/*
 * Copyright(c) 2016 - 2020 Intel Corporation.
 *
 * This file is provided under a dual BSD/GPLv2 license.  When using or
 * redistributing this file, you may do so under either license.
 *
 * GPL LICENSE SUMMARY
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * BSD LICENSE
 *
 * 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.
 *  - Neither the name of Intel Corporation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <linux/hash.h>
#include <linux/bitops.h>
#include <linux/lockdep.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <rdma/ib_verbs.h>
#include <rdma/ib_hdrs.h>
#include <rdma/opa_addr.h>
#include <rdma/uverbs_ioctl.h>
#include "qp.h"
#include "vt.h"
#include "trace.h"

#define RVT_RWQ_COUNT_THRESHOLD 16

static void rvt_rc_timeout(struct timer_list *t);
static void rvt_reset_qp(struct rvt_dev_info *rdi, struct rvt_qp *qp,
                         enum ib_qp_type type);

/*
 * Convert the AETH RNR timeout code into the number of microseconds.
 */
static const u32 ib_rvt_rnr_table[32] = {
        655360, /* 00: 655.36 */
        10,     /* 01:    .01 */
        20,     /* 02     .02 */
        30,     /* 03:    .03 */
        40,     /* 04:    .04 */
        60,     /* 05:    .06 */
        80,     /* 06:    .08 */
        120,    /* 07:    .12 */
        160,    /* 08:    .16 */
        240,    /* 09:    .24 */
        320,    /* 0A:    .32 */
        480,    /* 0B:    .48 */
        640,    /* 0C:    .64 */
        960,    /* 0D:    .96 */
        1280,   /* 0E:   1.28 */
        1920,   /* 0F:   1.92 */
        2560,   /* 10:   2.56 */
        3840,   /* 11:   3.84 */
        5120,   /* 12:   5.12 */
        7680,   /* 13:   7.68 */
        10240,  /* 14:  10.24 */
        15360,  /* 15:  15.36 */
        20480,  /* 16:  20.48 */
        30720,  /* 17:  30.72 */
        40960,  /* 18:  40.96 */
        61440,  /* 19:  61.44 */
        81920,  /* 1A:  81.92 */
        122880, /* 1B: 122.88 */
        163840, /* 1C: 163.84 */
        245760, /* 1D: 245.76 */
        327680, /* 1E: 327.68 */
        491520  /* 1F: 491.52 */
};

/*
 * Note that it is OK to post send work requests in the SQE and ERR
 * states; rvt_do_send() will process them and generate error
 * completions as per IB 1.2 C10-96.
 */
const int ib_rvt_state_ops[IB_QPS_ERR + 1] = {
        [IB_QPS_RESET] = 0,
        [IB_QPS_INIT] = RVT_POST_RECV_OK,
        [IB_QPS_RTR] = RVT_POST_RECV_OK | RVT_PROCESS_RECV_OK,
        [IB_QPS_RTS] = RVT_POST_RECV_OK | RVT_PROCESS_RECV_OK |
            RVT_POST_SEND_OK | RVT_PROCESS_SEND_OK |
            RVT_PROCESS_NEXT_SEND_OK,
        [IB_QPS_SQD] = RVT_POST_RECV_OK | RVT_PROCESS_RECV_OK |
            RVT_POST_SEND_OK | RVT_PROCESS_SEND_OK,
        [IB_QPS_SQE] = RVT_POST_RECV_OK | RVT_PROCESS_RECV_OK |
            RVT_POST_SEND_OK | RVT_FLUSH_SEND,
        [IB_QPS_ERR] = RVT_POST_RECV_OK | RVT_FLUSH_RECV |
            RVT_POST_SEND_OK | RVT_FLUSH_SEND,
};
EXPORT_SYMBOL(ib_rvt_state_ops);

/* platform specific: return the last level cache (llc) size, in KiB */
static int rvt_wss_llc_size(void)
{
        /* assume that the boot CPU value is universal for all CPUs */
        return boot_cpu_data.x86_cache_size;
}

/* platform specific: cacheless copy */
static void cacheless_memcpy(void *dst, void *src, size_t n)
{
        /*
         * Use the only available X64 cacheless copy.  Add a __user cast
         * to quiet sparse.  The src agument is already in the kernel so
         * there are no security issues.  The extra fault recovery machinery
         * is not invoked.
         */
        __copy_user_nocache(dst, (void __user *)src, n, 0);
}

void rvt_wss_exit(struct rvt_dev_info *rdi)
{
        struct rvt_wss *wss = rdi->wss;

        if (!wss)
                return;

        /* coded to handle partially initialized and repeat callers */
        kfree(wss->entries);
        wss->entries = NULL;
        kfree(rdi->wss);
        rdi->wss = NULL;
}

/**
 * rvt_wss_init - Init wss data structures
 *
 * Return: 0 on success
 */
int rvt_wss_init(struct rvt_dev_info *rdi)
{
        unsigned int sge_copy_mode = rdi->dparms.sge_copy_mode;
        unsigned int wss_threshold = rdi->dparms.wss_threshold;
        unsigned int wss_clean_period = rdi->dparms.wss_clean_period;
        long llc_size;
        long llc_bits;
        long table_size;
        long table_bits;
        struct rvt_wss *wss;
        int node = rdi->dparms.node;

        if (sge_copy_mode != RVT_SGE_COPY_ADAPTIVE) {
                rdi->wss = NULL;
                return 0;
        }

        rdi->wss = kzalloc_node(sizeof(*rdi->wss), GFP_KERNEL, node);
        if (!rdi->wss)
                return -ENOMEM;
        wss = rdi->wss;

        /* check for a valid percent range - default to 80 if none or invalid */
        if (wss_threshold < 1 || wss_threshold > 100)
                wss_threshold = 80;

        /* reject a wildly large period */
        if (wss_clean_period > 1000000)
                wss_clean_period = 256;

        /* reject a zero period */
        if (wss_clean_period == 0)
                wss_clean_period = 1;

        /*
         * Calculate the table size - the next power of 2 larger than the
         * LLC size.  LLC size is in KiB.
         */
        llc_size = rvt_wss_llc_size() * 1024;
        table_size = roundup_pow_of_two(llc_size);

        /* one bit per page in rounded up table */
        llc_bits = llc_size / PAGE_SIZE;
        table_bits = table_size / PAGE_SIZE;
        wss->pages_mask = table_bits - 1;
        wss->num_entries = table_bits / BITS_PER_LONG;

        wss->threshold = (llc_bits * wss_threshold) / 100;
        if (wss->threshold == 0)
                wss->threshold = 1;

        wss->clean_period = wss_clean_period;
        atomic_set(&wss->clean_counter, wss_clean_period);

        wss->entries = kcalloc_node(wss->num_entries, sizeof(*wss->entries),
                                    GFP_KERNEL, node);
        if (!wss->entries) {
                rvt_wss_exit(rdi);
                return -ENOMEM;
        }

        return 0;
}

/*
 * Advance the clean counter.  When the clean period has expired,
 * clean an entry.
 *
 * This is implemented in atomics to avoid locking.  Because multiple
 * variables are involved, it can be racy which can lead to slightly
 * inaccurate information.  Since this is only a heuristic, this is
 * OK.  Any innaccuracies will clean themselves out as the counter
 * advances.  That said, it is unlikely the entry clean operation will
 * race - the next possible racer will not start until the next clean
 * period.
 *
 * The clean counter is implemented as a decrement to zero.  When zero
 * is reached an entry is cleaned.
 */
static void wss_advance_clean_counter(struct rvt_wss *wss)
{
        int entry;
        int weight;
        unsigned long bits;

        /* become the cleaner if we decrement the counter to zero */
        if (atomic_dec_and_test(&wss->clean_counter)) {
                /*
                 * Set, not add, the clean period.  This avoids an issue
                 * where the counter could decrement below the clean period.
                 * Doing a set can result in lost decrements, slowing the
                 * clean advance.  Since this a heuristic, this possible
                 * slowdown is OK.
                 *
                 * An alternative is to loop, advancing the counter by a
                 * clean period until the result is > 0. However, this could
                 * lead to several threads keeping another in the clean loop.
                 * This could be mitigated by limiting the number of times
                 * we stay in the loop.
                 */
                atomic_set(&wss->clean_counter, wss->clean_period);

                /*
                 * Uniquely grab the entry to clean and move to next.
                 * The current entry is always the lower bits of
                 * wss.clean_entry.  The table size, wss.num_entries,
                 * is always a power-of-2.
                 */
                entry = (atomic_inc_return(&wss->clean_entry) - 1)
                        & (wss->num_entries - 1);

                /* clear the entry and count the bits */
                bits = xchg(&wss->entries[entry], 0);
                weight = hweight64((u64)bits);
                /* only adjust the contended total count if needed */
                if (weight)
                        atomic_sub(weight, &wss->total_count);
        }
}

/*
 * Insert the given address into the working set array.
 */
static void wss_insert(struct rvt_wss *wss, void *address)
{
        u32 page = ((unsigned long)address >> PAGE_SHIFT) & wss->pages_mask;
        u32 entry = page / BITS_PER_LONG; /* assumes this ends up a shift */
        u32 nr = page & (BITS_PER_LONG - 1);

        if (!test_and_set_bit(nr, &wss->entries[entry]))
                atomic_inc(&wss->total_count);

        wss_advance_clean_counter(wss);
}

/*
 * Is the working set larger than the threshold?
 */
static inline bool wss_exceeds_threshold(struct rvt_wss *wss)
{
        return atomic_read(&wss->total_count) >= wss->threshold;
}

static void get_map_page(struct rvt_qpn_table *qpt,
                         struct rvt_qpn_map *map)
{
        unsigned long page = get_zeroed_page(GFP_KERNEL);

        /*
         * Free the page if someone raced with us installing it.
         */

        spin_lock(&qpt->lock);
        if (map->page)
                free_page(page);
        else
                map->page = (void *)page;
        spin_unlock(&qpt->lock);
}

/**
 * init_qpn_table - initialize the QP number table for a device
 * @qpt: the QPN table
 */
static int init_qpn_table(struct rvt_dev_info *rdi, struct rvt_qpn_table *qpt)
{
        u32 offset, i;
        struct rvt_qpn_map *map;
        int ret = 0;

        if (!(rdi->dparms.qpn_res_end >= rdi->dparms.qpn_res_start))
                return -EINVAL;

        spin_lock_init(&qpt->lock);

        qpt->last = rdi->dparms.qpn_start;
        qpt->incr = rdi->dparms.qpn_inc << rdi->dparms.qos_shift;

        /*
         * Drivers may want some QPs beyond what we need for verbs let them use
         * our qpn table. No need for two. Lets go ahead and mark the bitmaps
         * for those. The reserved range must be *after* the range which verbs
         * will pick from.
         */

        /* Figure out number of bit maps needed before reserved range */
        qpt->nmaps = rdi->dparms.qpn_res_start / RVT_BITS_PER_PAGE;

        /* This should always be zero */
        offset = rdi->dparms.qpn_res_start & RVT_BITS_PER_PAGE_MASK;

        /* Starting with the first reserved bit map */
        map = &qpt->map[qpt->nmaps];

        rvt_pr_info(rdi, "Reserving QPNs from 0x%x to 0x%x for non-verbs use\n",
                    rdi->dparms.qpn_res_start, rdi->dparms.qpn_res_end);
        for (i = rdi->dparms.qpn_res_start; i <= rdi->dparms.qpn_res_end; i++) {
                if (!map->page) {
                        get_map_page(qpt, map);
                        if (!map->page) {
                                ret = -ENOMEM;
                                break;
                        }
                }
                set_bit(offset, map->page);
                offset++;
                if (offset == RVT_BITS_PER_PAGE) {
                        /* next page */
                        qpt->nmaps++;
                        map++;
                        offset = 0;
                }
        }
        return ret;
}

/**
 * free_qpn_table - free the QP number table for a device
 * @qpt: the QPN table
 */
static void free_qpn_table(struct rvt_qpn_table *qpt)
{
        int i;

        for (i = 0; i < ARRAY_SIZE(qpt->map); i++)
                free_page((unsigned long)qpt->map[i].page);
}

/**
 * rvt_driver_qp_init - Init driver qp resources
 * @rdi: rvt dev strucutre
 *
 * Return: 0 on success
 */
int rvt_driver_qp_init(struct rvt_dev_info *rdi)
{
        int i;
        int ret = -ENOMEM;

        if (!rdi->dparms.qp_table_size)
                return -EINVAL;

        /*
         * If driver is not doing any QP allocation then make sure it is
         * providing the necessary QP functions.
         */
        if (!rdi->driver_f.free_all_qps ||
            !rdi->driver_f.qp_priv_alloc ||
            !rdi->driver_f.qp_priv_free ||
            !rdi->driver_f.notify_qp_reset ||
            !rdi->driver_f.notify_restart_rc)
                return -EINVAL;

        /* allocate parent object */
        rdi->qp_dev = kzalloc_node(sizeof(*rdi->qp_dev), GFP_KERNEL,
                                   rdi->dparms.node);
        if (!rdi->qp_dev)
                return -ENOMEM;

        /* allocate hash table */
        rdi->qp_dev->qp_table_size = rdi->dparms.qp_table_size;
        rdi->qp_dev->qp_table_bits = ilog2(rdi->dparms.qp_table_size);
        rdi->qp_dev->qp_table =
                kmalloc_array_node(rdi->qp_dev->qp_table_size,
                             sizeof(*rdi->qp_dev->qp_table),
                             GFP_KERNEL, rdi->dparms.node);
        if (!rdi->qp_dev->qp_table)
                goto no_qp_table;

        for (i = 0; i < rdi->qp_dev->qp_table_size; i++)
                RCU_INIT_POINTER(rdi->qp_dev->qp_table[i], NULL);

        spin_lock_init(&rdi->qp_dev->qpt_lock);

        /* initialize qpn map */
        if (init_qpn_table(rdi, &rdi->qp_dev->qpn_table))
                goto fail_table;

        spin_lock_init(&rdi->n_qps_lock);

        return 0;

fail_table:
        kfree(rdi->qp_dev->qp_table);
        free_qpn_table(&rdi->qp_dev->qpn_table);

no_qp_table:
        kfree(rdi->qp_dev);

        return ret;
}

/**
 * rvt_free_qp_cb - callback function to reset a qp
 * @qp: the qp to reset
 * @v: a 64-bit value
 *
 * This function resets the qp and removes it from the
 * qp hash table.
 */
static void rvt_free_qp_cb(struct rvt_qp *qp, u64 v)
{
        unsigned int *qp_inuse = (unsigned int *)v;
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);

        /* Reset the qp and remove it from the qp hash list */
        rvt_reset_qp(rdi, qp, qp->ibqp.qp_type);

        /* Increment the qp_inuse count */
        (*qp_inuse)++;
}

/**
 * rvt_free_all_qps - check for QPs still in use
 * @rdi: rvt device info structure
 *
 * There should not be any QPs still in use.
 * Free memory for table.
 * Return the number of QPs still in use.
 */
static unsigned rvt_free_all_qps(struct rvt_dev_info *rdi)
{
        unsigned int qp_inuse = 0;

        qp_inuse += rvt_mcast_tree_empty(rdi);

        rvt_qp_iter(rdi, (u64)&qp_inuse, rvt_free_qp_cb);

        return qp_inuse;
}

/**
 * rvt_qp_exit - clean up qps on device exit
 * @rdi: rvt dev structure
 *
 * Check for qp leaks and free resources.
 */
void rvt_qp_exit(struct rvt_dev_info *rdi)
{
        u32 qps_inuse = rvt_free_all_qps(rdi);

        if (qps_inuse)
                rvt_pr_err(rdi, "QP memory leak! %u still in use\n",
                           qps_inuse);
        if (!rdi->qp_dev)
                return;

        kfree(rdi->qp_dev->qp_table);
        free_qpn_table(&rdi->qp_dev->qpn_table);
        kfree(rdi->qp_dev);
}

static inline unsigned mk_qpn(struct rvt_qpn_table *qpt,
                              struct rvt_qpn_map *map, unsigned off)
{
        return (map - qpt->map) * RVT_BITS_PER_PAGE + off;
}

/**
 * alloc_qpn - Allocate the next available qpn or zero/one for QP type
 *             IB_QPT_SMI/IB_QPT_GSI
 * @rdi: rvt device info structure
 * @qpt: queue pair number table pointer
 * @port_num: IB port number, 1 based, comes from core
 * @exclude_prefix: prefix of special queue pair number being allocated
 *
 * Return: The queue pair number
 */
static int alloc_qpn(struct rvt_dev_info *rdi, struct rvt_qpn_table *qpt,
                     enum ib_qp_type type, u8 port_num, u8 exclude_prefix)
{
        u32 i, offset, max_scan, qpn;
        struct rvt_qpn_map *map;
        u32 ret;
        u32 max_qpn = exclude_prefix == RVT_AIP_QP_PREFIX ?
                RVT_AIP_QPN_MAX : RVT_QPN_MAX;

        if (rdi->driver_f.alloc_qpn)
                return rdi->driver_f.alloc_qpn(rdi, qpt, type, port_num);

        if (type == IB_QPT_SMI || type == IB_QPT_GSI) {
                unsigned n;

                ret = type == IB_QPT_GSI;
                n = 1 << (ret + 2 * (port_num - 1));
                spin_lock(&qpt->lock);
                if (qpt->flags & n)
                        ret = -EINVAL;
                else
                        qpt->flags |= n;
                spin_unlock(&qpt->lock);
                goto bail;
        }

        qpn = qpt->last + qpt->incr;
        if (qpn >= max_qpn)
                qpn = qpt->incr | ((qpt->last & 1) ^ 1);
        /* offset carries bit 0 */
        offset = qpn & RVT_BITS_PER_PAGE_MASK;
        map = &qpt->map[qpn / RVT_BITS_PER_PAGE];
        max_scan = qpt->nmaps - !offset;
        for (i = 0;;) {
                if (unlikely(!map->page)) {
                        get_map_page(qpt, map);
                        if (unlikely(!map->page))
                                break;
                }
                do {
                        if (!test_and_set_bit(offset, map->page)) {
                                qpt->last = qpn;
                                ret = qpn;
                                goto bail;
                        }
                        offset += qpt->incr;
                        /*
                         * This qpn might be bogus if offset >= BITS_PER_PAGE.
                         * That is OK.   It gets re-assigned below
                         */
                        qpn = mk_qpn(qpt, map, offset);
                } while (offset < RVT_BITS_PER_PAGE && qpn < RVT_QPN_MAX);
                /*
                 * In order to keep the number of pages allocated to a
                 * minimum, we scan the all existing pages before increasing
                 * the size of the bitmap table.
                 */
                if (++i > max_scan) {
                        if (qpt->nmaps == RVT_QPNMAP_ENTRIES)
                                break;
                        map = &qpt->map[qpt->nmaps++];
                        /* start at incr with current bit 0 */
                        offset = qpt->incr | (offset & 1);
                } else if (map < &qpt->map[qpt->nmaps]) {
                        ++map;
                        /* start at incr with current bit 0 */
                        offset = qpt->incr | (offset & 1);
                } else {
                        map = &qpt->map[0];
                        /* wrap to first map page, invert bit 0 */
                        offset = qpt->incr | ((offset & 1) ^ 1);
                }
                /* there can be no set bits in low-order QoS bits */
                WARN_ON(rdi->dparms.qos_shift > 1 &&
                        offset & ((BIT(rdi->dparms.qos_shift - 1) - 1) << 1));
                qpn = mk_qpn(qpt, map, offset);
        }

        ret = -ENOMEM;

bail:
        return ret;
}

/**
 * rvt_clear_mr_refs - Drop help mr refs
 * @qp: rvt qp data structure
 * @clr_sends: If shoudl clear send side or not
 */
static void rvt_clear_mr_refs(struct rvt_qp *qp, int clr_sends)
{
        unsigned n;
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);

        if (test_and_clear_bit(RVT_R_REWIND_SGE, &qp->r_aflags))
                rvt_put_ss(&qp->s_rdma_read_sge);

        rvt_put_ss(&qp->r_sge);

        if (clr_sends) {
                while (qp->s_last != qp->s_head) {
                        struct rvt_swqe *wqe = rvt_get_swqe_ptr(qp, qp->s_last);

                        rvt_put_qp_swqe(qp, wqe);
                        if (++qp->s_last >= qp->s_size)
                                qp->s_last = 0;
                        smp_wmb(); /* see qp_set_savail */
                }
                if (qp->s_rdma_mr) {
                        rvt_put_mr(qp->s_rdma_mr);
                        qp->s_rdma_mr = NULL;
                }
        }

        for (n = 0; qp->s_ack_queue && n < rvt_max_atomic(rdi); n++) {
                struct rvt_ack_entry *e = &qp->s_ack_queue[n];

                if (e->rdma_sge.mr) {
                        rvt_put_mr(e->rdma_sge.mr);
                        e->rdma_sge.mr = NULL;
                }
        }
}

/**
 * rvt_swqe_has_lkey - return true if lkey is used by swqe
 * @wqe - the send wqe
 * @lkey - the lkey
 *
 * Test the swqe for using lkey
 */
static bool rvt_swqe_has_lkey(struct rvt_swqe *wqe, u32 lkey)
{
        int i;

        for (i = 0; i < wqe->wr.num_sge; i++) {
                struct rvt_sge *sge = &wqe->sg_list[i];

                if (rvt_mr_has_lkey(sge->mr, lkey))
                        return true;
        }
        return false;
}

/**
 * rvt_qp_sends_has_lkey - return true is qp sends use lkey
 * @qp - the rvt_qp
 * @lkey - the lkey
 */
static bool rvt_qp_sends_has_lkey(struct rvt_qp *qp, u32 lkey)
{
        u32 s_last = qp->s_last;

        while (s_last != qp->s_head) {
                struct rvt_swqe *wqe = rvt_get_swqe_ptr(qp, s_last);

                if (rvt_swqe_has_lkey(wqe, lkey))
                        return true;

                if (++s_last >= qp->s_size)
                        s_last = 0;
        }
        if (qp->s_rdma_mr)
                if (rvt_mr_has_lkey(qp->s_rdma_mr, lkey))
                        return true;
        return false;
}

/**
 * rvt_qp_acks_has_lkey - return true if acks have lkey
 * @qp - the qp
 * @lkey - the lkey
 */
static bool rvt_qp_acks_has_lkey(struct rvt_qp *qp, u32 lkey)
{
        int i;
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);

        for (i = 0; qp->s_ack_queue && i < rvt_max_atomic(rdi); i++) {
                struct rvt_ack_entry *e = &qp->s_ack_queue[i];

                if (rvt_mr_has_lkey(e->rdma_sge.mr, lkey))
                        return true;
        }
        return false;
}

/*
 * rvt_qp_mr_clean - clean up remote ops for lkey
 * @qp - the qp
 * @lkey - the lkey that is being de-registered
 *
 * This routine checks if the lkey is being used by
 * the qp.
 *
 * If so, the qp is put into an error state to elminate
 * any references from the qp.
 */
void rvt_qp_mr_clean(struct rvt_qp *qp, u32 lkey)
{
        bool lastwqe = false;

        if (qp->ibqp.qp_type == IB_QPT_SMI ||
            qp->ibqp.qp_type == IB_QPT_GSI)
                /* avoid special QPs */
                return;
        spin_lock_irq(&qp->r_lock);
        spin_lock(&qp->s_hlock);
        spin_lock(&qp->s_lock);

        if (qp->state == IB_QPS_ERR || qp->state == IB_QPS_RESET)
                goto check_lwqe;

        if (rvt_ss_has_lkey(&qp->r_sge, lkey) ||
            rvt_qp_sends_has_lkey(qp, lkey) ||
            rvt_qp_acks_has_lkey(qp, lkey))
                lastwqe = rvt_error_qp(qp, IB_WC_LOC_PROT_ERR);
check_lwqe:
        spin_unlock(&qp->s_lock);
        spin_unlock(&qp->s_hlock);
        spin_unlock_irq(&qp->r_lock);
        if (lastwqe) {
                struct ib_event ev;

                ev.device = qp->ibqp.device;
                ev.element.qp = &qp->ibqp;
                ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
                qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
        }
}

/**
 * rvt_remove_qp - remove qp form table
 * @rdi: rvt dev struct
 * @qp: qp to remove
 *
 * Remove the QP from the table so it can't be found asynchronously by
 * the receive routine.
 */
static void rvt_remove_qp(struct rvt_dev_info *rdi, struct rvt_qp *qp)
{
        struct rvt_ibport *rvp = rdi->ports[qp->port_num - 1];
        u32 n = hash_32(qp->ibqp.qp_num, rdi->qp_dev->qp_table_bits);
        unsigned long flags;
        int removed = 1;

        spin_lock_irqsave(&rdi->qp_dev->qpt_lock, flags);

        if (rcu_dereference_protected(rvp->qp[0],
                        lockdep_is_held(&rdi->qp_dev->qpt_lock)) == qp) {
                RCU_INIT_POINTER(rvp->qp[0], NULL);
        } else if (rcu_dereference_protected(rvp->qp[1],
                        lockdep_is_held(&rdi->qp_dev->qpt_lock)) == qp) {
                RCU_INIT_POINTER(rvp->qp[1], NULL);
        } else {
                struct rvt_qp *q;
                struct rvt_qp __rcu **qpp;

                removed = 0;
                qpp = &rdi->qp_dev->qp_table[n];
                for (; (q = rcu_dereference_protected(*qpp,
                        lockdep_is_held(&rdi->qp_dev->qpt_lock))) != NULL;
                        qpp = &q->next) {
                        if (q == qp) {
                                RCU_INIT_POINTER(*qpp,
                                     rcu_dereference_protected(qp->next,
                                     lockdep_is_held(&rdi->qp_dev->qpt_lock)));
                                removed = 1;
                                trace_rvt_qpremove(qp, n);
                                break;
                        }
                }
        }

        spin_unlock_irqrestore(&rdi->qp_dev->qpt_lock, flags);
        if (removed) {
                synchronize_rcu();
                rvt_put_qp(qp);
        }
}

/**
 * rvt_alloc_rq - allocate memory for user or kernel buffer
 * @rq: receive queue data structure
 * @size: number of request queue entries
 * @node: The NUMA node
 * @udata: True if user data is available or not false
 *
 * Return: If memory allocation failed, return -ENONEM
 * This function is used by both shared receive
 * queues and non-shared receive queues to allocate
 * memory.
 */
int rvt_alloc_rq(struct rvt_rq *rq, u32 size, int node,
                 struct ib_udata *udata)
{
        if (udata) {
                rq->wq = vmalloc_user(sizeof(struct rvt_rwq) + size);
                if (!rq->wq)
                        goto bail;
                /* need kwq with no buffers */
                rq->kwq = kzalloc_node(sizeof(*rq->kwq), GFP_KERNEL, node);
                if (!rq->kwq)
                        goto bail;
                rq->kwq->curr_wq = rq->wq->wq;
        } else {
                /* need kwq with buffers */
                rq->kwq =
                        vzalloc_node(sizeof(struct rvt_krwq) + size, node);
                if (!rq->kwq)
                        goto bail;
                rq->kwq->curr_wq = rq->kwq->wq;
        }

        spin_lock_init(&rq->kwq->p_lock);
        spin_lock_init(&rq->kwq->c_lock);
        return 0;
bail:
        rvt_free_rq(rq);
        return -ENOMEM;
}

/**
 * rvt_init_qp - initialize the QP state to the reset state
 * @qp: the QP to init or reinit
 * @type: the QP type
 *
 * This function is called from both rvt_create_qp() and
 * rvt_reset_qp().   The difference is that the reset
 * patch the necessary locks to protect against concurent
 * access.
 */
static void rvt_init_qp(struct rvt_dev_info *rdi, struct rvt_qp *qp,
                        enum ib_qp_type type)
{
        qp->remote_qpn = 0;
        qp->qkey = 0;
        qp->qp_access_flags = 0;
        qp->s_flags &= RVT_S_SIGNAL_REQ_WR;
        qp->s_hdrwords = 0;
        qp->s_wqe = NULL;
        qp->s_draining = 0;
        qp->s_next_psn = 0;
        qp->s_last_psn = 0;
        qp->s_sending_psn = 0;
        qp->s_sending_hpsn = 0;
        qp->s_psn = 0;
        qp->r_psn = 0;
        qp->r_msn = 0;
        if (type == IB_QPT_RC) {
                qp->s_state = IB_OPCODE_RC_SEND_LAST;
                qp->r_state = IB_OPCODE_RC_SEND_LAST;
        } else {
                qp->s_state = IB_OPCODE_UC_SEND_LAST;
                qp->r_state = IB_OPCODE_UC_SEND_LAST;
        }
        qp->s_ack_state = IB_OPCODE_RC_ACKNOWLEDGE;
        qp->r_nak_state = 0;
        qp->r_aflags = 0;
        qp->r_flags = 0;
        qp->s_head = 0;
        qp->s_tail = 0;
        qp->s_cur = 0;
        qp->s_acked = 0;
        qp->s_last = 0;
        qp->s_ssn = 1;
        qp->s_lsn = 0;
        qp->s_mig_state = IB_MIG_MIGRATED;
        qp->r_head_ack_queue = 0;
        qp->s_tail_ack_queue = 0;
        qp->s_acked_ack_queue = 0;
        qp->s_num_rd_atomic = 0;
        qp->r_sge.num_sge = 0;
        atomic_set(&qp->s_reserved_used, 0);
}

/**
 * _rvt_reset_qp - initialize the QP state to the reset state
 * @qp: the QP to reset
 * @type: the QP type
 *
 * r_lock, s_hlock, and s_lock are required to be held by the caller
 */
static void _rvt_reset_qp(struct rvt_dev_info *rdi, struct rvt_qp *qp,
                          enum ib_qp_type type)
        __must_hold(&qp->s_lock)
        __must_hold(&qp->s_hlock)
        __must_hold(&qp->r_lock)
{
        lockdep_assert_held(&qp->r_lock);
        lockdep_assert_held(&qp->s_hlock);
        lockdep_assert_held(&qp->s_lock);
        if (qp->state != IB_QPS_RESET) {
                qp->state = IB_QPS_RESET;

                /* Let drivers flush their waitlist */
                rdi->driver_f.flush_qp_waiters(qp);
                rvt_stop_rc_timers(qp);
                qp->s_flags &= ~(RVT_S_TIMER | RVT_S_ANY_WAIT);
                spin_unlock(&qp->s_lock);
                spin_unlock(&qp->s_hlock);
                spin_unlock_irq(&qp->r_lock);

                /* Stop the send queue and the retry timer */
                rdi->driver_f.stop_send_queue(qp);
                rvt_del_timers_sync(qp);
                /* Wait for things to stop */
                rdi->driver_f.quiesce_qp(qp);

                /* take qp out the hash and wait for it to be unused */
                rvt_remove_qp(rdi, qp);

                /* grab the lock b/c it was locked at call time */
                spin_lock_irq(&qp->r_lock);
                spin_lock(&qp->s_hlock);
                spin_lock(&qp->s_lock);

                rvt_clear_mr_refs(qp, 1);
                /*
                 * Let the driver do any tear down or re-init it needs to for
                 * a qp that has been reset
                 */
                rdi->driver_f.notify_qp_reset(qp);
        }
        rvt_init_qp(rdi, qp, type);
        lockdep_assert_held(&qp->r_lock);
        lockdep_assert_held(&qp->s_hlock);
        lockdep_assert_held(&qp->s_lock);
}

/**
 * rvt_reset_qp - initialize the QP state to the reset state
 * @rdi: the device info
 * @qp: the QP to reset
 * @type: the QP type
 *
 * This is the wrapper function to acquire the r_lock, s_hlock, and s_lock
 * before calling _rvt_reset_qp().
 */
static void rvt_reset_qp(struct rvt_dev_info *rdi, struct rvt_qp *qp,
                         enum ib_qp_type type)
{
        spin_lock_irq(&qp->r_lock);
        spin_lock(&qp->s_hlock);
        spin_lock(&qp->s_lock);
        _rvt_reset_qp(rdi, qp, type);
        spin_unlock(&qp->s_lock);
        spin_unlock(&qp->s_hlock);
        spin_unlock_irq(&qp->r_lock);
}

/** rvt_free_qpn - Free a qpn from the bit map
 * @qpt: QP table
 * @qpn: queue pair number to free
 */
static void rvt_free_qpn(struct rvt_qpn_table *qpt, u32 qpn)
{
        struct rvt_qpn_map *map;

        if ((qpn & RVT_AIP_QP_PREFIX_MASK) == RVT_AIP_QP_BASE)
                qpn &= RVT_AIP_QP_SUFFIX;

        map = qpt->map + (qpn & RVT_QPN_MASK) / RVT_BITS_PER_PAGE;
        if (map->page)
                clear_bit(qpn & RVT_BITS_PER_PAGE_MASK, map->page);
}

/**
 * get_allowed_ops - Given a QP type return the appropriate allowed OP

 * @type: valid, supported, QP type
 */
static u8 get_allowed_ops(enum ib_qp_type type)
{
        return type == IB_QPT_RC ? IB_OPCODE_RC : type == IB_QPT_UC ?
                IB_OPCODE_UC : IB_OPCODE_UD;
}

/**
 * free_ud_wq_attr - Clean up AH attribute cache for UD QPs
 * @qp: Valid QP with allowed_ops set
 *
 * The rvt_swqe data structure being used is a union, so this is
 * only valid for UD QPs.
 */
static void free_ud_wq_attr(struct rvt_qp *qp)
{
        struct rvt_swqe *wqe;
        int i;

        for (i = 0; qp->allowed_ops == IB_OPCODE_UD && i < qp->s_size; i++) {
                wqe = rvt_get_swqe_ptr(qp, i);
                kfree(wqe->ud_wr.attr);
                wqe->ud_wr.attr = NULL;
        }
}

/**
 * alloc_ud_wq_attr - AH attribute cache for UD QPs
 * @qp: Valid QP with allowed_ops set
 * @node: Numa node for allocation
 *
 * The rvt_swqe data structure being used is a union, so this is
 * only valid for UD QPs.
 */
static int alloc_ud_wq_attr(struct rvt_qp *qp, int node)
{
        struct rvt_swqe *wqe;
        int i;

        for (i = 0; qp->allowed_ops == IB_OPCODE_UD && i < qp->s_size; i++) {
                wqe = rvt_get_swqe_ptr(qp, i);
                wqe->ud_wr.attr = kzalloc_node(sizeof(*wqe->ud_wr.attr),
                                               GFP_KERNEL, node);
                if (!wqe->ud_wr.attr) {
                        free_ud_wq_attr(qp);
                        return -ENOMEM;
                }
        }

        return 0;
}

/**
 * rvt_create_qp - create a queue pair for a device
 * @ibpd: the protection domain who's device we create the queue pair for
 * @init_attr: the attributes of the queue pair
 * @udata: user data for libibverbs.so
 *
 * Queue pair creation is mostly an rvt issue. However, drivers have their own
 * unique idea of what queue pair numbers mean. For instance there is a reserved
 * range for PSM.
 *
 * Return: the queue pair on success, otherwise returns an errno.
 *
 * Called by the ib_create_qp() core verbs function.
 */
struct ib_qp *rvt_create_qp(struct ib_pd *ibpd,
                            struct ib_qp_init_attr *init_attr,
                            struct ib_udata *udata)
{
        struct rvt_qp *qp;
        int err;
        struct rvt_swqe *swq = NULL;
        size_t sz;
        size_t sg_list_sz;
        struct ib_qp *ret = ERR_PTR(-ENOMEM);
        struct rvt_dev_info *rdi = ib_to_rvt(ibpd->device);
        void *priv = NULL;
        size_t sqsize;
        u8 exclude_prefix = 0;

        if (!rdi)
                return ERR_PTR(-EINVAL);

        if (init_attr->cap.max_send_sge > rdi->dparms.props.max_send_sge ||
            init_attr->cap.max_send_wr > rdi->dparms.props.max_qp_wr ||
            (init_attr->create_flags &&
             init_attr->create_flags != IB_QP_CREATE_NETDEV_USE))
                return ERR_PTR(-EINVAL);

        /* Check receive queue parameters if no SRQ is specified. */
        if (!init_attr->srq) {
                if (init_attr->cap.max_recv_sge >
                    rdi->dparms.props.max_recv_sge ||
                    init_attr->cap.max_recv_wr > rdi->dparms.props.max_qp_wr)
                        return ERR_PTR(-EINVAL);

                if (init_attr->cap.max_send_sge +
                    init_attr->cap.max_send_wr +
                    init_attr->cap.max_recv_sge +
                    init_attr->cap.max_recv_wr == 0)
                        return ERR_PTR(-EINVAL);
        }
        sqsize =
                init_attr->cap.max_send_wr + 1 +
                rdi->dparms.reserved_operations;
        switch (init_attr->qp_type) {
        case IB_QPT_SMI:
        case IB_QPT_GSI:
                if (init_attr->port_num == 0 ||
                    init_attr->port_num > ibpd->device->phys_port_cnt)
                        return ERR_PTR(-EINVAL);
                /* fall through */
        case IB_QPT_UC:
        case IB_QPT_RC:
        case IB_QPT_UD:
                sz = struct_size(swq, sg_list, init_attr->cap.max_send_sge);
                swq = vzalloc_node(array_size(sz, sqsize), rdi->dparms.node);
                if (!swq)
                        return ERR_PTR(-ENOMEM);

                sz = sizeof(*qp);
                sg_list_sz = 0;
                if (init_attr->srq) {
                        struct rvt_srq *srq = ibsrq_to_rvtsrq(init_attr->srq);

                        if (srq->rq.max_sge > 1)
                                sg_list_sz = sizeof(*qp->r_sg_list) *
                                        (srq->rq.max_sge - 1);
                } else if (init_attr->cap.max_recv_sge > 1)
                        sg_list_sz = sizeof(*qp->r_sg_list) *
                                (init_attr->cap.max_recv_sge - 1);
                qp = kzalloc_node(sz + sg_list_sz, GFP_KERNEL,
                                  rdi->dparms.node);
                if (!qp)
                        goto bail_swq;
                qp->allowed_ops = get_allowed_ops(init_attr->qp_type);

                RCU_INIT_POINTER(qp->next, NULL);
                if (init_attr->qp_type == IB_QPT_RC) {
                        qp->s_ack_queue =
                                kcalloc_node(rvt_max_atomic(rdi),
                                             sizeof(*qp->s_ack_queue),
                                             GFP_KERNEL,
                                             rdi->dparms.node);
                        if (!qp->s_ack_queue)
                                goto bail_qp;
                }
                /* initialize timers needed for rc qp */
                timer_setup(&qp->s_timer, rvt_rc_timeout, 0);
                hrtimer_init(&qp->s_rnr_timer, CLOCK_MONOTONIC,
                             HRTIMER_MODE_REL);
                qp->s_rnr_timer.function = rvt_rc_rnr_retry;

                /*
                 * Driver needs to set up it's private QP structure and do any
                 * initialization that is needed.
                 */
                priv = rdi->driver_f.qp_priv_alloc(rdi, qp);
                if (IS_ERR(priv)) {
                        ret = priv;
                        goto bail_qp;
                }
                qp->priv = priv;
                qp->timeout_jiffies =
                        usecs_to_jiffies((4096UL * (1UL << qp->timeout)) /
                                1000UL);
                if (init_attr->srq) {
                        sz = 0;
                } else {
                        qp->r_rq.size = init_attr->cap.max_recv_wr + 1;
                        qp->r_rq.max_sge = init_attr->cap.max_recv_sge;
                        sz = (sizeof(struct ib_sge) * qp->r_rq.max_sge) +
                                sizeof(struct rvt_rwqe);
                        err = rvt_alloc_rq(&qp->r_rq, qp->r_rq.size * sz,
                                           rdi->dparms.node, udata);
                        if (err) {
                                ret = ERR_PTR(err);
                                goto bail_driver_priv;
                        }
                }

                /*
                 * ib_create_qp() will initialize qp->ibqp
                 * except for qp->ibqp.qp_num.
                 */
                spin_lock_init(&qp->r_lock);
                spin_lock_init(&qp->s_hlock);
                spin_lock_init(&qp->s_lock);
                atomic_set(&qp->refcount, 0);
                atomic_set(&qp->local_ops_pending, 0);
                init_waitqueue_head(&qp->wait);
                INIT_LIST_HEAD(&qp->rspwait);
                qp->state = IB_QPS_RESET;
                qp->s_wq = swq;
                qp->s_size = sqsize;
                qp->s_avail = init_attr->cap.max_send_wr;
                qp->s_max_sge = init_attr->cap.max_send_sge;
                if (init_attr->sq_sig_type == IB_SIGNAL_REQ_WR)
                        qp->s_flags = RVT_S_SIGNAL_REQ_WR;
                err = alloc_ud_wq_attr(qp, rdi->dparms.node);
                if (err) {
                        ret = (ERR_PTR(err));
                        goto bail_rq_rvt;
                }

                if (init_attr->create_flags & IB_QP_CREATE_NETDEV_USE)
                        exclude_prefix = RVT_AIP_QP_PREFIX;

                err = alloc_qpn(rdi, &rdi->qp_dev->qpn_table,
                                init_attr->qp_type,
                                init_attr->port_num,
                                exclude_prefix);
                if (err < 0) {
                        ret = ERR_PTR(err);
                        goto bail_rq_wq;
                }
                qp->ibqp.qp_num = err;
                if (init_attr->create_flags & IB_QP_CREATE_NETDEV_USE)
                        qp->ibqp.qp_num |= RVT_AIP_QP_BASE;
                qp->port_num = init_attr->port_num;
                rvt_init_qp(rdi, qp, init_attr->qp_type);
                if (rdi->driver_f.qp_priv_init) {
                        err = rdi->driver_f.qp_priv_init(rdi, qp, init_attr);
                        if (err) {
                                ret = ERR_PTR(err);
                                goto bail_rq_wq;
                        }
                }
                break;

        default:
                /* Don't support raw QPs */
                return ERR_PTR(-EOPNOTSUPP);
        }

        init_attr->cap.max_inline_data = 0;

        /*
         * Return the address of the RWQ as the offset to mmap.
         * See rvt_mmap() for details.
         */
        if (udata && udata->outlen >= sizeof(__u64)) {
                if (!qp->r_rq.wq) {
                        __u64 offset = 0;

                        err = ib_copy_to_udata(udata, &offset,
                                               sizeof(offset));
                        if (err) {
                                ret = ERR_PTR(err);
                                goto bail_qpn;
                        }
                } else {
                        u32 s = sizeof(struct rvt_rwq) + qp->r_rq.size * sz;

                        qp->ip = rvt_create_mmap_info(rdi, s, udata,
                                                      qp->r_rq.wq);
                        if (IS_ERR(qp->ip)) {
                                ret = ERR_CAST(qp->ip);
                                goto bail_qpn;
                        }

                        err = ib_copy_to_udata(udata, &qp->ip->offset,
                                               sizeof(qp->ip->offset));
                        if (err) {
                                ret = ERR_PTR(err);
                                goto bail_ip;
                        }
                }
                qp->pid = current->pid;
        }

        spin_lock(&rdi->n_qps_lock);
        if (rdi->n_qps_allocated == rdi->dparms.props.max_qp) {
                spin_unlock(&rdi->n_qps_lock);
                ret = ERR_PTR(-ENOMEM);
                goto bail_ip;
        }

        rdi->n_qps_allocated++;
        /*
         * Maintain a busy_jiffies variable that will be added to the timeout
         * period in mod_retry_timer and add_retry_timer. This busy jiffies
         * is scaled by the number of rc qps created for the device to reduce
         * the number of timeouts occurring when there is a large number of
         * qps. busy_jiffies is incremented every rc qp scaling interval.
         * The scaling interval is selected based on extensive performance
         * evaluation of targeted workloads.
         */
        if (init_attr->qp_type == IB_QPT_RC) {
                rdi->n_rc_qps++;
                rdi->busy_jiffies = rdi->n_rc_qps / RC_QP_SCALING_INTERVAL;
        }
        spin_unlock(&rdi->n_qps_lock);

        if (qp->ip) {
                spin_lock_irq(&rdi->pending_lock);
                list_add(&qp->ip->pending_mmaps, &rdi->pending_mmaps);
                spin_unlock_irq(&rdi->pending_lock);
        }

        ret = &qp->ibqp;

        return ret;

bail_ip:
        if (qp->ip)
                kref_put(&qp->ip->ref, rvt_release_mmap_info);

bail_qpn:
        rvt_free_qpn(&rdi->qp_dev->qpn_table, qp->ibqp.qp_num);

bail_rq_wq:
        free_ud_wq_attr(qp);

bail_rq_rvt:
        rvt_free_rq(&qp->r_rq);

bail_driver_priv:
        rdi->driver_f.qp_priv_free(rdi, qp);

bail_qp:
        kfree(qp->s_ack_queue);
        kfree(qp);

bail_swq:
        vfree(swq);

        return ret;
}

/**
 * rvt_error_qp - put a QP into the error state
 * @qp: the QP to put into the error state
 * @err: the receive completion error to signal if a RWQE is active
 *
 * Flushes both send and receive work queues.
 *
 * Return: true if last WQE event should be generated.
 * The QP r_lock and s_lock should be held and interrupts disabled.
 * If we are already in error state, just return.
 */
int rvt_error_qp(struct rvt_qp *qp, enum ib_wc_status err)
{
        struct ib_wc wc;
        int ret = 0;
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);

        lockdep_assert_held(&qp->r_lock);
        lockdep_assert_held(&qp->s_lock);
        if (qp->state == IB_QPS_ERR || qp->state == IB_QPS_RESET)
                goto bail;

        qp->state = IB_QPS_ERR;

        if (qp->s_flags & (RVT_S_TIMER | RVT_S_WAIT_RNR)) {
                qp->s_flags &= ~(RVT_S_TIMER | RVT_S_WAIT_RNR);
                del_timer(&qp->s_timer);
        }

        if (qp->s_flags & RVT_S_ANY_WAIT_SEND)
                qp->s_flags &= ~RVT_S_ANY_WAIT_SEND;

        rdi->driver_f.notify_error_qp(qp);

        /* Schedule the sending tasklet to drain the send work queue. */
        if (READ_ONCE(qp->s_last) != qp->s_head)
                rdi->driver_f.schedule_send(qp);

        rvt_clear_mr_refs(qp, 0);

        memset(&wc, 0, sizeof(wc));
        wc.qp = &qp->ibqp;
        wc.opcode = IB_WC_RECV;

        if (test_and_clear_bit(RVT_R_WRID_VALID, &qp->r_aflags)) {
                wc.wr_id = qp->r_wr_id;
                wc.status = err;
                rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc, 1);
        }
        wc.status = IB_WC_WR_FLUSH_ERR;

        if (qp->r_rq.kwq) {
                u32 head;
                u32 tail;
                struct rvt_rwq *wq = NULL;
                struct rvt_krwq *kwq = NULL;

                spin_lock(&qp->r_rq.kwq->c_lock);
                /* qp->ip used to validate if there is a  user buffer mmaped */
                if (qp->ip) {
                        wq = qp->r_rq.wq;
                        head = RDMA_READ_UAPI_ATOMIC(wq->head);
                        tail = RDMA_READ_UAPI_ATOMIC(wq->tail);
                } else {
                        kwq = qp->r_rq.kwq;
                        head = kwq->head;
                        tail = kwq->tail;
                }
                /* sanity check pointers before trusting them */
                if (head >= qp->r_rq.size)
                        head = 0;
                if (tail >= qp->r_rq.size)
                        tail = 0;
                while (tail != head) {
                        wc.wr_id = rvt_get_rwqe_ptr(&qp->r_rq, tail)->wr_id;
                        if (++tail >= qp->r_rq.size)
                                tail = 0;
                        rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc, 1);
                }
                if (qp->ip)
                        RDMA_WRITE_UAPI_ATOMIC(wq->tail, tail);
                else
                        kwq->tail = tail;
                spin_unlock(&qp->r_rq.kwq->c_lock);
        } else if (qp->ibqp.event_handler) {
                ret = 1;
        }

bail:
        return ret;
}
EXPORT_SYMBOL(rvt_error_qp);

/*
 * Put the QP into the hash table.
 * The hash table holds a reference to the QP.
 */
static void rvt_insert_qp(struct rvt_dev_info *rdi, struct rvt_qp *qp)
{
        struct rvt_ibport *rvp = rdi->ports[qp->port_num - 1];
        unsigned long flags;

        rvt_get_qp(qp);
        spin_lock_irqsave(&rdi->qp_dev->qpt_lock, flags);

        if (qp->ibqp.qp_num <= 1) {
                rcu_assign_pointer(rvp->qp[qp->ibqp.qp_num], qp);
        } else {
                u32 n = hash_32(qp->ibqp.qp_num, rdi->qp_dev->qp_table_bits);

                qp->next = rdi->qp_dev->qp_table[n];
                rcu_assign_pointer(rdi->qp_dev->qp_table[n], qp);
                trace_rvt_qpinsert(qp, n);
        }

        spin_unlock_irqrestore(&rdi->qp_dev->qpt_lock, flags);
}

/**
 * rvt_modify_qp - modify the attributes of a queue pair
 * @ibqp: the queue pair who's attributes we're modifying
 * @attr: the new attributes
 * @attr_mask: the mask of attributes to modify
 * @udata: user data for libibverbs.so
 *
 * Return: 0 on success, otherwise returns an errno.
 */
int rvt_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
                  int attr_mask, struct ib_udata *udata)
{
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);
        struct rvt_qp *qp = ibqp_to_rvtqp(ibqp);
        enum ib_qp_state cur_state, new_state;
        struct ib_event ev;
        int lastwqe = 0;
        int mig = 0;
        int pmtu = 0; /* for gcc warning only */
        int opa_ah;

        spin_lock_irq(&qp->r_lock);
        spin_lock(&qp->s_hlock);
        spin_lock(&qp->s_lock);

        cur_state = attr_mask & IB_QP_CUR_STATE ?
                attr->cur_qp_state : qp->state;
        new_state = attr_mask & IB_QP_STATE ? attr->qp_state : cur_state;
        opa_ah = rdma_cap_opa_ah(ibqp->device, qp->port_num);

        if (!ib_modify_qp_is_ok(cur_state, new_state, ibqp->qp_type,
                                attr_mask))
                goto inval;

        if (rdi->driver_f.check_modify_qp &&
            rdi->driver_f.check_modify_qp(qp, attr, attr_mask, udata))
                goto inval;

        if (attr_mask & IB_QP_AV) {
                if (opa_ah) {
                        if (rdma_ah_get_dlid(&attr->ah_attr) >=
                                opa_get_mcast_base(OPA_MCAST_NR))
                                goto inval;
                } else {
                        if (rdma_ah_get_dlid(&attr->ah_attr) >=
                                be16_to_cpu(IB_MULTICAST_LID_BASE))
                                goto inval;
                }

                if (rvt_check_ah(qp->ibqp.device, &attr->ah_attr))
                        goto inval;
        }

        if (attr_mask & IB_QP_ALT_PATH) {
                if (opa_ah) {
                        if (rdma_ah_get_dlid(&attr->alt_ah_attr) >=
                                opa_get_mcast_base(OPA_MCAST_NR))
                                goto inval;
                } else {
                        if (rdma_ah_get_dlid(&attr->alt_ah_attr) >=
                                be16_to_cpu(IB_MULTICAST_LID_BASE))
                                goto inval;
                }

                if (rvt_check_ah(qp->ibqp.device, &attr->alt_ah_attr))
                        goto inval;
                if (attr->alt_pkey_index >= rvt_get_npkeys(rdi))
                        goto inval;
        }

        if (attr_mask & IB_QP_PKEY_INDEX)
                if (attr->pkey_index >= rvt_get_npkeys(rdi))
                        goto inval;

        if (attr_mask & IB_QP_MIN_RNR_TIMER)
                if (attr->min_rnr_timer > 31)
                        goto inval;

        if (attr_mask & IB_QP_PORT)
                if (qp->ibqp.qp_type == IB_QPT_SMI ||
                    qp->ibqp.qp_type == IB_QPT_GSI ||
                    attr->port_num == 0 ||
                    attr->port_num > ibqp->device->phys_port_cnt)
                        goto inval;

        if (attr_mask & IB_QP_DEST_QPN)
                if (attr->dest_qp_num > RVT_QPN_MASK)
                        goto inval;

        if (attr_mask & IB_QP_RETRY_CNT)
                if (attr->retry_cnt > 7)
                        goto inval;

        if (attr_mask & IB_QP_RNR_RETRY)
                if (attr->rnr_retry > 7)
                        goto inval;

        /*
         * Don't allow invalid path_mtu values.  OK to set greater
         * than the active mtu (or even the max_cap, if we have tuned
         * that to a small mtu.  We'll set qp->path_mtu
         * to the lesser of requested attribute mtu and active,
         * for packetizing messages.
         * Note that the QP port has to be set in INIT and MTU in RTR.
         */
        if (attr_mask & IB_QP_PATH_MTU) {
                pmtu = rdi->driver_f.get_pmtu_from_attr(rdi, qp, attr);
                if (pmtu < 0)
                        goto inval;
        }

        if (attr_mask & IB_QP_PATH_MIG_STATE) {
                if (attr->path_mig_state == IB_MIG_REARM) {
                        if (qp->s_mig_state == IB_MIG_ARMED)
                                goto inval;
                        if (new_state != IB_QPS_RTS)
                                goto inval;
                } else if (attr->path_mig_state == IB_MIG_MIGRATED) {
                        if (qp->s_mig_state == IB_MIG_REARM)
                                goto inval;
                        if (new_state != IB_QPS_RTS && new_state != IB_QPS_SQD)
                                goto inval;
                        if (qp->s_mig_state == IB_MIG_ARMED)
                                mig = 1;
                } else {
                        goto inval;
                }
        }

        if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC)
                if (attr->max_dest_rd_atomic > rdi->dparms.max_rdma_atomic)
                        goto inval;

        switch (new_state) {
        case IB_QPS_RESET:
                if (qp->state != IB_QPS_RESET)
                        _rvt_reset_qp(rdi, qp, ibqp->qp_type);
                break;

        case IB_QPS_RTR:
                /* Allow event to re-trigger if QP set to RTR more than once */
                qp->r_flags &= ~RVT_R_COMM_EST;
                qp->state = new_state;
                break;

        case IB_QPS_SQD:
                qp->s_draining = qp->s_last != qp->s_cur;
                qp->state = new_state;
                break;

        case IB_QPS_SQE:
                if (qp->ibqp.qp_type == IB_QPT_RC)
                        goto inval;
                qp->state = new_state;
                break;

        case IB_QPS_ERR:
                lastwqe = rvt_error_qp(qp, IB_WC_WR_FLUSH_ERR);
                break;

        default:
                qp->state = new_state;
                break;
        }

        if (attr_mask & IB_QP_PKEY_INDEX)
                qp->s_pkey_index = attr->pkey_index;

        if (attr_mask & IB_QP_PORT)
                qp->port_num = attr->port_num;

        if (attr_mask & IB_QP_DEST_QPN)
                qp->remote_qpn = attr->dest_qp_num;

        if (attr_mask & IB_QP_SQ_PSN) {
                qp->s_next_psn = attr->sq_psn & rdi->dparms.psn_modify_mask;
                qp->s_psn = qp->s_next_psn;
                qp->s_sending_psn = qp->s_next_psn;
                qp->s_last_psn = qp->s_next_psn - 1;
                qp->s_sending_hpsn = qp->s_last_psn;
        }

        if (attr_mask & IB_QP_RQ_PSN)
                qp->r_psn = attr->rq_psn & rdi->dparms.psn_modify_mask;

        if (attr_mask & IB_QP_ACCESS_FLAGS)
                qp->qp_access_flags = attr->qp_access_flags;

        if (attr_mask & IB_QP_AV) {
                rdma_replace_ah_attr(&qp->remote_ah_attr, &attr->ah_attr);
                qp->s_srate = rdma_ah_get_static_rate(&attr->ah_attr);
                qp->srate_mbps = ib_rate_to_mbps(qp->s_srate);
        }

        if (attr_mask & IB_QP_ALT_PATH) {
                rdma_replace_ah_attr(&qp->alt_ah_attr, &attr->alt_ah_attr);
                qp->s_alt_pkey_index = attr->alt_pkey_index;
        }

        if (attr_mask & IB_QP_PATH_MIG_STATE) {
                qp->s_mig_state = attr->path_mig_state;
                if (mig) {
                        qp->remote_ah_attr = qp->alt_ah_attr;
                        qp->port_num = rdma_ah_get_port_num(&qp->alt_ah_attr);
                        qp->s_pkey_index = qp->s_alt_pkey_index;
                }
        }

        if (attr_mask & IB_QP_PATH_MTU) {
                qp->pmtu = rdi->driver_f.mtu_from_qp(rdi, qp, pmtu);
                qp->log_pmtu = ilog2(qp->pmtu);
        }

        if (attr_mask & IB_QP_RETRY_CNT) {
                qp->s_retry_cnt = attr->retry_cnt;
                qp->s_retry = attr->retry_cnt;
        }

        if (attr_mask & IB_QP_RNR_RETRY) {
                qp->s_rnr_retry_cnt = attr->rnr_retry;
                qp->s_rnr_retry = attr->rnr_retry;
        }

        if (attr_mask & IB_QP_MIN_RNR_TIMER)
                qp->r_min_rnr_timer = attr->min_rnr_timer;

        if (attr_mask & IB_QP_TIMEOUT) {
                qp->timeout = attr->timeout;
                qp->timeout_jiffies = rvt_timeout_to_jiffies(qp->timeout);
        }

        if (attr_mask & IB_QP_QKEY)
                qp->qkey = attr->qkey;

        if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC)
                qp->r_max_rd_atomic = attr->max_dest_rd_atomic;

        if (attr_mask & IB_QP_MAX_QP_RD_ATOMIC)
                qp->s_max_rd_atomic = attr->max_rd_atomic;

        if (rdi->driver_f.modify_qp)
                rdi->driver_f.modify_qp(qp, attr, attr_mask, udata);

        spin_unlock(&qp->s_lock);
        spin_unlock(&qp->s_hlock);
        spin_unlock_irq(&qp->r_lock);

        if (cur_state == IB_QPS_RESET && new_state == IB_QPS_INIT)
                rvt_insert_qp(rdi, qp);

        if (lastwqe) {
                ev.device = qp->ibqp.device;
                ev.element.qp = &qp->ibqp;
                ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
                qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
        }
        if (mig) {
                ev.device = qp->ibqp.device;
                ev.element.qp = &qp->ibqp;
                ev.event = IB_EVENT_PATH_MIG;
                qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
        }
        return 0;

inval:
        spin_unlock(&qp->s_lock);
        spin_unlock(&qp->s_hlock);
        spin_unlock_irq(&qp->r_lock);
        return -EINVAL;
}

/**
 * rvt_destroy_qp - destroy a queue pair
 * @ibqp: the queue pair to destroy
 *
 * Note that this can be called while the QP is actively sending or
 * receiving!
 *
 * Return: 0 on success.
 */
int rvt_destroy_qp(struct ib_qp *ibqp, struct ib_udata *udata)
{
        struct rvt_qp *qp = ibqp_to_rvtqp(ibqp);
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);

        rvt_reset_qp(rdi, qp, ibqp->qp_type);

        wait_event(qp->wait, !atomic_read(&qp->refcount));
        /* qpn is now available for use again */
        rvt_free_qpn(&rdi->qp_dev->qpn_table, qp->ibqp.qp_num);

        spin_lock(&rdi->n_qps_lock);
        rdi->n_qps_allocated--;
        if (qp->ibqp.qp_type == IB_QPT_RC) {
                rdi->n_rc_qps--;
                rdi->busy_jiffies = rdi->n_rc_qps / RC_QP_SCALING_INTERVAL;
        }
        spin_unlock(&rdi->n_qps_lock);

        if (qp->ip)
                kref_put(&qp->ip->ref, rvt_release_mmap_info);
        kvfree(qp->r_rq.kwq);
        rdi->driver_f.qp_priv_free(rdi, qp);
        kfree(qp->s_ack_queue);
        rdma_destroy_ah_attr(&qp->remote_ah_attr);
        rdma_destroy_ah_attr(&qp->alt_ah_attr);
        free_ud_wq_attr(qp);
        vfree(qp->s_wq);
        kfree(qp);
        return 0;
}

/**
 * rvt_query_qp - query an ipbq
 * @ibqp: IB qp to query
 * @attr: attr struct to fill in
 * @attr_mask: attr mask ignored
 * @init_attr: struct to fill in
 *
 * Return: always 0
 */
int rvt_query_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
                 int attr_mask, struct ib_qp_init_attr *init_attr)
{
        struct rvt_qp *qp = ibqp_to_rvtqp(ibqp);
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);

        attr->qp_state = qp->state;
        attr->cur_qp_state = attr->qp_state;
        attr->path_mtu = rdi->driver_f.mtu_to_path_mtu(qp->pmtu);
        attr->path_mig_state = qp->s_mig_state;
        attr->qkey = qp->qkey;
        attr->rq_psn = qp->r_psn & rdi->dparms.psn_mask;
        attr->sq_psn = qp->s_next_psn & rdi->dparms.psn_mask;
        attr->dest_qp_num = qp->remote_qpn;
        attr->qp_access_flags = qp->qp_access_flags;
        attr->cap.max_send_wr = qp->s_size - 1 -
                rdi->dparms.reserved_operations;
        attr->cap.max_recv_wr = qp->ibqp.srq ? 0 : qp->r_rq.size - 1;
        attr->cap.max_send_sge = qp->s_max_sge;
        attr->cap.max_recv_sge = qp->r_rq.max_sge;
        attr->cap.max_inline_data = 0;
        attr->ah_attr = qp->remote_ah_attr;
        attr->alt_ah_attr = qp->alt_ah_attr;
        attr->pkey_index = qp->s_pkey_index;
        attr->alt_pkey_index = qp->s_alt_pkey_index;
        attr->en_sqd_async_notify = 0;
        attr->sq_draining = qp->s_draining;
        attr->max_rd_atomic = qp->s_max_rd_atomic;
        attr->max_dest_rd_atomic = qp->r_max_rd_atomic;
        attr->min_rnr_timer = qp->r_min_rnr_timer;
        attr->port_num = qp->port_num;
        attr->timeout = qp->timeout;
        attr->retry_cnt = qp->s_retry_cnt;
        attr->rnr_retry = qp->s_rnr_retry_cnt;
        attr->alt_port_num =
                rdma_ah_get_port_num(&qp->alt_ah_attr);
        attr->alt_timeout = qp->alt_timeout;

        init_attr->event_handler = qp->ibqp.event_handler;
        init_attr->qp_context = qp->ibqp.qp_context;
        init_attr->send_cq = qp->ibqp.send_cq;
        init_attr->recv_cq = qp->ibqp.recv_cq;
        init_attr->srq = qp->ibqp.srq;
        init_attr->cap = attr->cap;
        if (qp->s_flags & RVT_S_SIGNAL_REQ_WR)
                init_attr->sq_sig_type = IB_SIGNAL_REQ_WR;
        else
                init_attr->sq_sig_type = IB_SIGNAL_ALL_WR;
        init_attr->qp_type = qp->ibqp.qp_type;
        init_attr->port_num = qp->port_num;
        return 0;
}

/**
 * rvt_post_receive - post a receive on a QP
 * @ibqp: the QP to post the receive on
 * @wr: the WR to post
 * @bad_wr: the first bad WR is put here
 *
 * This may be called from interrupt context.
 *
 * Return: 0 on success otherwise errno
 */
int rvt_post_recv(struct ib_qp *ibqp, const struct ib_recv_wr *wr,
                  const struct ib_recv_wr **bad_wr)
{
        struct rvt_qp *qp = ibqp_to_rvtqp(ibqp);
        struct rvt_krwq *wq = qp->r_rq.kwq;
        unsigned long flags;
        int qp_err_flush = (ib_rvt_state_ops[qp->state] & RVT_FLUSH_RECV) &&
                                !qp->ibqp.srq;

        /* Check that state is OK to post receive. */
        if (!(ib_rvt_state_ops[qp->state] & RVT_POST_RECV_OK) || !wq) {
                *bad_wr = wr;
                return -EINVAL;
        }

        for (; wr; wr = wr->next) {
                struct rvt_rwqe *wqe;
                u32 next;
                int i;

                if ((unsigned)wr->num_sge > qp->r_rq.max_sge) {
                        *bad_wr = wr;
                        return -EINVAL;
                }

                spin_lock_irqsave(&qp->r_rq.kwq->p_lock, flags);
                next = wq->head + 1;
                if (next >= qp->r_rq.size)
                        next = 0;
                if (next == READ_ONCE(wq->tail)) {
                        spin_unlock_irqrestore(&qp->r_rq.kwq->p_lock, flags);
                        *bad_wr = wr;
                        return -ENOMEM;
                }
                if (unlikely(qp_err_flush)) {
                        struct ib_wc wc;

                        memset(&wc, 0, sizeof(wc));
                        wc.qp = &qp->ibqp;
                        wc.opcode = IB_WC_RECV;
                        wc.wr_id = wr->wr_id;
                        wc.status = IB_WC_WR_FLUSH_ERR;
                        rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc, 1);
                } else {
                        wqe = rvt_get_rwqe_ptr(&qp->r_rq, wq->head);
                        wqe->wr_id = wr->wr_id;
                        wqe->num_sge = wr->num_sge;
                        for (i = 0; i < wr->num_sge; i++) {
                                wqe->sg_list[i].addr = wr->sg_list[i].addr;
                                wqe->sg_list[i].length = wr->sg_list[i].length;
                                wqe->sg_list[i].lkey = wr->sg_list[i].lkey;
                        }
                        /*
                         * Make sure queue entry is written
                         * before the head index.
                         */
                        smp_store_release(&wq->head, next);
                }
                spin_unlock_irqrestore(&qp->r_rq.kwq->p_lock, flags);
        }
        return 0;
}

/**
 * rvt_qp_valid_operation - validate post send wr request
 * @qp - the qp
 * @post-parms - the post send table for the driver
 * @wr - the work request
 *
 * The routine validates the operation based on the
 * validation table an returns the length of the operation
 * which can extend beyond the ib_send_bw.  Operation
 * dependent flags key atomic operation validation.
 *
 * There is an exception for UD qps that validates the pd and
 * overrides the length to include the additional UD specific
 * length.
 *
 * Returns a negative error or the length of the work request
 * for building the swqe.
 */
static inline int rvt_qp_valid_operation(
        struct rvt_qp *qp,
        const struct rvt_operation_params *post_parms,
        const struct ib_send_wr *wr)
{
        int len;

        if (wr->opcode >= RVT_OPERATION_MAX || !post_parms[wr->opcode].length)
                return -EINVAL;
        if (!(post_parms[wr->opcode].qpt_support & BIT(qp->ibqp.qp_type)))
                return -EINVAL;
        if ((post_parms[wr->opcode].flags & RVT_OPERATION_PRIV) &&
            ibpd_to_rvtpd(qp->ibqp.pd)->user)
                return -EINVAL;
        if (post_parms[wr->opcode].flags & RVT_OPERATION_ATOMIC_SGE &&
            (wr->num_sge == 0 ||
             wr->sg_list[0].length < sizeof(u64) ||
             wr->sg_list[0].addr & (sizeof(u64) - 1)))
                return -EINVAL;
        if (post_parms[wr->opcode].flags & RVT_OPERATION_ATOMIC &&
            !qp->s_max_rd_atomic)
                return -EINVAL;
        len = post_parms[wr->opcode].length;
        /* UD specific */
        if (qp->ibqp.qp_type != IB_QPT_UC &&
            qp->ibqp.qp_type != IB_QPT_RC) {
                if (qp->ibqp.pd != ud_wr(wr)->ah->pd)
                        return -EINVAL;
                len = sizeof(struct ib_ud_wr);
        }
        return len;
}

/**
 * rvt_qp_is_avail - determine queue capacity
 * @qp: the qp
 * @rdi: the rdmavt device
 * @reserved_op: is reserved operation
 *
 * This assumes the s_hlock is held but the s_last
 * qp variable is uncontrolled.
 *
 * For non reserved operations, the qp->s_avail
 * may be changed.
 *
 * The return value is zero or a -ENOMEM.
 */
static inline int rvt_qp_is_avail(
        struct rvt_qp *qp,
        struct rvt_dev_info *rdi,
        bool reserved_op)
{
        u32 slast;
        u32 avail;
        u32 reserved_used;

        /* see rvt_qp_wqe_unreserve() */
        smp_mb__before_atomic();
        if (unlikely(reserved_op)) {
                /* see rvt_qp_wqe_unreserve() */
                reserved_used = atomic_read(&qp->s_reserved_used);
                if (reserved_used >= rdi->dparms.reserved_operations)
                        return -ENOMEM;
                return 0;
        }
        /* non-reserved operations */
        if (likely(qp->s_avail))
                return 0;
        /* See rvt_qp_complete_swqe() */
        slast = smp_load_acquire(&qp->s_last);
        if (qp->s_head >= slast)
                avail = qp->s_size - (qp->s_head - slast);
        else
                avail = slast - qp->s_head;

        reserved_used = atomic_read(&qp->s_reserved_used);
        avail =  avail - 1 -
                (rdi->dparms.reserved_operations - reserved_used);
        /* insure we don't assign a negative s_avail */
        if ((s32)avail <= 0)
                return -ENOMEM;
        qp->s_avail = avail;
        if (WARN_ON(qp->s_avail >
                    (qp->s_size - 1 - rdi->dparms.reserved_operations)))
                rvt_pr_err(rdi,

                           "More avail entries than QP RB size.\nQP: %u, size: %u, avail: %u\nhead: %u, tail: %u, cur: %u, acked: %u, last: %u",
                           qp->ibqp.qp_num, qp->s_size, qp->s_avail,
                           qp->s_head, qp->s_tail, qp->s_cur,
                           qp->s_acked, qp->s_last);
        return 0;
}

/**
 * rvt_post_one_wr - post one RC, UC, or UD send work request
 * @qp: the QP to post on
 * @wr: the work request to send
 */
static int rvt_post_one_wr(struct rvt_qp *qp,
                           const struct ib_send_wr *wr,
                           bool *call_send)
{
        struct rvt_swqe *wqe;
        u32 next;
        int i;
        int j;
        int acc;
        struct rvt_lkey_table *rkt;
        struct rvt_pd *pd;
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
        u8 log_pmtu;
        int ret;
        size_t cplen;
        bool reserved_op;
        int local_ops_delayed = 0;

        BUILD_BUG_ON(IB_QPT_MAX >= (sizeof(u32) * BITS_PER_BYTE));

        /* IB spec says that num_sge == 0 is OK. */
        if (unlikely(wr->num_sge > qp->s_max_sge))
                return -EINVAL;

        ret = rvt_qp_valid_operation(qp, rdi->post_parms, wr);
        if (ret < 0)
                return ret;
        cplen = ret;

        /*
         * Local operations include fast register and local invalidate.
         * Fast register needs to be processed immediately because the
         * registered lkey may be used by following work requests and the
         * lkey needs to be valid at the time those requests are posted.
         * Local invalidate can be processed immediately if fencing is
         * not required and no previous local invalidate ops are pending.
         * Signaled local operations that have been processed immediately
         * need to have requests with "completion only" flags set posted
         * to the send queue in order to generate completions.
         */
        if ((rdi->post_parms[wr->opcode].flags & RVT_OPERATION_LOCAL)) {
                switch (wr->opcode) {
                case IB_WR_REG_MR:
                        ret = rvt_fast_reg_mr(qp,
                                              reg_wr(wr)->mr,
                                              reg_wr(wr)->key,
                                              reg_wr(wr)->access);
                        if (ret || !(wr->send_flags & IB_SEND_SIGNALED))
                                return ret;
                        break;
                case IB_WR_LOCAL_INV:
                        if ((wr->send_flags & IB_SEND_FENCE) ||
                            atomic_read(&qp->local_ops_pending)) {
                                local_ops_delayed = 1;
                        } else {
                                ret = rvt_invalidate_rkey(
                                        qp, wr->ex.invalidate_rkey);
                                if (ret || !(wr->send_flags & IB_SEND_SIGNALED))
                                        return ret;
                        }
                        break;
                default:
                        return -EINVAL;
                }
        }

        reserved_op = rdi->post_parms[wr->opcode].flags &
                        RVT_OPERATION_USE_RESERVE;
        /* check for avail */
        ret = rvt_qp_is_avail(qp, rdi, reserved_op);
        if (ret)
                return ret;
        next = qp->s_head + 1;
        if (next >= qp->s_size)
                next = 0;

        rkt = &rdi->lkey_table;
        pd = ibpd_to_rvtpd(qp->ibqp.pd);
        wqe = rvt_get_swqe_ptr(qp, qp->s_head);

        /* cplen has length from above */
        memcpy(&wqe->wr, wr, cplen);

        wqe->length = 0;
        j = 0;
        if (wr->num_sge) {
                struct rvt_sge *last_sge = NULL;

                acc = wr->opcode >= IB_WR_RDMA_READ ?
                        IB_ACCESS_LOCAL_WRITE : 0;
                for (i = 0; i < wr->num_sge; i++) {
                        u32 length = wr->sg_list[i].length;

                        if (length == 0)
                                continue;
                        ret = rvt_lkey_ok(rkt, pd, &wqe->sg_list[j], last_sge,
                                          &wr->sg_list[i], acc);
                        if (unlikely(ret < 0))
                                goto bail_inval_free;
                        wqe->length += length;
                        if (ret)
                                last_sge = &wqe->sg_list[j];
                        j += ret;
                }
                wqe->wr.num_sge = j;
        }

        /*
         * Calculate and set SWQE PSN values prior to handing it off
         * to the driver's check routine. This give the driver the
         * opportunity to adjust PSN values based on internal checks.
         */
        log_pmtu = qp->log_pmtu;
        if (qp->allowed_ops == IB_OPCODE_UD) {
                struct rvt_ah *ah = rvt_get_swqe_ah(wqe);

                log_pmtu = ah->log_pmtu;
                rdma_copy_ah_attr(wqe->ud_wr.attr, &ah->attr);
        }

        if (rdi->post_parms[wr->opcode].flags & RVT_OPERATION_LOCAL) {
                if (local_ops_delayed)
                        atomic_inc(&qp->local_ops_pending);
                else
                        wqe->wr.send_flags |= RVT_SEND_COMPLETION_ONLY;
                wqe->ssn = 0;
                wqe->psn = 0;
                wqe->lpsn = 0;
        } else {
                wqe->ssn = qp->s_ssn++;
                wqe->psn = qp->s_next_psn;
                wqe->lpsn = wqe->psn +
                                (wqe->length ?
                                        ((wqe->length - 1) >> log_pmtu) :
                                        0);
        }

        /* general part of wqe valid - allow for driver checks */
        if (rdi->driver_f.setup_wqe) {
                ret = rdi->driver_f.setup_wqe(qp, wqe, call_send);
                if (ret < 0)
                        goto bail_inval_free_ref;
        }

        if (!(rdi->post_parms[wr->opcode].flags & RVT_OPERATION_LOCAL))
                qp->s_next_psn = wqe->lpsn + 1;

        if (unlikely(reserved_op)) {
                wqe->wr.send_flags |= RVT_SEND_RESERVE_USED;
                rvt_qp_wqe_reserve(qp, wqe);
        } else {
                wqe->wr.send_flags &= ~RVT_SEND_RESERVE_USED;
                qp->s_avail--;
        }
        trace_rvt_post_one_wr(qp, wqe, wr->num_sge);
        smp_wmb(); /* see request builders */
        qp->s_head = next;

        return 0;

bail_inval_free_ref:
        if (qp->allowed_ops == IB_OPCODE_UD)
                rdma_destroy_ah_attr(wqe->ud_wr.attr);
bail_inval_free:
        /* release mr holds */
        while (j) {
                struct rvt_sge *sge = &wqe->sg_list[--j];

                rvt_put_mr(sge->mr);
        }
        return ret;
}

/**
 * rvt_post_send - post a send on a QP
 * @ibqp: the QP to post the send on
 * @wr: the list of work requests to post
 * @bad_wr: the first bad WR is put here
 *
 * This may be called from interrupt context.
 *
 * Return: 0 on success else errno
 */
int rvt_post_send(struct ib_qp *ibqp, const struct ib_send_wr *wr,
                  const struct ib_send_wr **bad_wr)
{
        struct rvt_qp *qp = ibqp_to_rvtqp(ibqp);
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);
        unsigned long flags = 0;
        bool call_send;
        unsigned nreq = 0;
        int err = 0;

        spin_lock_irqsave(&qp->s_hlock, flags);

        /*
         * Ensure QP state is such that we can send. If not bail out early,
         * there is no need to do this every time we post a send.
         */
        if (unlikely(!(ib_rvt_state_ops[qp->state] & RVT_POST_SEND_OK))) {
                spin_unlock_irqrestore(&qp->s_hlock, flags);
                return -EINVAL;
        }

        /*
         * If the send queue is empty, and we only have a single WR then just go
         * ahead and kick the send engine into gear. Otherwise we will always
         * just schedule the send to happen later.
         */
        call_send = qp->s_head == READ_ONCE(qp->s_last) && !wr->next;

        for (; wr; wr = wr->next) {
                err = rvt_post_one_wr(qp, wr, &call_send);
                if (unlikely(err)) {
                        *bad_wr = wr;
                        goto bail;
                }
                nreq++;
        }
bail:
        spin_unlock_irqrestore(&qp->s_hlock, flags);
        if (nreq) {
                /*
                 * Only call do_send if there is exactly one packet, and the
                 * driver said it was ok.
                 */
                if (nreq == 1 && call_send)
                        rdi->driver_f.do_send(qp);
                else
                        rdi->driver_f.schedule_send_no_lock(qp);
        }
        return err;
}

/**
 * rvt_post_srq_receive - post a receive on a shared receive queue
 * @ibsrq: the SRQ to post the receive on
 * @wr: the list of work requests to post
 * @bad_wr: A pointer to the first WR to cause a problem is put here
 *
 * This may be called from interrupt context.
 *
 * Return: 0 on success else errno
 */
int rvt_post_srq_recv(struct ib_srq *ibsrq, const struct ib_recv_wr *wr,
                      const struct ib_recv_wr **bad_wr)
{
        struct rvt_srq *srq = ibsrq_to_rvtsrq(ibsrq);
        struct rvt_krwq *wq;
        unsigned long flags;

        for (; wr; wr = wr->next) {
                struct rvt_rwqe *wqe;
                u32 next;
                int i;

                if ((unsigned)wr->num_sge > srq->rq.max_sge) {
                        *bad_wr = wr;
                        return -EINVAL;
                }

                spin_lock_irqsave(&srq->rq.kwq->p_lock, flags);
                wq = srq->rq.kwq;
                next = wq->head + 1;
                if (next >= srq->rq.size)
                        next = 0;
                if (next == READ_ONCE(wq->tail)) {
                        spin_unlock_irqrestore(&srq->rq.kwq->p_lock, flags);
                        *bad_wr = wr;
                        return -ENOMEM;
                }

                wqe = rvt_get_rwqe_ptr(&srq->rq, wq->head);
                wqe->wr_id = wr->wr_id;
                wqe->num_sge = wr->num_sge;
                for (i = 0; i < wr->num_sge; i++) {
                        wqe->sg_list[i].addr = wr->sg_list[i].addr;
                        wqe->sg_list[i].length = wr->sg_list[i].length;
                        wqe->sg_list[i].lkey = wr->sg_list[i].lkey;
                }
                /* Make sure queue entry is written before the head index. */
                smp_store_release(&wq->head, next);
                spin_unlock_irqrestore(&srq->rq.kwq->p_lock, flags);
        }
        return 0;
}

/*
 * rvt used the internal kernel struct as part of its ABI, for now make sure
 * the kernel struct does not change layout. FIXME: rvt should never cast the
 * user struct to a kernel struct.
 */
static struct ib_sge *rvt_cast_sge(struct rvt_wqe_sge *sge)
{
        BUILD_BUG_ON(offsetof(struct ib_sge, addr) !=
                     offsetof(struct rvt_wqe_sge, addr));
        BUILD_BUG_ON(offsetof(struct ib_sge, length) !=
                     offsetof(struct rvt_wqe_sge, length));
        BUILD_BUG_ON(offsetof(struct ib_sge, lkey) !=
                     offsetof(struct rvt_wqe_sge, lkey));
        return (struct ib_sge *)sge;
}

/*
 * Validate a RWQE and fill in the SGE state.
 * Return 1 if OK.
 */
static int init_sge(struct rvt_qp *qp, struct rvt_rwqe *wqe)
{
        int i, j, ret;
        struct ib_wc wc;
        struct rvt_lkey_table *rkt;
        struct rvt_pd *pd;
        struct rvt_sge_state *ss;
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);

        rkt = &rdi->lkey_table;
        pd = ibpd_to_rvtpd(qp->ibqp.srq ? qp->ibqp.srq->pd : qp->ibqp.pd);
        ss = &qp->r_sge;
        ss->sg_list = qp->r_sg_list;
        qp->r_len = 0;
        for (i = j = 0; i < wqe->num_sge; i++) {
                if (wqe->sg_list[i].length == 0)
                        continue;
                /* Check LKEY */
                ret = rvt_lkey_ok(rkt, pd, j ? &ss->sg_list[j - 1] : &ss->sge,
                                  NULL, rvt_cast_sge(&wqe->sg_list[i]),
                                  IB_ACCESS_LOCAL_WRITE);
                if (unlikely(ret <= 0))
                        goto bad_lkey;
                qp->r_len += wqe->sg_list[i].length;
                j++;
        }
        ss->num_sge = j;
        ss->total_len = qp->r_len;
        return 1;

bad_lkey:
        while (j) {
                struct rvt_sge *sge = --j ? &ss->sg_list[j - 1] : &ss->sge;

                rvt_put_mr(sge->mr);
        }
        ss->num_sge = 0;
        memset(&wc, 0, sizeof(wc));
        wc.wr_id = wqe->wr_id;
        wc.status = IB_WC_LOC_PROT_ERR;
        wc.opcode = IB_WC_RECV;
        wc.qp = &qp->ibqp;
        /* Signal solicited completion event. */
        rvt_cq_enter(ibcq_to_rvtcq(qp->ibqp.recv_cq), &wc, 1);
        return 0;
}

/**
 * get_rvt_head - get head indices of the circular buffer
 * @rq: data structure for request queue entry
 * @ip: the QP
 *
 * Return - head index value
 */
static inline u32 get_rvt_head(struct rvt_rq *rq, void *ip)
{
        u32 head;

        if (ip)
                head = RDMA_READ_UAPI_ATOMIC(rq->wq->head);
        else
                head = rq->kwq->head;

        return head;
}

/**
 * rvt_get_rwqe - copy the next RWQE into the QP's RWQE
 * @qp: the QP
 * @wr_id_only: update qp->r_wr_id only, not qp->r_sge
 *
 * Return -1 if there is a local error, 0 if no RWQE is available,
 * otherwise return 1.
 *
 * Can be called from interrupt level.
 */
int rvt_get_rwqe(struct rvt_qp *qp, bool wr_id_only)
{
        unsigned long flags;
        struct rvt_rq *rq;
        struct rvt_krwq *kwq = NULL;
        struct rvt_rwq *wq;
        struct rvt_srq *srq;
        struct rvt_rwqe *wqe;
        void (*handler)(struct ib_event *, void *);
        u32 tail;
        u32 head;
        int ret;
        void *ip = NULL;

        if (qp->ibqp.srq) {
                srq = ibsrq_to_rvtsrq(qp->ibqp.srq);
                handler = srq->ibsrq.event_handler;
                rq = &srq->rq;
                ip = srq->ip;
        } else {
                srq = NULL;
                handler = NULL;
                rq = &qp->r_rq;
                ip = qp->ip;
        }

        spin_lock_irqsave(&rq->kwq->c_lock, flags);
        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK)) {
                ret = 0;
                goto unlock;
        }
        kwq = rq->kwq;
        if (ip) {
                wq = rq->wq;
                tail = RDMA_READ_UAPI_ATOMIC(wq->tail);
        } else {
                tail = kwq->tail;
        }

        /* Validate tail before using it since it is user writable. */
        if (tail >= rq->size)
                tail = 0;

        if (kwq->count < RVT_RWQ_COUNT_THRESHOLD) {
                head = get_rvt_head(rq, ip);
                kwq->count = rvt_get_rq_count(rq, head, tail);
        }
        if (unlikely(kwq->count == 0)) {
                ret = 0;
                goto unlock;
        }
        /* Make sure entry is read after the count is read. */
        smp_rmb();
        wqe = rvt_get_rwqe_ptr(rq, tail);
        /*
         * Even though we update the tail index in memory, the verbs
         * consumer is not supposed to post more entries until a
         * completion is generated.
         */
        if (++tail >= rq->size)
                tail = 0;
        if (ip)
                RDMA_WRITE_UAPI_ATOMIC(wq->tail, tail);
        else
                kwq->tail = tail;
        if (!wr_id_only && !init_sge(qp, wqe)) {
                ret = -1;
                goto unlock;
        }
        qp->r_wr_id = wqe->wr_id;

        kwq->count--;
        ret = 1;
        set_bit(RVT_R_WRID_VALID, &qp->r_aflags);
        if (handler) {
                /*
                 * Validate head pointer value and compute
                 * the number of remaining WQEs.
                 */
                if (kwq->count < srq->limit) {
                        kwq->count =
                                rvt_get_rq_count(rq,
                                                 get_rvt_head(rq, ip), tail);
                        if (kwq->count < srq->limit) {
                                struct ib_event ev;

                                srq->limit = 0;
                                spin_unlock_irqrestore(&rq->kwq->c_lock, flags);
                                ev.device = qp->ibqp.device;
                                ev.element.srq = qp->ibqp.srq;
                                ev.event = IB_EVENT_SRQ_LIMIT_REACHED;
                                handler(&ev, srq->ibsrq.srq_context);
                                goto bail;
                        }
                }
        }
unlock:
        spin_unlock_irqrestore(&rq->kwq->c_lock, flags);
bail:
        return ret;
}
EXPORT_SYMBOL(rvt_get_rwqe);

/**
 * qp_comm_est - handle trap with QP established
 * @qp: the QP
 */
void rvt_comm_est(struct rvt_qp *qp)
{
        qp->r_flags |= RVT_R_COMM_EST;
        if (qp->ibqp.event_handler) {
                struct ib_event ev;

                ev.device = qp->ibqp.device;
                ev.element.qp = &qp->ibqp;
                ev.event = IB_EVENT_COMM_EST;
                qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
        }
}
EXPORT_SYMBOL(rvt_comm_est);

void rvt_rc_error(struct rvt_qp *qp, enum ib_wc_status err)
{
        unsigned long flags;
        int lastwqe;

        spin_lock_irqsave(&qp->s_lock, flags);
        lastwqe = rvt_error_qp(qp, err);
        spin_unlock_irqrestore(&qp->s_lock, flags);

        if (lastwqe) {
                struct ib_event ev;

                ev.device = qp->ibqp.device;
                ev.element.qp = &qp->ibqp;
                ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
                qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
        }
}
EXPORT_SYMBOL(rvt_rc_error);

/*
 *  rvt_rnr_tbl_to_usec - return index into ib_rvt_rnr_table
 *  @index - the index
 *  return usec from an index into ib_rvt_rnr_table
 */
unsigned long rvt_rnr_tbl_to_usec(u32 index)
{
        return ib_rvt_rnr_table[(index & IB_AETH_CREDIT_MASK)];
}
EXPORT_SYMBOL(rvt_rnr_tbl_to_usec);

static inline unsigned long rvt_aeth_to_usec(u32 aeth)
{
        return ib_rvt_rnr_table[(aeth >> IB_AETH_CREDIT_SHIFT) &
                                  IB_AETH_CREDIT_MASK];
}

/*
 *  rvt_add_retry_timer_ext - add/start a retry timer
 *  @qp - the QP
 *  @shift - timeout shift to wait for multiple packets
 *  add a retry timer on the QP
 */
void rvt_add_retry_timer_ext(struct rvt_qp *qp, u8 shift)
{
        struct ib_qp *ibqp = &qp->ibqp;
        struct rvt_dev_info *rdi = ib_to_rvt(ibqp->device);

        lockdep_assert_held(&qp->s_lock);
        qp->s_flags |= RVT_S_TIMER;
       /* 4.096 usec. * (1 << qp->timeout) */
        qp->s_timer.expires = jiffies + rdi->busy_jiffies +
                              (qp->timeout_jiffies << shift);
        add_timer(&qp->s_timer);
}
EXPORT_SYMBOL(rvt_add_retry_timer_ext);

/**
 * rvt_add_rnr_timer - add/start an rnr timer on the QP
 * @qp: the QP
 * @aeth: aeth of RNR timeout, simulated aeth for loopback
 */
void rvt_add_rnr_timer(struct rvt_qp *qp, u32 aeth)
{
        u32 to;

        lockdep_assert_held(&qp->s_lock);
        qp->s_flags |= RVT_S_WAIT_RNR;
        to = rvt_aeth_to_usec(aeth);
        trace_rvt_rnrnak_add(qp, to);
        hrtimer_start(&qp->s_rnr_timer,
                      ns_to_ktime(1000 * to), HRTIMER_MODE_REL_PINNED);
}
EXPORT_SYMBOL(rvt_add_rnr_timer);

/**
 * rvt_stop_rc_timers - stop all timers
 * @qp: the QP
 * stop any pending timers
 */
void rvt_stop_rc_timers(struct rvt_qp *qp)
{
        lockdep_assert_held(&qp->s_lock);
        /* Remove QP from all timers */
        if (qp->s_flags & (RVT_S_TIMER | RVT_S_WAIT_RNR)) {
                qp->s_flags &= ~(RVT_S_TIMER | RVT_S_WAIT_RNR);
                del_timer(&qp->s_timer);
                hrtimer_try_to_cancel(&qp->s_rnr_timer);
        }
}
EXPORT_SYMBOL(rvt_stop_rc_timers);

/**
 * rvt_stop_rnr_timer - stop an rnr timer
 * @qp - the QP
 *
 * stop an rnr timer and return if the timer
 * had been pending.
 */
static void rvt_stop_rnr_timer(struct rvt_qp *qp)
{
        lockdep_assert_held(&qp->s_lock);
        /* Remove QP from rnr timer */
        if (qp->s_flags & RVT_S_WAIT_RNR) {
                qp->s_flags &= ~RVT_S_WAIT_RNR;
                trace_rvt_rnrnak_stop(qp, 0);
        }
}

/**
 * rvt_del_timers_sync - wait for any timeout routines to exit
 * @qp: the QP
 */
void rvt_del_timers_sync(struct rvt_qp *qp)
{
        del_timer_sync(&qp->s_timer);
        hrtimer_cancel(&qp->s_rnr_timer);
}
EXPORT_SYMBOL(rvt_del_timers_sync);

/*
 * This is called from s_timer for missing responses.
 */
static void rvt_rc_timeout(struct timer_list *t)
{
        struct rvt_qp *qp = from_timer(qp, t, s_timer);
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
        unsigned long flags;

        spin_lock_irqsave(&qp->r_lock, flags);
        spin_lock(&qp->s_lock);
        if (qp->s_flags & RVT_S_TIMER) {
                struct rvt_ibport *rvp = rdi->ports[qp->port_num - 1];

                qp->s_flags &= ~RVT_S_TIMER;
                rvp->n_rc_timeouts++;
                del_timer(&qp->s_timer);
                trace_rvt_rc_timeout(qp, qp->s_last_psn + 1);
                if (rdi->driver_f.notify_restart_rc)
                        rdi->driver_f.notify_restart_rc(qp,
                                                        qp->s_last_psn + 1,
                                                        1);
                rdi->driver_f.schedule_send(qp);
        }
        spin_unlock(&qp->s_lock);
        spin_unlock_irqrestore(&qp->r_lock, flags);
}

/*
 * This is called from s_timer for RNR timeouts.
 */
enum hrtimer_restart rvt_rc_rnr_retry(struct hrtimer *t)
{
        struct rvt_qp *qp = container_of(t, struct rvt_qp, s_rnr_timer);
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
        unsigned long flags;

        spin_lock_irqsave(&qp->s_lock, flags);
        rvt_stop_rnr_timer(qp);
        trace_rvt_rnrnak_timeout(qp, 0);
        rdi->driver_f.schedule_send(qp);
        spin_unlock_irqrestore(&qp->s_lock, flags);
        return HRTIMER_NORESTART;
}
EXPORT_SYMBOL(rvt_rc_rnr_retry);

/**
 * rvt_qp_iter_init - initial for QP iteration
 * @rdi: rvt devinfo
 * @v: u64 value
 * @cb: user-defined callback
 *
 * This returns an iterator suitable for iterating QPs
 * in the system.
 *
 * The @cb is a user-defined callback and @v is a 64-bit
 * value passed to and relevant for processing in the
 * @cb.  An example use case would be to alter QP processing
 * based on criteria not part of the rvt_qp.
 *
 * Use cases that require memory allocation to succeed
 * must preallocate appropriately.
 *
 * Return: a pointer to an rvt_qp_iter or NULL
 */
struct rvt_qp_iter *rvt_qp_iter_init(struct rvt_dev_info *rdi,
                                     u64 v,
                                     void (*cb)(struct rvt_qp *qp, u64 v))
{
        struct rvt_qp_iter *i;

        i = kzalloc(sizeof(*i), GFP_KERNEL);
        if (!i)
                return NULL;

        i->rdi = rdi;
        /* number of special QPs (SMI/GSI) for device */
        i->specials = rdi->ibdev.phys_port_cnt * 2;
        i->v = v;
        i->cb = cb;

        return i;
}
EXPORT_SYMBOL(rvt_qp_iter_init);

/**
 * rvt_qp_iter_next - return the next QP in iter
 * @iter: the iterator
 *
 * Fine grained QP iterator suitable for use
 * with debugfs seq_file mechanisms.
 *
 * Updates iter->qp with the current QP when the return
 * value is 0.
 *
 * Return: 0 - iter->qp is valid 1 - no more QPs
 */
int rvt_qp_iter_next(struct rvt_qp_iter *iter)
        __must_hold(RCU)
{
        int n = iter->n;
        int ret = 1;
        struct rvt_qp *pqp = iter->qp;
        struct rvt_qp *qp;
        struct rvt_dev_info *rdi = iter->rdi;

        /*
         * The approach is to consider the special qps
         * as additional table entries before the
         * real hash table.  Since the qp code sets
         * the qp->next hash link to NULL, this works just fine.
         *
         * iter->specials is 2 * # ports
         *
         * n = 0..iter->specials is the special qp indices
         *
         * n = iter->specials..rdi->qp_dev->qp_table_size+iter->specials are
         * the potential hash bucket entries
         *
         */
        for (; n <  rdi->qp_dev->qp_table_size + iter->specials; n++) {
                if (pqp) {
                        qp = rcu_dereference(pqp->next);
                } else {
                        if (n < iter->specials) {
                                struct rvt_ibport *rvp;
                                int pidx;

                                pidx = n % rdi->ibdev.phys_port_cnt;
                                rvp = rdi->ports[pidx];
                                qp = rcu_dereference(rvp->qp[n & 1]);
                        } else {
                                qp = rcu_dereference(
                                        rdi->qp_dev->qp_table[
                                                (n - iter->specials)]);
                        }
                }
                pqp = qp;
                if (qp) {
                        iter->qp = qp;
                        iter->n = n;
                        return 0;
                }
        }
        return ret;
}
EXPORT_SYMBOL(rvt_qp_iter_next);

/**
 * rvt_qp_iter - iterate all QPs
 * @rdi: rvt devinfo
 * @v: a 64-bit value
 * @cb: a callback
 *
 * This provides a way for iterating all QPs.
 *
 * The @cb is a user-defined callback and @v is a 64-bit
 * value passed to and relevant for processing in the
 * cb.  An example use case would be to alter QP processing
 * based on criteria not part of the rvt_qp.
 *
 * The code has an internal iterator to simplify
 * non seq_file use cases.
 */
void rvt_qp_iter(struct rvt_dev_info *rdi,
                 u64 v,
                 void (*cb)(struct rvt_qp *qp, u64 v))
{
        int ret;
        struct rvt_qp_iter i = {
                .rdi = rdi,
                .specials = rdi->ibdev.phys_port_cnt * 2,
                .v = v,
                .cb = cb
        };

        rcu_read_lock();
        do {
                ret = rvt_qp_iter_next(&i);
                if (!ret) {
                        rvt_get_qp(i.qp);
                        rcu_read_unlock();
                        i.cb(i.qp, i.v);
                        rcu_read_lock();
                        rvt_put_qp(i.qp);
                }
        } while (!ret);
        rcu_read_unlock();
}
EXPORT_SYMBOL(rvt_qp_iter);

/*
 * This should be called with s_lock held.
 */
void rvt_send_complete(struct rvt_qp *qp, struct rvt_swqe *wqe,
                       enum ib_wc_status status)
{
        u32 old_last, last;
        struct rvt_dev_info *rdi;

        if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_OR_FLUSH_SEND))
                return;
        rdi = ib_to_rvt(qp->ibqp.device);

        old_last = qp->s_last;
        trace_rvt_qp_send_completion(qp, wqe, old_last);
        last = rvt_qp_complete_swqe(qp, wqe, rdi->wc_opcode[wqe->wr.opcode],
                                    status);
        if (qp->s_acked == old_last)
                qp->s_acked = last;
        if (qp->s_cur == old_last)
                qp->s_cur = last;
        if (qp->s_tail == old_last)
                qp->s_tail = last;
        if (qp->state == IB_QPS_SQD && last == qp->s_cur)
                qp->s_draining = 0;
}
EXPORT_SYMBOL(rvt_send_complete);

/**
 * rvt_copy_sge - copy data to SGE memory
 * @qp: associated QP
 * @ss: the SGE state
 * @data: the data to copy
 * @length: the length of the data
 * @release: boolean to release MR
 * @copy_last: do a separate copy of the last 8 bytes
 */
void rvt_copy_sge(struct rvt_qp *qp, struct rvt_sge_state *ss,
                  void *data, u32 length,
                  bool release, bool copy_last)
{
        struct rvt_sge *sge = &ss->sge;
        int i;
        bool in_last = false;
        bool cacheless_copy = false;
        struct rvt_dev_info *rdi = ib_to_rvt(qp->ibqp.device);
        struct rvt_wss *wss = rdi->wss;
        unsigned int sge_copy_mode = rdi->dparms.sge_copy_mode;

        if (sge_copy_mode == RVT_SGE_COPY_CACHELESS) {
                cacheless_copy = length >= PAGE_SIZE;
        } else if (sge_copy_mode == RVT_SGE_COPY_ADAPTIVE) {
                if (length >= PAGE_SIZE) {
                        /*
                         * NOTE: this *assumes*:
                         * o The first vaddr is the dest.
                         * o If multiple pages, then vaddr is sequential.
                         */
                        wss_insert(wss, sge->vaddr);
                        if (length >= (2 * PAGE_SIZE))
                                wss_insert(wss, (sge->vaddr + PAGE_SIZE));

                        cacheless_copy = wss_exceeds_threshold(wss);
                } else {
                        wss_advance_clean_counter(wss);
                }
        }

        if (copy_last) {
                if (length > 8) {
                        length -= 8;
                } else {
                        copy_last = false;
                        in_last = true;
                }
        }

again:
        while (length) {
                u32 len = rvt_get_sge_length(sge, length);

                WARN_ON_ONCE(len == 0);
                if (unlikely(in_last)) {
                        /* enforce byte transfer ordering */
                        for (i = 0; i < len; i++)
                                ((u8 *)sge->vaddr)[i] = ((u8 *)data)[i];
                } else if (cacheless_copy) {
                        cacheless_memcpy(sge->vaddr, data, len);
                } else {
                        memcpy(sge->vaddr, data, len);
                }
                rvt_update_sge(ss, len, release);
                data += len;
                length -= len;
        }

        if (copy_last) {
                copy_last = false;
                in_last = true;
                length = 8;
                goto again;
        }
}
EXPORT_SYMBOL(rvt_copy_sge);

static enum ib_wc_status loopback_qp_drop(struct rvt_ibport *rvp,
                                          struct rvt_qp *sqp)
{
        rvp->n_pkt_drops++;
        /*
         * For RC, the requester would timeout and retry so
         * shortcut the timeouts and just signal too many retries.
         */
        return sqp->ibqp.qp_type == IB_QPT_RC ?
                IB_WC_RETRY_EXC_ERR : IB_WC_SUCCESS;
}

/**
 * ruc_loopback - handle UC and RC loopback requests
 * @sqp: the sending QP
 *
 * This is called from rvt_do_send() to forward a WQE addressed to the same HFI
 * Note that although we are single threaded due to the send engine, we still
 * have to protect against post_send().  We don't have to worry about
 * receive interrupts since this is a connected protocol and all packets
 * will pass through here.
 */
void rvt_ruc_loopback(struct rvt_qp *sqp)
{
        struct rvt_ibport *rvp =  NULL;
        struct rvt_dev_info *rdi = ib_to_rvt(sqp->ibqp.device);
        struct rvt_qp *qp;
        struct rvt_swqe *wqe;
        struct rvt_sge *sge;
        unsigned long flags;
        struct ib_wc wc;
        u64 sdata;
        atomic64_t *maddr;
        enum ib_wc_status send_status;
        bool release;
        int ret;
        bool copy_last = false;
        int local_ops = 0;

        rcu_read_lock();
        rvp = rdi->ports[sqp->port_num - 1];

        /*
         * Note that we check the responder QP state after
         * checking the requester's state.
         */

        qp = rvt_lookup_qpn(ib_to_rvt(sqp->ibqp.device), rvp,
                            sqp->remote_qpn);

        spin_lock_irqsave(&sqp->s_lock, flags);

        /* Return if we are already busy processing a work request. */
        if ((sqp->s_flags & (RVT_S_BUSY | RVT_S_ANY_WAIT)) ||
            !(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_OR_FLUSH_SEND))
                goto unlock;

        sqp->s_flags |= RVT_S_BUSY;

again:
        if (sqp->s_last == READ_ONCE(sqp->s_head))
                goto clr_busy;
        wqe = rvt_get_swqe_ptr(sqp, sqp->s_last);

        /* Return if it is not OK to start a new work request. */
        if (!(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_NEXT_SEND_OK)) {
                if (!(ib_rvt_state_ops[sqp->state] & RVT_FLUSH_SEND))
                        goto clr_busy;