Merge remote-tracking branch 'origin/master'

[unleashed/lotheac.git] / usr / src / uts / common / io / ib / clients / rdsv3 / ib_recv.c

/*
 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*
 * This file contains code imported from the OFED rds source file ib_recv.c
 * Oracle elects to have and use the contents of ib_recv.c under and governed
 * by the OpenIB.org BSD license (see below for full license text). However,
 * the following notice accompanied the original version of this file:
 */

/*
 * Copyright (c) 2006 Oracle.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */
#include <sys/types.h>
#include <sys/kmem.h>
#include <sys/cpuvar.h>
#include <sys/rds.h>
#include <sys/containerof.h>

#include <sys/ib/clients/rdsv3/rdsv3.h>
#include <sys/ib/clients/rdsv3/ib.h>
#include <sys/ib/clients/rdsv3/rdsv3_debug.h>

static struct kmem_cache *rdsv3_ib_incoming_slab;
static atomic_t rdsv3_ib_allocation = ATOMIC_INIT(0);

void
rdsv3_ib_recv_init_ring(struct rdsv3_ib_connection *ic)
{
        struct rdsv3_ib_recv_work *recv;
        struct rdsv3_header *hdrp;
        uint32_t i;

        RDSV3_DPRINTF4("rdsv3_ib_recv_init_ring", "ic: %p", ic);

        hdrp = ic->i_recv_hdrs;
        for (i = 0, recv = ic->i_recvs; i < ic->i_recv_ring.w_nr; i++, recv++) {
                recv->r_ibinc = NULL;
                recv->r_frag = NULL;

                /* initialize the hdr sgl permanently */
                recv->r_sge[0].ds_va = (ib_vaddr_t)(uintptr_t)hdrp++;
                recv->r_sge[0].ds_len = sizeof (struct rdsv3_header);
                recv->r_sge[0].ds_key = ic->i_mr->lkey;
        }
}

static void
rdsv3_ib_recv_clear_one(struct rdsv3_ib_connection *ic,
    struct rdsv3_ib_recv_work *recv)
{
        RDSV3_DPRINTF4("rdsv3_ib_recv_clear_one", "ic: %p, recv: %p",
            ic, recv);

        if (recv->r_ibinc) {
                rdsv3_inc_put(&recv->r_ibinc->ii_inc);
                recv->r_ibinc = NULL;
        }

        if (recv->r_frag) {
                kmem_cache_free(ic->rds_ibdev->ib_frag_slab, recv->r_frag);
                recv->r_frag = NULL;
        }

        RDSV3_DPRINTF4("rdsv3_ib_recv_clear_one", "Return: ic: %p, recv: %p",
            ic, recv);
}

void
rdsv3_ib_recv_clear_ring(struct rdsv3_ib_connection *ic)
{
        uint32_t i;

        RDSV3_DPRINTF4("rdsv3_ib_recv_clear_ring", "ic: %p", ic);

        for (i = 0; i < ic->i_recv_ring.w_nr; i++)
                rdsv3_ib_recv_clear_one(ic, &ic->i_recvs[i]);
}

extern int atomic_add_unless(atomic_t *, uint_t, ulong_t);

static int
rdsv3_ib_recv_refill_one(struct rdsv3_connection *conn,
    struct rdsv3_ib_recv_work *recv)
{
        struct rdsv3_ib_connection *ic = conn->c_transport_data;
        ibt_mi_hdl_t mi_hdl;
        ibt_iov_attr_t iov_attr;
        ibt_iov_t iov_arr[1];

        RDSV3_DPRINTF5("rdsv3_ib_recv_refill_one", "conn: %p, recv: %p",
            conn, recv);

        if (!recv->r_ibinc) {
                if (!atomic_add_unless(&rdsv3_ib_allocation, 1,
                    ic->i_max_recv_alloc)) {
                        rdsv3_ib_stats_inc(s_ib_rx_alloc_limit);
                        goto out;
                }
                recv->r_ibinc = kmem_cache_alloc(rdsv3_ib_incoming_slab,
                    KM_NOSLEEP);
                if (recv->r_ibinc == NULL) {
                        atomic_dec_32(&rdsv3_ib_allocation);
                        goto out;
                }
                rdsv3_inc_init(&recv->r_ibinc->ii_inc, conn, conn->c_faddr);
                recv->r_ibinc->ii_ibdev = ic->rds_ibdev;
                recv->r_ibinc->ii_pool = ic->rds_ibdev->inc_pool;
        }

        if (!recv->r_frag) {
                recv->r_frag = kmem_cache_alloc(ic->rds_ibdev->ib_frag_slab,
                    KM_NOSLEEP);
                if (!recv->r_frag)
                        goto out;
        }

        /* Data sge, structure copy */
        recv->r_sge[1] = recv->r_frag->f_sge;

        RDSV3_DPRINTF5("rdsv3_ib_recv_refill_one", "Return: conn: %p, recv: %p",
            conn, recv);

        return (0);
out:
        if (recv->r_ibinc) {
                kmem_cache_free(rdsv3_ib_incoming_slab, recv->r_ibinc);
                atomic_dec_32(&rdsv3_ib_allocation);
                recv->r_ibinc = NULL;
        }
        return (-ENOMEM);
}

/*
 * This tries to allocate and post unused work requests after making sure that
 * they have all the allocations they need to queue received fragments into
 * sockets.  The i_recv_mutex is held here so that ring_alloc and _unalloc
 * pairs don't go unmatched.
 *
 * -1 is returned if posting fails due to temporary resource exhaustion.
 */
int
rdsv3_ib_recv_refill(struct rdsv3_connection *conn, int prefill)
{
        struct rdsv3_ib_connection *ic = conn->c_transport_data;
        struct rdsv3_ib_recv_work *recv;
        unsigned int posted = 0;
        int ret = 0, avail;
        uint32_t pos, i;

        RDSV3_DPRINTF4("rdsv3_ib_recv_refill", "conn: %p, prefill: %d",
            conn, prefill);

        if (prefill || rdsv3_conn_up(conn)) {
                uint_t w_nr = ic->i_recv_ring.w_nr;

                avail = rdsv3_ib_ring_alloc(&ic->i_recv_ring, w_nr, &pos);
                if ((avail <= 0) || (pos >= w_nr)) {
                        RDSV3_DPRINTF2("rdsv3_ib_recv_refill",
                            "Argh - ring alloc returned pos=%u, avail: %d",
                            pos, avail);
                        return (-EINVAL);
                }

                /* populate the WRs */
                for (i = 0; i < avail; i++) {
                        recv = &ic->i_recvs[pos];
                        ret = rdsv3_ib_recv_refill_one(conn, recv);
                        if (ret) {
                                rdsv3_ib_ring_unalloc(&ic->i_recv_ring,
                                    avail - i);
                                break;
                        }
                        ic->i_recv_wrs[i].wr_id = (ibt_wrid_t)pos;
                        ic->i_recv_wrs[i].wr_nds = RDSV3_IB_RECV_SGE;
                        ic->i_recv_wrs[i].wr_sgl = &recv->r_sge[0];

                        pos = (pos + 1) % w_nr;
                }

                if (i) {
                        /* post the WRs at one shot */
                        ret = ibt_post_recv(ib_get_ibt_channel_hdl(ic->i_cm_id),
                            &ic->i_recv_wrs[0], i, &posted);
                        RDSV3_DPRINTF3("rdsv3_ib_recv_refill",
                            "attempted: %d posted: %d WRs ret %d",
                            i, posted, ret);
                        if (ret) {
                                RDSV3_DPRINTF2("rdsv3_ib_recv_refill",
                                    "disconnecting and reconnecting\n",
                                    NIPQUAD(conn->c_faddr), ret);
                                rdsv3_ib_ring_unalloc(&ic->i_recv_ring,
                                    i - posted);
                                rdsv3_conn_drop(conn);
                        }
                }
        }

        /* We're doing flow control - update the window. */
        if (ic->i_flowctl && posted)
                rdsv3_ib_advertise_credits(conn, posted);

        RDSV3_DPRINTF4("rdsv3_ib_recv_refill", "Return: conn: %p, posted: %d",
            conn, posted);
        return (ret);
}

/*
 * delayed freed incoming's
 */
struct rdsv3_inc_pool {
        list_t                  f_list; /* list of freed incoming */
        kmutex_t                f_lock; /* lock of fmr pool */
        int32_t                 f_listcnt;
};

void
rdsv3_ib_destroy_inc_pool(struct rdsv3_ib_device *rds_ibdev)
{
        struct rdsv3_inc_pool *pool = rds_ibdev->inc_pool;

        if (pool) {
                list_destroy(&pool->f_list);
                kmem_free((void *) pool, sizeof (*pool));
        }
}

int
rdsv3_ib_create_inc_pool(struct rdsv3_ib_device *rds_ibdev)
{
        struct rdsv3_inc_pool *pool;

        pool = kmem_zalloc(sizeof (*pool), KM_NOSLEEP);
        if (pool == NULL) {
                return (-ENOMEM);
        }
        list_create(&pool->f_list, sizeof (struct rdsv3_ib_incoming),
            offsetof(struct rdsv3_ib_incoming, ii_obj));
        mutex_init(&pool->f_lock, NULL, MUTEX_DRIVER, NULL);
        rds_ibdev->inc_pool = pool;
        return (0);
}

static void
rdsv3_ib_inc_drop(struct rdsv3_ib_incoming *ibinc)
{
        struct rdsv3_page_frag *frag;
        struct rdsv3_page_frag *pos;

        RDSV3_FOR_EACH_LIST_NODE_SAFE(frag, pos, &ibinc->ii_frags, f_item) {
                list_remove_node(&frag->f_item);
                kmem_cache_free(ibinc->ii_ibdev->ib_frag_slab, frag);
        }

        ASSERT(list_is_empty(&ibinc->ii_frags));
        kmem_cache_free(rdsv3_ib_incoming_slab, ibinc);
        atomic_dec_uint(&rdsv3_ib_allocation);
}

void
rdsv3_ib_drain_inclist(void *data)
{
        struct rdsv3_inc_pool *pool = (struct rdsv3_inc_pool *)data;
        struct rdsv3_ib_incoming *ibinc;
        list_t *listp = &pool->f_list;
        kmutex_t *lockp = &pool->f_lock;
        int i = 0;

        for (;;) {
                mutex_enter(lockp);
                ibinc = (struct rdsv3_ib_incoming *)list_remove_head(listp);
                if (ibinc)
                        pool->f_listcnt--;
                mutex_exit(lockp);
                if (!ibinc)
                        break;
                i++;
                rdsv3_ib_inc_drop(ibinc);
        }
}

void
rdsv3_ib_inc_free(struct rdsv3_incoming *inc)
{
        struct rdsv3_ib_incoming *ibinc;
        rdsv3_af_thr_t *af_thr;

        RDSV3_DPRINTF4("rdsv3_ib_inc_free", "inc: %p", inc);

        ibinc = __containerof(inc, struct rdsv3_ib_incoming, ii_inc);
        /* save af_thr in a local as ib_inc might be freed at mutex_exit */
        af_thr = ibinc->ii_ibdev->inc_soft_cq;

        mutex_enter(&ibinc->ii_pool->f_lock);
        list_insert_tail(&ibinc->ii_pool->f_list, ibinc);
        ibinc->ii_pool->f_listcnt++;
        mutex_exit(&ibinc->ii_pool->f_lock);

        rdsv3_af_thr_fire(af_thr);
}

int
rdsv3_ib_inc_copy_to_user(struct rdsv3_incoming *inc, uio_t *uiop,
    size_t size)
{
        struct rdsv3_ib_incoming *ibinc;
        struct rdsv3_page_frag *frag;
        unsigned long to_copy;
        unsigned long frag_off = 0;
        int copied = 0;
        int ret;
        uint32_t len;

        ibinc = __containerof(inc, struct rdsv3_ib_incoming, ii_inc);
        frag = list_head(&ibinc->ii_frags);
        len = ntohl(inc->i_hdr.h_len);

        RDSV3_DPRINTF4("rdsv3_ib_inc_copy_to_user", "inc: %p, size: %d len: %d",
            inc, size, len);

        while (copied < size && copied < len) {
                if (frag_off == RDSV3_FRAG_SIZE) {
                        frag = list_next(&ibinc->ii_frags, frag);
                        frag_off = 0;
                }

                to_copy = min(len - copied, RDSV3_FRAG_SIZE - frag_off);
                to_copy = min(size - copied, to_copy);

                RDSV3_DPRINTF5("rdsv3_ib_inc_copy_to_user",
                    "%lu bytes to user %p from frag [%p, %u] + %lu",
                    to_copy, uiop,
                    frag->f_page, frag->f_offset, frag_off);

                ret = uiomove((caddr_t)(frag->f_page +
                    frag->f_offset + frag_off),
                    to_copy, UIO_READ, uiop);
                if (ret) {
                        RDSV3_DPRINTF2("rdsv3_ib_inc_copy_to_user",
                            "uiomove (%d) returned: %d", to_copy, ret);
                        break;
                }

                frag_off += to_copy;
                copied += to_copy;
        }

        RDSV3_DPRINTF4("rdsv3_ib_inc_copy_to_user",
            "Return: inc: %p, copied: %d", inc, copied);

        return (copied);
}

/* ic starts out kmem_zalloc()ed */
void
rdsv3_ib_recv_init_ack(struct rdsv3_ib_connection *ic)
{
        ibt_send_wr_t *wr = &ic->i_ack_wr;
        ibt_wr_ds_t *sge = &ic->i_ack_sge;

        RDSV3_DPRINTF4("rdsv3_ib_recv_init_ack", "ic: %p", ic);

        sge->ds_va = ic->i_ack_dma;
        sge->ds_len = sizeof (struct rdsv3_header);
        sge->ds_key = ic->i_mr->lkey;

        wr->wr_sgl = sge;
        wr->wr_nds = 1;
        wr->wr_opcode = IBT_WRC_SEND;
        wr->wr_id = RDSV3_IB_ACK_WR_ID;
        wr->wr_flags = IBT_WR_SEND_SIGNAL | IBT_WR_SEND_SOLICIT;
}

/*
 * You'd think that with reliable IB connections you wouldn't need to ack
 * messages that have been received.  The problem is that IB hardware generates
 * an ack message before it has DMAed the message into memory.  This creates a
 * potential message loss if the HCA is disabled for any reason between when it
 * sends the ack and before the message is DMAed and processed.  This is only a
 * potential issue if another HCA is available for fail-over.
 *
 * When the remote host receives our ack they'll free the sent message from
 * their send queue.  To decrease the latency of this we always send an ack
 * immediately after we've received messages.
 *
 * For simplicity, we only have one ack in flight at a time.  This puts
 * pressure on senders to have deep enough send queues to absorb the latency of
 * a single ack frame being in flight.  This might not be good enough.
 *
 * This is implemented by have a long-lived send_wr and sge which point to a
 * statically allocated ack frame.  This ack wr does not fall under the ring
 * accounting that the tx and rx wrs do.  The QP attribute specifically makes
 * room for it beyond the ring size.  Send completion notices its special
 * wr_id and avoids working with the ring in that case.
 */
void
rdsv3_ib_set_ack(struct rdsv3_ib_connection *ic, uint64_t seq,
    int ack_required)
{
        RDSV3_DPRINTF4("rdsv3_ib_set_ack", "ic: %p, seq: %lld ack: %d",
            ic, seq, ack_required);

        mutex_enter(&ic->i_ack_lock);
        ic->i_ack_next = seq;
        if (ack_required)
                set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
        mutex_exit(&ic->i_ack_lock);
}

static uint64_t
rdsv3_ib_get_ack(struct rdsv3_ib_connection *ic)
{
        uint64_t seq;

        RDSV3_DPRINTF4("rdsv3_ib_get_ack", "ic: %p", ic);

        clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);

        mutex_enter(&ic->i_ack_lock);
        seq = ic->i_ack_next;
        mutex_exit(&ic->i_ack_lock);

        return (seq);
}

static void
rdsv3_ib_send_ack(struct rdsv3_ib_connection *ic, unsigned int adv_credits)
{
        struct rdsv3_header *hdr = ic->i_ack;
        uint64_t seq;
        int ret;

        RDSV3_DPRINTF4("rdsv3_ib_send_ack", "ic: %p adv_credits: %d",
            ic, adv_credits);

        seq = rdsv3_ib_get_ack(ic);

        RDSV3_DPRINTF4("rdsv3_ib_send_ack", "send_ack: ic %p ack %llu",
            ic, (unsigned long long) seq);
        rdsv3_message_populate_header(hdr, 0, 0, 0);
        hdr->h_ack = htonll(seq);
        hdr->h_credit = adv_credits;
        rdsv3_message_make_checksum(hdr);
        ic->i_ack_queued = jiffies;

        ret = ibt_post_send(RDSV3_QP2CHANHDL(ic->i_cm_id->qp), &ic->i_ack_wr, 1,
            NULL);
        if (ret) {
                /*
                 * Failed to send. Release the WR, and
                 * force another ACK.
                 */
                clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
                set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
                rdsv3_ib_stats_inc(s_ib_ack_send_failure);
                RDSV3_DPRINTF2("rdsv3_ib_send_ack", "sending ack failed\n");
                rdsv3_conn_drop(ic->conn);
        } else {
                rdsv3_ib_stats_inc(s_ib_ack_sent);
        }
        RDSV3_DPRINTF4("rdsv3_ib_send_ack", "Return: ic: %p adv_credits: %d",
            ic, adv_credits);
}

/*
 * There are 3 ways of getting acknowledgements to the peer:
 *  1.  We call rdsv3_ib_attempt_ack from the recv completion handler
 *      to send an ACK-only frame.
 *      However, there can be only one such frame in the send queue
 *      at any time, so we may have to postpone it.
 *  2.  When another (data) packet is transmitted while there's
 *      an ACK in the queue, we piggyback the ACK sequence number
 *      on the data packet.
 *  3.  If the ACK WR is done sending, we get called from the
 *      send queue completion handler, and check whether there's
 *      another ACK pending (postponed because the WR was on the
 *      queue). If so, we transmit it.
 *
 * We maintain 2 variables:
 *  -   i_ack_flags, which keeps track of whether the ACK WR
 *      is currently in the send queue or not (IB_ACK_IN_FLIGHT)
 *  -   i_ack_next, which is the last sequence number we received
 *
 * Potentially, send queue and receive queue handlers can run concurrently.
 * It would be nice to not have to use a spinlock to synchronize things,
 * but the one problem that rules this out is that 64bit updates are
 * not atomic on all platforms. Things would be a lot simpler if
 * we had atomic64 or maybe cmpxchg64 everywhere.
 *
 * Reconnecting complicates this picture just slightly. When we
 * reconnect, we may be seeing duplicate packets. The peer
 * is retransmitting them, because it hasn't seen an ACK for
 * them. It is important that we ACK these.
 *
 * ACK mitigation adds a header flag "ACK_REQUIRED"; any packet with
 * this flag set *MUST* be acknowledged immediately.
 */

/*
 * When we get here, we're called from the recv queue handler.
 * Check whether we ought to transmit an ACK.
 */
void
rdsv3_ib_attempt_ack(struct rdsv3_ib_connection *ic)
{
        unsigned int adv_credits;

        RDSV3_DPRINTF4("rdsv3_ib_attempt_ack", "ic: %p", ic);

        if (!test_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
                return;

        if (test_and_set_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags)) {
                rdsv3_ib_stats_inc(s_ib_ack_send_delayed);
                return;
        }

        /* Can we get a send credit? */
        if (!rdsv3_ib_send_grab_credits(ic, 1, &adv_credits, 0)) {
                rdsv3_ib_stats_inc(s_ib_tx_throttle);
                clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
                return;
        }

        clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
        rdsv3_ib_send_ack(ic, adv_credits);

        RDSV3_DPRINTF4("rdsv3_ib_attempt_ack", "Return: ic: %p", ic);
}

/*
 * We get here from the send completion handler, when the
 * adapter tells us the ACK frame was sent.
 */
void
rdsv3_ib_ack_send_complete(struct rdsv3_ib_connection *ic)
{
        RDSV3_DPRINTF4("rdsv3_ib_ack_send_complete", "ic: %p", ic);
        clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
        rdsv3_ib_attempt_ack(ic);
}

/*
 * This is called by the regular xmit code when it wants to piggyback
 * an ACK on an outgoing frame.
 */
uint64_t
rdsv3_ib_piggyb_ack(struct rdsv3_ib_connection *ic)
{
        RDSV3_DPRINTF4("rdsv3_ib_piggyb_ack", "ic: %p", ic);
        if (test_and_clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags)) {
                rdsv3_ib_stats_inc(s_ib_ack_send_piggybacked);
        }
        return (rdsv3_ib_get_ack(ic));
}

/*
 * It's kind of lame that we're copying from the posted receive pages into
 * long-lived bitmaps.  We could have posted the bitmaps and rdma written into
 * them.  But receiving new congestion bitmaps should be a *rare* event, so
 * hopefully we won't need to invest that complexity in making it more
 * efficient.  By copying we can share a simpler core with TCP which has to
 * copy.
 */
static void
rdsv3_ib_cong_recv(struct rdsv3_connection *conn,
    struct rdsv3_ib_incoming *ibinc)
{
        struct rdsv3_cong_map *map;
        unsigned int map_off;
        unsigned int map_page;
        struct rdsv3_page_frag *frag;
        unsigned long frag_off;
        unsigned long to_copy;
        unsigned long copied;
        uint64_t uncongested = 0;
        caddr_t addr;

        RDSV3_DPRINTF4("rdsv3_ib_cong_recv", "conn: %p, ibinc: %p",
            conn, ibinc);

        /* catch completely corrupt packets */
        if (ntohl(ibinc->ii_inc.i_hdr.h_len) != RDSV3_CONG_MAP_BYTES)
                return;

        map = conn->c_fcong;
        map_page = 0;
        map_off = 0;

        frag = list_head(&ibinc->ii_frags);
        frag_off = 0;

        copied = 0;

        while (copied < RDSV3_CONG_MAP_BYTES) {
                uint64_t *src, *dst;
                unsigned int k;

                to_copy = min(RDSV3_FRAG_SIZE - frag_off, PAGE_SIZE - map_off);
                ASSERT(!(to_copy & 7)); /* Must be 64bit aligned. */

                addr = frag->f_page + frag->f_offset;

                src = (uint64_t *)(addr + frag_off);
                dst = (uint64_t *)(map->m_page_addrs[map_page] + map_off);
                RDSV3_DPRINTF4("rdsv3_ib_cong_recv",
                    "src: %p dst: %p copied: %d", src, dst, copied);
                for (k = 0; k < to_copy; k += 8) {
                        /*
                         * Record ports that became uncongested, ie
                         * bits that changed from 0 to 1.
                         */
                        uncongested |= ~(*src) & *dst;
                        *dst++ = *src++;
                }

                copied += to_copy;
                RDSV3_DPRINTF4("rdsv3_ib_cong_recv",
                    "src: %p dst: %p copied: %d", src, dst, copied);

                map_off += to_copy;
                if (map_off == PAGE_SIZE) {
                        map_off = 0;
                        map_page++;
                }

                frag_off += to_copy;
                if (frag_off == RDSV3_FRAG_SIZE) {
                        frag = list_next(&ibinc->ii_frags, frag);
                        frag_off = 0;
                }
        }

#if 0
XXX
        /* the congestion map is in little endian order */
        uncongested = le64_to_cpu(uncongested);
#endif

        rdsv3_cong_map_updated(map, uncongested);

        RDSV3_DPRINTF4("rdsv3_ib_cong_recv", "Return: conn: %p, ibinc: %p",
            conn, ibinc);
}

static void
rdsv3_ib_process_recv(struct rdsv3_connection *conn,
    struct rdsv3_ib_recv_work *recv, uint32_t data_len,
    struct rdsv3_ib_ack_state *state)
{
        struct rdsv3_ib_connection *ic = conn->c_transport_data;
        struct rdsv3_ib_incoming *ibinc = ic->i_ibinc;
        struct rdsv3_header *ihdr, *hdr;

        /* XXX shut down the connection if port 0,0 are seen? */

        RDSV3_DPRINTF5("rdsv3_ib_process_recv",
            "ic %p ibinc %p recv %p byte len %u", ic, ibinc, recv, data_len);

        if (data_len < sizeof (struct rdsv3_header)) {
                RDSV3_DPRINTF2("rdsv3_ib_process_recv",
                    "incoming message from %u.%u.%u.%u didn't include a "
                    "header, disconnecting and reconnecting",
                    NIPQUAD(conn->c_faddr));
                rdsv3_conn_drop(conn);
                return;
        }
        data_len -= sizeof (struct rdsv3_header);

        ihdr = &ic->i_recv_hdrs[recv - ic->i_recvs];

        /* Validate the checksum. */
        if (!rdsv3_message_verify_checksum(ihdr)) {
                RDSV3_DPRINTF2("rdsv3_ib_process_recv", "incoming message "
                    "from %u.%u.%u.%u has corrupted header - "
                    "forcing a reconnect",
                    NIPQUAD(conn->c_faddr));
                rdsv3_conn_drop(conn);
                rdsv3_stats_inc(s_recv_drop_bad_checksum);
                return;
        }

        /* Process the ACK sequence which comes with every packet */
        state->ack_recv = ntohll(ihdr->h_ack);
        state->ack_recv_valid = 1;

        /* Process the credits update if there was one */
        if (ihdr->h_credit)
                rdsv3_ib_send_add_credits(conn, ihdr->h_credit);

        if (ihdr->h_sport == 0 && ihdr->h_dport == 0 && data_len == 0) {
                /*
                 * This is an ACK-only packet. The fact that it gets
                 * special treatment here is that historically, ACKs
                 * were rather special beasts.
                 */
                rdsv3_ib_stats_inc(s_ib_ack_received);
                return;
        }

        /*
         * If we don't already have an inc on the connection then this
         * fragment has a header and starts a message.. copy its header
         * into the inc and save the inc so we can hang upcoming fragments
         * off its list.
         */
        if (!ibinc) {
                ibinc = recv->r_ibinc;
                recv->r_ibinc = NULL;
                ic->i_ibinc = ibinc;

                hdr = &ibinc->ii_inc.i_hdr;
                (void) memcpy(hdr, ihdr, sizeof (*hdr));
                ic->i_recv_data_rem = ntohl(hdr->h_len);

                RDSV3_DPRINTF5("rdsv3_ib_process_recv",
                    "ic %p ibinc %p rem %u flag 0x%x", ic, ibinc,
                    ic->i_recv_data_rem, hdr->h_flags);
        } else {
                hdr = &ibinc->ii_inc.i_hdr;
                /*
                 * We can't just use memcmp here; fragments of a
                 * single message may carry different ACKs
                 */
                if (hdr->h_sequence != ihdr->h_sequence ||
                    hdr->h_len != ihdr->h_len ||
                    hdr->h_sport != ihdr->h_sport ||
                    hdr->h_dport != ihdr->h_dport) {
                        RDSV3_DPRINTF2("rdsv3_ib_process_recv",
                            "fragment header mismatch; forcing reconnect");
                        rdsv3_conn_drop(conn);
                        return;
                }
        }

        list_insert_tail(&ibinc->ii_frags, recv->r_frag);
        recv->r_frag = NULL;

        if (ic->i_recv_data_rem > RDSV3_FRAG_SIZE)
                ic->i_recv_data_rem -= RDSV3_FRAG_SIZE;
        else {
                ic->i_recv_data_rem = 0;
                ic->i_ibinc = NULL;

                if (ibinc->ii_inc.i_hdr.h_flags == RDSV3_FLAG_CONG_BITMAP)
                        rdsv3_ib_cong_recv(conn, ibinc);
                else {
                        rdsv3_recv_incoming(conn, conn->c_faddr, conn->c_laddr,
                            &ibinc->ii_inc, KM_NOSLEEP);
                        state->ack_next = ntohll(hdr->h_sequence);
                        state->ack_next_valid = 1;
                }

                /*
                 * Evaluate the ACK_REQUIRED flag *after* we received
                 * the complete frame, and after bumping the next_rx
                 * sequence.
                 */
                if (hdr->h_flags & RDSV3_FLAG_ACK_REQUIRED) {
                        rdsv3_stats_inc(s_recv_ack_required);
                        state->ack_required = 1;
                }

                rdsv3_inc_put(&ibinc->ii_inc);
        }

        RDSV3_DPRINTF4("rdsv3_ib_process_recv",
            "Return: conn: %p recv: %p len: %d state: %p",
            conn, recv, data_len, state);
}

void
rdsv3_ib_recv_cqe_handler(struct rdsv3_ib_connection *ic, ibt_wc_t *wc,
    struct rdsv3_ib_ack_state *state)
{
        struct rdsv3_connection *conn = ic->conn;
        struct rdsv3_ib_recv_work *recv;
        struct rdsv3_ib_work_ring *recv_ringp = &ic->i_recv_ring;

        RDSV3_DPRINTF4("rdsv3_ib_recv_cqe_handler",
            "rwc wc_id 0x%llx status %u byte_len %u imm_data %u\n",
            (unsigned long long)wc->wc_id, wc->wc_status,
            wc->wc_bytes_xfer, ntohl(wc->wc_immed_data));

        rdsv3_ib_stats_inc(s_ib_rx_cq_event);

        recv = &ic->i_recvs[rdsv3_ib_ring_oldest(recv_ringp)];

        /*
         * Also process recvs in connecting state because it is possible
         * to get a recv completion _before_ the rdmacm ESTABLISHED
         * event is processed.
         */
        if (rdsv3_conn_up(conn) || rdsv3_conn_connecting(conn)) {
                /* We expect errors as the qp is drained during shutdown */
                if (wc->wc_status == IBT_WC_SUCCESS) {
                        rdsv3_ib_process_recv(conn, recv,
                            wc->wc_bytes_xfer, state);
                } else {
                        RDSV3_DPRINTF2("rdsv3_ib_recv_cqe_handler",
                            "recv completion on "
                            "%u.%u.%u.%u had status %u, "
                            "disconnecting and reconnecting\n",
                            NIPQUAD(conn->c_faddr),
                            wc->wc_status);
                        rdsv3_conn_drop(conn);
                }
        }

        rdsv3_ib_ring_free(recv_ringp, 1);

        /*
         * If we ever end up with a really empty receive ring, we're
         * in deep trouble, as the sender will definitely see RNR
         * timeouts.
         */
        if (rdsv3_ib_ring_empty(recv_ringp))
                rdsv3_ib_stats_inc(s_ib_rx_ring_empty);

        if (rdsv3_ib_ring_low(recv_ringp)) {
                rdsv3_af_thr_fire(ic->i_refill_rq);
        }
}

int
rdsv3_ib_recv(struct rdsv3_connection *conn)
{
        struct rdsv3_ib_connection *ic = conn->c_transport_data;
        int ret = 0;

        RDSV3_DPRINTF4("rdsv3_ib_recv", "conn %p\n", conn);

        if (rdsv3_conn_up(conn))
                rdsv3_ib_attempt_ack(ic);

        RDSV3_DPRINTF4("rdsv3_ib_recv", "Return: conn: %p", conn);

        return (ret);
}

extern int rdsv3_ib_inc_constructor(void *buf, void *arg, int kmflags);
extern void rdsv3_ib_inc_destructor(void *buf, void *arg);

int
rdsv3_ib_recv_init(void)
{
        RDSV3_DPRINTF4("rdsv3_ib_recv_init", "Enter");

        rdsv3_ib_incoming_slab = kmem_cache_create("rdsv3_ib_incoming",
            sizeof (struct rdsv3_ib_incoming), 0, rdsv3_ib_inc_constructor,
            rdsv3_ib_inc_destructor, NULL, NULL, NULL, 0);
        if (!rdsv3_ib_incoming_slab) {
                RDSV3_DPRINTF2("rdsv3_ib_recv_init", "kmem_cache_create "
                    "failed");
                return (-ENOMEM);
        }

        RDSV3_DPRINTF4("rdsv3_ib_recv_init", "Return");
        return (0);
}

void
rdsv3_ib_recv_exit(void)
{
        RDSV3_DPRINTF4("rdsv3_ib_recv_exit", "Enter");
        kmem_cache_destroy(rdsv3_ib_incoming_slab);
        RDSV3_DPRINTF4("rdsv3_ib_recv_exit", "Return");
}