text: /*
   * 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 "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;
  	struct sockaddr_in *addr = (struct sockaddr_in *) &ep->rep_remote_addr;
  	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:
  		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: %u.%u.%u.%u:%u"
  			" (ep 0x%p event 0x%x)\n",
  			__func__,
  			(event->event <= 11) ? conn[event->event] :
  						"unknown connection error",
  			NIPQUAD(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:
  		ia->ri_async_rc = -EINVAL;
  		dprintk("RPC:       %s: unexpected CM event %X\n",
  			__func__, event->event);
  		complete(&ia->ri_done);
  		break;
  	}
  
  	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;
  
  	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 = 0;
  	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(&ia->ri_done);
  	rc = ia->ri_async_rc;
  	if (rc)
  		goto out;
  
  	ia->ri_async_rc = 0;
  	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(&ia->ri_done);
  	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;
  	struct rpcrdma_ia *ia = &xprt->rx_ia;
  
  	init_completion(&ia->ri_done);
  
  	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;
  	}
  
  	/*
  	 * 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.
  	 */
  	if (memreg > RPCRDMA_REGISTER) {
  		int mem_priv = IB_ACCESS_LOCAL_WRITE;
  		switch (memreg) {
  #if RPCRDMA_PERSISTENT_REGISTRATION
  		case RPCRDMA_ALLPHYSICAL:
  			mem_priv |= IB_ACCESS_REMOTE_WRITE;
  			mem_priv |= IB_ACCESS_REMOTE_READ;
  			break;
  #endif
  		case RPCRDMA_MEMWINDOWS_ASYNC:
  		case RPCRDMA_MEMWINDOWS:
  			mem_priv |= IB_ACCESS_MW_BIND;
  			break;
  		default:
  			break;
  		}
  		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;
  		}
  	}
  
  	/* Else will do memory reg/dereg for each chunk */
  	ia->ri_memreg_strategy = memreg;
  
  	return 0;
  out2:
  	rdma_destroy_id(ia->ri_id);
  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) && ia->ri_id->qp)
  		rdma_destroy_qp(ia->ri_id);
  	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);
  	}
  	if (ia->ri_id != NULL && !IS_ERR(ia->ri_id))
  		rdma_destroy_id(ia->ri_id);
  }
  
  /*
   * 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;
  
  	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_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 */
  	switch (ia->ri_memreg_strategy) {
  	case RPCRDMA_BOUNCEBUFFERS:
  		ep->rep_remote_cma.responder_resources = 0;
  		break;
  	case RPCRDMA_MTHCAFMR:
  	case RPCRDMA_REGISTER:
  		ep->rep_remote_cma.responder_resources = cdata->max_requests *
  				(RPCRDMA_MAX_DATA_SEGS / 8);
  		break;
  	case RPCRDMA_MEMWINDOWS:
  	case RPCRDMA_MEMWINDOWS_ASYNC:
  #if RPCRDMA_PERSISTENT_REGISTRATION
  	case RPCRDMA_ALLPHYSICAL:
  #endif
  		ep->rep_remote_cma.responder_resources = cdata->max_requests *
  				(RPCRDMA_MAX_DATA_SEGS / 2);
  		break;
  	default:
  		break;
  	}
  	if (ep->rep_remote_cma.responder_resources > devattr.max_qp_rd_atom)
  		ep->rep_remote_cma.responder_resources = devattr.max_qp_rd_atom;
  	ep->rep_remote_cma.initiator_depth = 0;
  
  	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:
  	if (ib_destroy_cq(ep->rep_cq))
  		;
  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);
  	}
  
  	ep->rep_func = 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;
  	}
  
  	if (ia->ri_id->qp) {
  		rdma_destroy_qp(ia->ri_id);
  		ia->ri_id->qp = 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;
  	int reconnect = (ep->rep_connected != 0);
  
  	if (reconnect) {
  		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_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);
  	}
  }
  
  	/* Theoretically a client initiator_depth > 0 is not needed,
  	 * but many peers fail to complete the connection unless they
  	 * == responder_resources! */
  	if (ep->rep_remote_cma.initiator_depth !=
  				ep->rep_remote_cma.responder_resources)
  		ep->rep_remote_cma.initiator_depth =
  			ep->rep_remote_cma.responder_resources;
  
  	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;
  	}
  
  	if (reconnect)
  		return 0;
  
  	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. */
  		ep->rep_remote_cma.initiator_depth =
  					ep->rep_remote_cma.responder_resources;
  		if (ep->rep_remote_cma.initiator_depth == 0)
  			++ep->rep_remote_cma.initiator_depth;
  		if (ep->rep_remote_cma.responder_resources == 0)
  			++ep->rep_remote_cma.responder_resources;
  		if (retry_count++ == 0)
  			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;
  
  	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, 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_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);
  	switch (ia->ri_memreg_strategy) {
  	case RPCRDMA_MTHCAFMR:
  		{
  		struct rpcrdma_mw *r = (struct rpcrdma_mw *)p;
  		struct ib_fmr_attr fa = {
  			RPCRDMA_MAX_DATA_SEGS, 1, PAGE_SHIFT
  		};
  		/* TBD we are perhaps overallocating here */
  		for (i = (buf->rb_max_requests+1) * RPCRDMA_MAX_SEGS; i; i--) {
  			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:
  		{
  		struct rpcrdma_mw *r = (struct rpcrdma_mw *)p;
  		/* 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);
  
  	/* 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)) {
  				struct rpcrdma_mw *r;
  				r = list_entry(buf->rb_mws.next,
  					struct rpcrdma_mw, mw_list);
  				list_del(&r->mw_list);
  				switch (ia->ri_memreg_strategy) {
  				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;
  
  	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)) {
  		int i = RPCRDMA_MAX_SEGS - 1;
  		do {
  			struct rpcrdma_mw *r;
  			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_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_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);
  }
  
  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 mem_priv = (writing ? IB_ACCESS_REMOTE_WRITE :
  				  IB_ACCESS_REMOTE_READ);
  	struct rpcrdma_mr_seg *seg1 = seg;
  	int i;
  	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 fast memory registration */
  	case RPCRDMA_MTHCAFMR:
  		{
  		u64 physaddrs[RPCRDMA_MAX_DATA_SEGS];
  		int len, pageoff = offset_in_page(seg->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;
  		}
  		nsegs = i;
  		rc = ib_map_phys_fmr(seg1->mr_chunk.rl_mw->r.fmr,
  					physaddrs, nsegs, 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, nsegs, rc);
  			while (nsegs--)
  				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 = nsegs;
  			seg1->mr_len = len;
  		}
  		}
  		break;
  
  	/* Registration using memory windows */
  	case RPCRDMA_MEMWINDOWS_ASYNC:
  	case RPCRDMA_MEMWINDOWS:
  		{
  		struct ib_mw_bind param;
  		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;
  			nsegs = 1;
  		}
  		}
  		break;
  
  	/* Default registration each time */
  	default:
  		{
  		struct ib_phys_buf ipb[RPCRDMA_MAX_DATA_SEGS];
  		int len = 0;
  		if (nsegs > RPCRDMA_MAX_DATA_SEGS)
  			nsegs = RPCRDMA_MAX_DATA_SEGS;
  		for (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;
  		}
  		nsegs = i;
  		seg1->mr_base = seg1->mr_dma;
  		seg1->mr_chunk.rl_mr = ib_reg_phys_mr(ia->ri_pd,
  					ipb, nsegs, 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, nsegs, rc);
  			while (nsegs--)
  				rpcrdma_unmap_one(ia, --seg);
  		} else {
  			seg1->mr_rkey = seg1->mr_chunk.rl_mr->rkey;
  			seg1->mr_nsegs = nsegs;
  			seg1->mr_len = len;
  		}
  		}
  		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;
  	struct rpcrdma_mr_seg *seg1 = seg;
  	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_MTHCAFMR:
  		{
  		LIST_HEAD(l);
  		list_add(&seg->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);
  		break;
  
  	case RPCRDMA_MEMWINDOWS_ASYNC:
  	case RPCRDMA_MEMWINDOWS:
  		{
  		struct ib_mw_bind param;
  		BUG_ON(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 */
  		break;
  
  	default:
  		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);
  		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;
  	send_wr.imm_data = 0;
  	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;
  }
  