frags,
                  u64 mapping[IPOIB_CM_RX_SG])
{
    int i;

    ib_dma_unmap_single(priv->ca, mapping[0], IPOIB_CM_HEAD_SIZE, DMA_FROM_DEVICE);

    for (i = 0; i < frags; ++i)
        ib_dma_unmap_page(priv->ca, mapping[i + 1], PAGE_SIZE, DMA_FROM_DEVICE);
}

static int ipoib_cm_post_receive_srq(struct net_device *dev, int id)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ib_recv_wr *bad_wr;
    int i, ret;

    priv->cm.rx_wr.wr_id = id | IPOIB_OP_CM | IPOIB_OP_RECV;

    for (i = 0; i < priv->cm.num_frags; ++i)
        priv->cm.rx_sge[i].addr = priv->cm.srq_ring[id].mapping[i];

    ret = ib_post_srq_recv(priv->cm.srq, &priv->cm.rx_wr, &bad_wr);
    if (unlikely(ret)) {
        ipoib_warn(priv, "post srq failed for buf %d (%d)\n", id, ret);
        ipoib_cm_dma_unmap_rx(priv, priv->cm.num_frags - 1,
                      priv->cm.srq_ring[id].mapping);
        dev_kfree_skb_any(priv->cm.srq_ring[id].skb);
        priv->cm.srq_ring[id].skb = NULL;
    }

    return ret;
}

static int ipoib_cm_post_receive_nonsrq(struct net_device *dev,
                    struct ipoib_cm_rx *rx,
                    struct ib_recv_wr *wr,
                    struct ib_sge *sge, int id)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ib_recv_wr *bad_wr;
    int i, ret;

    wr->wr_id = id | IPOIB_OP_CM | IPOIB_OP_RECV;

    for (i = 0; i < IPOIB_CM_RX_SG; ++i)
        sge[i].addr = rx->rx_ring[id].mapping[i];

    ret = ib_post_recv(rx->qp, wr, &bad_wr);
    if (unlikely(ret)) {
        ipoib_warn(priv, "post recv failed for buf %d (%d)\n", id, ret);
        ipoib_cm_dma_unmap_rx(priv, IPOIB_CM_RX_SG - 1,
                      rx->rx_ring[id].mapping);
        dev_kfree_skb_any(rx->rx_ring[id].skb);
        rx->rx_ring[id].skb = NULL;
    }

    return ret;
}

static struct sk_buff *ipoib_cm_alloc_rx_skb(struct net_device *dev,
                         struct ipoib_cm_rx_buf *rx_ring,
                         int id, int frags,
                         u64 mapping[IPOIB_CM_RX_SG])
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct sk_buff *skb;
    int i;

    skb = dev_alloc_skb(IPOIB_CM_HEAD_SIZE + 12);
    if (unlikely(!skb))
        return NULL;

    /*
     * IPoIB adds a 4 byte header. So we need 12 more bytes to align the
     * IP header to a multiple of 16.
     */
    skb_reserve(skb, 12);

    mapping[0] = ib_dma_map_single(priv->ca, skb->data, IPOIB_CM_HEAD_SIZE,
                       DMA_FROM_DEVICE);
    if (unlikely(ib_dma_mapping_error(priv->ca, mapping[0]))) {
        dev_kfree_skb_any(skb);
        return NULL;
    }

    for (i = 0; i < frags; i++) {
        struct page *page = alloc_page(GFP_ATOMIC);

        if (!page)
            goto partial_error;
        skb_fill_page_desc(skb, i, page, 0, PAGE_SIZE);

        mapping[i + 1] = ib_dma_map_page(priv->ca, page,
                         0, PAGE_SIZE, DMA_FROM_DEVICE);
        if (unlikely(ib_dma_mapping_error(priv->ca, mapping[i + 1])))
            goto partial_error;
    }

    rx_ring[id].skb = skb;
    return skb;

partial_error:

    ib_dma_unmap_single(priv->ca, mapping[0], IPOIB_CM_HEAD_SIZE, DMA_FROM_DEVICE);

    for (; i > 0; --i)
        ib_dma_unmap_page(priv->ca, mapping[i], PAGE_SIZE, DMA_FROM_DEVICE);

    dev_kfree_skb_any(skb);
    return NULL;
}

static void ipoib_cm_free_rx_ring(struct net_device *dev,
                  struct ipoib_cm_rx_buf *rx_ring)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    int i;

    for (i = 0; i < ipoib_recvq_size; ++i)
        if (rx_ring[i].skb) {
            ipoib_cm_dma_unmap_rx(priv, IPOIB_CM_RX_SG - 1,
                          rx_ring[i].mapping);
            dev_kfree_skb_any(rx_ring[i].skb);
        }

    vfree(rx_ring);
}

static void ipoib_cm_start_rx_drain(struct ipoib_dev_priv *priv)
{
    struct ib_send_wr *bad_wr;
    struct ipoib_cm_rx *p;

    /* We only reserved 1 extra slot in CQ for drain WRs, so
     * make sure we have at most 1 outstanding WR. */
    if (list_empty(&priv->cm.rx_flush_list) ||
        !list_empty(&priv->cm.rx_drain_list))
        return;

    /*
     * QPs on flush list are error state.  This way, a "flush
     * error" WC will be immediately generated for each WR we post.
     */
    p = list_entry(priv->cm.rx_flush_list.next, typeof(*p), list);
    if (ib_post_send(p->qp, &ipoib_cm_rx_drain_wr, &bad_wr))
        ipoib_warn(priv, "failed to post drain wr\n");

    list_splice_init(&priv->cm.rx_flush_list, &priv->cm.rx_drain_list);
}

static void ipoib_cm_rx_event_handler(struct ib_event *event, void *ctx)
{
    struct ipoib_cm_rx *p = ctx;
    struct ipoib_dev_priv *priv = netdev_priv(p->dev);
    unsigned long flags;

    if (event->event != IB_EVENT_QP_LAST_WQE_REACHED)
        return;

    spin_lock_irqsave(&priv->lock, flags);
    list_move(&p->list, &priv->cm.rx_flush_list);
    p->state = IPOIB_CM_RX_FLUSH;
    ipoib_cm_start_rx_drain(priv);
    spin_unlock_irqrestore(&priv->lock, flags);
}

static struct ib_qp *ipoib_cm_create_rx_qp(struct net_device *dev,
                       struct ipoib_cm_rx *p)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ib_qp_init_attr attr = {
        .event_handler = ipoib_cm_rx_event_handler,
        .send_cq = priv->recv_cq, /* For drain WR */
        .recv_cq = priv->recv_cq,
        .srq = priv->cm.srq,
        .cap.max_send_wr = 1, /* For drain WR */
        .cap.max_send_sge = 1, /* FIXME: 0 Seems not to work */
        .sq_sig_type = IB_SIGNAL_ALL_WR,
        .qp_type = IB_QPT_RC,
        .qp_context = p,
    };

    if (!ipoib_cm_has_srq(dev)) {
        attr.cap.max_recv_wr  = ipoib_recvq_size;
        attr.cap.max_recv_sge = IPOIB_CM_RX_SG;
    }

    return ib_create_qp(priv->pd, &attr);
}

static int ipoib_cm_modify_rx_qp(struct net_device *dev,
                 struct ib_cm_id *cm_id, struct ib_qp *qp,
                 unsigned psn)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ib_qp_attr qp_attr;
    int qp_attr_mask, ret;

    qp_attr.qp_state = IB_QPS_INIT;
    ret = ib_cm_init_qp_attr(cm_id, &qp_attr, &qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to init QP attr for INIT: %d\n", ret);
        return ret;
    }
    ret = ib_modify_qp(qp, &qp_attr, qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to modify QP to INIT: %d\n", ret);
        return ret;
    }
    qp_attr.qp_state = IB_QPS_RTR;
    ret = ib_cm_init_qp_attr(cm_id, &qp_attr, &qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to init QP attr for RTR: %d\n", ret);
        return ret;
    }
    qp_attr.rq_psn = psn;
    ret = ib_modify_qp(qp, &qp_attr, qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to modify QP to RTR: %d\n", ret);
        return ret;
    }

    /*
     * Current Mellanox HCA firmware won't generate completions
     * with error for drain WRs unless the QP has been moved to
     * RTS first. This work-around leaves a window where a QP has
     * moved to error asynchronously, but this will eventually get
     * fixed in firmware, so let's not error out if modify QP
     * fails.
     */
    qp_attr.qp_state = IB_QPS_RTS;
    ret = ib_cm_init_qp_attr(cm_id, &qp_attr, &qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to init QP attr for RTS: %d\n", ret);
        return 0;
    }
    ret = ib_modify_qp(qp, &qp_attr, qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to modify QP to RTS: %d\n", ret);
        return 0;
    }

    return 0;
}

static void ipoib_cm_init_rx_wr(struct net_device *dev,
                struct ib_recv_wr *wr,
                struct ib_sge *sge)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    int i;

    for (i = 0; i < priv->cm.num_frags; ++i)
        sge[i].lkey = priv->mr->lkey;

    sge[0].length = IPOIB_CM_HEAD_SIZE;
    for (i = 1; i < priv->cm.num_frags; ++i)
        sge[i].length = PAGE_SIZE;

    wr->next    = NULL;
    wr->sg_list = sge;
    wr->num_sge = priv->cm.num_frags;
}

static int ipoib_cm_nonsrq_init_rx(struct net_device *dev, struct ib_cm_id *cm_id,
                   struct ipoib_cm_rx *rx)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct {
        struct ib_recv_wr wr;
        struct ib_sge sge[IPOIB_CM_RX_SG];
    } *t;
    int ret;
    int i;

    rx->rx_ring = vzalloc(ipoib_recvq_size * sizeof *rx->rx_ring);
    if (!rx->rx_ring) {
        printk(KERN_WARNING "%s: failed to allocate CM non-SRQ ring (%d entries)\n",
               priv->ca->name, ipoib_recvq_size);
        return -ENOMEM;
    }

    t = kmalloc(sizeof *t, GFP_KERNEL);
    if (!t) {
        ret = -ENOMEM;
        goto err_free;
    }

    ipoib_cm_init_rx_wr(dev, &t->wr, t->sge);

    spin_lock_irq(&priv->lock);

    if (priv->cm.nonsrq_conn_qp >= ipoib_max_conn_qp) {
        spin_unlock_irq(&priv->lock);
        ib_send_cm_rej(cm_id, IB_CM_REJ_NO_QP, NULL, 0, NULL, 0);
        ret = -EINVAL;
        goto err_free;
    } else
        ++priv->cm.nonsrq_conn_qp;

    spin_unlock_irq(&priv->lock);

    for (i = 0; i < ipoib_recvq_size; ++i) {
        if (!ipoib_cm_alloc_rx_skb(dev, rx->rx_ring, i, IPOIB_CM_RX_SG - 1,
                       rx->rx_ring[i].mapping)) {
            ipoib_warn(priv, "failed to allocate receive buffer %d\n", i);
                ret = -ENOMEM;
                goto err_count;
        }
        ret = ipoib_cm_post_receive_nonsrq(dev, rx, &t->wr, t->sge, i);
        if (ret) {
            ipoib_warn(priv, "ipoib_cm_post_receive_nonsrq "
                   "failed for buf %d\n", i);
            ret = -EIO;
            goto err_count;
        }
    }

    rx->recv_count = ipoib_recvq_size;

    kfree(t);

    return 0;

err_count:
    spin_lock_irq(&priv->lock);
    --priv->cm.nonsrq_conn_qp;
    spin_unlock_irq(&priv->lock);

err_free:
    kfree(t);
    ipoib_cm_free_rx_ring(dev, rx->rx_ring);

    return ret;
}

static int ipoib_cm_send_rep(struct net_device *dev, struct ib_cm_id *cm_id,
                 struct ib_qp *qp, struct ib_cm_req_event_param *req,
                 unsigned psn)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_data data = {};
    struct ib_cm_rep_param rep = {};

    data.qpn = cpu_to_be32(priv->qp->qp_num);
    data.mtu = cpu_to_be32(IPOIB_CM_BUF_SIZE);

    rep.private_data = &data;
    rep.private_data_len = sizeof data;
    rep.flow_control = 0;
    rep.rnr_retry_count = req->rnr_retry_count;
    rep.srq = ipoib_cm_has_srq(dev);
    rep.qp_num = qp->qp_num;
    rep.starting_psn = psn;
    return ib_send_cm_rep(cm_id, &rep);
}

static int ipoib_cm_req_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
{
    struct net_device *dev = cm_id->context;
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_rx *p;
    unsigned psn;
    int ret;

    ipoib_dbg(priv, "REQ arrived\n");
    p = kzalloc(sizeof *p, GFP_KERNEL);
    if (!p)
        return -ENOMEM;
    p->dev = dev;
    p->id = cm_id;
    cm_id->context = p;
    p->state = IPOIB_CM_RX_LIVE;
    p->jiffies = jiffies;
    INIT_LIST_HEAD(&p->list);

    p->qp = ipoib_cm_create_rx_qp(dev, p);
    if (IS_ERR(p->qp)) {
        ret = PTR_ERR(p->qp);
        goto err_qp;
    }

    psn = random32() & 0xffffff;
    ret = ipoib_cm_modify_rx_qp(dev, cm_id, p->qp, psn);
    if (ret)
        goto err_modify;

    if (!ipoib_cm_has_srq(dev)) {
        ret = ipoib_cm_nonsrq_init_rx(dev, cm_id, p);
        if (ret)
            goto err_modify;
    }

    spin_lock_irq(&priv->lock);
    queue_delayed_work(ipoib_workqueue,
               &priv->cm.stale_task, IPOIB_CM_RX_DELAY);
    /* Add this entry to passive ids list head, but do not re-add it
     * if IB_EVENT_QP_LAST_WQE_REACHED has moved it to flush list. */
    p->jiffies = jiffies;
    if (p->state == IPOIB_CM_RX_LIVE)
        list_move(&p->list, &priv->cm.passive_ids);
    spin_unlock_irq(&priv->lock);

    ret = ipoib_cm_send_rep(dev, cm_id, p->qp, &event->param.req_rcvd, psn);
    if (ret) {
        ipoib_warn(priv, "failed to send REP: %d\n", ret);
        if (ib_modify_qp(p->qp, &ipoib_cm_err_attr, IB_QP_STATE))
            ipoib_warn(priv, "unable to move qp to error state\n");
    }
    return 0;

err_modify:
    ib_destroy_qp(p->qp);
err_qp:
    kfree(p);
    return ret;
}

static int ipoib_cm_rx_handler(struct ib_cm_id *cm_id,
                   struct ib_cm_event *event)
{
    struct ipoib_cm_rx *p;
    struct ipoib_dev_priv *priv;

    switch (event->event) {
    case IB_CM_REQ_RECEIVED:
        return ipoib_cm_req_handler(cm_id, event);
    case IB_CM_DREQ_RECEIVED:
        p = cm_id->context;
        ib_send_cm_drep(cm_id, NULL, 0);
        /* Fall through */
    case IB_CM_REJ_RECEIVED:
        p = cm_id->context;
        priv = netdev_priv(p->dev);
        if (ib_modify_qp(p->qp, &ipoib_cm_err_attr, IB_QP_STATE))
            ipoib_warn(priv, "unable to move qp to error state\n");
        /* Fall through */
    default:
        return 0;
    }
}
/* Adjust length of skb with fragments to match received data */
static void skb_put_frags(struct sk_buff *skb, unsigned int hdr_space,
              unsigned int length, struct sk_buff *toskb)
{
    int i, num_frags;
    unsigned int size;

    /* put header into skb */
    size = min(length, hdr_space);
    skb->tail += size;
    skb->len += size;
    length -= size;

    num_frags = skb_shinfo(skb)->nr_frags;
    for (i = 0; i < num_frags; i++) {
        skb_frag_t *frag = &skb_shinfo(skb)->frags[i];

        if (length == 0) {
            /* don't need this page */
            skb_fill_page_desc(toskb, i, skb_frag_page(frag),
                       0, PAGE_SIZE);
            --skb_shinfo(skb)->nr_frags;
        } else {
            size = min(length, (unsigned) PAGE_SIZE);

            skb_frag_size_set(frag, size);
            skb->data_len += size;
            skb->truesize += size;
            skb->len += size;
            length -= size;
        }
    }
}

void ipoib_cm_handle_rx_wc(struct net_device *dev, struct ib_wc *wc)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_rx_buf *rx_ring;
    unsigned int wr_id = wc->wr_id & ~(IPOIB_OP_CM | IPOIB_OP_RECV);
    struct sk_buff *skb, *newskb;
    struct ipoib_cm_rx *p;
    unsigned long flags;
    u64 mapping[IPOIB_CM_RX_SG];
    int frags;
    int has_srq;
    struct sk_buff *small_skb;

    ipoib_dbg_data(priv, "cm recv completion: id %d, status: %d\n",
               wr_id, wc->status);

    if (unlikely(wr_id >= ipoib_recvq_size)) {
        if (wr_id == (IPOIB_CM_RX_DRAIN_WRID & ~(IPOIB_OP_CM | IPOIB_OP_RECV))) {
            spin_lock_irqsave(&priv->lock, flags);
            list_splice_init(&priv->cm.rx_drain_list, &priv->cm.rx_reap_list);
            ipoib_cm_start_rx_drain(priv);
            queue_work(ipoib_workqueue, &priv->cm.rx_reap_task);
            spin_unlock_irqrestore(&priv->lock, flags);
        } else
            ipoib_warn(priv, "cm recv completion event with wrid %d (> %d)\n",
                   wr_id, ipoib_recvq_size);
        return;
    }

    p = wc->qp->qp_context;

    has_srq = ipoib_cm_has_srq(dev);
    rx_ring = has_srq ? priv->cm.srq_ring : p->rx_ring;

    skb = rx_ring[wr_id].skb;

    if (unlikely(wc->status != IB_WC_SUCCESS)) {
        ipoib_dbg(priv, "cm recv error "
               "(status=%d, wrid=%d vend_err %x)\n",
               wc->status, wr_id, wc->vendor_err);
        ++dev->stats.rx_dropped;
        if (has_srq)
            goto repost;
        else {
            if (!--p->recv_count) {
                spin_lock_irqsave(&priv->lock, flags);
                list_move(&p->list, &priv->cm.rx_reap_list);
                spin_unlock_irqrestore(&priv->lock, flags);
                queue_work(ipoib_workqueue, &priv->cm.rx_reap_task);
            }
            return;
        }
    }

    if (unlikely(!(wr_id & IPOIB_CM_RX_UPDATE_MASK))) {
        if (p && time_after_eq(jiffies, p->jiffies + IPOIB_CM_RX_UPDATE_TIME)) {
            spin_lock_irqsave(&priv->lock, flags);
            p->jiffies = jiffies;
            /* Move this entry to list head, but do not re-add it
             * if it has been moved out of list. */
            if (p->state == IPOIB_CM_RX_LIVE)
                list_move(&p->list, &priv->cm.passive_ids);
            spin_unlock_irqrestore(&priv->lock, flags);
        }
    }

    if (wc->byte_len < IPOIB_CM_COPYBREAK) {
        int dlen = wc->byte_len;

        small_skb = dev_alloc_skb(dlen + 12);
        if (small_skb) {
            skb_reserve(small_skb, 12);
            ib_dma_sync_single_for_cpu(priv->ca, rx_ring[wr_id].mapping[0],
                           dlen, DMA_FROM_DEVICE);
            skb_copy_from_linear_data(skb, small_skb->data, dlen);
            ib_dma_sync_single_for_device(priv->ca, rx_ring[wr_id].mapping[0],
                              dlen, DMA_FROM_DEVICE);
            skb_put(small_skb, dlen);
            skb = small_skb;
            goto copied;
        }
    }

    frags = PAGE_ALIGN(wc->byte_len - min(wc->byte_len,
                          (unsigned)IPOIB_CM_HEAD_SIZE)) / PAGE_SIZE;

    newskb = ipoib_cm_alloc_rx_skb(dev, rx_ring, wr_id, frags, mapping);
    if (unlikely(!newskb)) {
        /*
         * If we can't allocate a new RX buffer, dump
         * this packet and reuse the old buffer.
         */
        ipoib_dbg(priv, "failed to allocate receive buffer %d\n", wr_id);
        ++dev->stats.rx_dropped;
        goto repost;
    }

    ipoib_cm_dma_unmap_rx(priv, frags, rx_ring[wr_id].mapping);
    memcpy(rx_ring[wr_id].mapping, mapping, (frags + 1) * sizeof *mapping);

    ipoib_dbg_data(priv, "received %d bytes, SLID 0x%04x\n",
               wc->byte_len, wc->slid);

    skb_put_frags(skb, IPOIB_CM_HEAD_SIZE, wc->byte_len, newskb);

copied:
    skb->protocol = ((struct ipoib_header *) skb->data)->proto;
    skb_reset_mac_header(skb);
    skb_pull(skb, IPOIB_ENCAP_LEN);

    ++dev->stats.rx_packets;
    dev->stats.rx_bytes += skb->len;

    skb->dev = dev;
    /* XXX get correct PACKET_ type here */
    skb->pkt_type = PACKET_HOST;
    netif_receive_skb(skb);

repost:
    if (has_srq) {
        if (unlikely(ipoib_cm_post_receive_srq(dev, wr_id)))
            ipoib_warn(priv, "ipoib_cm_post_receive_srq failed "
                   "for buf %d\n", wr_id);
    } else {
        if (unlikely(ipoib_cm_post_receive_nonsrq(dev, p,
                              &priv->cm.rx_wr,
                              priv->cm.rx_sge,
                              wr_id))) {
            --p->recv_count;
            ipoib_warn(priv, "ipoib_cm_post_receive_nonsrq failed "
                   "for buf %d\n", wr_id);
        }
    }
}

static inline int post_send(struct ipoib_dev_priv *priv,
                struct ipoib_cm_tx *tx,
                unsigned int wr_id,
                u64 addr, int len)
{
    struct ib_send_wr *bad_wr;

    priv->tx_sge[0].addr          = addr;
    priv->tx_sge[0].length        = len;

    priv->tx_wr.num_sge = 1;
    priv->tx_wr.wr_id   = wr_id | IPOIB_OP_CM;

    return ib_post_send(tx->qp, &priv->tx_wr, &bad_wr);
}

void ipoib_cm_send(struct net_device *dev, struct sk_buff *skb, struct ipoib_cm_tx *tx)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_tx_buf *tx_req;
    u64 addr;
    int rc;

    if (unlikely(skb->len > tx->mtu)) {
        ipoib_warn(priv, "packet len %d (> %d) too long to send, dropping\n",
               skb->len, tx->mtu);
        ++dev->stats.tx_dropped;
        ++dev->stats.tx_errors;
        ipoib_cm_skb_too_long(dev, skb, tx->mtu - IPOIB_ENCAP_LEN);
        return;
    }

    ipoib_dbg_data(priv, "sending packet: head 0x%x length %d connection 0x%x\n",
               tx->tx_head, skb->len, tx->qp->qp_num);

    /*
     * We put the skb into the tx_ring _before_ we call post_send()
     * because it's entirely possible that the completion handler will
     * run before we execute anything after the post_send().  That
     * means we have to make sure everything is properly recorded and
     * our state is consistent before we call post_send().
     */
    tx_req = &tx->tx_ring[tx->tx_head & (ipoib_sendq_size - 1)];
    tx_req->skb = skb;
    addr = ib_dma_map_single(priv->ca, skb->data, skb->len, DMA_TO_DEVICE);
    if (unlikely(ib_dma_mapping_error(priv->ca, addr))) {
        ++dev->stats.tx_errors;
        dev_kfree_skb_any(skb);
        return;
    }

    tx_req->mapping = addr;

    rc = post_send(priv, tx, tx->tx_head & (ipoib_sendq_size - 1),
               addr, skb->len);
    if (unlikely(rc)) {
        ipoib_warn(priv, "post_send failed, error %d\n", rc);
        ++dev->stats.tx_errors;
        ib_dma_unmap_single(priv->ca, addr, skb->len, DMA_TO_DEVICE);
        dev_kfree_skb_any(skb);
    } else {
        dev->trans_start = jiffies;
        ++tx->tx_head;

        if (++priv->tx_outstanding == ipoib_sendq_size) {
            ipoib_dbg(priv, "TX ring 0x%x full, stopping kernel net queue\n",
                  tx->qp->qp_num);
            if (ib_req_notify_cq(priv->send_cq, IB_CQ_NEXT_COMP))
                ipoib_warn(priv, "request notify on send CQ failed\n");
            netif_stop_queue(dev);
        }
    }
}

void ipoib_cm_handle_tx_wc(struct net_device *dev, struct ib_wc *wc)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_tx *tx = wc->qp->qp_context;
    unsigned int wr_id = wc->wr_id & ~IPOIB_OP_CM;
    struct ipoib_cm_tx_buf *tx_req;
    unsigned long flags;

    ipoib_dbg_data(priv, "cm send completion: id %d, status: %d\n",
               wr_id, wc->status);

    if (unlikely(wr_id >= ipoib_sendq_size)) {
        ipoib_warn(priv, "cm send completion event with wrid %d (> %d)\n",
               wr_id, ipoib_sendq_size);
        return;
    }

    tx_req = &tx->tx_ring[wr_id];

    ib_dma_unmap_single(priv->ca, tx_req->mapping, tx_req->skb->len, DMA_TO_DEVICE);

    /* FIXME: is this right? Shouldn't we only increment on success? */
    ++dev->stats.tx_packets;
    dev->stats.tx_bytes += tx_req->skb->len;

    dev_kfree_skb_any(tx_req->skb);

    netif_tx_lock(dev);

    ++tx->tx_tail;
    if (unlikely(--priv->tx_outstanding == ipoib_sendq_size >> 1) &&
        netif_queue_stopped(dev) &&
        test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
        netif_wake_queue(dev);

    if (wc->status != IB_WC_SUCCESS &&
        wc->status != IB_WC_WR_FLUSH_ERR) {
        struct ipoib_neigh *neigh;

        ipoib_dbg(priv, "failed cm send event "
               "(status=%d, wrid=%d vend_err %x)\n",
               wc->status, wr_id, wc->vendor_err);

        spin_lock_irqsave(&priv->lock, flags);
        neigh = tx->neigh;

        if (neigh) {
            neigh->cm = NULL;
            list_del(&neigh->list);
            ipoib_neigh_free(neigh);

            tx->neigh = NULL;
        }

        if (test_and_clear_bit(IPOIB_FLAG_INITIALIZED, &tx->flags)) {
            list_move(&tx->list, &priv->cm.reap_list);
            queue_work(ipoib_workqueue, &priv->cm.reap_task);
        }

        clear_bit(IPOIB_FLAG_OPER_UP, &tx->flags);

        spin_unlock_irqrestore(&priv->lock, flags);
    }

    netif_tx_unlock(dev);
}

int ipoib_cm_dev_open(struct net_device *dev)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    int ret;

    if (!IPOIB_CM_SUPPORTED(dev->dev_addr))
        return 0;

    priv->cm.id = ib_create_cm_id(priv->ca, ipoib_cm_rx_handler, dev);
    if (IS_ERR(priv->cm.id)) {
        printk(KERN_WARNING "%s: failed to create CM ID\n", priv->ca->name);
        ret = PTR_ERR(priv->cm.id);
        goto err_cm;
    }

    ret = ib_cm_listen(priv->cm.id, cpu_to_be64(IPOIB_CM_IETF_ID | priv->qp->qp_num),
               0, NULL);
    if (ret) {
        printk(KERN_WARNING "%s: failed to listen on ID 0x%llx\n", priv->ca->name,
               IPOIB_CM_IETF_ID | priv->qp->qp_num);
        goto err_listen;
    }

    return 0;

err_listen:
    ib_destroy_cm_id(priv->cm.id);
err_cm:
    priv->cm.id = NULL;
    return ret;
}

static void ipoib_cm_free_rx_reap_list(struct net_device *dev)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_rx *rx, *n;
    LIST_HEAD(list);

    spin_lock_irq(&priv->lock);
    list_splice_init(&priv->cm.rx_reap_list, &list);
    spin_unlock_irq(&priv->lock);

    list_for_each_entry_safe(rx, n, &list, list) {
        ib_destroy_cm_id(rx->id);
        ib_destroy_qp(rx->qp);
        if (!ipoib_cm_has_srq(dev)) {
            ipoib_cm_free_rx_ring(priv->dev, rx->rx_ring);
            spin_lock_irq(&priv->lock);
            --priv->cm.nonsrq_conn_qp;
            spin_unlock_irq(&priv->lock);
        }
        kfree(rx);
    }
}

void ipoib_cm_dev_stop(struct net_device *dev)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_rx *p;
    unsigned long begin;
    int ret;

    if (!IPOIB_CM_SUPPORTED(dev->dev_addr) || !priv->cm.id)
        return;

    ib_destroy_cm_id(priv->cm.id);
    priv->cm.id = NULL;

    spin_lock_irq(&priv->lock);
    while (!list_empty(&priv->cm.passive_ids)) {
        p = list_entry(priv->cm.passive_ids.next, typeof(*p), list);
        list_move(&p->list, &priv->cm.rx_error_list);
        p->state = IPOIB_CM_RX_ERROR;
        spin_unlock_irq(&priv->lock);
        ret = ib_modify_qp(p->qp, &ipoib_cm_err_attr, IB_QP_STATE);
        if (ret)
            ipoib_warn(priv, "unable to move qp to error state: %d\n", ret);
        spin_lock_irq(&priv->lock);
    }

    /* Wait for all RX to be drained */
    begin = jiffies;

    while (!list_empty(&priv->cm.rx_error_list) ||
           !list_empty(&priv->cm.rx_flush_list) ||
           !list_empty(&priv->cm.rx_drain_list)) {
        if (time_after(jiffies, begin + 5 * HZ)) {
            ipoib_warn(priv, "RX drain timing out\n");

            /*
             * assume the HW is wedged and just free up everything.
             */
            list_splice_init(&priv->cm.rx_flush_list,
                     &priv->cm.rx_reap_list);
            list_splice_init(&priv->cm.rx_error_list,
                     &priv->cm.rx_reap_list);
            list_splice_init(&priv->cm.rx_drain_list,
                     &priv->cm.rx_reap_list);
            break;
        }
        spin_unlock_irq(&priv->lock);
        msleep(1);
        ipoib_drain_cq(dev);
        spin_lock_irq(&priv->lock);
    }

    spin_unlock_irq(&priv->lock);

    ipoib_cm_free_rx_reap_list(dev);

    cancel_delayed_work(&priv->cm.stale_task);
}

static int ipoib_cm_rep_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
{
    struct ipoib_cm_tx *p = cm_id->context;
    struct ipoib_dev_priv *priv = netdev_priv(p->dev);
    struct ipoib_cm_data *data = event->private_data;
    struct sk_buff_head skqueue;
    struct ib_qp_attr qp_attr;
    int qp_attr_mask, ret;
    struct sk_buff *skb;

    p->mtu = be32_to_cpu(data->mtu);

    if (p->mtu <= IPOIB_ENCAP_LEN) {
        ipoib_warn(priv, "Rejecting connection: mtu %d <= %d\n",
               p->mtu, IPOIB_ENCAP_LEN);
        return -EINVAL;
    }

    qp_attr.qp_state = IB_QPS_RTR;
    ret = ib_cm_init_qp_attr(cm_id, &qp_attr, &qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to init QP attr for RTR: %d\n", ret);
        return ret;
    }

    qp_attr.rq_psn = 0 /* FIXME */;
    ret = ib_modify_qp(p->qp, &qp_attr, qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to modify QP to RTR: %d\n", ret);
        return ret;
    }

    qp_attr.qp_state = IB_QPS_RTS;
    ret = ib_cm_init_qp_attr(cm_id, &qp_attr, &qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to init QP attr for RTS: %d\n", ret);
        return ret;
    }
    ret = ib_modify_qp(p->qp, &qp_attr, qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to modify QP to RTS: %d\n", ret);
        return ret;
    }

    skb_queue_head_init(&skqueue);

    spin_lock_irq(&priv->lock);
    set_bit(IPOIB_FLAG_OPER_UP, &p->flags);
    if (p->neigh)
        while ((skb = __skb_dequeue(&p->neigh->queue)))
            __skb_queue_tail(&skqueue, skb);
    spin_unlock_irq(&priv->lock);

    while ((skb = __skb_dequeue(&skqueue))) {
        skb->dev = p->dev;
        if (dev_queue_xmit(skb))
            ipoib_warn(priv, "dev_queue_xmit failed "
                   "to requeue packet\n");
    }

    ret = ib_send_cm_rtu(cm_id, NULL, 0);
    if (ret) {
        ipoib_warn(priv, "failed to send RTU: %d\n", ret);
        return ret;
    }
    return 0;
}

static struct ib_qp *ipoib_cm_create_tx_qp(struct net_device *dev, struct ipoib_cm_tx *tx)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ib_qp_init_attr attr = {
        .send_cq        = priv->recv_cq,
        .recv_cq        = priv->recv_cq,
        .srq            = priv->cm.srq,
        .cap.max_send_wr    = ipoib_sendq_size,
        .cap.max_send_sge   = 1,
        .sq_sig_type        = IB_SIGNAL_ALL_WR,
        .qp_type        = IB_QPT_RC,
        .qp_context     = tx
    };

    return ib_create_qp(priv->pd, &attr);
}

static int ipoib_cm_send_req(struct net_device *dev,
                 struct ib_cm_id *id, struct ib_qp *qp,
                 u32 qpn,
                 struct ib_sa_path_rec *pathrec)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_data data = {};
    struct ib_cm_req_param req = {};

    data.qpn = cpu_to_be32(priv->qp->qp_num);
    data.mtu = cpu_to_be32(IPOIB_CM_BUF_SIZE);

    req.primary_path        = pathrec;
    req.alternate_path      = NULL;
    req.service_id          = cpu_to_be64(IPOIB_CM_IETF_ID | qpn);
    req.qp_num          = qp->qp_num;
    req.qp_type         = qp->qp_type;
    req.private_data        = &data;
    req.private_data_len        = sizeof data;
    req.flow_control        = 0;

    req.starting_psn        = 0; /* FIXME */

    /*
     * Pick some arbitrary defaults here; we could make these
     * module parameters if anyone cared about setting them.
     */
    req.responder_resources     = 4;
    req.remote_cm_response_timeout  = 20;
    req.local_cm_response_timeout   = 20;
    req.retry_count         = 0; /* RFC draft warns against retries */
    req.rnr_retry_count     = 0; /* RFC draft warns against retries */
    req.max_cm_retries      = 15;
    req.srq             = ipoib_cm_has_srq(dev);
    return ib_send_cm_req(id, &req);
}

static int ipoib_cm_modify_tx_init(struct net_device *dev,
                  struct ib_cm_id *cm_id, struct ib_qp *qp)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ib_qp_attr qp_attr;
    int qp_attr_mask, ret;
    ret = ib_find_pkey(priv->ca, priv->port, priv->pkey, &qp_attr.pkey_index);
    if (ret) {
        ipoib_warn(priv, "pkey 0x%x not found: %d\n", priv->pkey, ret);
        return ret;
    }

    qp_attr.qp_state = IB_QPS_INIT;
    qp_attr.qp_access_flags = IB_ACCESS_LOCAL_WRITE;
    qp_attr.port_num = priv->port;
    qp_attr_mask = IB_QP_STATE | IB_QP_ACCESS_FLAGS | IB_QP_PKEY_INDEX | IB_QP_PORT;

    ret = ib_modify_qp(qp, &qp_attr, qp_attr_mask);
    if (ret) {
        ipoib_warn(priv, "failed to modify tx QP to INIT: %d\n", ret);
        return ret;
    }
    return 0;
}

static int ipoib_cm_tx_init(struct ipoib_cm_tx *p, u32 qpn,
                struct ib_sa_path_rec *pathrec)
{
    struct ipoib_dev_priv *priv = netdev_priv(p->dev);
    int ret;

    p->tx_ring = vzalloc(ipoib_sendq_size * sizeof *p->tx_ring);
    if (!p->tx_ring) {
        ipoib_warn(priv, "failed to allocate tx ring\n");
        ret = -ENOMEM;
        goto err_tx;
    }

    p->qp = ipoib_cm_create_tx_qp(p->dev, p);
    if (IS_ERR(p->qp)) {
        ret = PTR_ERR(p->qp);
        ipoib_warn(priv, "failed to allocate tx qp: %d\n", ret);
        goto err_qp;
    }

    p->id = ib_create_cm_id(priv->ca, ipoib_cm_tx_handler, p);
    if (IS_ERR(p->id)) {
        ret = PTR_ERR(p->id);
        ipoib_warn(priv, "failed to create tx cm id: %d\n", ret);
        goto err_id;
    }

    ret = ipoib_cm_modify_tx_init(p->dev, p->id,  p->qp);
    if (ret) {
        ipoib_warn(priv, "failed to modify tx qp to rtr: %d\n", ret);
        goto err_modify;
    }

    ret = ipoib_cm_send_req(p->dev, p->id, p->qp, qpn, pathrec);
    if (ret) {
        ipoib_warn(priv, "failed to send cm req: %d\n", ret);
        goto err_send_cm;
    }

    ipoib_dbg(priv, "Request connection 0x%x for gid %pI6 qpn 0x%x\n",
          p->qp->qp_num, pathrec->dgid.raw, qpn);

    return 0;

err_send_cm:
err_modify:
    ib_destroy_cm_id(p->id);
err_id:
    p->id = NULL;
    ib_destroy_qp(p->qp);
err_qp:
    p->qp = NULL;
    vfree(p->tx_ring);
err_tx:
    return ret;
}

static void ipoib_cm_tx_destroy(struct ipoib_cm_tx *p)
{
    struct ipoib_dev_priv *priv = netdev_priv(p->dev);
    struct ipoib_cm_tx_buf *tx_req;
    unsigned long begin;

    ipoib_dbg(priv, "Destroy active connection 0x%x head 0x%x tail 0x%x\n",
          p->qp ? p->qp->qp_num : 0, p->tx_head, p->tx_tail);

    if (p->id)
        ib_destroy_cm_id(p->id);

    if (p->tx_ring) {
        /* Wait for all sends to complete */
        begin = jiffies;
        while ((int) p->tx_tail - (int) p->tx_head < 0) {
            if (time_after(jiffies, begin + 5 * HZ)) {
                ipoib_warn(priv, "timing out; %d sends not completed\n",
                       p->tx_head - p->tx_tail);
                goto timeout;
            }

            msleep(1);
        }
    }

timeout:

    while ((int) p->tx_tail - (int) p->tx_head < 0) {
        tx_req = &p->tx_ring[p->tx_tail & (ipoib_sendq_size - 1)];
        ib_dma_unmap_single(priv->ca, tx_req->mapping, tx_req->skb->len,
                    DMA_TO_DEVICE);
        dev_kfree_skb_any(tx_req->skb);
        ++p->tx_tail;
        netif_tx_lock_bh(p->dev);
        if (unlikely(--priv->tx_outstanding == ipoib_sendq_size >> 1) &&
            netif_queue_stopped(p->dev) &&
            test_bit(IPOIB_FLAG_ADMIN_UP, &priv->flags))
            netif_wake_queue(p->dev);
        netif_tx_unlock_bh(p->dev);
    }

    if (p->qp)
        ib_destroy_qp(p->qp);

    vfree(p->tx_ring);
    kfree(p);
}

static int ipoib_cm_tx_handler(struct ib_cm_id *cm_id,
                   struct ib_cm_event *event)
{
    struct ipoib_cm_tx *tx = cm_id->context;
    struct ipoib_dev_priv *priv = netdev_priv(tx->dev);
    struct net_device *dev = priv->dev;
    struct ipoib_neigh *neigh;
    unsigned long flags;
    int ret;

    switch (event->event) {
    case IB_CM_DREQ_RECEIVED:
        ipoib_dbg(priv, "DREQ received.\n");
        ib_send_cm_drep(cm_id, NULL, 0);
        break;
    case IB_CM_REP_RECEIVED:
        ipoib_dbg(priv, "REP received.\n");
        ret = ipoib_cm_rep_handler(cm_id, event);
        if (ret)
            ib_send_cm_rej(cm_id, IB_CM_REJ_CONSUMER_DEFINED,
                       NULL, 0, NULL, 0);
        break;
    case IB_CM_REQ_ERROR:
    case IB_CM_REJ_RECEIVED:
    case IB_CM_TIMEWAIT_EXIT:
        ipoib_dbg(priv, "CM error %d.\n", event->event);
        netif_tx_lock_bh(dev);
        spin_lock_irqsave(&priv->lock, flags);
        neigh = tx->neigh;

        if (neigh) {
            neigh->cm = NULL;
            list_del(&neigh->list);
            ipoib_neigh_free(neigh);

            tx->neigh = NULL;
        }

        if (test_and_clear_bit(IPOIB_FLAG_INITIALIZED, &tx->flags)) {
            list_move(&tx->list, &priv->cm.reap_list);
            queue_work(ipoib_workqueue, &priv->cm.reap_task);
        }

        spin_unlock_irqrestore(&priv->lock, flags);
        netif_tx_unlock_bh(dev);
        break;
    default:
        break;
    }

    return 0;
}

struct ipoib_cm_tx *ipoib_cm_create_tx(struct net_device *dev, struct ipoib_path *path,
                       struct ipoib_neigh *neigh)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ipoib_cm_tx *tx;

    tx = kzalloc(sizeof *tx, GFP_ATOMIC);
    if (!tx)
        return NULL;

    neigh->cm = tx;
    tx->neigh = neigh;
    tx->path = path;
    tx->dev = dev;
    list_add(&tx->list, &priv->cm.start_list);
    set_bit(IPOIB_FLAG_INITIALIZED, &tx->flags);
    queue_work(ipoib_workqueue, &priv->cm.start_task);
    return tx;
}

void ipoib_cm_destroy_tx(struct ipoib_cm_tx *tx)
{
    struct ipoib_dev_priv *priv = netdev_priv(tx->dev);
    unsigned long flags;
    if (test_and_clear_bit(IPOIB_FLAG_INITIALIZED, &tx->flags)) {
        spin_lock_irqsave(&priv->lock, flags);
        list_move(&tx->list, &priv->cm.reap_list);
        queue_work(ipoib_workqueue, &priv->cm.reap_task);
        ipoib_dbg(priv, "Reap connection for gid %pI6\n",
              tx->neigh->daddr + 4);
        tx->neigh = NULL;
        spin_unlock_irqrestore(&priv->lock, flags);
    }
}

static void ipoib_cm_tx_start(struct work_struct *work)
{
    struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv,
                           cm.start_task);
    struct net_device *dev = priv->dev;
    struct ipoib_neigh *neigh;
    struct ipoib_cm_tx *p;
    unsigned long flags;
    int ret;

    struct ib_sa_path_rec pathrec;
    u32 qpn;

    netif_tx_lock_bh(dev);
    spin_lock_irqsave(&priv->lock, flags);

    while (!list_empty(&priv->cm.start_list)) {
        p = list_entry(priv->cm.start_list.next, typeof(*p), list);
        list_del_init(&p->list);
        neigh = p->neigh;
        qpn = IPOIB_QPN(neigh->daddr);
        memcpy(&pathrec, &p->path->pathrec, sizeof pathrec);

        spin_unlock_irqrestore(&priv->lock, flags);
        netif_tx_unlock_bh(dev);

        ret = ipoib_cm_tx_init(p, qpn, &pathrec);

        netif_tx_lock_bh(dev);
        spin_lock_irqsave(&priv->lock, flags);

        if (ret) {
            neigh = p->neigh;
            if (neigh) {
                neigh->cm = NULL;
                list_del(&neigh->list);
                ipoib_neigh_free(neigh);
            }
            list_del(&p->list);
            kfree(p);
        }
    }

    spin_unlock_irqrestore(&priv->lock, flags);
    netif_tx_unlock_bh(dev);
}

static void ipoib_cm_tx_reap(struct work_struct *work)
{
    struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv,
                           cm.reap_task);
    struct net_device *dev = priv->dev;
    struct ipoib_cm_tx *p;
    unsigned long flags;

    netif_tx_lock_bh(dev);
    spin_lock_irqsave(&priv->lock, flags);

    while (!list_empty(&priv->cm.reap_list)) {
        p = list_entry(priv->cm.reap_list.next, typeof(*p), list);
        list_del(&p->list);
        spin_unlock_irqrestore(&priv->lock, flags);
        netif_tx_unlock_bh(dev);
        ipoib_cm_tx_destroy(p);
        netif_tx_lock_bh(dev);
        spin_lock_irqsave(&priv->lock, flags);
    }

    spin_unlock_irqrestore(&priv->lock, flags);
    netif_tx_unlock_bh(dev);
}

static void ipoib_cm_skb_reap(struct work_struct *work)
{
    struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv,
                           cm.skb_task);
    struct net_device *dev = priv->dev;
    struct sk_buff *skb;
    unsigned long flags;
    unsigned mtu = priv->mcast_mtu;

    netif_tx_lock_bh(dev);
    spin_lock_irqsave(&priv->lock, flags);

    while ((skb = skb_dequeue(&priv->cm.skb_queue))) {
        spin_unlock_irqrestore(&priv->lock, flags);
        netif_tx_unlock_bh(dev);

        if (skb->protocol == htons(ETH_P_IP))
            icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu));
#if IS_ENABLED(CONFIG_IPV6)
        else if (skb->protocol == htons(ETH_P_IPV6))
            icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu);
#endif
        dev_kfree_skb_any(skb);

        netif_tx_lock_bh(dev);
        spin_lock_irqsave(&priv->lock, flags);
    }

    spin_unlock_irqrestore(&priv->lock, flags);
    netif_tx_unlock_bh(dev);
}

void ipoib_cm_skb_too_long(struct net_device *dev, struct sk_buff *skb,
               unsigned int mtu)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    int e = skb_queue_empty(&priv->cm.skb_queue);

    if (skb_dst(skb))
        skb_dst(skb)->ops->update_pmtu(skb_dst(skb), NULL, skb, mtu);

    skb_queue_tail(&priv->cm.skb_queue, skb);
    if (e)
        queue_work(ipoib_workqueue, &priv->cm.skb_task);
}

static void ipoib_cm_rx_reap(struct work_struct *work)
{
    ipoib_cm_free_rx_reap_list(container_of(work, struct ipoib_dev_priv,
                        cm.rx_reap_task)->dev);
}

static void ipoib_cm_stale_task(struct work_struct *work)
{
    struct ipoib_dev_priv *priv = container_of(work, struct ipoib_dev_priv,
                           cm.stale_task.work);
    struct ipoib_cm_rx *p;
    int ret;

    spin_lock_irq(&priv->lock);
    while (!list_empty(&priv->cm.passive_ids)) {
        /* List is sorted by LRU, start from tail,
         * stop when we see a recently used entry */
        p = list_entry(priv->cm.passive_ids.prev, typeof(*p), list);
        if (time_before_eq(jiffies, p->jiffies + IPOIB_CM_RX_TIMEOUT))
            break;
        list_move(&p->list, &priv->cm.rx_error_list);
        p->state = IPOIB_CM_RX_ERROR;
        spin_unlock_irq(&priv->lock);
        ret = ib_modify_qp(p->qp, &ipoib_cm_err_attr, IB_QP_STATE);
        if (ret)
            ipoib_warn(priv, "unable to move qp to error state: %d\n", ret);
        spin_lock_irq(&priv->lock);
    }

    if (!list_empty(&priv->cm.passive_ids))
        queue_delayed_work(ipoib_workqueue,
                   &priv->cm.stale_task, IPOIB_CM_RX_DELAY);
    spin_unlock_irq(&priv->lock);
}


static ssize_t show_mode(struct device *d, struct device_attribute *attr,
             char *buf)
{
    struct ipoib_dev_priv *priv = netdev_priv(to_net_dev(d));

    if (test_bit(IPOIB_FLAG_ADMIN_CM, &priv->flags))
        return sprintf(buf, "connected\n");
    else
        return sprintf(buf, "datagram\n");
}

static ssize_t set_mode(struct device *d, struct device_attribute *attr,
            const char *buf, size_t count)
{
    struct net_device *dev = to_net_dev(d);
    int ret;

    if (!rtnl_trylock())
        return restart_syscall();

    ret = ipoib_set_mode(dev, buf);

    rtnl_unlock();

    if (!ret)
        return count;

    return ret;
}

static DEVICE_ATTR(mode, S_IWUSR | S_IRUGO, show_mode, set_mode);

int ipoib_cm_add_mode_attr(struct net_device *dev)
{
    return device_create_file(&dev->dev, &dev_attr_mode);
}

static void ipoib_cm_create_srq(struct net_device *dev, int max_sge)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    struct ib_srq_init_attr srq_init_attr = {
        .srq_type = IB_SRQT_BASIC,
        .attr = {
            .max_wr  = ipoib_recvq_size,
            .max_sge = max_sge
        }
    };

    priv->cm.srq = ib_create_srq(priv->pd, &srq_init_attr);
    if (IS_ERR(priv->cm.srq)) {
        if (PTR_ERR(priv->cm.srq) != -ENOSYS)
            printk(KERN_WARNING "%s: failed to allocate SRQ, error %ld\n",
                   priv->ca->name, PTR_ERR(priv->cm.srq));
        priv->cm.srq = NULL;
        return;
    }

    priv->cm.srq_ring = vzalloc(ipoib_recvq_size * sizeof *priv->cm.srq_ring);
    if (!priv->cm.srq_ring) {
        printk(KERN_WARNING "%s: failed to allocate CM SRQ ring (%d entries)\n",
               priv->ca->name, ipoib_recvq_size);
        ib_destroy_srq(priv->cm.srq);
        priv->cm.srq = NULL;
        return;
    }

}

int ipoib_cm_dev_init(struct net_device *dev)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    int i, ret;
    struct ib_device_attr attr;

    INIT_LIST_HEAD(&priv->cm.passive_ids);
    INIT_LIST_HEAD(&priv->cm.reap_list);
    INIT_LIST_HEAD(&priv->cm.start_list);
    INIT_LIST_HEAD(&priv->cm.rx_error_list);
    INIT_LIST_HEAD(&priv->cm.rx_flush_list);
    INIT_LIST_HEAD(&priv->cm.rx_drain_list);
    INIT_LIST_HEAD(&priv->cm.rx_reap_list);
    INIT_WORK(&priv->cm.start_task, ipoib_cm_tx_start);
    INIT_WORK(&priv->cm.reap_task, ipoib_cm_tx_reap);
    INIT_WORK(&priv->cm.skb_task, ipoib_cm_skb_reap);
    INIT_WORK(&priv->cm.rx_reap_task, ipoib_cm_rx_reap);
    INIT_DELAYED_WORK(&priv->cm.stale_task, ipoib_cm_stale_task);

    skb_queue_head_init(&priv->cm.skb_queue);

    ret = ib_query_device(priv->ca, &attr);
    if (ret) {
        printk(KERN_WARNING "ib_query_device() failed with %d\n", ret);
        return ret;
    }

    ipoib_dbg(priv, "max_srq_sge=%d\n", attr.max_srq_sge);

    attr.max_srq_sge = min_t(int, IPOIB_CM_RX_SG, attr.max_srq_sge);
    ipoib_cm_create_srq(dev, attr.max_srq_sge);
    if (ipoib_cm_has_srq(dev)) {
        priv->cm.max_cm_mtu = attr.max_srq_sge * PAGE_SIZE - 0x10;
        priv->cm.num_frags  = attr.max_srq_sge;
        ipoib_dbg(priv, "max_cm_mtu = 0x%x, num_frags=%d\n",
              priv->cm.max_cm_mtu, priv->cm.num_frags);
    } else {
        priv->cm.max_cm_mtu = IPOIB_CM_MTU;
        priv->cm.num_frags  = IPOIB_CM_RX_SG;
    }

    ipoib_cm_init_rx_wr(dev, &priv->cm.rx_wr, priv->cm.rx_sge);

    if (ipoib_cm_has_srq(dev)) {
        for (i = 0; i < ipoib_recvq_size; ++i) {
            if (!ipoib_cm_alloc_rx_skb(dev, priv->cm.srq_ring, i,
                           priv->cm.num_frags - 1,
                           priv->cm.srq_ring[i].mapping)) {
                ipoib_warn(priv, "failed to allocate "
                       "receive buffer %d\n", i);
                ipoib_cm_dev_cleanup(dev);
                return -ENOMEM;
            }

            if (ipoib_cm_post_receive_srq(dev, i)) {
                ipoib_warn(priv, "ipoib_cm_post_receive_srq "
                       "failed for buf %d\n", i);
                ipoib_cm_dev_cleanup(dev);
                return -EIO;
            }
        }
    }

    priv->dev->dev_addr[0] = IPOIB_FLAGS_RC;
    return 0;
}

void ipoib_cm_dev_cleanup(struct net_device *dev)
{
    struct ipoib_dev_priv *priv = netdev_priv(dev);
    int ret;

    if (!priv->cm.srq)
        return;

    ipoib_dbg(priv, "Cleanup ipoib connected mode.\n");

    ret = ib_destroy_srq(priv->cm.srq);
    if (ret)
        ipoib_warn(priv, "ib_destroy_srq failed: %d\n", ret);

    priv->cm.srq = NULL;
    if (!priv->cm.srq_ring)
        return;

    ipoib_cm_free_rx_ring(dev, priv->cm.srq_ring);
    priv->cm.srq_ring = NULL;
}