/*
 * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the BSD-type
 * license below:
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *      Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *      Redistributions in binary form must reproduce the above
 *      copyright notice, this list of conditions and the following
 *      disclaimer in the documentation and/or other materials provided
 *      with the distribution.
 *
 *      Neither the name of the Network Appliance, Inc. 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.
 */

/*
 * verbs.c
 *
 * Encapsulates the major functions managing:
 *  o adapters
 *  o endpoints
 *  o connections
 *  o buffer memory
 */

#include <linux/pci.h>  /* for Tavor hack below */
#include <linux/slab.h>

#include "xprt_rdma.h"

/*
 * Globals/Macros
 */

#ifdef RPC_DEBUG
# define RPCDBG_FACILITY        RPCDBG_TRANS
#endif

/*
 * internal functions
 */

/*
 * handle replies in tasklet context, using a single, global list
 * rdma tasklet function -- just turn around and call the func
 * for all replies on the list
 */

static DEFINE_SPINLOCK(rpcrdma_tk_lock_g);
static LIST_HEAD(rpcrdma_tasklets_g);

static void
rpcrdma_run_tasklet(unsigned long data)
{
        struct rpcrdma_rep *rep;
        void (*func)(struct rpcrdma_rep *);
        unsigned long flags;

        data = data;
        spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
        while (!list_empty(&rpcrdma_tasklets_g)) {
                rep = list_entry(rpcrdma_tasklets_g.next,
                                 struct rpcrdma_rep, rr_list);
                list_del(&rep->rr_list);
                func = rep->rr_func;
                rep->rr_func = NULL;
                spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);

                if (func)
                        func(rep);
                else
                        rpcrdma_recv_buffer_put(rep);

                spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
        }
        spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);
}

static DECLARE_TASKLET(rpcrdma_tasklet_g, rpcrdma_run_tasklet, 0UL);

static inline void
rpcrdma_schedule_tasklet(struct rpcrdma_rep *rep)
{
        unsigned long flags;

        spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
        list_add_tail(&rep->rr_list, &rpcrdma_tasklets_g);
        spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);
        tasklet_schedule(&rpcrdma_tasklet_g);
}

static void
rpcrdma_qp_async_error_upcall(struct ib_event *event, void *context)
{
        struct rpcrdma_ep *ep = context;

        dprintk("RPC:       %s: QP error %X on device %s ep %p\n",
                __func__, event->event, event->device->name, context);
        if (ep->rep_connected == 1) {
                ep->rep_connected = -EIO;
                ep->rep_func(ep);
                wake_up_all(&ep->rep_connect_wait);
        }
}

static void
rpcrdma_cq_async_error_upcall(struct ib_event *event, void *context)
{
        struct rpcrdma_ep *ep = context;

        dprintk("RPC:       %s: CQ error %X on device %s ep %p\n",
                __func__, event->event, event->device->name, context);
        if (ep->rep_connected == 1) {
                ep->rep_connected = -EIO;
                ep->rep_func(ep);
                wake_up_all(&ep->rep_connect_wait);
        }
}

static inline
void rpcrdma_event_process(struct ib_wc *wc)
{
        struct rpcrdma_rep *rep =
                        (struct rpcrdma_rep *)(unsigned long) wc->wr_id;

        dprintk("RPC:       %s: event rep %p status %X opcode %X length %u\n",
                __func__, rep, wc->status, wc->opcode, wc->byte_len);

        if (!rep) /* send or bind completion that we don't care about */
                return;

        if (IB_WC_SUCCESS != wc->status) {
                dprintk("RPC:       %s: %s WC status %X, connection lost\n",
                        __func__, (wc->opcode & IB_WC_RECV) ? "recv" : "send",
                         wc->status);
                rep->rr_len = ~0U;
                rpcrdma_schedule_tasklet(rep);
                return;
        }

        switch (wc->opcode) {
        case IB_WC_RECV:
                rep->rr_len = wc->byte_len;
                ib_dma_sync_single_for_cpu(
                        rdmab_to_ia(rep->rr_buffer)->ri_id->device,
                        rep->rr_iov.addr, rep->rr_len, DMA_FROM_DEVICE);
                /* Keep (only) the most recent credits, after check validity */
                if (rep->rr_len >= 16) {
                        struct rpcrdma_msg *p =
                                        (struct rpcrdma_msg *) rep->rr_base;
                        unsigned int credits = ntohl(p->rm_credit);
                        if (credits == 0) {
                                dprintk("RPC:       %s: server"
                                        " dropped credits to 0!\n", __func__);
                                /* don't deadlock */
                                credits = 1;
                        } else if (credits > rep->rr_buffer->rb_max_requests) {
                                dprintk("RPC:       %s: server"
                                        " over-crediting: %d (%d)\n",
                                        __func__, credits,
                                        rep->rr_buffer->rb_max_requests);
                                credits = rep->rr_buffer->rb_max_requests;
                        }
                        atomic_set(&rep->rr_buffer->rb_credits, credits);
                }
                /* fall through */
        case IB_WC_BIND_MW:
                rpcrdma_schedule_tasklet(rep);
                break;
        default:
                dprintk("RPC:       %s: unexpected WC event %X\n",
                        __func__, wc->opcode);
                break;
        }
}

static inline int
rpcrdma_cq_poll(struct ib_cq *cq)
{
        struct ib_wc wc;
        int rc;

        for (;;) {
                rc = ib_poll_cq(cq, 1, &wc);
                if (rc < 0) {
                        dprintk("RPC:       %s: ib_poll_cq failed %i\n",
                                __func__, rc);
                        return rc;
                }
                if (rc == 0)
                        break;

                rpcrdma_event_process(&wc);
        }

        return 0;
}

/*
 * rpcrdma_cq_event_upcall
 *
 * This upcall handles recv, send, bind and unbind events.
 * It is reentrant but processes single events in order to maintain
 * ordering of receives to keep server credits.
 *
 * It is the responsibility of the scheduled tasklet to return
 * recv buffers to the pool. NOTE: this affects synchronization of
 * connection shutdown. That is, the structures required for
 * the completion of the reply handler must remain intact until
 * all memory has been reclaimed.
 *
 * Note that send events are suppressed and do not result in an upcall.
 */
static void
rpcrdma_cq_event_upcall(struct ib_cq *cq, void *context)
{
        int rc;

        rc = rpcrdma_cq_poll(cq);
        if (rc)
                return;

        rc = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
        if (rc) {
                dprintk("RPC:       %s: ib_req_notify_cq failed %i\n",
                        __func__, rc);
                return;
        }

        rpcrdma_cq_poll(cq);
}

#ifdef RPC_DEBUG
static const char * const conn[] = {
        "address resolved",
        "address error",
        "route resolved",
        "route error",
        "connect request",
        "connect response",
        "connect error",
        "unreachable",
        "rejected",
        "established",
        "disconnected",
        "device removal"
};
#endif

static int
rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
{
        struct rpcrdma_xprt *xprt = id->context;
        struct rpcrdma_ia *ia = &xprt->rx_ia;
        struct rpcrdma_ep *ep = &xprt->rx_ep;
#ifdef RPC_DEBUG
        struct sockaddr_in *addr = (struct sockaddr_in *) &ep->rep_remote_addr;
#endif
        struct ib_qp_attr attr;
        struct ib_qp_init_attr iattr;
        int connstate = 0;

        switch (event->event) {
        case RDMA_CM_EVENT_ADDR_RESOLVED:
        case RDMA_CM_EVENT_ROUTE_RESOLVED:
                ia->ri_async_rc = 0;
                complete(&ia->ri_done);
                break;
        case RDMA_CM_EVENT_ADDR_ERROR:
                ia->ri_async_rc = -EHOSTUNREACH;
                dprintk("RPC:       %s: CM address resolution error, ep 0x%p\n",
                        __func__, ep);
                complete(&ia->ri_done);
                break;
        case RDMA_CM_EVENT_ROUTE_ERROR:
                ia->ri_async_rc = -ENETUNREACH;
                dprintk("RPC:       %s: CM route resolution error, ep 0x%p\n",
                        __func__, ep);
                complete(&ia->ri_done);
                break;
        case RDMA_CM_EVENT_ESTABLISHED:
                connstate = 1;
                ib_query_qp(ia->ri_id->qp, &attr,
                        IB_QP_MAX_QP_RD_ATOMIC | IB_QP_MAX_DEST_RD_ATOMIC,
                        &iattr);
                dprintk("RPC:       %s: %d responder resources"
                        " (%d initiator)\n",
                        __func__, attr.max_dest_rd_atomic, attr.max_rd_atomic);
                goto connected;
        case RDMA_CM_EVENT_CONNECT_ERROR:
                connstate = -ENOTCONN;
                goto connected;
        case RDMA_CM_EVENT_UNREACHABLE:
                connstate = -ENETDOWN;
                goto connected;
        case RDMA_CM_EVENT_REJECTED:
                connstate = -ECONNREFUSED;
                goto connected;
        case RDMA_CM_EVENT_DISCONNECTED:
                connstate = -ECONNABORTED;
                goto connected;
        case RDMA_CM_EVENT_DEVICE_REMOVAL:
                connstate = -ENODEV;
connected:
                dprintk("RPC:       %s: %s: %pI4:%u (ep 0x%p event 0x%x)\n",
                        __func__,
                        (event->event <= 11) ? conn[event->event] :
                                                "unknown connection error",
                        &addr->sin_addr.s_addr,
                        ntohs(addr->sin_port),
                        ep, event->event);
                atomic_set(&rpcx_to_rdmax(ep->rep_xprt)->rx_buf.rb_credits, 1);
                dprintk("RPC:       %s: %sconnected\n",
                                        __func__, connstate > 0 ? "" : "dis");
                ep->rep_connected = connstate;
                ep->rep_func(ep);
                wake_up_all(&ep->rep_connect_wait);
                break;
        default:
                dprintk("RPC:       %s: unexpected CM event %d\n",
                        __func__, event->event);
                break;
        }

#ifdef RPC_DEBUG
        if (connstate == 1) {
                int ird = attr.max_dest_rd_atomic;
                int tird = ep->rep_remote_cma.responder_resources;
                printk(KERN_INFO "rpcrdma: connection to %pI4:%u "
                        "on %s, memreg %d slots %d ird %d%s\n",
                        &addr->sin_addr.s_addr,
                        ntohs(addr->sin_port),
                        ia->ri_id->device->name,
                        ia->ri_memreg_strategy,
                        xprt->rx_buf.rb_max_requests,
                        ird, ird < 4 && ird < tird / 2 ? " (low!)" : "");
        } else if (connstate < 0) {
                printk(KERN_INFO "rpcrdma: connection to %pI4:%u closed (%d)\n",
                        &addr->sin_addr.s_addr,
                        ntohs(addr->sin_port),
                        connstate);
        }
#endif

        return 0;
}

static struct rdma_cm_id *
rpcrdma_create_id(struct rpcrdma_xprt *xprt,
                        struct rpcrdma_ia *ia, struct sockaddr *addr)
{
        struct rdma_cm_id *id;
        int rc;

        init_completion(&ia->ri_done);

        id = rdma_create_id(rpcrdma_conn_upcall, xprt, RDMA_PS_TCP);
        if (IS_ERR(id)) {
                rc = PTR_ERR(id);
                dprintk("RPC:       %s: rdma_create_id() failed %i\n",
                        __func__, rc);
                return id;
        }

        ia->ri_async_rc = -ETIMEDOUT;
        rc = rdma_resolve_addr(id, NULL, addr, RDMA_RESOLVE_TIMEOUT);
        if (rc) {
                dprintk("RPC:       %s: rdma_resolve_addr() failed %i\n",
                        __func__, rc);
                goto out;
        }
        wait_for_completion_interruptible_timeout(&ia->ri_done,
                                msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1);
        rc = ia->ri_async_rc;
        if (rc)
                goto out;

        ia->ri_async_rc = -ETIMEDOUT;
        rc = rdma_resolve_route(id, RDMA_RESOLVE_TIMEOUT);
        if (rc) {
                dprintk("RPC:       %s: rdma_resolve_route() failed %i\n",
                        __func__, rc);
                goto out;
        }
        wait_for_completion_interruptible_timeout(&ia->ri_done,
                                msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1);
        rc = ia->ri_async_rc;
        if (rc)
                goto out;

        return id;

out:
        rdma_destroy_id(id);
        return ERR_PTR(rc);
}

/*
 * Drain any cq, prior to teardown.
 */
static void
rpcrdma_clean_cq(struct ib_cq *cq)
{
        struct ib_wc wc;
        int count = 0;

        while (1 == ib_poll_cq(cq, 1, &wc))
                ++count;

        if (count)
                dprintk("RPC:       %s: flushed %d events (last 0x%x)\n",
                        __func__, count, wc.opcode);
}

/*
 * Exported functions.
 */

/*
 * Open and initialize an Interface Adapter.
 *  o initializes fields of struct rpcrdma_ia, including
 *    interface and provider attributes and protection zone.
 */
int
rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
{
        int rc, mem_priv;
        struct ib_device_attr devattr;
        struct rpcrdma_ia *ia = &xprt->rx_ia;

        ia->ri_id = rpcrdma_create_id(xprt, ia, addr);
        if (IS_ERR(ia->ri_id)) {
                rc = PTR_ERR(ia->ri_id);
                goto out1;
        }

        ia->ri_pd = ib_alloc_pd(ia->ri_id->device);
        if (IS_ERR(ia->ri_pd)) {
                rc = PTR_ERR(ia->ri_pd);
                dprintk("RPC:       %s: ib_alloc_pd() failed %i\n",
                        __func__, rc);
                goto out2;
        }

        /*
         * Query the device to determine if the requested memory
         * registration strategy is supported. If it isn't, set the
         * strategy to a globally supported model.
         */
        rc = ib_query_device(ia->ri_id->device, &devattr);
        if (rc) {
                dprintk("RPC:       %s: ib_query_device failed %d\n",
                        __func__, rc);
                goto out2;
        }

        if (devattr.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY) {
                ia->ri_have_dma_lkey = 1;
                ia->ri_dma_lkey = ia->ri_id->device->local_dma_lkey;
        }

        switch (memreg) {
        case RPCRDMA_MEMWINDOWS:
        case RPCRDMA_MEMWINDOWS_ASYNC:
                if (!(devattr.device_cap_flags & IB_DEVICE_MEM_WINDOW)) {
                        dprintk("RPC:       %s: MEMWINDOWS registration "
                                "specified but not supported by adapter, "
                                "using slower RPCRDMA_REGISTER\n",
                                __func__);
                        memreg = RPCRDMA_REGISTER;
                }
                break;
        case RPCRDMA_MTHCAFMR:
                if (!ia->ri_id->device->alloc_fmr) {
#if RPCRDMA_PERSISTENT_REGISTRATION
                        dprintk("RPC:       %s: MTHCAFMR registration "
                                "specified but not supported by adapter, "
                                "using riskier RPCRDMA_ALLPHYSICAL\n",
                                __func__);
                        memreg = RPCRDMA_ALLPHYSICAL;
#else
                        dprintk("RPC:       %s: MTHCAFMR registration "
                                "specified but not supported by adapter, "
                                "using slower RPCRDMA_REGISTER\n",
                                __func__);
                        memreg = RPCRDMA_REGISTER;
#endif
                }
                break;
        case RPCRDMA_FRMR:
                /* Requires both frmr reg and local dma lkey */
                if ((devattr.device_cap_flags &
                     (IB_DEVICE_MEM_MGT_EXTENSIONS|IB_DEVICE_LOCAL_DMA_LKEY)) !=
                    (IB_DEVICE_MEM_MGT_EXTENSIONS|IB_DEVICE_LOCAL_DMA_LKEY)) {
#if RPCRDMA_PERSISTENT_REGISTRATION
                        dprintk("RPC:       %s: FRMR registration "
                                "specified but not supported by adapter, "
                                "using riskier RPCRDMA_ALLPHYSICAL\n",
                                __func__);
                        memreg = RPCRDMA_ALLPHYSICAL;
#else
                        dprintk("RPC:       %s: FRMR registration "
                                "specified but not supported by adapter, "
                                "using slower RPCRDMA_REGISTER\n",
                                __func__);
                        memreg = RPCRDMA_REGISTER;
#endif
                }
                break;
        }

        /*
         * Optionally obtain an underlying physical identity mapping in
         * order to do a memory window-based bind. This base registration
         * is protected from remote access - that is enabled only by binding
         * for the specific bytes targeted during each RPC operation, and
         * revoked after the corresponding completion similar to a storage
         * adapter.
         */
        switch (memreg) {
        case RPCRDMA_BOUNCEBUFFERS:
        case RPCRDMA_REGISTER:
        case RPCRDMA_FRMR:
                break;
#if RPCRDMA_PERSISTENT_REGISTRATION
        case RPCRDMA_ALLPHYSICAL:
                mem_priv = IB_ACCESS_LOCAL_WRITE |
                                IB_ACCESS_REMOTE_WRITE |
                                IB_ACCESS_REMOTE_READ;
                goto register_setup;
#endif
        case RPCRDMA_MEMWINDOWS_ASYNC:
        case RPCRDMA_MEMWINDOWS:
                mem_priv = IB_ACCESS_LOCAL_WRITE |
                                IB_ACCESS_MW_BIND;
                goto register_setup;
        case RPCRDMA_MTHCAFMR:
                if (ia->ri_have_dma_lkey)
                        break;
                mem_priv = IB_ACCESS_LOCAL_WRITE;
        register_setup:
                ia->ri_bind_mem = ib_get_dma_mr(ia->ri_pd, mem_priv);
                if (IS_ERR(ia->ri_bind_mem)) {
                        printk(KERN_ALERT "%s: ib_get_dma_mr for "
                                "phys register failed with %lX\n\t"
                                "Will continue with degraded performance\n",
                                __func__, PTR_ERR(ia->ri_bind_mem));
                        memreg = RPCRDMA_REGISTER;
                        ia->ri_bind_mem = NULL;
                }
                break;
        default:
                printk(KERN_ERR "%s: invalid memory registration mode %d\n",
                                __func__, memreg);
                rc = -EINVAL;
                goto out2;
        }
        dprintk("RPC:       %s: memory registration strategy is %d\n",
                __func__, memreg);

        /* Else will do memory reg/dereg for each chunk */
        ia->ri_memreg_strategy = memreg;

        return 0;
out2:
        rdma_destroy_id(ia->ri_id);
        ia->ri_id = NULL;
out1:
        return rc;
}

/*
 * Clean up/close an IA.
 *   o if event handles and PD have been initialized, free them.
 *   o close the IA
 */
void
rpcrdma_ia_close(struct rpcrdma_ia *ia)
{
        int rc;

        dprintk("RPC:       %s: entering\n", __func__);
        if (ia->ri_bind_mem != NULL) {
                rc = ib_dereg_mr(ia->ri_bind_mem);
                dprintk("RPC:       %s: ib_dereg_mr returned %i\n",
                        __func__, rc);
        }
        if (ia->ri_id != NULL && !IS_ERR(ia->ri_id)) {
                if (ia->ri_id->qp)
                        rdma_destroy_qp(ia->ri_id);
                rdma_destroy_id(ia->ri_id);
                ia->ri_id = NULL;
        }
        if (ia->ri_pd != NULL && !IS_ERR(ia->ri_pd)) {
                rc = ib_dealloc_pd(ia->ri_pd);
                dprintk("RPC:       %s: ib_dealloc_pd returned %i\n",
                        __func__, rc);
        }
}

/*
 * Create unconnected endpoint.
 */
int
rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
                                struct rpcrdma_create_data_internal *cdata)
{
        struct ib_device_attr devattr;
        int rc, err;

        rc = ib_query_device(ia->ri_id->device, &devattr);
        if (rc) {
                dprintk("RPC:       %s: ib_query_device failed %d\n",
                        __func__, rc);
                return rc;
        }

        /* check provider's send/recv wr limits */
        if (cdata->max_requests > devattr.max_qp_wr)
                cdata->max_requests = devattr.max_qp_wr;

        ep->rep_attr.event_handler = rpcrdma_qp_async_error_upcall;
        ep->rep_attr.qp_context = ep;
        /* send_cq and recv_cq initialized below */
        ep->rep_attr.srq = NULL;
        ep->rep_attr.cap.max_send_wr = cdata->max_requests;
        switch (ia->ri_memreg_strategy) {
        case RPCRDMA_FRMR:
                /* Add room for frmr register and invalidate WRs.
                 * 1. FRMR reg WR for head
                 * 2. FRMR invalidate WR for head
                 * 3. FRMR reg WR for pagelist
                 * 4. FRMR invalidate WR for pagelist
                 * 5. FRMR reg WR for tail
                 * 6. FRMR invalidate WR for tail
                 * 7. The RDMA_SEND WR
                 */
                ep->rep_attr.cap.max_send_wr *= 7;
                if (ep->rep_attr.cap.max_send_wr > devattr.max_qp_wr) {
                        cdata->max_requests = devattr.max_qp_wr / 7;
                        if (!cdata->max_requests)
                                return -EINVAL;
                        ep->rep_attr.cap.max_send_wr = cdata->max_requests * 7;
                }
                break;
        case RPCRDMA_MEMWINDOWS_ASYNC:
        case RPCRDMA_MEMWINDOWS:
                /* Add room for mw_binds+unbinds - overkill! */
                ep->rep_attr.cap.max_send_wr++;
                ep->rep_attr.cap.max_send_wr *= (2 * RPCRDMA_MAX_SEGS);
                if (ep->rep_attr.cap.max_send_wr > devattr.max_qp_wr)
                        return -EINVAL;
                break;
        default:
                break;
        }
        ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
        ep->rep_attr.cap.max_send_sge = (cdata->padding ? 4 : 2);
        ep->rep_attr.cap.max_recv_sge = 1;
        ep->rep_attr.cap.max_inline_data = 0;
        ep->rep_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
        ep->rep_attr.qp_type = IB_QPT_RC;
        ep->rep_attr.port_num = ~0;

        dprintk("RPC:       %s: requested max: dtos: send %d recv %d; "
                "iovs: send %d recv %d\n",
                __func__,
                ep->rep_attr.cap.max_send_wr,
                ep->rep_attr.cap.max_recv_wr,
                ep->rep_attr.cap.max_send_sge,
                ep->rep_attr.cap.max_recv_sge);

        /* set trigger for requesting send completion */
        ep->rep_cqinit = ep->rep_attr.cap.max_send_wr/2 /*  - 1*/;
        switch (ia->ri_memreg_strategy) {
        case RPCRDMA_MEMWINDOWS_ASYNC:
        case RPCRDMA_MEMWINDOWS:
                ep->rep_cqinit -= RPCRDMA_MAX_SEGS;
                break;
        default:
                break;
        }
        if (ep->rep_cqinit <= 2)
                ep->rep_cqinit = 0;
        INIT_CQCOUNT(ep);
        ep->rep_ia = ia;
        init_waitqueue_head(&ep->rep_connect_wait);

        /*
         * Create a single cq for receive dto and mw_bind (only ever
         * care about unbind, really). Send completions are suppressed.
         * Use single threaded tasklet upcalls to maintain ordering.
         */
        ep->rep_cq = ib_create_cq(ia->ri_id->device, rpcrdma_cq_event_upcall,
                                  rpcrdma_cq_async_error_upcall, NULL,
                                  ep->rep_attr.cap.max_recv_wr +
                                  ep->rep_attr.cap.max_send_wr + 1, 0);
        if (IS_ERR(ep->rep_cq)) {
                rc = PTR_ERR(ep->rep_cq);
                dprintk("RPC:       %s: ib_create_cq failed: %i\n",
                        __func__, rc);
                goto out1;
        }

        rc = ib_req_notify_cq(ep->rep_cq, IB_CQ_NEXT_COMP);
        if (rc) {
                dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
                        __func__, rc);
                goto out2;
        }

        ep->rep_attr.send_cq = ep->rep_cq;
        ep->rep_attr.recv_cq = ep->rep_cq;

        /* Initialize cma parameters */

        /* RPC/RDMA does not use private data */
        ep->rep_remote_cma.private_data = NULL;
        ep->rep_remote_cma.private_data_len = 0;

        /* Client offers RDMA Read but does not initiate */
        ep->rep_remote_cma.initiator_depth = 0;
        if (ia->ri_memreg_strategy == RPCRDMA_BOUNCEBUFFERS)
                ep->rep_remote_cma.responder_resources = 0;
        else if (devattr.max_qp_rd_atom > 32)   /* arbitrary but <= 255 */
                ep->rep_remote_cma.responder_resources = 32;
        else
                ep->rep_remote_cma.responder_resources = devattr.max_qp_rd_atom;

        ep->rep_remote_cma.retry_count = 7;
        ep->rep_remote_cma.flow_control = 0;
        ep->rep_remote_cma.rnr_retry_count = 0;

        return 0;

out2:
        err = ib_destroy_cq(ep->rep_cq);
        if (err)
                dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
                        __func__, err);
out1:
        return rc;
}

/*
 * rpcrdma_ep_destroy
 *
 * Disconnect and destroy endpoint. After this, the only
 * valid operations on the ep are to free it (if dynamically
 * allocated) or re-create it.
 *
 * The caller's error handling must be sure to not leak the endpoint
 * if this function fails.
 */
int
rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
{
        int rc;

        dprintk("RPC:       %s: entering, connected is %d\n",
                __func__, ep->rep_connected);

        if (ia->ri_id->qp) {
                rc = rpcrdma_ep_disconnect(ep, ia);
                if (rc)
                        dprintk("RPC:       %s: rpcrdma_ep_disconnect"
                                " returned %i\n", __func__, rc);
                rdma_destroy_qp(ia->ri_id);
                ia->ri_id->qp = NULL;
        }

        /* padding - could be done in rpcrdma_buffer_destroy... */
        if (ep->rep_pad_mr) {
                rpcrdma_deregister_internal(ia, ep->rep_pad_mr, &ep->rep_pad);
                ep->rep_pad_mr = NULL;
        }

        rpcrdma_clean_cq(ep->rep_cq);
        rc = ib_destroy_cq(ep->rep_cq);
        if (rc)
                dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
                        __func__, rc);

        return rc;
}

/*
 * Connect unconnected endpoint.
 */
int
rpcrdma_ep_connect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
{
        struct rdma_cm_id *id;
        int rc = 0;
        int retry_count = 0;

        if (ep->rep_connected != 0) {
                struct rpcrdma_xprt *xprt;
retry:
                rc = rpcrdma_ep_disconnect(ep, ia);
                if (rc && rc != -ENOTCONN)
                        dprintk("RPC:       %s: rpcrdma_ep_disconnect"
                                " status %i\n", __func__, rc);
                rpcrdma_clean_cq(ep->rep_cq);

                xprt = container_of(ia, struct rpcrdma_xprt, rx_ia);
                id = rpcrdma_create_id(xprt, ia,
                                (struct sockaddr *)&xprt->rx_data.addr);
                if (IS_ERR(id)) {
                        rc = PTR_ERR(id);
                        goto out;
                }
                /* TEMP TEMP TEMP - fail if new device:
                 * Deregister/remarshal *all* requests!
                 * Close and recreate adapter, pd, etc!
                 * Re-determine all attributes still sane!
                 * More stuff I haven't thought of!
                 * Rrrgh!
                 */
                if (ia->ri_id->device != id->device) {
                        printk("RPC:       %s: can't reconnect on "
                                "different device!\n", __func__);
                        rdma_destroy_id(id);
                        rc = -ENETDOWN;
                        goto out;
                }
                /* END TEMP */
                rdma_destroy_qp(ia->ri_id);
                rdma_destroy_id(ia->ri_id);
                ia->ri_id = id;
        }

        rc = rdma_create_qp(ia->ri_id, ia->ri_pd, &ep->rep_attr);
        if (rc) {
                dprintk("RPC:       %s: rdma_create_qp failed %i\n",
                        __func__, rc);
                goto out;
        }

/* XXX Tavor device performs badly with 2K MTU! */
if (strnicmp(ia->ri_id->device->dma_device->bus->name, "pci", 3) == 0) {
        struct pci_dev *pcid = to_pci_dev(ia->ri_id->device->dma_device);
        if (pcid->device == PCI_DEVICE_ID_MELLANOX_TAVOR &&
            (pcid->vendor == PCI_VENDOR_ID_MELLANOX ||
             pcid->vendor == PCI_VENDOR_ID_TOPSPIN)) {
                struct ib_qp_attr attr = {
                        .path_mtu = IB_MTU_1024
                };
                rc = ib_modify_qp(ia->ri_id->qp, &attr, IB_QP_PATH_MTU);
        }
}

        ep->rep_connected = 0;

        rc = rdma_connect(ia->ri_id, &ep->rep_remote_cma);
        if (rc) {
                dprintk("RPC:       %s: rdma_connect() failed with %i\n",
                                __func__, rc);
                goto out;
        }

        wait_event_interruptible(ep->rep_connect_wait, ep->rep_connected != 0);

        /*
         * Check state. A non-peer reject indicates no listener
         * (ECONNREFUSED), which may be a transient state. All
         * others indicate a transport condition which has already
         * undergone a best-effort.
         */
        if (ep->rep_connected == -ECONNREFUSED &&
            ++retry_count <= RDMA_CONNECT_RETRY_MAX) {
                dprintk("RPC:       %s: non-peer_reject, retry\n", __func__);
                goto retry;
        }
        if (ep->rep_connected <= 0) {
                /* Sometimes, the only way to reliably connect to remote
                 * CMs is to use same nonzero values for ORD and IRD. */
                if (retry_count++ <= RDMA_CONNECT_RETRY_MAX + 1 &&
                    (ep->rep_remote_cma.responder_resources == 0 ||
                     ep->rep_remote_cma.initiator_depth !=
                                ep->rep_remote_cma.responder_resources)) {
                        if (ep->rep_remote_cma.responder_resources == 0)
                                ep->rep_remote_cma.responder_resources = 1;
                        ep->rep_remote_cma.initiator_depth =
                                ep->rep_remote_cma.responder_resources;
                        goto retry;
                }
                rc = ep->rep_connected;
        } else {
                dprintk("RPC:       %s: connected\n", __func__);
        }

out:
        if (rc)
                ep->rep_connected = rc;
        return rc;
}

/*
 * rpcrdma_ep_disconnect
 *
 * This is separate from destroy to facilitate the ability
 * to reconnect without recreating the endpoint.
 *
 * This call is not reentrant, and must not be made in parallel
 * on the same endpoint.
 */
int
rpcrdma_ep_disconnect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
{
        int rc;

        rpcrdma_clean_cq(ep->rep_cq);
        rc = rdma_disconnect(ia->ri_id);
        if (!rc) {
                /* returns without wait if not connected */
                wait_event_interruptible(ep->rep_connect_wait,
                                                        ep->rep_connected != 1);
                dprintk("RPC:       %s: after wait, %sconnected\n", __func__,
                        (ep->rep_connected == 1) ? "still " : "dis");
        } else {
                dprintk("RPC:       %s: rdma_disconnect %i\n", __func__, rc);
                ep->rep_connected = rc;
        }
        return rc;
}

/*
 * Initialize buffer memory
 */
int
rpcrdma_buffer_create(struct rpcrdma_buffer *buf, struct rpcrdma_ep *ep,
        struct rpcrdma_ia *ia, struct rpcrdma_create_data_internal *cdata)
{
        char *p;
        size_t len;
        int i, rc;
        struct rpcrdma_mw *r;

        buf->rb_max_requests = cdata->max_requests;
        spin_lock_init(&buf->rb_lock);
        atomic_set(&buf->rb_credits, 1);

        /* Need to allocate:
         *   1.  arrays for send and recv pointers
         *   2.  arrays of struct rpcrdma_req to fill in pointers
         *   3.  array of struct rpcrdma_rep for replies
         *   4.  padding, if any
         *   5.  mw's, fmr's or frmr's, if any
         * Send/recv buffers in req/rep need to be registered
         */

        len = buf->rb_max_requests *
                (sizeof(struct rpcrdma_req *) + sizeof(struct rpcrdma_rep *));
        len += cdata->padding;
        switch (ia->ri_memreg_strategy) {
        case RPCRDMA_FRMR:
                len += buf->rb_max_requests * RPCRDMA_MAX_SEGS *
                                sizeof(struct rpcrdma_mw);
                break;
        case RPCRDMA_MTHCAFMR:
                /* TBD we are perhaps overallocating here */
                len += (buf->rb_max_requests + 1) * RPCRDMA_MAX_SEGS *
                                sizeof(struct rpcrdma_mw);
                break;
        case RPCRDMA_MEMWINDOWS_ASYNC:
        case RPCRDMA_MEMWINDOWS:
                len += (buf->rb_max_requests + 1) * RPCRDMA_MAX_SEGS *
                                sizeof(struct rpcrdma_mw);
                break;
        default:
                break;
        }

        /* allocate 1, 4 and 5 in one shot */
        p = kzalloc(len, GFP_KERNEL);

        if (p == NULL) {
                dprintk("RPC:       %s: req_t/rep_t/pad kzalloc(%zd) failed\n",
                        __func__, len);
                rc = -ENOMEM;
                goto out;
        }
        buf->rb_pool = p;       /* for freeing it later */

        buf->rb_send_bufs = (struct rpcrdma_req **) p;
        p = (char *) &buf->rb_send_bufs[buf->rb_max_requests];
        buf->rb_recv_bufs = (struct rpcrdma_rep **) p;
        p = (char *) &buf->rb_recv_bufs[buf->rb_max_requests];

        /*
         * Register the zeroed pad buffer, if any.
         */
        if (cdata->padding) {
                rc = rpcrdma_register_internal(ia, p, cdata->padding,
                                            &ep->rep_pad_mr, &ep->rep_pad);
                if (rc)
                        goto out;
        }
        p += cdata->padding;

        /*
         * Allocate the fmr's, or mw's for mw_bind chunk registration.
         * We "cycle" the mw's in order to minimize rkey reuse,
         * and also reduce unbind-to-bind collision.
         */
        INIT_LIST_HEAD(&buf->rb_mws);
        r = (struct rpcrdma_mw *)p;
        switch (ia->ri_memreg_strategy) {
        case RPCRDMA_FRMR:
                for (i = buf->rb_max_requests * RPCRDMA_MAX_SEGS; i; i--) {
                        r->r.frmr.fr_mr = ib_alloc_fast_reg_mr(ia->ri_pd,
                                                         RPCRDMA_MAX_SEGS);
                        if (IS_ERR(r->r.frmr.fr_mr)) {
                                rc = PTR_ERR(r->r.frmr.fr_mr);
                                dprintk("RPC:       %s: ib_alloc_fast_reg_mr"
                                        " failed %i\n", __func__, rc);
                                goto out;
                        }
                        r->r.frmr.fr_pgl =
                                ib_alloc_fast_reg_page_list(ia->ri_id->device,
                                                            RPCRDMA_MAX_SEGS);
                        if (IS_ERR(r->r.frmr.fr_pgl)) {
                                rc = PTR_ERR(r->r.frmr.fr_pgl);
                                dprintk("RPC:       %s: "
                                        "ib_alloc_fast_reg_page_list "
                                        "failed %i\n", __func__, rc);
                                goto out;
                        }
                        list_add(&r->mw_list, &buf->rb_mws);
                        ++r;
                }
                break;
        case RPCRDMA_MTHCAFMR:
                /* TBD we are perhaps overallocating here */
                for (i = (buf->rb_max_requests+1) * RPCRDMA_MAX_SEGS; i; i--) {
                        static struct ib_fmr_attr fa =
                                { RPCRDMA_MAX_DATA_SEGS, 1, PAGE_SHIFT };
                        r->r.fmr = ib_alloc_fmr(ia->ri_pd,
                                IB_ACCESS_REMOTE_WRITE | IB_ACCESS_REMOTE_READ,
                                &fa);
                        if (IS_ERR(r->r.fmr)) {
                                rc = PTR_ERR(r->r.fmr);
                                dprintk("RPC:       %s: ib_alloc_fmr"
                                        " failed %i\n", __func__, rc);
                                goto out;
                        }
                        list_add(&r->mw_list, &buf->rb_mws);
                        ++r;
                }
                break;
        case RPCRDMA_MEMWINDOWS_ASYNC:
        case RPCRDMA_MEMWINDOWS:
                /* Allocate one extra request's worth, for full cycling */
                for (i = (buf->rb_max_requests+1) * RPCRDMA_MAX_SEGS; i; i--) {
                        r->r.mw = ib_alloc_mw(ia->ri_pd);
                        if (IS_ERR(r->r.mw)) {
                                rc = PTR_ERR(r->r.mw);
                                dprintk("RPC:       %s: ib_alloc_mw"
                                        " failed %i\n", __func__, rc);
                                goto out;
                        }
                        list_add(&r->mw_list, &buf->rb_mws);
                        ++r;
                }
                break;
        default:
                break;
        }

        /*
         * Allocate/init the request/reply buffers. Doing this
         * using kmalloc for now -- one for each buf.
         */
        for (i = 0; i < buf->rb_max_requests; i++) {
                struct rpcrdma_req *req;
                struct rpcrdma_rep *rep;

                len = cdata->inline_wsize + sizeof(struct rpcrdma_req);
                /* RPC layer requests *double* size + 1K RPC_SLACK_SPACE! */
                /* Typical ~2400b, so rounding up saves work later */
                if (len < 4096)
                        len = 4096;
                req = kmalloc(len, GFP_KERNEL);
                if (req == NULL) {
                        dprintk("RPC:       %s: request buffer %d alloc"
                                " failed\n", __func__, i);
                        rc = -ENOMEM;
                        goto out;
                }
                memset(req, 0, sizeof(struct rpcrdma_req));
                buf->rb_send_bufs[i] = req;
                buf->rb_send_bufs[i]->rl_buffer = buf;

                rc = rpcrdma_register_internal(ia, req->rl_base,
                                len - offsetof(struct rpcrdma_req, rl_base),
                                &buf->rb_send_bufs[i]->rl_handle,
                                &buf->rb_send_bufs[i]->rl_iov);
                if (rc)
                        goto out;

                buf->rb_send_bufs[i]->rl_size = len-sizeof(struct rpcrdma_req);

                len = cdata->inline_rsize + sizeof(struct rpcrdma_rep);
                rep = kmalloc(len, GFP_KERNEL);
                if (rep == NULL) {
                        dprintk("RPC:       %s: reply buffer %d alloc failed\n",
                                __func__, i);
                        rc = -ENOMEM;
                        goto out;
                }
                memset(rep, 0, sizeof(struct rpcrdma_rep));
                buf->rb_recv_bufs[i] = rep;
                buf->rb_recv_bufs[i]->rr_buffer = buf;
                init_waitqueue_head(&rep->rr_unbind);

                rc = rpcrdma_register_internal(ia, rep->rr_base,
                                len - offsetof(struct rpcrdma_rep, rr_base),
                                &buf->rb_recv_bufs[i]->rr_handle,
                                &buf->rb_recv_bufs[i]->rr_iov);
                if (rc)
                        goto out;

        }
        dprintk("RPC:       %s: max_requests %d\n",
                __func__, buf->rb_max_requests);
        /* done */
        return 0;
out:
        rpcrdma_buffer_destroy(buf);
        return rc;
}

/*
 * Unregister and destroy buffer memory. Need to deal with
 * partial initialization, so it's callable from failed create.
 * Must be called before destroying endpoint, as registrations
 * reference it.
 */
void
rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
{
        int rc, i;
        struct rpcrdma_ia *ia = rdmab_to_ia(buf);
        struct rpcrdma_mw *r;

        /* clean up in reverse order from create
         *   1.  recv mr memory (mr free, then kfree)
         *   1a. bind mw memory
         *   2.  send mr memory (mr free, then kfree)
         *   3.  padding (if any) [moved to rpcrdma_ep_destroy]
         *   4.  arrays
         */
        dprintk("RPC:       %s: entering\n", __func__);

        for (i = 0; i < buf->rb_max_requests; i++) {
                if (buf->rb_recv_bufs && buf->rb_recv_bufs[i]) {
                        rpcrdma_deregister_internal(ia,
                                        buf->rb_recv_bufs[i]->rr_handle,
                                        &buf->rb_recv_bufs[i]->rr_iov);
                        kfree(buf->rb_recv_bufs[i]);
                }
                if (buf->rb_send_bufs && buf->rb_send_bufs[i]) {
                        while (!list_empty(&buf->rb_mws)) {
                                r = list_entry(buf->rb_mws.next,
                                        struct rpcrdma_mw, mw_list);
                                list_del(&r->mw_list);
                                switch (ia->ri_memreg_strategy) {
                                case RPCRDMA_FRMR:
                                        rc = ib_dereg_mr(r->r.frmr.fr_mr);
                                        if (rc)
                                                dprintk("RPC:       %s:"
                                                        " ib_dereg_mr"
                                                        " failed %i\n",
                                                        __func__, rc);
                                        ib_free_fast_reg_page_list(r->r.frmr.fr_pgl);
                                        break;
                                case RPCRDMA_MTHCAFMR:
                                        rc = ib_dealloc_fmr(r->r.fmr);
                                        if (rc)
                                                dprintk("RPC:       %s:"
                                                        " ib_dealloc_fmr"
                                                        " failed %i\n",
                                                        __func__, rc);
                                        break;
                                case RPCRDMA_MEMWINDOWS_ASYNC:
                                case RPCRDMA_MEMWINDOWS:
                                        rc = ib_dealloc_mw(r->r.mw);
                                        if (rc)
                                                dprintk("RPC:       %s:"
                                                        " ib_dealloc_mw"
                                                        " failed %i\n",
                                                        __func__, rc);
                                        break;
                                default:
                                        break;
                                }
                        }
                        rpcrdma_deregister_internal(ia,
                                        buf->rb_send_bufs[i]->rl_handle,
                                        &buf->rb_send_bufs[i]->rl_iov);
                        kfree(buf->rb_send_bufs[i]);
                }
        }

        kfree(buf->rb_pool);
}

/*
 * Get a set of request/reply buffers.
 *
 * Reply buffer (if needed) is attached to send buffer upon return.
 * Rule:
 *    rb_send_index and rb_recv_index MUST always be pointing to the
 *    *next* available buffer (non-NULL). They are incremented after
 *    removing buffers, and decremented *before* returning them.
 */
struct rpcrdma_req *
rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
{
        struct rpcrdma_req *req;
        unsigned long flags;
        int i;
        struct rpcrdma_mw *r;

        spin_lock_irqsave(&buffers->rb_lock, flags);
        if (buffers->rb_send_index == buffers->rb_max_requests) {
                spin_unlock_irqrestore(&buffers->rb_lock, flags);
                dprintk("RPC:       %s: out of request buffers\n", __func__);
                return ((struct rpcrdma_req *)NULL);
        }

        req = buffers->rb_send_bufs[buffers->rb_send_index];
        if (buffers->rb_send_index < buffers->rb_recv_index) {
                dprintk("RPC:       %s: %d extra receives outstanding (ok)\n",
                        __func__,
                        buffers->rb_recv_index - buffers->rb_send_index);
                req->rl_reply = NULL;
        } else {
                req->rl_reply = buffers->rb_recv_bufs[buffers->rb_recv_index];
                buffers->rb_recv_bufs[buffers->rb_recv_index++] = NULL;
        }
        buffers->rb_send_bufs[buffers->rb_send_index++] = NULL;
        if (!list_empty(&buffers->rb_mws)) {
                i = RPCRDMA_MAX_SEGS - 1;
                do {
                        r = list_entry(buffers->rb_mws.next,
                                        struct rpcrdma_mw, mw_list);
                        list_del(&r->mw_list);
                        req->rl_segments[i].mr_chunk.rl_mw = r;
                } while (--i >= 0);
        }
        spin_unlock_irqrestore(&buffers->rb_lock, flags);
        return req;
}

/*
 * Put request/reply buffers back into pool.
 * Pre-decrement counter/array index.
 */
void
rpcrdma_buffer_put(struct rpcrdma_req *req)
{
        struct rpcrdma_buffer *buffers = req->rl_buffer;
        struct rpcrdma_ia *ia = rdmab_to_ia(buffers);
        int i;
        unsigned long flags;

        BUG_ON(req->rl_nchunks != 0);
        spin_lock_irqsave(&buffers->rb_lock, flags);
        buffers->rb_send_bufs[--buffers->rb_send_index] = req;
        req->rl_niovs = 0;
        if (req->rl_reply) {
                buffers->rb_recv_bufs[--buffers->rb_recv_index] = req->rl_reply;
                init_waitqueue_head(&req->rl_reply->rr_unbind);
                req->rl_reply->rr_func = NULL;
                req->rl_reply = NULL;
        }
        switch (ia->ri_memreg_strategy) {
        case RPCRDMA_FRMR:
        case RPCRDMA_MTHCAFMR:
        case RPCRDMA_MEMWINDOWS_ASYNC:
        case RPCRDMA_MEMWINDOWS:
                /*
                 * Cycle mw's back in reverse order, and "spin" them.
                 * This delays and scrambles reuse as much as possible.
                 */
                i = 1;
                do {
                        struct rpcrdma_mw **mw;
                        mw = &req->rl_segments[i].mr_chunk.rl_mw;
                        list_add_tail(&(*mw)->mw_list, &buffers->rb_mws);
                        *mw = NULL;
                } while (++i < RPCRDMA_MAX_SEGS);
                list_add_tail(&req->rl_segments[0].mr_chunk.rl_mw->mw_list,
                                        &buffers->rb_mws);
                req->rl_segments[0].mr_chunk.rl_mw = NULL;
                break;
        default:
                break;
        }
        spin_unlock_irqrestore(&buffers->rb_lock, flags);
}

/*
 * Recover reply buffers from pool.
 * This happens when recovering from error conditions.
 * Post-increment counter/array index.
 */
void
rpcrdma_recv_buffer_get(struct rpcrdma_req *req)
{
        struct rpcrdma_buffer *buffers = req->rl_buffer;
        unsigned long flags;

        if (req->rl_iov.length == 0)    /* special case xprt_rdma_allocate() */
                buffers = ((struct rpcrdma_req *) buffers)->rl_buffer;
        spin_lock_irqsave(&buffers->rb_lock, flags);
        if (buffers->rb_recv_index < buffers->rb_max_requests) {
                req->rl_reply = buffers->rb_recv_bufs[buffers->rb_recv_index];
                buffers->rb_recv_bufs[buffers->rb_recv_index++] = NULL;
        }
        spin_unlock_irqrestore(&buffers->rb_lock, flags);
}

/*
 * Put reply buffers back into pool when not attached to
 * request. This happens in error conditions, and when
 * aborting unbinds. Pre-decrement counter/array index.
 */
void
rpcrdma_recv_buffer_put(struct rpcrdma_rep *rep)
{
        struct rpcrdma_buffer *buffers = rep->rr_buffer;
        unsigned long flags;

        rep->rr_func = NULL;
        spin_lock_irqsave(&buffers->rb_lock, flags);
        buffers->rb_recv_bufs[--buffers->rb_recv_index] = rep;
        spin_unlock_irqrestore(&buffers->rb_lock, flags);
}

/*
 * Wrappers for internal-use kmalloc memory registration, used by buffer code.
 */

int
rpcrdma_register_internal(struct rpcrdma_ia *ia, void *va, int len,
                                struct ib_mr **mrp, struct ib_sge *iov)
{
        struct ib_phys_buf ipb;
        struct ib_mr *mr;
        int rc;

        /*
         * All memory passed here was kmalloc'ed, therefore phys-contiguous.
         */
        iov->addr = ib_dma_map_single(ia->ri_id->device,
                        va, len, DMA_BIDIRECTIONAL);
        iov->length = len;

        if (ia->ri_have_dma_lkey) {
                *mrp = NULL;
                iov->lkey = ia->ri_dma_lkey;
                return 0;
        } else if (ia->ri_bind_mem != NULL) {
                *mrp = NULL;
                iov->lkey = ia->ri_bind_mem->lkey;
                return 0;
        }

        ipb.addr = iov->addr;
        ipb.size = iov->length;
        mr = ib_reg_phys_mr(ia->ri_pd, &ipb, 1,
                        IB_ACCESS_LOCAL_WRITE, &iov->addr);

        dprintk("RPC:       %s: phys convert: 0x%llx "
                        "registered 0x%llx length %d\n",
                        __func__, (unsigned long long)ipb.addr,
                        (unsigned long long)iov->addr, len);

        if (IS_ERR(mr)) {
                *mrp = NULL;
                rc = PTR_ERR(mr);
                dprintk("RPC:       %s: failed with %i\n", __func__, rc);
        } else {
                *mrp = mr;
                iov->lkey = mr->lkey;
                rc = 0;
        }

        return rc;
}

int
rpcrdma_deregister_internal(struct rpcrdma_ia *ia,
                                struct ib_mr *mr, struct ib_sge *iov)
{
        int rc;

        ib_dma_unmap_single(ia->ri_id->device,
                        iov->addr, iov->length, DMA_BIDIRECTIONAL);

        if (NULL == mr)
                return 0;

        rc = ib_dereg_mr(mr);
        if (rc)
                dprintk("RPC:       %s: ib_dereg_mr failed %i\n", __func__, rc);
        return rc;
}

/*
 * Wrappers for chunk registration, shared by read/write chunk code.
 */

static void
rpcrdma_map_one(struct rpcrdma_ia *ia, struct rpcrdma_mr_seg *seg, int writing)
{
        seg->mr_dir = writing ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
        seg->mr_dmalen = seg->mr_len;
        if (seg->mr_page)
                seg->mr_dma = ib_dma_map_page(ia->ri_id->device,
                                seg->mr_page, offset_in_page(seg->mr_offset),
                                seg->mr_dmalen, seg->mr_dir);
        else
                seg->mr_dma = ib_dma_map_single(ia->ri_id->device,
                                seg->mr_offset,
                                seg->mr_dmalen, seg->mr_dir);
}

static void
rpcrdma_unmap_one(struct rpcrdma_ia *ia, struct rpcrdma_mr_seg *seg)
{
        if (seg->mr_page)
                ib_dma_unmap_page(ia->ri_id->device,
                                seg->mr_dma, seg->mr_dmalen, seg->mr_dir);
        else
                ib_dma_unmap_single(ia->ri_id->device,
                                seg->mr_dma, seg->mr_dmalen, seg->mr_dir);
}

static int
rpcrdma_register_frmr_external(struct rpcrdma_mr_seg *seg,
                        int *nsegs, int writing, struct rpcrdma_ia *ia,
                        struct rpcrdma_xprt *r_xprt)
{
        struct rpcrdma_mr_seg *seg1 = seg;
        struct ib_send_wr frmr_wr, *bad_wr;
        u8 key;
        int len, pageoff;
        int i, rc;

        pageoff = offset_in_page(seg1->mr_offset);
        seg1->mr_offset -= pageoff;     /* start of page */
        seg1->mr_len += pageoff;
        len = -pageoff;
        if (*nsegs > RPCRDMA_MAX_DATA_SEGS)
                *nsegs = RPCRDMA_MAX_DATA_SEGS;
        for (i = 0; i < *nsegs;) {
                rpcrdma_map_one(ia, seg, writing);
                seg1->mr_chunk.rl_mw->r.frmr.fr_pgl->page_list[i] = seg->mr_dma;
                len += seg->mr_len;
                ++seg;
                ++i;
                /* Check for holes */
                if ((i < *nsegs && offset_in_page(seg->mr_offset)) ||
                    offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
                        break;
        }
        dprintk("RPC:       %s: Using frmr %p to map %d segments\n",
                __func__, seg1->mr_chunk.rl_mw, i);

        /* Bump the key */
        key = (u8)(seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey & 0x000000FF);
        ib_update_fast_reg_key(seg1->mr_chunk.rl_mw->r.frmr.fr_mr, ++key);

        /* Prepare FRMR WR */
        memset(&frmr_wr, 0, sizeof frmr_wr);
        frmr_wr.opcode = IB_WR_FAST_REG_MR;
        frmr_wr.send_flags = 0;                 /* unsignaled */
        frmr_wr.wr.fast_reg.iova_start = seg1->mr_dma;
        frmr_wr.wr.fast_reg.page_list = seg1->mr_chunk.rl_mw->r.frmr.fr_pgl;
        frmr_wr.wr.fast_reg.page_list_len = i;
        frmr_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
        frmr_wr.wr.fast_reg.length = i << PAGE_SHIFT;
        frmr_wr.wr.fast_reg.access_flags = (writing ?
                                IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
                                IB_ACCESS_REMOTE_READ);
        frmr_wr.wr.fast_reg.rkey = seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey;
        DECR_CQCOUNT(&r_xprt->rx_ep);

        rc = ib_post_send(ia->ri_id->qp, &frmr_wr, &bad_wr);

        if (rc) {
                dprintk("RPC:       %s: failed ib_post_send for register,"
                        " status %i\n", __func__, rc);
                while (i--)
                        rpcrdma_unmap_one(ia, --seg);
        } else {
                seg1->mr_rkey = seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey;
                seg1->mr_base = seg1->mr_dma + pageoff;
                seg1->mr_nsegs = i;
                seg1->mr_len = len;
        }
        *nsegs = i;
        return rc;
}

static int
rpcrdma_deregister_frmr_external(struct rpcrdma_mr_seg *seg,
                        struct rpcrdma_ia *ia, struct rpcrdma_xprt *r_xprt)
{
        struct rpcrdma_mr_seg *seg1 = seg;
        struct ib_send_wr invalidate_wr, *bad_wr;
        int rc;

        while (seg1->mr_nsegs--)
                rpcrdma_unmap_one(ia, seg++);

        memset(&invalidate_wr, 0, sizeof invalidate_wr);
        invalidate_wr.opcode = IB_WR_LOCAL_INV;
        invalidate_wr.send_flags = 0;                   /* unsignaled */
        invalidate_wr.ex.invalidate_rkey = seg1->mr_chunk.rl_mw->r.frmr.fr_mr->rkey;
        DECR_CQCOUNT(&r_xprt->rx_ep);

        rc = ib_post_send(ia->ri_id->qp, &invalidate_wr, &bad_wr);
        if (rc)
                dprintk("RPC:       %s: failed ib_post_send for invalidate,"
                        " status %i\n", __func__, rc);
        return rc;
}

static int
rpcrdma_register_fmr_external(struct rpcrdma_mr_seg *seg,
                        int *nsegs, int writing, struct rpcrdma_ia *ia)
{
        struct rpcrdma_mr_seg *seg1 = seg;
        u64 physaddrs[RPCRDMA_MAX_DATA_SEGS];
        int len, pageoff, i, rc;

        pageoff = offset_in_page(seg1->mr_offset);
        seg1->mr_offset -= pageoff;     /* start of page */
        seg1->mr_len += pageoff;
        len = -pageoff;
        if (*nsegs > RPCRDMA_MAX_DATA_SEGS)
                *nsegs = RPCRDMA_MAX_DATA_SEGS;
        for (i = 0; i < *nsegs;) {
                rpcrdma_map_one(ia, seg, writing);
                physaddrs[i] = seg->mr_dma;
                len += seg->mr_len;
                ++seg;
                ++i;
                /* Check for holes */
                if ((i < *nsegs && offset_in_page(seg->mr_offset)) ||
                    offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
                        break;
        }
        rc = ib_map_phys_fmr(seg1->mr_chunk.rl_mw->r.fmr,
                                physaddrs, i, seg1->mr_dma);
        if (rc) {
                dprintk("RPC:       %s: failed ib_map_phys_fmr "
                        "%u@0x%llx+%i (%d)... status %i\n", __func__,
                        len, (unsigned long long)seg1->mr_dma,
                        pageoff, i, rc);
                while (i--)
                        rpcrdma_unmap_one(ia, --seg);
        } else {
                seg1->mr_rkey = seg1->mr_chunk.rl_mw->r.fmr->rkey;
                seg1->mr_base = seg1->mr_dma + pageoff;
                seg1->mr_nsegs = i;
                seg1->mr_len = len;
        }
        *nsegs = i;
        return rc;
}

static int
rpcrdma_deregister_fmr_external(struct rpcrdma_mr_seg *seg,
                        struct rpcrdma_ia *ia)
{
        struct rpcrdma_mr_seg *seg1 = seg;
        LIST_HEAD(l);
        int rc;

        list_add(&seg1->mr_chunk.rl_mw->r.fmr->list, &l);
        rc = ib_unmap_fmr(&l);
        while (seg1->mr_nsegs--)
                rpcrdma_unmap_one(ia, seg++);
        if (rc)
                dprintk("RPC:       %s: failed ib_unmap_fmr,"
                        " status %i\n", __func__, rc);
        return rc;
}

static int
rpcrdma_register_memwin_external(struct rpcrdma_mr_seg *seg,
                        int *nsegs, int writing, struct rpcrdma_ia *ia,
                        struct rpcrdma_xprt *r_xprt)
{
        int mem_priv = (writing ? IB_ACCESS_REMOTE_WRITE :
                                  IB_ACCESS_REMOTE_READ);
        struct ib_mw_bind param;
        int rc;

        *nsegs = 1;
        rpcrdma_map_one(ia, seg, writing);
        param.mr = ia->ri_bind_mem;
        param.wr_id = 0ULL;     /* no send cookie */
        param.addr = seg->mr_dma;
        param.length = seg->mr_len;
        param.send_flags = 0;
        param.mw_access_flags = mem_priv;

        DECR_CQCOUNT(&r_xprt->rx_ep);
        rc = ib_bind_mw(ia->ri_id->qp, seg->mr_chunk.rl_mw->r.mw, &param);
        if (rc) {
                dprintk("RPC:       %s: failed ib_bind_mw "
                        "%u@0x%llx status %i\n",
                        __func__, seg->mr_len,
                        (unsigned long long)seg->mr_dma, rc);
                rpcrdma_unmap_one(ia, seg);
        } else {
                seg->mr_rkey = seg->mr_chunk.rl_mw->r.mw->rkey;
                seg->mr_base = param.addr;
                seg->mr_nsegs = 1;
        }
        return rc;
}

static int
rpcrdma_deregister_memwin_external(struct rpcrdma_mr_seg *seg,
                        struct rpcrdma_ia *ia,
                        struct rpcrdma_xprt *r_xprt, void **r)
{
        struct ib_mw_bind param;
        LIST_HEAD(l);
        int rc;

        BUG_ON(seg->mr_nsegs != 1);
        param.mr = ia->ri_bind_mem;
        param.addr = 0ULL;      /* unbind */
        param.length = 0;
        param.mw_access_flags = 0;
        if (*r) {
                param.wr_id = (u64) (unsigned long) *r;
                param.send_flags = IB_SEND_SIGNALED;
                INIT_CQCOUNT(&r_xprt->rx_ep);
        } else {
                param.wr_id = 0ULL;
                param.send_flags = 0;
                DECR_CQCOUNT(&r_xprt->rx_ep);
        }
        rc = ib_bind_mw(ia->ri_id->qp, seg->mr_chunk.rl_mw->r.mw, &param);
        rpcrdma_unmap_one(ia, seg);
        if (rc)
                dprintk("RPC:       %s: failed ib_(un)bind_mw,"
                        " status %i\n", __func__, rc);
        else
                *r = NULL;      /* will upcall on completion */
        return rc;
}

static int
rpcrdma_register_default_external(struct rpcrdma_mr_seg *seg,
                        int *nsegs, int writing, struct rpcrdma_ia *ia)
{
        int mem_priv = (writing ? IB_ACCESS_REMOTE_WRITE :
                                  IB_ACCESS_REMOTE_READ);
        struct rpcrdma_mr_seg *seg1 = seg;
        struct ib_phys_buf ipb[RPCRDMA_MAX_DATA_SEGS];
        int len, i, rc = 0;

        if (*nsegs > RPCRDMA_MAX_DATA_SEGS)
                *nsegs = RPCRDMA_MAX_DATA_SEGS;
        for (len = 0, i = 0; i < *nsegs;) {
                rpcrdma_map_one(ia, seg, writing);
                ipb[i].addr = seg->mr_dma;
                ipb[i].size = seg->mr_len;
                len += seg->mr_len;
                ++seg;
                ++i;
                /* Check for holes */
                if ((i < *nsegs && offset_in_page(seg->mr_offset)) ||
                    offset_in_page((seg-1)->mr_offset+(seg-1)->mr_len))
                        break;
        }
        seg1->mr_base = seg1->mr_dma;
        seg1->mr_chunk.rl_mr = ib_reg_phys_mr(ia->ri_pd,
                                ipb, i, mem_priv, &seg1->mr_base);
        if (IS_ERR(seg1->mr_chunk.rl_mr)) {
                rc = PTR_ERR(seg1->mr_chunk.rl_mr);
                dprintk("RPC:       %s: failed ib_reg_phys_mr "
                        "%u@0x%llx (%d)... status %i\n",
                        __func__, len,
                        (unsigned long long)seg1->mr_dma, i, rc);
                while (i--)
                        rpcrdma_unmap_one(ia, --seg);
        } else {
                seg1->mr_rkey = seg1->mr_chunk.rl_mr->rkey;
                seg1->mr_nsegs = i;
                seg1->mr_len = len;
        }
        *nsegs = i;
        return rc;
}

static int
rpcrdma_deregister_default_external(struct rpcrdma_mr_seg *seg,
                        struct rpcrdma_ia *ia)
{
        struct rpcrdma_mr_seg *seg1 = seg;
        int rc;

        rc = ib_dereg_mr(seg1->mr_chunk.rl_mr);
        seg1->mr_chunk.rl_mr = NULL;
        while (seg1->mr_nsegs--)
                rpcrdma_unmap_one(ia, seg++);
        if (rc)
                dprintk("RPC:       %s: failed ib_dereg_mr,"
                        " status %i\n", __func__, rc);
        return rc;
}

int
rpcrdma_register_external(struct rpcrdma_mr_seg *seg,
                        int nsegs, int writing, struct rpcrdma_xprt *r_xprt)
{
        struct rpcrdma_ia *ia = &r_xprt->rx_ia;
        int rc = 0;

        switch (ia->ri_memreg_strategy) {

#if RPCRDMA_PERSISTENT_REGISTRATION
        case RPCRDMA_ALLPHYSICAL:
                rpcrdma_map_one(ia, seg, writing);
                seg->mr_rkey = ia->ri_bind_mem->rkey;
                seg->mr_base = seg->mr_dma;
                seg->mr_nsegs = 1;
                nsegs = 1;
                break;
#endif

        /* Registration using frmr registration */
        case RPCRDMA_FRMR:
                rc = rpcrdma_register_frmr_external(seg, &nsegs, writing, ia, r_xprt);
                break;

        /* Registration using fmr memory registration */
        case RPCRDMA_MTHCAFMR:
                rc = rpcrdma_register_fmr_external(seg, &nsegs, writing, ia);
                break;

        /* Registration using memory windows */
        case RPCRDMA_MEMWINDOWS_ASYNC:
        case RPCRDMA_MEMWINDOWS:
                rc = rpcrdma_register_memwin_external(seg, &nsegs, writing, ia, r_xprt);
                break;

        /* Default registration each time */
        default:
                rc = rpcrdma_register_default_external(seg, &nsegs, writing, ia);
                break;
        }
        if (rc)
                return -1;

        return nsegs;
}

int
rpcrdma_deregister_external(struct rpcrdma_mr_seg *seg,
                struct rpcrdma_xprt *r_xprt, void *r)
{
        struct rpcrdma_ia *ia = &r_xprt->rx_ia;
        int nsegs = seg->mr_nsegs, rc;

        switch (ia->ri_memreg_strategy) {

#if RPCRDMA_PERSISTENT_REGISTRATION
        case RPCRDMA_ALLPHYSICAL:
                BUG_ON(nsegs != 1);
                rpcrdma_unmap_one(ia, seg);
                rc = 0;
                break;
#endif

        case RPCRDMA_FRMR:
                rc = rpcrdma_deregister_frmr_external(seg, ia, r_xprt);
                break;

        case RPCRDMA_MTHCAFMR:
                rc = rpcrdma_deregister_fmr_external(seg, ia);
                break;

        case RPCRDMA_MEMWINDOWS_ASYNC:
        case RPCRDMA_MEMWINDOWS:
                rc = rpcrdma_deregister_memwin_external(seg, ia, r_xprt, &r);
                break;

        default:
                rc = rpcrdma_deregister_default_external(seg, ia);
                break;
        }
        if (r) {
                struct rpcrdma_rep *rep = r;
                void (*func)(struct rpcrdma_rep *) = rep->rr_func;
                rep->rr_func = NULL;
                func(rep);      /* dereg done, callback now */
        }
        return nsegs;
}

/*
 * Prepost any receive buffer, then post send.
 *
 * Receive buffer is donated to hardware, reclaimed upon recv completion.
 */
int
rpcrdma_ep_post(struct rpcrdma_ia *ia,
                struct rpcrdma_ep *ep,
                struct rpcrdma_req *req)
{
        struct ib_send_wr send_wr, *send_wr_fail;
        struct rpcrdma_rep *rep = req->rl_reply;
        int rc;

        if (rep) {
                rc = rpcrdma_ep_post_recv(ia, ep, rep);
                if (rc)
                        goto out;
                req->rl_reply = NULL;
        }

        send_wr.next = NULL;
        send_wr.wr_id = 0ULL;   /* no send cookie */
        send_wr.sg_list = req->rl_send_iov;
        send_wr.num_sge = req->rl_niovs;
        send_wr.opcode = IB_WR_SEND;
        if (send_wr.num_sge == 4)       /* no need to sync any pad (constant) */
                ib_dma_sync_single_for_device(ia->ri_id->device,
                        req->rl_send_iov[3].addr, req->rl_send_iov[3].length,
                        DMA_TO_DEVICE);
        ib_dma_sync_single_for_device(ia->ri_id->device,
                req->rl_send_iov[1].addr, req->rl_send_iov[1].length,
                DMA_TO_DEVICE);
        ib_dma_sync_single_for_device(ia->ri_id->device,
                req->rl_send_iov[0].addr, req->rl_send_iov[0].length,
                DMA_TO_DEVICE);

        if (DECR_CQCOUNT(ep) > 0)
                send_wr.send_flags = 0;
        else { /* Provider must take a send completion every now and then */
                INIT_CQCOUNT(ep);
                send_wr.send_flags = IB_SEND_SIGNALED;
        }

        rc = ib_post_send(ia->ri_id->qp, &send_wr, &send_wr_fail);
        if (rc)
                dprintk("RPC:       %s: ib_post_send returned %i\n", __func__,
                        rc);
out:
        return rc;
}

/*
 * (Re)post a receive buffer.
 */
int
rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
                     struct rpcrdma_ep *ep,
                     struct rpcrdma_rep *rep)
{
        struct ib_recv_wr recv_wr, *recv_wr_fail;
        int rc;

        recv_wr.next = NULL;
        recv_wr.wr_id = (u64) (unsigned long) rep;
        recv_wr.sg_list = &rep->rr_iov;
        recv_wr.num_sge = 1;

        ib_dma_sync_single_for_cpu(ia->ri_id->device,
                rep->rr_iov.addr, rep->rr_iov.length, DMA_BIDIRECTIONAL);

        DECR_CQCOUNT(ep);
        rc = ib_post_recv(ia->ri_id->qp, &recv_wr, &recv_wr_fail);

        if (rc)
                dprintk("RPC:       %s: ib_post_recv returned %i\n", __func__,
                        rc);
        return rc;
}