Merge tag 'nfs-rdma-for-4.3-2' of git://git.linux-nfs.org/projects/anna/nfs-rdma

[people/ms/linux.git] / net / sunrpc / xprtrdma / verbs.c

/*
 * 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/interrupt.h>
#include <linux/slab.h>
#include <linux/prefetch.h>
#include <linux/sunrpc/addr.h>
#include <asm/bitops.h>
#include <linux/module.h> /* try_module_get()/module_put() */

#include "xprt_rdma.h"

/*
 * Globals/Macros
 */

#if IS_ENABLED(CONFIG_SUNRPC_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;
        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);
                spin_unlock_irqrestore(&rpcrdma_tk_lock_g, flags);

                rpcrdma_reply_handler(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 void
rpcrdma_schedule_tasklet(struct list_head *sched_list)
{
        unsigned long flags;

        spin_lock_irqsave(&rpcrdma_tk_lock_g, flags);
        list_splice_tail(sched_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;

        pr_err("RPC:       %s: %s on device %s ep %p\n",
               __func__, ib_event_msg(event->event),
                event->device->name, context);
        if (ep->rep_connected == 1) {
                ep->rep_connected = -EIO;
                rpcrdma_conn_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;

        pr_err("RPC:       %s: %s on device %s ep %p\n",
               __func__, ib_event_msg(event->event),
                event->device->name, context);
        if (ep->rep_connected == 1) {
                ep->rep_connected = -EIO;
                rpcrdma_conn_func(ep);
                wake_up_all(&ep->rep_connect_wait);
        }
}

static void
rpcrdma_sendcq_process_wc(struct ib_wc *wc)
{
        /* WARNING: Only wr_id and status are reliable at this point */
        if (wc->wr_id == RPCRDMA_IGNORE_COMPLETION) {
                if (wc->status != IB_WC_SUCCESS &&
                    wc->status != IB_WC_WR_FLUSH_ERR)
                        pr_err("RPC:       %s: SEND: %s\n",
                               __func__, ib_wc_status_msg(wc->status));
        } else {
                struct rpcrdma_mw *r;

                r = (struct rpcrdma_mw *)(unsigned long)wc->wr_id;
                r->mw_sendcompletion(wc);
        }
}

static int
rpcrdma_sendcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{
        struct ib_wc *wcs;
        int budget, count, rc;

        budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
        do {
                wcs = ep->rep_send_wcs;

                rc = ib_poll_cq(cq, RPCRDMA_POLLSIZE, wcs);
                if (rc <= 0)
                        return rc;

                count = rc;
                while (count-- > 0)
                        rpcrdma_sendcq_process_wc(wcs++);
        } while (rc == RPCRDMA_POLLSIZE && --budget);
        return 0;
}

/*
 * Handle send, fast_reg_mr, and local_inv completions.
 *
 * Send events are typically suppressed and thus do not result
 * in an upcall. Occasionally one is signaled, however. This
 * prevents the provider's completion queue from wrapping and
 * losing a completion.
 */
static void
rpcrdma_sendcq_upcall(struct ib_cq *cq, void *cq_context)
{
        struct rpcrdma_ep *ep = (struct rpcrdma_ep *)cq_context;
        int rc;

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

        rc = ib_req_notify_cq(cq,
                        IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
        if (rc == 0)
                return;
        if (rc < 0) {
                dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
                        __func__, rc);
                return;
        }

        rpcrdma_sendcq_poll(cq, ep);
}

static void
rpcrdma_recvcq_process_wc(struct ib_wc *wc, struct list_head *sched_list)
{
        struct rpcrdma_rep *rep =
                        (struct rpcrdma_rep *)(unsigned long)wc->wr_id;

        /* WARNING: Only wr_id and status are reliable at this point */
        if (wc->status != IB_WC_SUCCESS)
                goto out_fail;

        /* status == SUCCESS means all fields in wc are trustworthy */
        if (wc->opcode != IB_WC_RECV)
                return;

        dprintk("RPC:       %s: rep %p opcode 'recv', length %u: success\n",
                __func__, rep, wc->byte_len);

        rep->rr_len = wc->byte_len;
        ib_dma_sync_single_for_cpu(rep->rr_device,
                                   rdmab_addr(rep->rr_rdmabuf),
                                   rep->rr_len, DMA_FROM_DEVICE);
        prefetch(rdmab_to_msg(rep->rr_rdmabuf));

out_schedule:
        list_add_tail(&rep->rr_list, sched_list);
        return;
out_fail:
        if (wc->status != IB_WC_WR_FLUSH_ERR)
                pr_err("RPC:       %s: rep %p: %s\n",
                       __func__, rep, ib_wc_status_msg(wc->status));
        rep->rr_len = ~0U;
        goto out_schedule;
}

static int
rpcrdma_recvcq_poll(struct ib_cq *cq, struct rpcrdma_ep *ep)
{
        struct list_head sched_list;
        struct ib_wc *wcs;
        int budget, count, rc;

        INIT_LIST_HEAD(&sched_list);
        budget = RPCRDMA_WC_BUDGET / RPCRDMA_POLLSIZE;
        do {
                wcs = ep->rep_recv_wcs;

                rc = ib_poll_cq(cq, RPCRDMA_POLLSIZE, wcs);
                if (rc <= 0)
                        goto out_schedule;

                count = rc;
                while (count-- > 0)
                        rpcrdma_recvcq_process_wc(wcs++, &sched_list);
        } while (rc == RPCRDMA_POLLSIZE && --budget);
        rc = 0;

out_schedule:
        rpcrdma_schedule_tasklet(&sched_list);
        return rc;
}

/*
 * Handle receive completions.
 *
 * 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.
 */
static void
rpcrdma_recvcq_upcall(struct ib_cq *cq, void *cq_context)
{
        struct rpcrdma_ep *ep = (struct rpcrdma_ep *)cq_context;
        int rc;

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

        rc = ib_req_notify_cq(cq,
                        IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS);
        if (rc == 0)
                return;
        if (rc < 0) {
                dprintk("RPC:       %s: ib_req_notify_cq failed: %i\n",
                        __func__, rc);
                return;
        }

        rpcrdma_recvcq_poll(cq, ep);
}

static void
rpcrdma_flush_cqs(struct rpcrdma_ep *ep)
{
        struct ib_wc wc;
        LIST_HEAD(sched_list);

        while (ib_poll_cq(ep->rep_attr.recv_cq, 1, &wc) > 0)
                rpcrdma_recvcq_process_wc(&wc, &sched_list);
        if (!list_empty(&sched_list))
                rpcrdma_schedule_tasklet(&sched_list);
        while (ib_poll_cq(ep->rep_attr.send_cq, 1, &wc) > 0)
                rpcrdma_sendcq_process_wc(&wc);
}

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;
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
        struct sockaddr *sap = (struct sockaddr *)&ep->rep_remote_addr;
#endif
        struct ib_qp_attr *attr = &ia->ri_qp_attr;
        struct ib_qp_init_attr *iattr = &ia->ri_qp_init_attr;
        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: %sconnected\n",
                                        __func__, connstate > 0 ? "" : "dis");
                ep->rep_connected = connstate;
                rpcrdma_conn_func(ep);
                wake_up_all(&ep->rep_connect_wait);
                /*FALLTHROUGH*/
        default:
                dprintk("RPC:       %s: %pIS:%u (ep 0x%p): %s\n",
                        __func__, sap, rpc_get_port(sap), ep,
                        rdma_event_msg(event->event));
                break;
        }

#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
        if (connstate == 1) {
                int ird = attr->max_dest_rd_atomic;
                int tird = ep->rep_remote_cma.responder_resources;

                pr_info("rpcrdma: connection to %pIS:%u on %s, memreg '%s', %d credits, %d responders%s\n",
                        sap, rpc_get_port(sap),
                        ia->ri_device->name,
                        ia->ri_ops->ro_displayname,
                        xprt->rx_buf.rb_max_requests,
                        ird, ird < 4 && ird < tird / 2 ? " (low!)" : "");
        } else if (connstate < 0) {
                pr_info("rpcrdma: connection to %pIS:%u closed (%d)\n",
                        sap, rpc_get_port(sap), connstate);
        }
#endif

        return 0;
}

static void rpcrdma_destroy_id(struct rdma_cm_id *id)
{
        if (id) {
                module_put(id->device->owner);
                rdma_destroy_id(id);
        }
}

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, IB_QPT_RC);
        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);

        /* FIXME:
         * Until xprtrdma supports DEVICE_REMOVAL, the provider must
         * be pinned while there are active NFS/RDMA mounts to prevent
         * hangs and crashes at umount time.
         */
        if (!ia->ri_async_rc && !try_module_get(id->device->owner)) {
                dprintk("RPC:       %s: Failed to get device module\n",
                        __func__);
                ia->ri_async_rc = -ENODEV;
        }
        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 put;
        }
        wait_for_completion_interruptible_timeout(&ia->ri_done,
                                msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1);
        rc = ia->ri_async_rc;
        if (rc)
                goto put;

        return id;
put:
        module_put(id->device->owner);
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)
{
        struct rpcrdma_ia *ia = &xprt->rx_ia;
        struct ib_device_attr *devattr = &ia->ri_devattr;
        int rc;

        ia->ri_dma_mr = NULL;

        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_device = ia->ri_id->device;

        ia->ri_pd = ib_alloc_pd(ia->ri_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;
        }

        rc = ib_query_device(ia->ri_device, devattr);
        if (rc) {
                dprintk("RPC:       %s: ib_query_device failed %d\n",
                        __func__, rc);
                goto out3;
        }

        if (memreg == 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)) ||
                      (devattr->max_fast_reg_page_list_len == 0)) {
                        dprintk("RPC:       %s: FRMR registration "
                                "not supported by HCA\n", __func__);
                        memreg = RPCRDMA_MTHCAFMR;
                }
        }
        if (memreg == RPCRDMA_MTHCAFMR) {
                if (!ia->ri_device->alloc_fmr) {
                        dprintk("RPC:       %s: MTHCAFMR registration "
                                "not supported by HCA\n", __func__);
                        goto out3;
                }
        }

        switch (memreg) {
        case RPCRDMA_FRMR:
                ia->ri_ops = &rpcrdma_frwr_memreg_ops;
                break;
        case RPCRDMA_ALLPHYSICAL:
                ia->ri_ops = &rpcrdma_physical_memreg_ops;
                break;
        case RPCRDMA_MTHCAFMR:
                ia->ri_ops = &rpcrdma_fmr_memreg_ops;
                break;
        default:
                printk(KERN_ERR "RPC: Unsupported memory "
                                "registration mode: %d\n", memreg);
                rc = -ENOMEM;
                goto out3;
        }
        dprintk("RPC:       %s: memory registration strategy is '%s'\n",
                __func__, ia->ri_ops->ro_displayname);

        rwlock_init(&ia->ri_qplock);
        return 0;

out3:
        ib_dealloc_pd(ia->ri_pd);
        ia->ri_pd = NULL;
out2:
        rpcrdma_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)
{
        dprintk("RPC:       %s: entering\n", __func__);
        if (ia->ri_id != NULL && !IS_ERR(ia->ri_id)) {
                if (ia->ri_id->qp)
                        rdma_destroy_qp(ia->ri_id);
                rpcrdma_destroy_id(ia->ri_id);
                ia->ri_id = NULL;
        }

        /* If the pd is still busy, xprtrdma missed freeing a resource */
        if (ia->ri_pd && !IS_ERR(ia->ri_pd))
                ib_dealloc_pd(ia->ri_pd);
}

/*
 * 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 = &ia->ri_devattr;
        struct ib_cq *sendcq, *recvcq;
        struct ib_cq_init_attr cq_attr = {};
        int rc, err;

        if (devattr->max_sge < RPCRDMA_MAX_IOVS) {
                dprintk("RPC:       %s: insufficient sge's available\n",
                        __func__);
                return -ENOMEM;
        }

        /* 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;
        ep->rep_attr.srq = NULL;
        ep->rep_attr.cap.max_send_wr = cdata->max_requests;
        rc = ia->ri_ops->ro_open(ia, ep, cdata);
        if (rc)
                return rc;
        ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
        ep->rep_attr.cap.max_send_sge = RPCRDMA_MAX_IOVS;
        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;
        if (ep->rep_cqinit > RPCRDMA_MAX_UNSIGNALED_SENDS)
                ep->rep_cqinit = RPCRDMA_MAX_UNSIGNALED_SENDS;
        else if (ep->rep_cqinit <= 2)
                ep->rep_cqinit = 0;
        INIT_CQCOUNT(ep);
        init_waitqueue_head(&ep->rep_connect_wait);
        INIT_DELAYED_WORK(&ep->rep_connect_worker, rpcrdma_connect_worker);

        cq_attr.cqe = ep->rep_attr.cap.max_send_wr + 1;
        sendcq = ib_create_cq(ia->ri_device, rpcrdma_sendcq_upcall,
                              rpcrdma_cq_async_error_upcall, ep, &cq_attr);
        if (IS_ERR(sendcq)) {
                rc = PTR_ERR(sendcq);
                dprintk("RPC:       %s: failed to create send CQ: %i\n",
                        __func__, rc);
                goto out1;
        }

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

        cq_attr.cqe = ep->rep_attr.cap.max_recv_wr + 1;
        recvcq = ib_create_cq(ia->ri_device, rpcrdma_recvcq_upcall,
                              rpcrdma_cq_async_error_upcall, ep, &cq_attr);
        if (IS_ERR(recvcq)) {
                rc = PTR_ERR(recvcq);
                dprintk("RPC:       %s: failed to create recv CQ: %i\n",
                        __func__, rc);
                goto out2;
        }

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

        ep->rep_attr.send_cq = sendcq;
        ep->rep_attr.recv_cq = recvcq;

        /* 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 (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(sendcq);
        if (err)
                dprintk("RPC:       %s: ib_destroy_cq returned %i\n",
                        __func__, err);
out1:
        if (ia->ri_dma_mr)
                ib_dereg_mr(ia->ri_dma_mr);
        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.
 */
void
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);

        cancel_delayed_work_sync(&ep->rep_connect_worker);

        if (ia->ri_id->qp)
                rpcrdma_ep_disconnect(ep, ia);

        rpcrdma_clean_cq(ep->rep_attr.recv_cq);
        rpcrdma_clean_cq(ep->rep_attr.send_cq);

        if (ia->ri_id->qp) {
                rdma_destroy_qp(ia->ri_id);
                ia->ri_id->qp = NULL;
        }

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

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

        if (ia->ri_dma_mr) {
                rc = ib_dereg_mr(ia->ri_dma_mr);
                dprintk("RPC:       %s: ib_dereg_mr returned %i\n",
                        __func__, rc);
        }
}

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

        if (ep->rep_connected != 0) {
                struct rpcrdma_xprt *xprt;
retry:
                dprintk("RPC:       %s: reconnecting...\n", __func__);

                rpcrdma_ep_disconnect(ep, ia);
                rpcrdma_flush_cqs(ep);

                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 = -EHOSTUNREACH;
                        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_device != id->device) {
                        printk("RPC:       %s: can't reconnect on "
                                "different device!\n", __func__);
                        rpcrdma_destroy_id(id);
                        rc = -ENETUNREACH;
                        goto out;
                }
                /* END TEMP */
                rc = rdma_create_qp(id, ia->ri_pd, &ep->rep_attr);
                if (rc) {
                        dprintk("RPC:       %s: rdma_create_qp failed %i\n",
                                __func__, rc);
                        rpcrdma_destroy_id(id);
                        rc = -ENETUNREACH;
                        goto out;
                }

                write_lock(&ia->ri_qplock);
                old = ia->ri_id;
                ia->ri_id = id;
                write_unlock(&ia->ri_qplock);

                rdma_destroy_qp(old);
                rpcrdma_destroy_id(old);
        } else {
                dprintk("RPC:       %s: connecting...\n", __func__);
                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);
                        /* do not update ep->rep_connected */
                        return -ENETUNREACH;
                }
        }

        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.
 */
void
rpcrdma_ep_disconnect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
{
        int rc;

        rpcrdma_flush_cqs(ep);
        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;
        }
}

static struct rpcrdma_req *
rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
{
        struct rpcrdma_req *req;

        req = kzalloc(sizeof(*req), GFP_KERNEL);
        if (req == NULL)
                return ERR_PTR(-ENOMEM);

        req->rl_buffer = &r_xprt->rx_buf;
        return req;
}

static struct rpcrdma_rep *
rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
{
        struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
        struct rpcrdma_ia *ia = &r_xprt->rx_ia;
        struct rpcrdma_rep *rep;
        int rc;

        rc = -ENOMEM;
        rep = kzalloc(sizeof(*rep), GFP_KERNEL);
        if (rep == NULL)
                goto out;

        rep->rr_rdmabuf = rpcrdma_alloc_regbuf(ia, cdata->inline_rsize,
                                               GFP_KERNEL);
        if (IS_ERR(rep->rr_rdmabuf)) {
                rc = PTR_ERR(rep->rr_rdmabuf);
                goto out_free;
        }

        rep->rr_device = ia->ri_device;
        rep->rr_rxprt = r_xprt;
        return rep;

out_free:
        kfree(rep);
out:
        return ERR_PTR(rc);
}

int
rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
{
        struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
        struct rpcrdma_ia *ia = &r_xprt->rx_ia;
        struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
        char *p;
        size_t len;
        int i, rc;

        buf->rb_max_requests = cdata->max_requests;
        spin_lock_init(&buf->rb_lock);

        /* 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
         * Send/recv buffers in req/rep need to be registered
         */
        len = buf->rb_max_requests *
                (sizeof(struct rpcrdma_req *) + sizeof(struct rpcrdma_rep *));

        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];

        rc = ia->ri_ops->ro_init(r_xprt);
        if (rc)
                goto out;

        for (i = 0; i < buf->rb_max_requests; i++) {
                struct rpcrdma_req *req;
                struct rpcrdma_rep *rep;

                req = rpcrdma_create_req(r_xprt);
                if (IS_ERR(req)) {
                        dprintk("RPC:       %s: request buffer %d alloc"
                                " failed\n", __func__, i);
                        rc = PTR_ERR(req);
                        goto out;
                }
                buf->rb_send_bufs[i] = req;

                rep = rpcrdma_create_rep(r_xprt);
                if (IS_ERR(rep)) {
                        dprintk("RPC:       %s: reply buffer %d alloc failed\n",
                                __func__, i);
                        rc = PTR_ERR(rep);
                        goto out;
                }
                buf->rb_recv_bufs[i] = rep;
        }

        return 0;
out:
        rpcrdma_buffer_destroy(buf);
        return rc;
}

static void
rpcrdma_destroy_rep(struct rpcrdma_ia *ia, struct rpcrdma_rep *rep)
{
        if (!rep)
                return;

        rpcrdma_free_regbuf(ia, rep->rr_rdmabuf);
        kfree(rep);
}

static void
rpcrdma_destroy_req(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
{
        if (!req)
                return;

        rpcrdma_free_regbuf(ia, req->rl_sendbuf);
        rpcrdma_free_regbuf(ia, req->rl_rdmabuf);
        kfree(req);
}

void
rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
{
        struct rpcrdma_ia *ia = rdmab_to_ia(buf);
        int i;

        /* clean up in reverse order from create
         *   1.  recv mr memory (mr free, then kfree)
         *   2.  send mr memory (mr free, then kfree)
         *   3.  MWs
         */
        dprintk("RPC:       %s: entering\n", __func__);

        for (i = 0; i < buf->rb_max_requests; i++) {
                if (buf->rb_recv_bufs)
                        rpcrdma_destroy_rep(ia, buf->rb_recv_bufs[i]);
                if (buf->rb_send_bufs)
                        rpcrdma_destroy_req(ia, buf->rb_send_bufs[i]);
        }

        ia->ri_ops->ro_destroy(buf);

        kfree(buf->rb_pool);
}

struct rpcrdma_mw *
rpcrdma_get_mw(struct rpcrdma_xprt *r_xprt)
{
        struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
        struct rpcrdma_mw *mw = NULL;

        spin_lock(&buf->rb_mwlock);
        if (!list_empty(&buf->rb_mws)) {
                mw = list_first_entry(&buf->rb_mws,
                                      struct rpcrdma_mw, mw_list);
                list_del_init(&mw->mw_list);
        }
        spin_unlock(&buf->rb_mwlock);

        if (!mw)
                pr_err("RPC:       %s: no MWs available\n", __func__);
        return mw;
}

void
rpcrdma_put_mw(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mw *mw)
{
        struct rpcrdma_buffer *buf = &r_xprt->rx_buf;

        spin_lock(&buf->rb_mwlock);
        list_add_tail(&mw->mw_list, &buf->rb_mws);
        spin_unlock(&buf->rb_mwlock);
}

static void
rpcrdma_buffer_put_sendbuf(struct rpcrdma_req *req, struct rpcrdma_buffer *buf)
{
        buf->rb_send_bufs[--buf->rb_send_index] = req;
        req->rl_niovs = 0;
        if (req->rl_reply) {
                buf->rb_recv_bufs[--buf->rb_recv_index] = req->rl_reply;
                req->rl_reply = NULL;
        }
}

/*
 * 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;

        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;

        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;
        unsigned long flags;

        spin_lock_irqsave(&buffers->rb_lock, flags);
        rpcrdma_buffer_put_sendbuf(req, buffers);
        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;

        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.
 */
void
rpcrdma_recv_buffer_put(struct rpcrdma_rep *rep)
{
        struct rpcrdma_buffer *buffers = &rep->rr_rxprt->rx_buf;
        unsigned long flags;

        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.
 */

void
rpcrdma_mapping_error(struct rpcrdma_mr_seg *seg)
{
        dprintk("RPC:       map_one: offset %p iova %llx len %zu\n",
                seg->mr_offset,
                (unsigned long long)seg->mr_dma, seg->mr_dmalen);
}

/**
 * rpcrdma_alloc_regbuf - kmalloc and register memory for SEND/RECV buffers
 * @ia: controlling rpcrdma_ia
 * @size: size of buffer to be allocated, in bytes
 * @flags: GFP flags
 *
 * Returns pointer to private header of an area of internally
 * registered memory, or an ERR_PTR. The registered buffer follows
 * the end of the private header.
 *
 * xprtrdma uses a regbuf for posting an outgoing RDMA SEND, or for
 * receiving the payload of RDMA RECV operations. regbufs are not
 * used for RDMA READ/WRITE operations, thus are registered only for
 * LOCAL access.
 */
struct rpcrdma_regbuf *
rpcrdma_alloc_regbuf(struct rpcrdma_ia *ia, size_t size, gfp_t flags)
{
        struct rpcrdma_regbuf *rb;
        struct ib_sge *iov;

        rb = kmalloc(sizeof(*rb) + size, flags);
        if (rb == NULL)
                goto out;

        iov = &rb->rg_iov;
        iov->addr = ib_dma_map_single(ia->ri_device,
                                      (void *)rb->rg_base, size,
                                      DMA_BIDIRECTIONAL);
        if (ib_dma_mapping_error(ia->ri_device, iov->addr))
                goto out_free;

        iov->length = size;
        iov->lkey = ia->ri_pd->local_dma_lkey;
        rb->rg_size = size;
        rb->rg_owner = NULL;
        return rb;

out_free:
        kfree(rb);
out:
        return ERR_PTR(-ENOMEM);
}

/**
 * rpcrdma_free_regbuf - deregister and free registered buffer
 * @ia: controlling rpcrdma_ia
 * @rb: regbuf to be deregistered and freed
 */
void
rpcrdma_free_regbuf(struct rpcrdma_ia *ia, struct rpcrdma_regbuf *rb)
{
        struct ib_sge *iov;

        if (!rb)
                return;

        iov = &rb->rg_iov;
        ib_dma_unmap_single(ia->ri_device,
                            iov->addr, iov->length, DMA_BIDIRECTIONAL);
        kfree(rb);
}

/*
 * 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_device *device = ia->ri_device;
        struct ib_send_wr send_wr, *send_wr_fail;
        struct rpcrdma_rep *rep = req->rl_reply;
        struct ib_sge *iov = req->rl_send_iov;
        int i, 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 = RPCRDMA_IGNORE_COMPLETION;
        send_wr.sg_list = iov;
        send_wr.num_sge = req->rl_niovs;
        send_wr.opcode = IB_WR_SEND;

        for (i = 0; i < send_wr.num_sge; i++)
                ib_dma_sync_single_for_device(device, iov[i].addr,
                                              iov[i].length, DMA_TO_DEVICE);
        dprintk("RPC:       %s: posting %d s/g entries\n",
                __func__, send_wr.num_sge);

        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_rdmabuf->rg_iov;
        recv_wr.num_sge = 1;

        ib_dma_sync_single_for_cpu(ia->ri_device,
                                   rdmab_addr(rep->rr_rdmabuf),
                                   rdmab_length(rep->rr_rdmabuf),
                                   DMA_BIDIRECTIONAL);

        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;
}

/* How many chunk list items fit within our inline buffers?
 */
unsigned int
rpcrdma_max_segments(struct rpcrdma_xprt *r_xprt)
{
        struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
        int bytes, segments;

        bytes = min_t(unsigned int, cdata->inline_wsize, cdata->inline_rsize);
        bytes -= RPCRDMA_HDRLEN_MIN;
        if (bytes < sizeof(struct rpcrdma_segment) * 2) {
                pr_warn("RPC:       %s: inline threshold too small\n",
                        __func__);
                return 0;
        }

        segments = 1 << (fls(bytes / sizeof(struct rpcrdma_segment)) - 1);
        dprintk("RPC:       %s: max chunk list size = %d segments\n",
                __func__, segments);
        return segments;
}