xref: /openbmc/linux/net/sunrpc/xprtrdma/verbs.c (revision 93032e31)
1 /*
2  * Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
3  *
4  * This software is available to you under a choice of one of two
5  * licenses.  You may choose to be licensed under the terms of the GNU
6  * General Public License (GPL) Version 2, available from the file
7  * COPYING in the main directory of this source tree, or the BSD-type
8  * license below:
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  *
14  *      Redistributions of source code must retain the above copyright
15  *      notice, this list of conditions and the following disclaimer.
16  *
17  *      Redistributions in binary form must reproduce the above
18  *      copyright notice, this list of conditions and the following
19  *      disclaimer in the documentation and/or other materials provided
20  *      with the distribution.
21  *
22  *      Neither the name of the Network Appliance, Inc. nor the names of
23  *      its contributors may be used to endorse or promote products
24  *      derived from this software without specific prior written
25  *      permission.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
28  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
29  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
30  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
31  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
32  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
33  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
34  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
35  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
36  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
37  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38  */
39 
40 /*
41  * verbs.c
42  *
43  * Encapsulates the major functions managing:
44  *  o adapters
45  *  o endpoints
46  *  o connections
47  *  o buffer memory
48  */
49 
50 #include <linux/interrupt.h>
51 #include <linux/slab.h>
52 #include <linux/prefetch.h>
53 #include <linux/sunrpc/addr.h>
54 #include <linux/sunrpc/svc_rdma.h>
55 #include <asm/bitops.h>
56 #include <linux/module.h> /* try_module_get()/module_put() */
57 
58 #include "xprt_rdma.h"
59 
60 /*
61  * Globals/Macros
62  */
63 
64 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
65 # define RPCDBG_FACILITY	RPCDBG_TRANS
66 #endif
67 
68 /*
69  * internal functions
70  */
71 
72 static struct workqueue_struct *rpcrdma_receive_wq;
73 
74 int
75 rpcrdma_alloc_wq(void)
76 {
77 	struct workqueue_struct *recv_wq;
78 
79 	recv_wq = alloc_workqueue("xprtrdma_receive",
80 				  WQ_MEM_RECLAIM | WQ_UNBOUND | WQ_HIGHPRI,
81 				  0);
82 	if (!recv_wq)
83 		return -ENOMEM;
84 
85 	rpcrdma_receive_wq = recv_wq;
86 	return 0;
87 }
88 
89 void
90 rpcrdma_destroy_wq(void)
91 {
92 	struct workqueue_struct *wq;
93 
94 	if (rpcrdma_receive_wq) {
95 		wq = rpcrdma_receive_wq;
96 		rpcrdma_receive_wq = NULL;
97 		destroy_workqueue(wq);
98 	}
99 }
100 
101 static void
102 rpcrdma_qp_async_error_upcall(struct ib_event *event, void *context)
103 {
104 	struct rpcrdma_ep *ep = context;
105 
106 	pr_err("RPC:       %s: %s on device %s ep %p\n",
107 	       __func__, ib_event_msg(event->event),
108 		event->device->name, context);
109 	if (ep->rep_connected == 1) {
110 		ep->rep_connected = -EIO;
111 		rpcrdma_conn_func(ep);
112 		wake_up_all(&ep->rep_connect_wait);
113 	}
114 }
115 
116 /**
117  * rpcrdma_wc_send - Invoked by RDMA provider for each polled Send WC
118  * @cq:	completion queue (ignored)
119  * @wc:	completed WR
120  *
121  */
122 static void
123 rpcrdma_wc_send(struct ib_cq *cq, struct ib_wc *wc)
124 {
125 	/* WARNING: Only wr_cqe and status are reliable at this point */
126 	if (wc->status != IB_WC_SUCCESS && wc->status != IB_WC_WR_FLUSH_ERR)
127 		pr_err("rpcrdma: Send: %s (%u/0x%x)\n",
128 		       ib_wc_status_msg(wc->status),
129 		       wc->status, wc->vendor_err);
130 }
131 
132 /* Perform basic sanity checking to avoid using garbage
133  * to update the credit grant value.
134  */
135 static void
136 rpcrdma_update_granted_credits(struct rpcrdma_rep *rep)
137 {
138 	struct rpcrdma_msg *rmsgp = rdmab_to_msg(rep->rr_rdmabuf);
139 	struct rpcrdma_buffer *buffer = &rep->rr_rxprt->rx_buf;
140 	u32 credits;
141 
142 	if (rep->rr_len < RPCRDMA_HDRLEN_ERR)
143 		return;
144 
145 	credits = be32_to_cpu(rmsgp->rm_credit);
146 	if (credits == 0)
147 		credits = 1;	/* don't deadlock */
148 	else if (credits > buffer->rb_max_requests)
149 		credits = buffer->rb_max_requests;
150 
151 	atomic_set(&buffer->rb_credits, credits);
152 }
153 
154 /**
155  * rpcrdma_wc_receive - Invoked by RDMA provider for each polled Receive WC
156  * @cq:	completion queue (ignored)
157  * @wc:	completed WR
158  *
159  */
160 static void
161 rpcrdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
162 {
163 	struct ib_cqe *cqe = wc->wr_cqe;
164 	struct rpcrdma_rep *rep = container_of(cqe, struct rpcrdma_rep,
165 					       rr_cqe);
166 
167 	/* WARNING: Only wr_id and status are reliable at this point */
168 	if (wc->status != IB_WC_SUCCESS)
169 		goto out_fail;
170 
171 	/* status == SUCCESS means all fields in wc are trustworthy */
172 	if (wc->opcode != IB_WC_RECV)
173 		return;
174 
175 	dprintk("RPC:       %s: rep %p opcode 'recv', length %u: success\n",
176 		__func__, rep, wc->byte_len);
177 
178 	rep->rr_len = wc->byte_len;
179 	rep->rr_wc_flags = wc->wc_flags;
180 	rep->rr_inv_rkey = wc->ex.invalidate_rkey;
181 
182 	ib_dma_sync_single_for_cpu(rep->rr_device,
183 				   rdmab_addr(rep->rr_rdmabuf),
184 				   rep->rr_len, DMA_FROM_DEVICE);
185 
186 	rpcrdma_update_granted_credits(rep);
187 
188 out_schedule:
189 	queue_work(rpcrdma_receive_wq, &rep->rr_work);
190 	return;
191 
192 out_fail:
193 	if (wc->status != IB_WC_WR_FLUSH_ERR)
194 		pr_err("rpcrdma: Recv: %s (%u/0x%x)\n",
195 		       ib_wc_status_msg(wc->status),
196 		       wc->status, wc->vendor_err);
197 	rep->rr_len = RPCRDMA_BAD_LEN;
198 	goto out_schedule;
199 }
200 
201 static void
202 rpcrdma_update_connect_private(struct rpcrdma_xprt *r_xprt,
203 			       struct rdma_conn_param *param)
204 {
205 	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
206 	const struct rpcrdma_connect_private *pmsg = param->private_data;
207 	unsigned int rsize, wsize;
208 
209 	/* Default settings for RPC-over-RDMA Version One */
210 	r_xprt->rx_ia.ri_reminv_expected = false;
211 	rsize = RPCRDMA_V1_DEF_INLINE_SIZE;
212 	wsize = RPCRDMA_V1_DEF_INLINE_SIZE;
213 
214 	if (pmsg &&
215 	    pmsg->cp_magic == rpcrdma_cmp_magic &&
216 	    pmsg->cp_version == RPCRDMA_CMP_VERSION) {
217 		r_xprt->rx_ia.ri_reminv_expected = true;
218 		rsize = rpcrdma_decode_buffer_size(pmsg->cp_send_size);
219 		wsize = rpcrdma_decode_buffer_size(pmsg->cp_recv_size);
220 	}
221 
222 	if (rsize < cdata->inline_rsize)
223 		cdata->inline_rsize = rsize;
224 	if (wsize < cdata->inline_wsize)
225 		cdata->inline_wsize = wsize;
226 	pr_info("rpcrdma: max send %u, max recv %u\n",
227 		cdata->inline_wsize, cdata->inline_rsize);
228 	rpcrdma_set_max_header_sizes(r_xprt);
229 }
230 
231 static int
232 rpcrdma_conn_upcall(struct rdma_cm_id *id, struct rdma_cm_event *event)
233 {
234 	struct rpcrdma_xprt *xprt = id->context;
235 	struct rpcrdma_ia *ia = &xprt->rx_ia;
236 	struct rpcrdma_ep *ep = &xprt->rx_ep;
237 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
238 	struct sockaddr *sap = (struct sockaddr *)&ep->rep_remote_addr;
239 #endif
240 	struct ib_qp_attr *attr = &ia->ri_qp_attr;
241 	struct ib_qp_init_attr *iattr = &ia->ri_qp_init_attr;
242 	int connstate = 0;
243 
244 	switch (event->event) {
245 	case RDMA_CM_EVENT_ADDR_RESOLVED:
246 	case RDMA_CM_EVENT_ROUTE_RESOLVED:
247 		ia->ri_async_rc = 0;
248 		complete(&ia->ri_done);
249 		break;
250 	case RDMA_CM_EVENT_ADDR_ERROR:
251 		ia->ri_async_rc = -EHOSTUNREACH;
252 		dprintk("RPC:       %s: CM address resolution error, ep 0x%p\n",
253 			__func__, ep);
254 		complete(&ia->ri_done);
255 		break;
256 	case RDMA_CM_EVENT_ROUTE_ERROR:
257 		ia->ri_async_rc = -ENETUNREACH;
258 		dprintk("RPC:       %s: CM route resolution error, ep 0x%p\n",
259 			__func__, ep);
260 		complete(&ia->ri_done);
261 		break;
262 	case RDMA_CM_EVENT_ESTABLISHED:
263 		connstate = 1;
264 		ib_query_qp(ia->ri_id->qp, attr,
265 			    IB_QP_MAX_QP_RD_ATOMIC | IB_QP_MAX_DEST_RD_ATOMIC,
266 			    iattr);
267 		dprintk("RPC:       %s: %d responder resources"
268 			" (%d initiator)\n",
269 			__func__, attr->max_dest_rd_atomic,
270 			attr->max_rd_atomic);
271 		rpcrdma_update_connect_private(xprt, &event->param.conn);
272 		goto connected;
273 	case RDMA_CM_EVENT_CONNECT_ERROR:
274 		connstate = -ENOTCONN;
275 		goto connected;
276 	case RDMA_CM_EVENT_UNREACHABLE:
277 		connstate = -ENETDOWN;
278 		goto connected;
279 	case RDMA_CM_EVENT_REJECTED:
280 		connstate = -ECONNREFUSED;
281 		goto connected;
282 	case RDMA_CM_EVENT_DISCONNECTED:
283 		connstate = -ECONNABORTED;
284 		goto connected;
285 	case RDMA_CM_EVENT_DEVICE_REMOVAL:
286 		connstate = -ENODEV;
287 connected:
288 		dprintk("RPC:       %s: %sconnected\n",
289 					__func__, connstate > 0 ? "" : "dis");
290 		atomic_set(&xprt->rx_buf.rb_credits, 1);
291 		ep->rep_connected = connstate;
292 		rpcrdma_conn_func(ep);
293 		wake_up_all(&ep->rep_connect_wait);
294 		/*FALLTHROUGH*/
295 	default:
296 		dprintk("RPC:       %s: %pIS:%u (ep 0x%p): %s\n",
297 			__func__, sap, rpc_get_port(sap), ep,
298 			rdma_event_msg(event->event));
299 		break;
300 	}
301 
302 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
303 	if (connstate == 1) {
304 		int ird = attr->max_dest_rd_atomic;
305 		int tird = ep->rep_remote_cma.responder_resources;
306 
307 		pr_info("rpcrdma: connection to %pIS:%u on %s, memreg '%s', %d credits, %d responders%s\n",
308 			sap, rpc_get_port(sap),
309 			ia->ri_device->name,
310 			ia->ri_ops->ro_displayname,
311 			xprt->rx_buf.rb_max_requests,
312 			ird, ird < 4 && ird < tird / 2 ? " (low!)" : "");
313 	} else if (connstate < 0) {
314 		pr_info("rpcrdma: connection to %pIS:%u closed (%d)\n",
315 			sap, rpc_get_port(sap), connstate);
316 	}
317 #endif
318 
319 	return 0;
320 }
321 
322 static void rpcrdma_destroy_id(struct rdma_cm_id *id)
323 {
324 	if (id) {
325 		module_put(id->device->owner);
326 		rdma_destroy_id(id);
327 	}
328 }
329 
330 static struct rdma_cm_id *
331 rpcrdma_create_id(struct rpcrdma_xprt *xprt,
332 			struct rpcrdma_ia *ia, struct sockaddr *addr)
333 {
334 	struct rdma_cm_id *id;
335 	int rc;
336 
337 	init_completion(&ia->ri_done);
338 
339 	id = rdma_create_id(&init_net, rpcrdma_conn_upcall, xprt, RDMA_PS_TCP,
340 			    IB_QPT_RC);
341 	if (IS_ERR(id)) {
342 		rc = PTR_ERR(id);
343 		dprintk("RPC:       %s: rdma_create_id() failed %i\n",
344 			__func__, rc);
345 		return id;
346 	}
347 
348 	ia->ri_async_rc = -ETIMEDOUT;
349 	rc = rdma_resolve_addr(id, NULL, addr, RDMA_RESOLVE_TIMEOUT);
350 	if (rc) {
351 		dprintk("RPC:       %s: rdma_resolve_addr() failed %i\n",
352 			__func__, rc);
353 		goto out;
354 	}
355 	wait_for_completion_interruptible_timeout(&ia->ri_done,
356 				msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1);
357 
358 	/* FIXME:
359 	 * Until xprtrdma supports DEVICE_REMOVAL, the provider must
360 	 * be pinned while there are active NFS/RDMA mounts to prevent
361 	 * hangs and crashes at umount time.
362 	 */
363 	if (!ia->ri_async_rc && !try_module_get(id->device->owner)) {
364 		dprintk("RPC:       %s: Failed to get device module\n",
365 			__func__);
366 		ia->ri_async_rc = -ENODEV;
367 	}
368 	rc = ia->ri_async_rc;
369 	if (rc)
370 		goto out;
371 
372 	ia->ri_async_rc = -ETIMEDOUT;
373 	rc = rdma_resolve_route(id, RDMA_RESOLVE_TIMEOUT);
374 	if (rc) {
375 		dprintk("RPC:       %s: rdma_resolve_route() failed %i\n",
376 			__func__, rc);
377 		goto put;
378 	}
379 	wait_for_completion_interruptible_timeout(&ia->ri_done,
380 				msecs_to_jiffies(RDMA_RESOLVE_TIMEOUT) + 1);
381 	rc = ia->ri_async_rc;
382 	if (rc)
383 		goto put;
384 
385 	return id;
386 put:
387 	module_put(id->device->owner);
388 out:
389 	rdma_destroy_id(id);
390 	return ERR_PTR(rc);
391 }
392 
393 /*
394  * Exported functions.
395  */
396 
397 /*
398  * Open and initialize an Interface Adapter.
399  *  o initializes fields of struct rpcrdma_ia, including
400  *    interface and provider attributes and protection zone.
401  */
402 int
403 rpcrdma_ia_open(struct rpcrdma_xprt *xprt, struct sockaddr *addr, int memreg)
404 {
405 	struct rpcrdma_ia *ia = &xprt->rx_ia;
406 	int rc;
407 
408 	ia->ri_id = rpcrdma_create_id(xprt, ia, addr);
409 	if (IS_ERR(ia->ri_id)) {
410 		rc = PTR_ERR(ia->ri_id);
411 		goto out1;
412 	}
413 	ia->ri_device = ia->ri_id->device;
414 
415 	ia->ri_pd = ib_alloc_pd(ia->ri_device, 0);
416 	if (IS_ERR(ia->ri_pd)) {
417 		rc = PTR_ERR(ia->ri_pd);
418 		pr_err("rpcrdma: ib_alloc_pd() returned %d\n", rc);
419 		goto out2;
420 	}
421 
422 	switch (memreg) {
423 	case RPCRDMA_FRMR:
424 		if (frwr_is_supported(ia)) {
425 			ia->ri_ops = &rpcrdma_frwr_memreg_ops;
426 			break;
427 		}
428 		/*FALLTHROUGH*/
429 	case RPCRDMA_MTHCAFMR:
430 		if (fmr_is_supported(ia)) {
431 			ia->ri_ops = &rpcrdma_fmr_memreg_ops;
432 			break;
433 		}
434 		/*FALLTHROUGH*/
435 	default:
436 		pr_err("rpcrdma: Unsupported memory registration mode: %d\n",
437 		       memreg);
438 		rc = -EINVAL;
439 		goto out3;
440 	}
441 
442 	return 0;
443 
444 out3:
445 	ib_dealloc_pd(ia->ri_pd);
446 	ia->ri_pd = NULL;
447 out2:
448 	rpcrdma_destroy_id(ia->ri_id);
449 	ia->ri_id = NULL;
450 out1:
451 	return rc;
452 }
453 
454 /*
455  * Clean up/close an IA.
456  *   o if event handles and PD have been initialized, free them.
457  *   o close the IA
458  */
459 void
460 rpcrdma_ia_close(struct rpcrdma_ia *ia)
461 {
462 	dprintk("RPC:       %s: entering\n", __func__);
463 	if (ia->ri_id != NULL && !IS_ERR(ia->ri_id)) {
464 		if (ia->ri_id->qp)
465 			rdma_destroy_qp(ia->ri_id);
466 		rpcrdma_destroy_id(ia->ri_id);
467 		ia->ri_id = NULL;
468 	}
469 
470 	/* If the pd is still busy, xprtrdma missed freeing a resource */
471 	if (ia->ri_pd && !IS_ERR(ia->ri_pd))
472 		ib_dealloc_pd(ia->ri_pd);
473 }
474 
475 /*
476  * Create unconnected endpoint.
477  */
478 int
479 rpcrdma_ep_create(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia,
480 				struct rpcrdma_create_data_internal *cdata)
481 {
482 	struct rpcrdma_connect_private *pmsg = &ep->rep_cm_private;
483 	struct ib_cq *sendcq, *recvcq;
484 	unsigned int max_qp_wr;
485 	int rc;
486 
487 	if (ia->ri_device->attrs.max_sge < RPCRDMA_MAX_SEND_SGES) {
488 		dprintk("RPC:       %s: insufficient sge's available\n",
489 			__func__);
490 		return -ENOMEM;
491 	}
492 
493 	if (ia->ri_device->attrs.max_qp_wr <= RPCRDMA_BACKWARD_WRS) {
494 		dprintk("RPC:       %s: insufficient wqe's available\n",
495 			__func__);
496 		return -ENOMEM;
497 	}
498 	max_qp_wr = ia->ri_device->attrs.max_qp_wr - RPCRDMA_BACKWARD_WRS - 1;
499 
500 	/* check provider's send/recv wr limits */
501 	if (cdata->max_requests > max_qp_wr)
502 		cdata->max_requests = max_qp_wr;
503 
504 	ep->rep_attr.event_handler = rpcrdma_qp_async_error_upcall;
505 	ep->rep_attr.qp_context = ep;
506 	ep->rep_attr.srq = NULL;
507 	ep->rep_attr.cap.max_send_wr = cdata->max_requests;
508 	ep->rep_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
509 	ep->rep_attr.cap.max_send_wr += 1;	/* drain cqe */
510 	rc = ia->ri_ops->ro_open(ia, ep, cdata);
511 	if (rc)
512 		return rc;
513 	ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
514 	ep->rep_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
515 	ep->rep_attr.cap.max_recv_wr += 1;	/* drain cqe */
516 	ep->rep_attr.cap.max_send_sge = RPCRDMA_MAX_SEND_SGES;
517 	ep->rep_attr.cap.max_recv_sge = 1;
518 	ep->rep_attr.cap.max_inline_data = 0;
519 	ep->rep_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
520 	ep->rep_attr.qp_type = IB_QPT_RC;
521 	ep->rep_attr.port_num = ~0;
522 
523 	dprintk("RPC:       %s: requested max: dtos: send %d recv %d; "
524 		"iovs: send %d recv %d\n",
525 		__func__,
526 		ep->rep_attr.cap.max_send_wr,
527 		ep->rep_attr.cap.max_recv_wr,
528 		ep->rep_attr.cap.max_send_sge,
529 		ep->rep_attr.cap.max_recv_sge);
530 
531 	/* set trigger for requesting send completion */
532 	ep->rep_cqinit = ep->rep_attr.cap.max_send_wr/2 - 1;
533 	if (ep->rep_cqinit <= 2)
534 		ep->rep_cqinit = 0;	/* always signal? */
535 	INIT_CQCOUNT(ep);
536 	init_waitqueue_head(&ep->rep_connect_wait);
537 	INIT_DELAYED_WORK(&ep->rep_connect_worker, rpcrdma_connect_worker);
538 
539 	sendcq = ib_alloc_cq(ia->ri_device, NULL,
540 			     ep->rep_attr.cap.max_send_wr + 1,
541 			     0, IB_POLL_SOFTIRQ);
542 	if (IS_ERR(sendcq)) {
543 		rc = PTR_ERR(sendcq);
544 		dprintk("RPC:       %s: failed to create send CQ: %i\n",
545 			__func__, rc);
546 		goto out1;
547 	}
548 
549 	recvcq = ib_alloc_cq(ia->ri_device, NULL,
550 			     ep->rep_attr.cap.max_recv_wr + 1,
551 			     0, IB_POLL_SOFTIRQ);
552 	if (IS_ERR(recvcq)) {
553 		rc = PTR_ERR(recvcq);
554 		dprintk("RPC:       %s: failed to create recv CQ: %i\n",
555 			__func__, rc);
556 		goto out2;
557 	}
558 
559 	ep->rep_attr.send_cq = sendcq;
560 	ep->rep_attr.recv_cq = recvcq;
561 
562 	/* Initialize cma parameters */
563 	memset(&ep->rep_remote_cma, 0, sizeof(ep->rep_remote_cma));
564 
565 	/* Prepare RDMA-CM private message */
566 	pmsg->cp_magic = rpcrdma_cmp_magic;
567 	pmsg->cp_version = RPCRDMA_CMP_VERSION;
568 	pmsg->cp_flags |= ia->ri_ops->ro_send_w_inv_ok;
569 	pmsg->cp_send_size = rpcrdma_encode_buffer_size(cdata->inline_wsize);
570 	pmsg->cp_recv_size = rpcrdma_encode_buffer_size(cdata->inline_rsize);
571 	ep->rep_remote_cma.private_data = pmsg;
572 	ep->rep_remote_cma.private_data_len = sizeof(*pmsg);
573 
574 	/* Client offers RDMA Read but does not initiate */
575 	ep->rep_remote_cma.initiator_depth = 0;
576 	if (ia->ri_device->attrs.max_qp_rd_atom > 32)	/* arbitrary but <= 255 */
577 		ep->rep_remote_cma.responder_resources = 32;
578 	else
579 		ep->rep_remote_cma.responder_resources =
580 						ia->ri_device->attrs.max_qp_rd_atom;
581 
582 	/* Limit transport retries so client can detect server
583 	 * GID changes quickly. RPC layer handles re-establishing
584 	 * transport connection and retransmission.
585 	 */
586 	ep->rep_remote_cma.retry_count = 6;
587 
588 	/* RPC-over-RDMA handles its own flow control. In addition,
589 	 * make all RNR NAKs visible so we know that RPC-over-RDMA
590 	 * flow control is working correctly (no NAKs should be seen).
591 	 */
592 	ep->rep_remote_cma.flow_control = 0;
593 	ep->rep_remote_cma.rnr_retry_count = 0;
594 
595 	return 0;
596 
597 out2:
598 	ib_free_cq(sendcq);
599 out1:
600 	return rc;
601 }
602 
603 /*
604  * rpcrdma_ep_destroy
605  *
606  * Disconnect and destroy endpoint. After this, the only
607  * valid operations on the ep are to free it (if dynamically
608  * allocated) or re-create it.
609  */
610 void
611 rpcrdma_ep_destroy(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
612 {
613 	dprintk("RPC:       %s: entering, connected is %d\n",
614 		__func__, ep->rep_connected);
615 
616 	cancel_delayed_work_sync(&ep->rep_connect_worker);
617 
618 	if (ia->ri_id->qp) {
619 		rpcrdma_ep_disconnect(ep, ia);
620 		rdma_destroy_qp(ia->ri_id);
621 		ia->ri_id->qp = NULL;
622 	}
623 
624 	ib_free_cq(ep->rep_attr.recv_cq);
625 	ib_free_cq(ep->rep_attr.send_cq);
626 }
627 
628 /*
629  * Connect unconnected endpoint.
630  */
631 int
632 rpcrdma_ep_connect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
633 {
634 	struct rdma_cm_id *id, *old;
635 	int rc = 0;
636 	int retry_count = 0;
637 
638 	if (ep->rep_connected != 0) {
639 		struct rpcrdma_xprt *xprt;
640 retry:
641 		dprintk("RPC:       %s: reconnecting...\n", __func__);
642 
643 		rpcrdma_ep_disconnect(ep, ia);
644 
645 		xprt = container_of(ia, struct rpcrdma_xprt, rx_ia);
646 		id = rpcrdma_create_id(xprt, ia,
647 				(struct sockaddr *)&xprt->rx_data.addr);
648 		if (IS_ERR(id)) {
649 			rc = -EHOSTUNREACH;
650 			goto out;
651 		}
652 		/* TEMP TEMP TEMP - fail if new device:
653 		 * Deregister/remarshal *all* requests!
654 		 * Close and recreate adapter, pd, etc!
655 		 * Re-determine all attributes still sane!
656 		 * More stuff I haven't thought of!
657 		 * Rrrgh!
658 		 */
659 		if (ia->ri_device != id->device) {
660 			printk("RPC:       %s: can't reconnect on "
661 				"different device!\n", __func__);
662 			rpcrdma_destroy_id(id);
663 			rc = -ENETUNREACH;
664 			goto out;
665 		}
666 		/* END TEMP */
667 		rc = rdma_create_qp(id, ia->ri_pd, &ep->rep_attr);
668 		if (rc) {
669 			dprintk("RPC:       %s: rdma_create_qp failed %i\n",
670 				__func__, rc);
671 			rpcrdma_destroy_id(id);
672 			rc = -ENETUNREACH;
673 			goto out;
674 		}
675 
676 		old = ia->ri_id;
677 		ia->ri_id = id;
678 
679 		rdma_destroy_qp(old);
680 		rpcrdma_destroy_id(old);
681 	} else {
682 		dprintk("RPC:       %s: connecting...\n", __func__);
683 		rc = rdma_create_qp(ia->ri_id, ia->ri_pd, &ep->rep_attr);
684 		if (rc) {
685 			dprintk("RPC:       %s: rdma_create_qp failed %i\n",
686 				__func__, rc);
687 			/* do not update ep->rep_connected */
688 			return -ENETUNREACH;
689 		}
690 	}
691 
692 	ep->rep_connected = 0;
693 
694 	rc = rdma_connect(ia->ri_id, &ep->rep_remote_cma);
695 	if (rc) {
696 		dprintk("RPC:       %s: rdma_connect() failed with %i\n",
697 				__func__, rc);
698 		goto out;
699 	}
700 
701 	wait_event_interruptible(ep->rep_connect_wait, ep->rep_connected != 0);
702 
703 	/*
704 	 * Check state. A non-peer reject indicates no listener
705 	 * (ECONNREFUSED), which may be a transient state. All
706 	 * others indicate a transport condition which has already
707 	 * undergone a best-effort.
708 	 */
709 	if (ep->rep_connected == -ECONNREFUSED &&
710 	    ++retry_count <= RDMA_CONNECT_RETRY_MAX) {
711 		dprintk("RPC:       %s: non-peer_reject, retry\n", __func__);
712 		goto retry;
713 	}
714 	if (ep->rep_connected <= 0) {
715 		/* Sometimes, the only way to reliably connect to remote
716 		 * CMs is to use same nonzero values for ORD and IRD. */
717 		if (retry_count++ <= RDMA_CONNECT_RETRY_MAX + 1 &&
718 		    (ep->rep_remote_cma.responder_resources == 0 ||
719 		     ep->rep_remote_cma.initiator_depth !=
720 				ep->rep_remote_cma.responder_resources)) {
721 			if (ep->rep_remote_cma.responder_resources == 0)
722 				ep->rep_remote_cma.responder_resources = 1;
723 			ep->rep_remote_cma.initiator_depth =
724 				ep->rep_remote_cma.responder_resources;
725 			goto retry;
726 		}
727 		rc = ep->rep_connected;
728 	} else {
729 		struct rpcrdma_xprt *r_xprt;
730 		unsigned int extras;
731 
732 		dprintk("RPC:       %s: connected\n", __func__);
733 
734 		r_xprt = container_of(ia, struct rpcrdma_xprt, rx_ia);
735 		extras = r_xprt->rx_buf.rb_bc_srv_max_requests;
736 
737 		if (extras) {
738 			rc = rpcrdma_ep_post_extra_recv(r_xprt, extras);
739 			if (rc) {
740 				pr_warn("%s: rpcrdma_ep_post_extra_recv: %i\n",
741 					__func__, rc);
742 				rc = 0;
743 			}
744 		}
745 	}
746 
747 out:
748 	if (rc)
749 		ep->rep_connected = rc;
750 	return rc;
751 }
752 
753 /*
754  * rpcrdma_ep_disconnect
755  *
756  * This is separate from destroy to facilitate the ability
757  * to reconnect without recreating the endpoint.
758  *
759  * This call is not reentrant, and must not be made in parallel
760  * on the same endpoint.
761  */
762 void
763 rpcrdma_ep_disconnect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
764 {
765 	int rc;
766 
767 	rc = rdma_disconnect(ia->ri_id);
768 	if (!rc) {
769 		/* returns without wait if not connected */
770 		wait_event_interruptible(ep->rep_connect_wait,
771 							ep->rep_connected != 1);
772 		dprintk("RPC:       %s: after wait, %sconnected\n", __func__,
773 			(ep->rep_connected == 1) ? "still " : "dis");
774 	} else {
775 		dprintk("RPC:       %s: rdma_disconnect %i\n", __func__, rc);
776 		ep->rep_connected = rc;
777 	}
778 
779 	ib_drain_qp(ia->ri_id->qp);
780 }
781 
782 static void
783 rpcrdma_mr_recovery_worker(struct work_struct *work)
784 {
785 	struct rpcrdma_buffer *buf = container_of(work, struct rpcrdma_buffer,
786 						  rb_recovery_worker.work);
787 	struct rpcrdma_mw *mw;
788 
789 	spin_lock(&buf->rb_recovery_lock);
790 	while (!list_empty(&buf->rb_stale_mrs)) {
791 		mw = list_first_entry(&buf->rb_stale_mrs,
792 				      struct rpcrdma_mw, mw_list);
793 		list_del_init(&mw->mw_list);
794 		spin_unlock(&buf->rb_recovery_lock);
795 
796 		dprintk("RPC:       %s: recovering MR %p\n", __func__, mw);
797 		mw->mw_xprt->rx_ia.ri_ops->ro_recover_mr(mw);
798 
799 		spin_lock(&buf->rb_recovery_lock);
800 	}
801 	spin_unlock(&buf->rb_recovery_lock);
802 }
803 
804 void
805 rpcrdma_defer_mr_recovery(struct rpcrdma_mw *mw)
806 {
807 	struct rpcrdma_xprt *r_xprt = mw->mw_xprt;
808 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
809 
810 	spin_lock(&buf->rb_recovery_lock);
811 	list_add(&mw->mw_list, &buf->rb_stale_mrs);
812 	spin_unlock(&buf->rb_recovery_lock);
813 
814 	schedule_delayed_work(&buf->rb_recovery_worker, 0);
815 }
816 
817 static void
818 rpcrdma_create_mrs(struct rpcrdma_xprt *r_xprt)
819 {
820 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
821 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
822 	unsigned int count;
823 	LIST_HEAD(free);
824 	LIST_HEAD(all);
825 
826 	for (count = 0; count < 32; count++) {
827 		struct rpcrdma_mw *mw;
828 		int rc;
829 
830 		mw = kzalloc(sizeof(*mw), GFP_KERNEL);
831 		if (!mw)
832 			break;
833 
834 		rc = ia->ri_ops->ro_init_mr(ia, mw);
835 		if (rc) {
836 			kfree(mw);
837 			break;
838 		}
839 
840 		mw->mw_xprt = r_xprt;
841 
842 		list_add(&mw->mw_list, &free);
843 		list_add(&mw->mw_all, &all);
844 	}
845 
846 	spin_lock(&buf->rb_mwlock);
847 	list_splice(&free, &buf->rb_mws);
848 	list_splice(&all, &buf->rb_all);
849 	r_xprt->rx_stats.mrs_allocated += count;
850 	spin_unlock(&buf->rb_mwlock);
851 
852 	dprintk("RPC:       %s: created %u MRs\n", __func__, count);
853 }
854 
855 static void
856 rpcrdma_mr_refresh_worker(struct work_struct *work)
857 {
858 	struct rpcrdma_buffer *buf = container_of(work, struct rpcrdma_buffer,
859 						  rb_refresh_worker.work);
860 	struct rpcrdma_xprt *r_xprt = container_of(buf, struct rpcrdma_xprt,
861 						   rx_buf);
862 
863 	rpcrdma_create_mrs(r_xprt);
864 }
865 
866 struct rpcrdma_req *
867 rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
868 {
869 	struct rpcrdma_buffer *buffer = &r_xprt->rx_buf;
870 	struct rpcrdma_req *req;
871 
872 	req = kzalloc(sizeof(*req), GFP_KERNEL);
873 	if (req == NULL)
874 		return ERR_PTR(-ENOMEM);
875 
876 	INIT_LIST_HEAD(&req->rl_free);
877 	spin_lock(&buffer->rb_reqslock);
878 	list_add(&req->rl_all, &buffer->rb_allreqs);
879 	spin_unlock(&buffer->rb_reqslock);
880 	req->rl_cqe.done = rpcrdma_wc_send;
881 	req->rl_buffer = &r_xprt->rx_buf;
882 	INIT_LIST_HEAD(&req->rl_registered);
883 	req->rl_send_wr.next = NULL;
884 	req->rl_send_wr.wr_cqe = &req->rl_cqe;
885 	req->rl_send_wr.sg_list = req->rl_send_sge;
886 	req->rl_send_wr.opcode = IB_WR_SEND;
887 	return req;
888 }
889 
890 struct rpcrdma_rep *
891 rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
892 {
893 	struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
894 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
895 	struct rpcrdma_rep *rep;
896 	int rc;
897 
898 	rc = -ENOMEM;
899 	rep = kzalloc(sizeof(*rep), GFP_KERNEL);
900 	if (rep == NULL)
901 		goto out;
902 
903 	rep->rr_rdmabuf = rpcrdma_alloc_regbuf(cdata->inline_rsize,
904 					       DMA_FROM_DEVICE, GFP_KERNEL);
905 	if (IS_ERR(rep->rr_rdmabuf)) {
906 		rc = PTR_ERR(rep->rr_rdmabuf);
907 		goto out_free;
908 	}
909 
910 	rep->rr_device = ia->ri_device;
911 	rep->rr_cqe.done = rpcrdma_wc_receive;
912 	rep->rr_rxprt = r_xprt;
913 	INIT_WORK(&rep->rr_work, rpcrdma_reply_handler);
914 	rep->rr_recv_wr.next = NULL;
915 	rep->rr_recv_wr.wr_cqe = &rep->rr_cqe;
916 	rep->rr_recv_wr.sg_list = &rep->rr_rdmabuf->rg_iov;
917 	rep->rr_recv_wr.num_sge = 1;
918 	return rep;
919 
920 out_free:
921 	kfree(rep);
922 out:
923 	return ERR_PTR(rc);
924 }
925 
926 int
927 rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
928 {
929 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
930 	int i, rc;
931 
932 	buf->rb_max_requests = r_xprt->rx_data.max_requests;
933 	buf->rb_bc_srv_max_requests = 0;
934 	atomic_set(&buf->rb_credits, 1);
935 	spin_lock_init(&buf->rb_mwlock);
936 	spin_lock_init(&buf->rb_lock);
937 	spin_lock_init(&buf->rb_recovery_lock);
938 	INIT_LIST_HEAD(&buf->rb_mws);
939 	INIT_LIST_HEAD(&buf->rb_all);
940 	INIT_LIST_HEAD(&buf->rb_stale_mrs);
941 	INIT_DELAYED_WORK(&buf->rb_refresh_worker,
942 			  rpcrdma_mr_refresh_worker);
943 	INIT_DELAYED_WORK(&buf->rb_recovery_worker,
944 			  rpcrdma_mr_recovery_worker);
945 
946 	rpcrdma_create_mrs(r_xprt);
947 
948 	INIT_LIST_HEAD(&buf->rb_send_bufs);
949 	INIT_LIST_HEAD(&buf->rb_allreqs);
950 	spin_lock_init(&buf->rb_reqslock);
951 	for (i = 0; i < buf->rb_max_requests; i++) {
952 		struct rpcrdma_req *req;
953 
954 		req = rpcrdma_create_req(r_xprt);
955 		if (IS_ERR(req)) {
956 			dprintk("RPC:       %s: request buffer %d alloc"
957 				" failed\n", __func__, i);
958 			rc = PTR_ERR(req);
959 			goto out;
960 		}
961 		req->rl_backchannel = false;
962 		list_add(&req->rl_free, &buf->rb_send_bufs);
963 	}
964 
965 	INIT_LIST_HEAD(&buf->rb_recv_bufs);
966 	for (i = 0; i < buf->rb_max_requests + RPCRDMA_MAX_BC_REQUESTS; i++) {
967 		struct rpcrdma_rep *rep;
968 
969 		rep = rpcrdma_create_rep(r_xprt);
970 		if (IS_ERR(rep)) {
971 			dprintk("RPC:       %s: reply buffer %d alloc failed\n",
972 				__func__, i);
973 			rc = PTR_ERR(rep);
974 			goto out;
975 		}
976 		list_add(&rep->rr_list, &buf->rb_recv_bufs);
977 	}
978 
979 	return 0;
980 out:
981 	rpcrdma_buffer_destroy(buf);
982 	return rc;
983 }
984 
985 static struct rpcrdma_req *
986 rpcrdma_buffer_get_req_locked(struct rpcrdma_buffer *buf)
987 {
988 	struct rpcrdma_req *req;
989 
990 	req = list_first_entry(&buf->rb_send_bufs,
991 			       struct rpcrdma_req, rl_free);
992 	list_del(&req->rl_free);
993 	return req;
994 }
995 
996 static struct rpcrdma_rep *
997 rpcrdma_buffer_get_rep_locked(struct rpcrdma_buffer *buf)
998 {
999 	struct rpcrdma_rep *rep;
1000 
1001 	rep = list_first_entry(&buf->rb_recv_bufs,
1002 			       struct rpcrdma_rep, rr_list);
1003 	list_del(&rep->rr_list);
1004 	return rep;
1005 }
1006 
1007 static void
1008 rpcrdma_destroy_rep(struct rpcrdma_rep *rep)
1009 {
1010 	rpcrdma_free_regbuf(rep->rr_rdmabuf);
1011 	kfree(rep);
1012 }
1013 
1014 void
1015 rpcrdma_destroy_req(struct rpcrdma_req *req)
1016 {
1017 	rpcrdma_free_regbuf(req->rl_recvbuf);
1018 	rpcrdma_free_regbuf(req->rl_sendbuf);
1019 	rpcrdma_free_regbuf(req->rl_rdmabuf);
1020 	kfree(req);
1021 }
1022 
1023 static void
1024 rpcrdma_destroy_mrs(struct rpcrdma_buffer *buf)
1025 {
1026 	struct rpcrdma_xprt *r_xprt = container_of(buf, struct rpcrdma_xprt,
1027 						   rx_buf);
1028 	struct rpcrdma_ia *ia = rdmab_to_ia(buf);
1029 	struct rpcrdma_mw *mw;
1030 	unsigned int count;
1031 
1032 	count = 0;
1033 	spin_lock(&buf->rb_mwlock);
1034 	while (!list_empty(&buf->rb_all)) {
1035 		mw = list_entry(buf->rb_all.next, struct rpcrdma_mw, mw_all);
1036 		list_del(&mw->mw_all);
1037 
1038 		spin_unlock(&buf->rb_mwlock);
1039 		ia->ri_ops->ro_release_mr(mw);
1040 		count++;
1041 		spin_lock(&buf->rb_mwlock);
1042 	}
1043 	spin_unlock(&buf->rb_mwlock);
1044 	r_xprt->rx_stats.mrs_allocated = 0;
1045 
1046 	dprintk("RPC:       %s: released %u MRs\n", __func__, count);
1047 }
1048 
1049 void
1050 rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
1051 {
1052 	cancel_delayed_work_sync(&buf->rb_recovery_worker);
1053 
1054 	while (!list_empty(&buf->rb_recv_bufs)) {
1055 		struct rpcrdma_rep *rep;
1056 
1057 		rep = rpcrdma_buffer_get_rep_locked(buf);
1058 		rpcrdma_destroy_rep(rep);
1059 	}
1060 	buf->rb_send_count = 0;
1061 
1062 	spin_lock(&buf->rb_reqslock);
1063 	while (!list_empty(&buf->rb_allreqs)) {
1064 		struct rpcrdma_req *req;
1065 
1066 		req = list_first_entry(&buf->rb_allreqs,
1067 				       struct rpcrdma_req, rl_all);
1068 		list_del(&req->rl_all);
1069 
1070 		spin_unlock(&buf->rb_reqslock);
1071 		rpcrdma_destroy_req(req);
1072 		spin_lock(&buf->rb_reqslock);
1073 	}
1074 	spin_unlock(&buf->rb_reqslock);
1075 	buf->rb_recv_count = 0;
1076 
1077 	rpcrdma_destroy_mrs(buf);
1078 }
1079 
1080 struct rpcrdma_mw *
1081 rpcrdma_get_mw(struct rpcrdma_xprt *r_xprt)
1082 {
1083 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
1084 	struct rpcrdma_mw *mw = NULL;
1085 
1086 	spin_lock(&buf->rb_mwlock);
1087 	if (!list_empty(&buf->rb_mws)) {
1088 		mw = list_first_entry(&buf->rb_mws,
1089 				      struct rpcrdma_mw, mw_list);
1090 		list_del_init(&mw->mw_list);
1091 	}
1092 	spin_unlock(&buf->rb_mwlock);
1093 
1094 	if (!mw)
1095 		goto out_nomws;
1096 	return mw;
1097 
1098 out_nomws:
1099 	dprintk("RPC:       %s: no MWs available\n", __func__);
1100 	schedule_delayed_work(&buf->rb_refresh_worker, 0);
1101 
1102 	/* Allow the reply handler and refresh worker to run */
1103 	cond_resched();
1104 
1105 	return NULL;
1106 }
1107 
1108 void
1109 rpcrdma_put_mw(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mw *mw)
1110 {
1111 	struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
1112 
1113 	spin_lock(&buf->rb_mwlock);
1114 	list_add_tail(&mw->mw_list, &buf->rb_mws);
1115 	spin_unlock(&buf->rb_mwlock);
1116 }
1117 
1118 static struct rpcrdma_rep *
1119 rpcrdma_buffer_get_rep(struct rpcrdma_buffer *buffers)
1120 {
1121 	/* If an RPC previously completed without a reply (say, a
1122 	 * credential problem or a soft timeout occurs) then hold off
1123 	 * on supplying more Receive buffers until the number of new
1124 	 * pending RPCs catches up to the number of posted Receives.
1125 	 */
1126 	if (unlikely(buffers->rb_send_count < buffers->rb_recv_count))
1127 		return NULL;
1128 
1129 	if (unlikely(list_empty(&buffers->rb_recv_bufs)))
1130 		return NULL;
1131 	buffers->rb_recv_count++;
1132 	return rpcrdma_buffer_get_rep_locked(buffers);
1133 }
1134 
1135 /*
1136  * Get a set of request/reply buffers.
1137  *
1138  * Reply buffer (if available) is attached to send buffer upon return.
1139  */
1140 struct rpcrdma_req *
1141 rpcrdma_buffer_get(struct rpcrdma_buffer *buffers)
1142 {
1143 	struct rpcrdma_req *req;
1144 
1145 	spin_lock(&buffers->rb_lock);
1146 	if (list_empty(&buffers->rb_send_bufs))
1147 		goto out_reqbuf;
1148 	buffers->rb_send_count++;
1149 	req = rpcrdma_buffer_get_req_locked(buffers);
1150 	req->rl_reply = rpcrdma_buffer_get_rep(buffers);
1151 	spin_unlock(&buffers->rb_lock);
1152 	return req;
1153 
1154 out_reqbuf:
1155 	spin_unlock(&buffers->rb_lock);
1156 	pr_warn("RPC:       %s: out of request buffers\n", __func__);
1157 	return NULL;
1158 }
1159 
1160 /*
1161  * Put request/reply buffers back into pool.
1162  * Pre-decrement counter/array index.
1163  */
1164 void
1165 rpcrdma_buffer_put(struct rpcrdma_req *req)
1166 {
1167 	struct rpcrdma_buffer *buffers = req->rl_buffer;
1168 	struct rpcrdma_rep *rep = req->rl_reply;
1169 
1170 	req->rl_send_wr.num_sge = 0;
1171 	req->rl_reply = NULL;
1172 
1173 	spin_lock(&buffers->rb_lock);
1174 	buffers->rb_send_count--;
1175 	list_add_tail(&req->rl_free, &buffers->rb_send_bufs);
1176 	if (rep) {
1177 		buffers->rb_recv_count--;
1178 		list_add_tail(&rep->rr_list, &buffers->rb_recv_bufs);
1179 	}
1180 	spin_unlock(&buffers->rb_lock);
1181 }
1182 
1183 /*
1184  * Recover reply buffers from pool.
1185  * This happens when recovering from disconnect.
1186  */
1187 void
1188 rpcrdma_recv_buffer_get(struct rpcrdma_req *req)
1189 {
1190 	struct rpcrdma_buffer *buffers = req->rl_buffer;
1191 
1192 	spin_lock(&buffers->rb_lock);
1193 	req->rl_reply = rpcrdma_buffer_get_rep(buffers);
1194 	spin_unlock(&buffers->rb_lock);
1195 }
1196 
1197 /*
1198  * Put reply buffers back into pool when not attached to
1199  * request. This happens in error conditions.
1200  */
1201 void
1202 rpcrdma_recv_buffer_put(struct rpcrdma_rep *rep)
1203 {
1204 	struct rpcrdma_buffer *buffers = &rep->rr_rxprt->rx_buf;
1205 
1206 	spin_lock(&buffers->rb_lock);
1207 	buffers->rb_recv_count--;
1208 	list_add_tail(&rep->rr_list, &buffers->rb_recv_bufs);
1209 	spin_unlock(&buffers->rb_lock);
1210 }
1211 
1212 /**
1213  * rpcrdma_alloc_regbuf - allocate and DMA-map memory for SEND/RECV buffers
1214  * @size: size of buffer to be allocated, in bytes
1215  * @direction: direction of data movement
1216  * @flags: GFP flags
1217  *
1218  * Returns an ERR_PTR, or a pointer to a regbuf, a buffer that
1219  * can be persistently DMA-mapped for I/O.
1220  *
1221  * xprtrdma uses a regbuf for posting an outgoing RDMA SEND, or for
1222  * receiving the payload of RDMA RECV operations. During Long Calls
1223  * or Replies they may be registered externally via ro_map.
1224  */
1225 struct rpcrdma_regbuf *
1226 rpcrdma_alloc_regbuf(size_t size, enum dma_data_direction direction,
1227 		     gfp_t flags)
1228 {
1229 	struct rpcrdma_regbuf *rb;
1230 
1231 	rb = kmalloc(sizeof(*rb) + size, flags);
1232 	if (rb == NULL)
1233 		return ERR_PTR(-ENOMEM);
1234 
1235 	rb->rg_device = NULL;
1236 	rb->rg_direction = direction;
1237 	rb->rg_iov.length = size;
1238 
1239 	return rb;
1240 }
1241 
1242 /**
1243  * __rpcrdma_map_regbuf - DMA-map a regbuf
1244  * @ia: controlling rpcrdma_ia
1245  * @rb: regbuf to be mapped
1246  */
1247 bool
1248 __rpcrdma_dma_map_regbuf(struct rpcrdma_ia *ia, struct rpcrdma_regbuf *rb)
1249 {
1250 	if (rb->rg_direction == DMA_NONE)
1251 		return false;
1252 
1253 	rb->rg_iov.addr = ib_dma_map_single(ia->ri_device,
1254 					    (void *)rb->rg_base,
1255 					    rdmab_length(rb),
1256 					    rb->rg_direction);
1257 	if (ib_dma_mapping_error(ia->ri_device, rdmab_addr(rb)))
1258 		return false;
1259 
1260 	rb->rg_device = ia->ri_device;
1261 	rb->rg_iov.lkey = ia->ri_pd->local_dma_lkey;
1262 	return true;
1263 }
1264 
1265 static void
1266 rpcrdma_dma_unmap_regbuf(struct rpcrdma_regbuf *rb)
1267 {
1268 	if (!rpcrdma_regbuf_is_mapped(rb))
1269 		return;
1270 
1271 	ib_dma_unmap_single(rb->rg_device, rdmab_addr(rb),
1272 			    rdmab_length(rb), rb->rg_direction);
1273 	rb->rg_device = NULL;
1274 }
1275 
1276 /**
1277  * rpcrdma_free_regbuf - deregister and free registered buffer
1278  * @rb: regbuf to be deregistered and freed
1279  */
1280 void
1281 rpcrdma_free_regbuf(struct rpcrdma_regbuf *rb)
1282 {
1283 	if (!rb)
1284 		return;
1285 
1286 	rpcrdma_dma_unmap_regbuf(rb);
1287 	kfree(rb);
1288 }
1289 
1290 /*
1291  * Prepost any receive buffer, then post send.
1292  *
1293  * Receive buffer is donated to hardware, reclaimed upon recv completion.
1294  */
1295 int
1296 rpcrdma_ep_post(struct rpcrdma_ia *ia,
1297 		struct rpcrdma_ep *ep,
1298 		struct rpcrdma_req *req)
1299 {
1300 	struct ib_send_wr *send_wr = &req->rl_send_wr;
1301 	struct ib_send_wr *send_wr_fail;
1302 	int rc;
1303 
1304 	if (req->rl_reply) {
1305 		rc = rpcrdma_ep_post_recv(ia, req->rl_reply);
1306 		if (rc)
1307 			return rc;
1308 		req->rl_reply = NULL;
1309 	}
1310 
1311 	dprintk("RPC:       %s: posting %d s/g entries\n",
1312 		__func__, send_wr->num_sge);
1313 
1314 	if (DECR_CQCOUNT(ep) > 0)
1315 		send_wr->send_flags = 0;
1316 	else { /* Provider must take a send completion every now and then */
1317 		INIT_CQCOUNT(ep);
1318 		send_wr->send_flags = IB_SEND_SIGNALED;
1319 	}
1320 
1321 	rc = ib_post_send(ia->ri_id->qp, send_wr, &send_wr_fail);
1322 	if (rc)
1323 		goto out_postsend_err;
1324 	return 0;
1325 
1326 out_postsend_err:
1327 	pr_err("rpcrdma: RDMA Send ib_post_send returned %i\n", rc);
1328 	return -ENOTCONN;
1329 }
1330 
1331 int
1332 rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
1333 		     struct rpcrdma_rep *rep)
1334 {
1335 	struct ib_recv_wr *recv_wr_fail;
1336 	int rc;
1337 
1338 	if (!rpcrdma_dma_map_regbuf(ia, rep->rr_rdmabuf))
1339 		goto out_map;
1340 	rc = ib_post_recv(ia->ri_id->qp, &rep->rr_recv_wr, &recv_wr_fail);
1341 	if (rc)
1342 		goto out_postrecv;
1343 	return 0;
1344 
1345 out_map:
1346 	pr_err("rpcrdma: failed to DMA map the Receive buffer\n");
1347 	return -EIO;
1348 
1349 out_postrecv:
1350 	pr_err("rpcrdma: ib_post_recv returned %i\n", rc);
1351 	return -ENOTCONN;
1352 }
1353 
1354 /**
1355  * rpcrdma_ep_post_extra_recv - Post buffers for incoming backchannel requests
1356  * @r_xprt: transport associated with these backchannel resources
1357  * @min_reqs: minimum number of incoming requests expected
1358  *
1359  * Returns zero if all requested buffers were posted, or a negative errno.
1360  */
1361 int
1362 rpcrdma_ep_post_extra_recv(struct rpcrdma_xprt *r_xprt, unsigned int count)
1363 {
1364 	struct rpcrdma_buffer *buffers = &r_xprt->rx_buf;
1365 	struct rpcrdma_ia *ia = &r_xprt->rx_ia;
1366 	struct rpcrdma_rep *rep;
1367 	int rc;
1368 
1369 	while (count--) {
1370 		spin_lock(&buffers->rb_lock);
1371 		if (list_empty(&buffers->rb_recv_bufs))
1372 			goto out_reqbuf;
1373 		rep = rpcrdma_buffer_get_rep_locked(buffers);
1374 		spin_unlock(&buffers->rb_lock);
1375 
1376 		rc = rpcrdma_ep_post_recv(ia, rep);
1377 		if (rc)
1378 			goto out_rc;
1379 	}
1380 
1381 	return 0;
1382 
1383 out_reqbuf:
1384 	spin_unlock(&buffers->rb_lock);
1385 	pr_warn("%s: no extra receive buffers\n", __func__);
1386 	return -ENOMEM;
1387 
1388 out_rc:
1389 	rpcrdma_recv_buffer_put(rep);
1390 	return rc;
1391 }
1392