Merge remote-tracking branches 'asoc/fix/dpcm', 'asoc/fix/imx', 'asoc/fix/msm8916...

[mirror_ubuntu-artful-kernel.git] / drivers / infiniband / ulp / ipoib / ipoib_cm.c

/*
 * 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 <linux/sched/signal.h>
#include <linux/sched/mm.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)

#define IPOIB_CM_RX_RESERVE     (ALIGN(IPOIB_HARD_LEN, 16) - IPOIB_ENCAP_LEN)

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 = {
        .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 = ipoib_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 = ipoib_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],
                                             gfp_t gfp)
{
        struct ipoib_dev_priv *priv = ipoib_priv(dev);
        struct sk_buff *skb;
        int i;

        skb = dev_alloc_skb(ALIGN(IPOIB_CM_HEAD_SIZE + IPOIB_PSEUDO_LEN, 16));
        if (unlikely(!skb))
                return NULL;

        /*
         * IPoIB adds a IPOIB_ENCAP_LEN byte header, this will align the
         * IP header to a multiple of 16.
         */
        skb_reserve(skb, IPOIB_CM_RX_RESERVE);

        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);

                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 = ipoib_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);
        ipoib_cm_rx_drain_wr.wr_id = IPOIB_CM_RX_DRAIN_WRID;
        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 = ipoib_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 = ipoib_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 = ipoib_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 = ipoib_priv(dev);
        int i;

        for (i = 0; i < priv->cm.num_frags; ++i)
                sge[i].lkey = priv->pd->local_dma_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 = ipoib_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)
                return -ENOMEM;

        t = kmalloc(sizeof *t, GFP_KERNEL);
        if (!t) {
                ret = -ENOMEM;
                goto err_free_1;
        }

        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,
                                           GFP_KERNEL)) {
                        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);

err_free_1:
        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 = ipoib_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 = ipoib_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 = prandom_u32() & 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(priv->wq,
                           &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 = ipoib_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 = ipoib_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(priv->wq, &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(priv->wq, &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 + IPOIB_CM_RX_RESERVE);
                if (small_skb) {
                        skb_reserve(small_skb, IPOIB_CM_RX_RESERVE);
                        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, GFP_ATOMIC);
        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_add_pseudo_hdr(skb);

        ++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,
                            struct ipoib_tx_buf *tx_req)
{
        struct ib_send_wr *bad_wr;

        ipoib_build_sge(priv, tx_req);

        priv->tx_wr.wr.wr_id    = wr_id | IPOIB_OP_CM;

        return ib_post_send(tx->qp, &priv->tx_wr.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 = ipoib_priv(dev);
        struct ipoib_tx_buf *tx_req;
        int rc;
        unsigned usable_sge = tx->max_send_sge - !!skb_headlen(skb);

        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;
        }
        if (skb_shinfo(skb)->nr_frags > usable_sge) {
                if (skb_linearize(skb) < 0) {
                        ipoib_warn(priv, "skb could not be linearized\n");
                        ++dev->stats.tx_dropped;
                        ++dev->stats.tx_errors;
                        dev_kfree_skb_any(skb);
                        return;
                }
                /* Does skb_linearize return ok without reducing nr_frags? */
                if (skb_shinfo(skb)->nr_frags > usable_sge) {
                        ipoib_warn(priv, "too many frags after skb linearize\n");
                        ++dev->stats.tx_dropped;
                        ++dev->stats.tx_errors;
                        dev_kfree_skb_any(skb);
                        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;

        if (unlikely(ipoib_dma_map_tx(priv->ca, tx_req))) {
                ++dev->stats.tx_errors;
                dev_kfree_skb_any(skb);
                return;
        }

        skb_orphan(skb);
        skb_dst_drop(skb);

        rc = post_send(priv, tx, tx->tx_head & (ipoib_sendq_size - 1), tx_req);
        if (unlikely(rc)) {
                ipoib_warn(priv, "post_send failed, error %d\n", rc);
                ++dev->stats.tx_errors;
                ipoib_dma_unmap_tx(priv, tx_req);
                dev_kfree_skb_any(skb);
        } else {
                netif_trans_update(dev);
                ++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);
                        netif_stop_queue(dev);
                        rc = ib_req_notify_cq(priv->send_cq,
                                IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
                        if (rc < 0)
                                ipoib_warn(priv, "request notify on send CQ failed\n");
                        else if (rc)
                                ipoib_send_comp_handler(priv->send_cq, dev);
                }
        }
}

void ipoib_cm_handle_tx_wc(struct net_device *dev, struct ib_wc *wc)
{
        struct ipoib_dev_priv *priv = ipoib_priv(dev);
        struct ipoib_cm_tx *tx = wc->qp->qp_context;
        unsigned int wr_id = wc->wr_id & ~IPOIB_OP_CM;
        struct ipoib_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];

        ipoib_dma_unmap_tx(priv, tx_req);

        /* 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;

                if (wc->status != IB_WC_RNR_RETRY_EXC_ERR)
                        ipoib_warn(priv, "failed cm send event (status=%d, wrid=%d vend_err %x)\n",
                                   wc->status, wr_id, wc->vendor_err);
                else
                        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;
                        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(priv->wq, &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 = ipoib_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);
        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 = ipoib_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 = ipoib_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);
                usleep_range(1000, 2000);
                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 = ipoib_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;
                ret = dev_queue_xmit(skb);
                if (ret)
                        ipoib_warn(priv, "%s:dev_queue_xmit failed to re-queue packet, ret:%d\n",
                                   __func__, ret);
        }

        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 = ipoib_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,
                .create_flags           = 0
        };
        struct ib_qp *tx_qp;

        if (dev->features & NETIF_F_SG)
                attr.cap.max_send_sge =
                        min_t(u32, priv->ca->attrs.max_sge, MAX_SKB_FRAGS + 1);

        tx_qp = ib_create_qp(priv->pd, &attr);
        tx->max_send_sge = attr.cap.max_send_sge;
        return tx_qp;
}

static int ipoib_cm_send_req(struct net_device *dev,
                             struct ib_cm_id *id, struct ib_qp *qp,
                             u32 qpn,
                             struct sa_path_rec *pathrec)
{
        struct ipoib_dev_priv *priv = ipoib_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 = ipoib_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 sa_path_rec *pathrec)
{
        struct ipoib_dev_priv *priv = ipoib_priv(p->dev);
        unsigned int noio_flag;
        int ret;

        noio_flag = memalloc_noio_save();
        p->tx_ring = vzalloc(ipoib_sendq_size * sizeof(*p->tx_ring));
        if (!p->tx_ring) {
                ret = -ENOMEM;
                goto err_tx;
        }
        memset(p->tx_ring, 0, ipoib_sendq_size * sizeof *p->tx_ring);

        p->qp = ipoib_cm_create_tx_qp(p->dev, p);
        memalloc_noio_restore(noio_flag);
        if (IS_ERR(p->qp)) {
                ret = PTR_ERR(p->qp);
                ipoib_warn(priv, "failed to create 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_send;
        }

        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_modify_send;
        }

        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_modify_send:
        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 = ipoib_priv(p->dev);
        struct ipoib_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;
                        }

                        usleep_range(1000, 2000);
                }
        }

timeout:

        while ((int) p->tx_tail - (int) p->tx_head < 0) {
                tx_req = &p->tx_ring[p->tx_tail & (ipoib_sendq_size - 1)];
                ipoib_dma_unmap_tx(priv, tx_req);
                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 = ipoib_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;
                        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(priv->wq, &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 = ipoib_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(priv->wq, &priv->cm.start_task);
        return tx;
}

void ipoib_cm_destroy_tx(struct ipoib_cm_tx *tx)
{
        struct ipoib_dev_priv *priv = ipoib_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(priv->wq, &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);
        }
}

#define QPN_AND_OPTIONS_OFFSET  4

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;
        struct ipoib_path *path;
        int ret;

        struct 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);
                /*
                 * As long as the search is with these 2 locks,
                 * path existence indicates its validity.
                 */
                path = __path_find(dev, neigh->daddr + QPN_AND_OPTIONS_OFFSET);
                if (!path) {
                        pr_info("%s ignore not valid path %pI6\n",
                                __func__,
                                neigh->daddr + QPN_AND_OPTIONS_OFFSET);
                        goto free_neigh;
                }
                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) {
free_neigh:
                        neigh = p->neigh;
                        if (neigh) {
                                neigh->cm = NULL;
                                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_init(&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 = ipoib_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(priv->wq, &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(priv->wq,
                                   &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 net_device *dev = to_net_dev(d);
        struct ipoib_dev_priv *priv = ipoib_priv(dev);

        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;
        struct ipoib_dev_priv *priv = ipoib_priv(dev);

        if (test_bit(IPOIB_FLAG_GOING_DOWN, &priv->flags))
                return -EPERM;

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

        ret = ipoib_set_mode(dev, buf);

        /* The assumption is that the function ipoib_set_mode returned
         * with the rtnl held by it, if not the value -EBUSY returned,
         * then no need to rtnl_unlock
         */
        if (ret != -EBUSY)
                rtnl_unlock();

        return (!ret || ret == -EBUSY) ? count : 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 = ipoib_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) {
                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 = ipoib_priv(dev);
        int max_srq_sge, i;

        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);

        ipoib_dbg(priv, "max_srq_sge=%d\n", priv->ca->attrs.max_srq_sge);

        max_srq_sge = min_t(int, IPOIB_CM_RX_SG, priv->ca->attrs.max_srq_sge);
        ipoib_cm_create_srq(dev, max_srq_sge);
        if (ipoib_cm_has_srq(dev)) {
                priv->cm.max_cm_mtu = max_srq_sge * PAGE_SIZE - 0x10;
                priv->cm.num_frags  = 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,
                                                   GFP_KERNEL)) {
                                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 = ipoib_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;
}