xref: /linux/net/sunrpc/xprtrdma/svc_rdma_transport.c (revision e58e871becec2d3b04ed91c0c16fe8deac9c9dfa)
1 /*
2  * Copyright (c) 2014 Open Grid Computing, Inc. All rights reserved.
3  * Copyright (c) 2005-2007 Network Appliance, Inc. All rights reserved.
4  *
5  * This software is available to you under a choice of one of two
6  * licenses.  You may choose to be licensed under the terms of the GNU
7  * General Public License (GPL) Version 2, available from the file
8  * COPYING in the main directory of this source tree, or the BSD-type
9  * license below:
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  *
15  *      Redistributions of source code must retain the above copyright
16  *      notice, this list of conditions and the following disclaimer.
17  *
18  *      Redistributions in binary form must reproduce the above
19  *      copyright notice, this list of conditions and the following
20  *      disclaimer in the documentation and/or other materials provided
21  *      with the distribution.
22  *
23  *      Neither the name of the Network Appliance, Inc. nor the names of
24  *      its contributors may be used to endorse or promote products
25  *      derived from this software without specific prior written
26  *      permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39  *
40  * Author: Tom Tucker <tom@opengridcomputing.com>
41  */
42 
43 #include <linux/sunrpc/svc_xprt.h>
44 #include <linux/sunrpc/addr.h>
45 #include <linux/sunrpc/debug.h>
46 #include <linux/sunrpc/rpc_rdma.h>
47 #include <linux/interrupt.h>
48 #include <linux/sched.h>
49 #include <linux/slab.h>
50 #include <linux/spinlock.h>
51 #include <linux/workqueue.h>
52 #include <rdma/ib_verbs.h>
53 #include <rdma/rdma_cm.h>
54 #include <linux/sunrpc/svc_rdma.h>
55 #include <linux/export.h>
56 #include "xprt_rdma.h"
57 
58 #define RPCDBG_FACILITY	RPCDBG_SVCXPRT
59 
60 static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *, int);
61 static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
62 					struct net *net,
63 					struct sockaddr *sa, int salen,
64 					int flags);
65 static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt);
66 static void svc_rdma_release_rqst(struct svc_rqst *);
67 static void svc_rdma_detach(struct svc_xprt *xprt);
68 static void svc_rdma_free(struct svc_xprt *xprt);
69 static int svc_rdma_has_wspace(struct svc_xprt *xprt);
70 static int svc_rdma_secure_port(struct svc_rqst *);
71 static void svc_rdma_kill_temp_xprt(struct svc_xprt *);
72 
73 static struct svc_xprt_ops svc_rdma_ops = {
74 	.xpo_create = svc_rdma_create,
75 	.xpo_recvfrom = svc_rdma_recvfrom,
76 	.xpo_sendto = svc_rdma_sendto,
77 	.xpo_release_rqst = svc_rdma_release_rqst,
78 	.xpo_detach = svc_rdma_detach,
79 	.xpo_free = svc_rdma_free,
80 	.xpo_prep_reply_hdr = svc_rdma_prep_reply_hdr,
81 	.xpo_has_wspace = svc_rdma_has_wspace,
82 	.xpo_accept = svc_rdma_accept,
83 	.xpo_secure_port = svc_rdma_secure_port,
84 	.xpo_kill_temp_xprt = svc_rdma_kill_temp_xprt,
85 };
86 
87 struct svc_xprt_class svc_rdma_class = {
88 	.xcl_name = "rdma",
89 	.xcl_owner = THIS_MODULE,
90 	.xcl_ops = &svc_rdma_ops,
91 	.xcl_max_payload = RPCSVC_MAXPAYLOAD_RDMA,
92 	.xcl_ident = XPRT_TRANSPORT_RDMA,
93 };
94 
95 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
96 static struct svc_xprt *svc_rdma_bc_create(struct svc_serv *, struct net *,
97 					   struct sockaddr *, int, int);
98 static void svc_rdma_bc_detach(struct svc_xprt *);
99 static void svc_rdma_bc_free(struct svc_xprt *);
100 
101 static struct svc_xprt_ops svc_rdma_bc_ops = {
102 	.xpo_create = svc_rdma_bc_create,
103 	.xpo_detach = svc_rdma_bc_detach,
104 	.xpo_free = svc_rdma_bc_free,
105 	.xpo_prep_reply_hdr = svc_rdma_prep_reply_hdr,
106 	.xpo_secure_port = svc_rdma_secure_port,
107 };
108 
109 struct svc_xprt_class svc_rdma_bc_class = {
110 	.xcl_name = "rdma-bc",
111 	.xcl_owner = THIS_MODULE,
112 	.xcl_ops = &svc_rdma_bc_ops,
113 	.xcl_max_payload = (1024 - RPCRDMA_HDRLEN_MIN)
114 };
115 
116 static struct svc_xprt *svc_rdma_bc_create(struct svc_serv *serv,
117 					   struct net *net,
118 					   struct sockaddr *sa, int salen,
119 					   int flags)
120 {
121 	struct svcxprt_rdma *cma_xprt;
122 	struct svc_xprt *xprt;
123 
124 	cma_xprt = rdma_create_xprt(serv, 0);
125 	if (!cma_xprt)
126 		return ERR_PTR(-ENOMEM);
127 	xprt = &cma_xprt->sc_xprt;
128 
129 	svc_xprt_init(net, &svc_rdma_bc_class, xprt, serv);
130 	set_bit(XPT_CONG_CTRL, &xprt->xpt_flags);
131 	serv->sv_bc_xprt = xprt;
132 
133 	dprintk("svcrdma: %s(%p)\n", __func__, xprt);
134 	return xprt;
135 }
136 
137 static void svc_rdma_bc_detach(struct svc_xprt *xprt)
138 {
139 	dprintk("svcrdma: %s(%p)\n", __func__, xprt);
140 }
141 
142 static void svc_rdma_bc_free(struct svc_xprt *xprt)
143 {
144 	struct svcxprt_rdma *rdma =
145 		container_of(xprt, struct svcxprt_rdma, sc_xprt);
146 
147 	dprintk("svcrdma: %s(%p)\n", __func__, xprt);
148 	if (xprt)
149 		kfree(rdma);
150 }
151 #endif	/* CONFIG_SUNRPC_BACKCHANNEL */
152 
153 static struct svc_rdma_op_ctxt *alloc_ctxt(struct svcxprt_rdma *xprt,
154 					   gfp_t flags)
155 {
156 	struct svc_rdma_op_ctxt *ctxt;
157 
158 	ctxt = kmalloc(sizeof(*ctxt), flags);
159 	if (ctxt) {
160 		ctxt->xprt = xprt;
161 		INIT_LIST_HEAD(&ctxt->list);
162 	}
163 	return ctxt;
164 }
165 
166 static bool svc_rdma_prealloc_ctxts(struct svcxprt_rdma *xprt)
167 {
168 	unsigned int i;
169 
170 	/* Each RPC/RDMA credit can consume a number of send
171 	 * and receive WQEs. One ctxt is allocated for each.
172 	 */
173 	i = xprt->sc_sq_depth + xprt->sc_rq_depth;
174 
175 	while (i--) {
176 		struct svc_rdma_op_ctxt *ctxt;
177 
178 		ctxt = alloc_ctxt(xprt, GFP_KERNEL);
179 		if (!ctxt) {
180 			dprintk("svcrdma: No memory for RDMA ctxt\n");
181 			return false;
182 		}
183 		list_add(&ctxt->list, &xprt->sc_ctxts);
184 	}
185 	return true;
186 }
187 
188 struct svc_rdma_op_ctxt *svc_rdma_get_context(struct svcxprt_rdma *xprt)
189 {
190 	struct svc_rdma_op_ctxt *ctxt = NULL;
191 
192 	spin_lock(&xprt->sc_ctxt_lock);
193 	xprt->sc_ctxt_used++;
194 	if (list_empty(&xprt->sc_ctxts))
195 		goto out_empty;
196 
197 	ctxt = list_first_entry(&xprt->sc_ctxts,
198 				struct svc_rdma_op_ctxt, list);
199 	list_del(&ctxt->list);
200 	spin_unlock(&xprt->sc_ctxt_lock);
201 
202 out:
203 	ctxt->count = 0;
204 	ctxt->mapped_sges = 0;
205 	ctxt->frmr = NULL;
206 	return ctxt;
207 
208 out_empty:
209 	/* Either pre-allocation missed the mark, or send
210 	 * queue accounting is broken.
211 	 */
212 	spin_unlock(&xprt->sc_ctxt_lock);
213 
214 	ctxt = alloc_ctxt(xprt, GFP_NOIO);
215 	if (ctxt)
216 		goto out;
217 
218 	spin_lock(&xprt->sc_ctxt_lock);
219 	xprt->sc_ctxt_used--;
220 	spin_unlock(&xprt->sc_ctxt_lock);
221 	WARN_ONCE(1, "svcrdma: empty RDMA ctxt list?\n");
222 	return NULL;
223 }
224 
225 void svc_rdma_unmap_dma(struct svc_rdma_op_ctxt *ctxt)
226 {
227 	struct svcxprt_rdma *xprt = ctxt->xprt;
228 	struct ib_device *device = xprt->sc_cm_id->device;
229 	u32 lkey = xprt->sc_pd->local_dma_lkey;
230 	unsigned int i;
231 
232 	for (i = 0; i < ctxt->mapped_sges; i++) {
233 		/*
234 		 * Unmap the DMA addr in the SGE if the lkey matches
235 		 * the local_dma_lkey, otherwise, ignore it since it is
236 		 * an FRMR lkey and will be unmapped later when the
237 		 * last WR that uses it completes.
238 		 */
239 		if (ctxt->sge[i].lkey == lkey)
240 			ib_dma_unmap_page(device,
241 					    ctxt->sge[i].addr,
242 					    ctxt->sge[i].length,
243 					    ctxt->direction);
244 	}
245 	ctxt->mapped_sges = 0;
246 }
247 
248 void svc_rdma_put_context(struct svc_rdma_op_ctxt *ctxt, int free_pages)
249 {
250 	struct svcxprt_rdma *xprt = ctxt->xprt;
251 	int i;
252 
253 	if (free_pages)
254 		for (i = 0; i < ctxt->count; i++)
255 			put_page(ctxt->pages[i]);
256 
257 	spin_lock(&xprt->sc_ctxt_lock);
258 	xprt->sc_ctxt_used--;
259 	list_add(&ctxt->list, &xprt->sc_ctxts);
260 	spin_unlock(&xprt->sc_ctxt_lock);
261 }
262 
263 static void svc_rdma_destroy_ctxts(struct svcxprt_rdma *xprt)
264 {
265 	while (!list_empty(&xprt->sc_ctxts)) {
266 		struct svc_rdma_op_ctxt *ctxt;
267 
268 		ctxt = list_first_entry(&xprt->sc_ctxts,
269 					struct svc_rdma_op_ctxt, list);
270 		list_del(&ctxt->list);
271 		kfree(ctxt);
272 	}
273 }
274 
275 /* QP event handler */
276 static void qp_event_handler(struct ib_event *event, void *context)
277 {
278 	struct svc_xprt *xprt = context;
279 
280 	switch (event->event) {
281 	/* These are considered benign events */
282 	case IB_EVENT_PATH_MIG:
283 	case IB_EVENT_COMM_EST:
284 	case IB_EVENT_SQ_DRAINED:
285 	case IB_EVENT_QP_LAST_WQE_REACHED:
286 		dprintk("svcrdma: QP event %s (%d) received for QP=%p\n",
287 			ib_event_msg(event->event), event->event,
288 			event->element.qp);
289 		break;
290 	/* These are considered fatal events */
291 	case IB_EVENT_PATH_MIG_ERR:
292 	case IB_EVENT_QP_FATAL:
293 	case IB_EVENT_QP_REQ_ERR:
294 	case IB_EVENT_QP_ACCESS_ERR:
295 	case IB_EVENT_DEVICE_FATAL:
296 	default:
297 		dprintk("svcrdma: QP ERROR event %s (%d) received for QP=%p, "
298 			"closing transport\n",
299 			ib_event_msg(event->event), event->event,
300 			event->element.qp);
301 		set_bit(XPT_CLOSE, &xprt->xpt_flags);
302 		break;
303 	}
304 }
305 
306 /**
307  * svc_rdma_wc_receive - Invoked by RDMA provider for each polled Receive WC
308  * @cq:        completion queue
309  * @wc:        completed WR
310  *
311  */
312 static void svc_rdma_wc_receive(struct ib_cq *cq, struct ib_wc *wc)
313 {
314 	struct svcxprt_rdma *xprt = cq->cq_context;
315 	struct ib_cqe *cqe = wc->wr_cqe;
316 	struct svc_rdma_op_ctxt *ctxt;
317 
318 	/* WARNING: Only wc->wr_cqe and wc->status are reliable */
319 	ctxt = container_of(cqe, struct svc_rdma_op_ctxt, cqe);
320 	svc_rdma_unmap_dma(ctxt);
321 
322 	if (wc->status != IB_WC_SUCCESS)
323 		goto flushed;
324 
325 	/* All wc fields are now known to be valid */
326 	ctxt->byte_len = wc->byte_len;
327 	spin_lock(&xprt->sc_rq_dto_lock);
328 	list_add_tail(&ctxt->list, &xprt->sc_rq_dto_q);
329 	spin_unlock(&xprt->sc_rq_dto_lock);
330 
331 	set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
332 	if (test_bit(RDMAXPRT_CONN_PENDING, &xprt->sc_flags))
333 		goto out;
334 	svc_xprt_enqueue(&xprt->sc_xprt);
335 	goto out;
336 
337 flushed:
338 	if (wc->status != IB_WC_WR_FLUSH_ERR)
339 		pr_warn("svcrdma: receive: %s (%u/0x%x)\n",
340 			ib_wc_status_msg(wc->status),
341 			wc->status, wc->vendor_err);
342 	set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
343 	svc_rdma_put_context(ctxt, 1);
344 
345 out:
346 	svc_xprt_put(&xprt->sc_xprt);
347 }
348 
349 static void svc_rdma_send_wc_common(struct svcxprt_rdma *xprt,
350 				    struct ib_wc *wc,
351 				    const char *opname)
352 {
353 	if (wc->status != IB_WC_SUCCESS)
354 		goto err;
355 
356 out:
357 	atomic_inc(&xprt->sc_sq_avail);
358 	wake_up(&xprt->sc_send_wait);
359 	return;
360 
361 err:
362 	set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
363 	if (wc->status != IB_WC_WR_FLUSH_ERR)
364 		pr_err("svcrdma: %s: %s (%u/0x%x)\n",
365 		       opname, ib_wc_status_msg(wc->status),
366 		       wc->status, wc->vendor_err);
367 	goto out;
368 }
369 
370 static void svc_rdma_send_wc_common_put(struct ib_cq *cq, struct ib_wc *wc,
371 					const char *opname)
372 {
373 	struct svcxprt_rdma *xprt = cq->cq_context;
374 
375 	svc_rdma_send_wc_common(xprt, wc, opname);
376 	svc_xprt_put(&xprt->sc_xprt);
377 }
378 
379 /**
380  * svc_rdma_wc_send - Invoked by RDMA provider for each polled Send WC
381  * @cq:        completion queue
382  * @wc:        completed WR
383  *
384  */
385 void svc_rdma_wc_send(struct ib_cq *cq, struct ib_wc *wc)
386 {
387 	struct ib_cqe *cqe = wc->wr_cqe;
388 	struct svc_rdma_op_ctxt *ctxt;
389 
390 	svc_rdma_send_wc_common_put(cq, wc, "send");
391 
392 	ctxt = container_of(cqe, struct svc_rdma_op_ctxt, cqe);
393 	svc_rdma_unmap_dma(ctxt);
394 	svc_rdma_put_context(ctxt, 1);
395 }
396 
397 /**
398  * svc_rdma_wc_reg - Invoked by RDMA provider for each polled FASTREG WC
399  * @cq:        completion queue
400  * @wc:        completed WR
401  *
402  */
403 void svc_rdma_wc_reg(struct ib_cq *cq, struct ib_wc *wc)
404 {
405 	svc_rdma_send_wc_common_put(cq, wc, "fastreg");
406 }
407 
408 /**
409  * svc_rdma_wc_read - Invoked by RDMA provider for each polled Read WC
410  * @cq:        completion queue
411  * @wc:        completed WR
412  *
413  */
414 void svc_rdma_wc_read(struct ib_cq *cq, struct ib_wc *wc)
415 {
416 	struct svcxprt_rdma *xprt = cq->cq_context;
417 	struct ib_cqe *cqe = wc->wr_cqe;
418 	struct svc_rdma_op_ctxt *ctxt;
419 
420 	svc_rdma_send_wc_common(xprt, wc, "read");
421 
422 	ctxt = container_of(cqe, struct svc_rdma_op_ctxt, cqe);
423 	svc_rdma_unmap_dma(ctxt);
424 	svc_rdma_put_frmr(xprt, ctxt->frmr);
425 
426 	if (test_bit(RDMACTXT_F_LAST_CTXT, &ctxt->flags)) {
427 		struct svc_rdma_op_ctxt *read_hdr;
428 
429 		read_hdr = ctxt->read_hdr;
430 		spin_lock(&xprt->sc_rq_dto_lock);
431 		list_add_tail(&read_hdr->list,
432 			      &xprt->sc_read_complete_q);
433 		spin_unlock(&xprt->sc_rq_dto_lock);
434 
435 		set_bit(XPT_DATA, &xprt->sc_xprt.xpt_flags);
436 		svc_xprt_enqueue(&xprt->sc_xprt);
437 	}
438 
439 	svc_rdma_put_context(ctxt, 0);
440 	svc_xprt_put(&xprt->sc_xprt);
441 }
442 
443 /**
444  * svc_rdma_wc_inv - Invoked by RDMA provider for each polled LOCAL_INV WC
445  * @cq:        completion queue
446  * @wc:        completed WR
447  *
448  */
449 void svc_rdma_wc_inv(struct ib_cq *cq, struct ib_wc *wc)
450 {
451 	svc_rdma_send_wc_common_put(cq, wc, "localInv");
452 }
453 
454 static struct svcxprt_rdma *rdma_create_xprt(struct svc_serv *serv,
455 					     int listener)
456 {
457 	struct svcxprt_rdma *cma_xprt = kzalloc(sizeof *cma_xprt, GFP_KERNEL);
458 
459 	if (!cma_xprt)
460 		return NULL;
461 	svc_xprt_init(&init_net, &svc_rdma_class, &cma_xprt->sc_xprt, serv);
462 	INIT_LIST_HEAD(&cma_xprt->sc_accept_q);
463 	INIT_LIST_HEAD(&cma_xprt->sc_rq_dto_q);
464 	INIT_LIST_HEAD(&cma_xprt->sc_read_complete_q);
465 	INIT_LIST_HEAD(&cma_xprt->sc_frmr_q);
466 	INIT_LIST_HEAD(&cma_xprt->sc_ctxts);
467 	INIT_LIST_HEAD(&cma_xprt->sc_rw_ctxts);
468 	init_waitqueue_head(&cma_xprt->sc_send_wait);
469 
470 	spin_lock_init(&cma_xprt->sc_lock);
471 	spin_lock_init(&cma_xprt->sc_rq_dto_lock);
472 	spin_lock_init(&cma_xprt->sc_frmr_q_lock);
473 	spin_lock_init(&cma_xprt->sc_ctxt_lock);
474 	spin_lock_init(&cma_xprt->sc_rw_ctxt_lock);
475 
476 	/*
477 	 * Note that this implies that the underlying transport support
478 	 * has some form of congestion control (see RFC 7530 section 3.1
479 	 * paragraph 2). For now, we assume that all supported RDMA
480 	 * transports are suitable here.
481 	 */
482 	set_bit(XPT_CONG_CTRL, &cma_xprt->sc_xprt.xpt_flags);
483 
484 	if (listener)
485 		set_bit(XPT_LISTENER, &cma_xprt->sc_xprt.xpt_flags);
486 
487 	return cma_xprt;
488 }
489 
490 int svc_rdma_post_recv(struct svcxprt_rdma *xprt, gfp_t flags)
491 {
492 	struct ib_recv_wr recv_wr, *bad_recv_wr;
493 	struct svc_rdma_op_ctxt *ctxt;
494 	struct page *page;
495 	dma_addr_t pa;
496 	int sge_no;
497 	int buflen;
498 	int ret;
499 
500 	ctxt = svc_rdma_get_context(xprt);
501 	buflen = 0;
502 	ctxt->direction = DMA_FROM_DEVICE;
503 	ctxt->cqe.done = svc_rdma_wc_receive;
504 	for (sge_no = 0; buflen < xprt->sc_max_req_size; sge_no++) {
505 		if (sge_no >= xprt->sc_max_sge) {
506 			pr_err("svcrdma: Too many sges (%d)\n", sge_no);
507 			goto err_put_ctxt;
508 		}
509 		page = alloc_page(flags);
510 		if (!page)
511 			goto err_put_ctxt;
512 		ctxt->pages[sge_no] = page;
513 		pa = ib_dma_map_page(xprt->sc_cm_id->device,
514 				     page, 0, PAGE_SIZE,
515 				     DMA_FROM_DEVICE);
516 		if (ib_dma_mapping_error(xprt->sc_cm_id->device, pa))
517 			goto err_put_ctxt;
518 		svc_rdma_count_mappings(xprt, ctxt);
519 		ctxt->sge[sge_no].addr = pa;
520 		ctxt->sge[sge_no].length = PAGE_SIZE;
521 		ctxt->sge[sge_no].lkey = xprt->sc_pd->local_dma_lkey;
522 		ctxt->count = sge_no + 1;
523 		buflen += PAGE_SIZE;
524 	}
525 	recv_wr.next = NULL;
526 	recv_wr.sg_list = &ctxt->sge[0];
527 	recv_wr.num_sge = ctxt->count;
528 	recv_wr.wr_cqe = &ctxt->cqe;
529 
530 	svc_xprt_get(&xprt->sc_xprt);
531 	ret = ib_post_recv(xprt->sc_qp, &recv_wr, &bad_recv_wr);
532 	if (ret) {
533 		svc_rdma_unmap_dma(ctxt);
534 		svc_rdma_put_context(ctxt, 1);
535 		svc_xprt_put(&xprt->sc_xprt);
536 	}
537 	return ret;
538 
539  err_put_ctxt:
540 	svc_rdma_unmap_dma(ctxt);
541 	svc_rdma_put_context(ctxt, 1);
542 	return -ENOMEM;
543 }
544 
545 int svc_rdma_repost_recv(struct svcxprt_rdma *xprt, gfp_t flags)
546 {
547 	int ret = 0;
548 
549 	ret = svc_rdma_post_recv(xprt, flags);
550 	if (ret) {
551 		pr_err("svcrdma: could not post a receive buffer, err=%d.\n",
552 		       ret);
553 		pr_err("svcrdma: closing transport %p.\n", xprt);
554 		set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
555 		ret = -ENOTCONN;
556 	}
557 	return ret;
558 }
559 
560 static void
561 svc_rdma_parse_connect_private(struct svcxprt_rdma *newxprt,
562 			       struct rdma_conn_param *param)
563 {
564 	const struct rpcrdma_connect_private *pmsg = param->private_data;
565 
566 	if (pmsg &&
567 	    pmsg->cp_magic == rpcrdma_cmp_magic &&
568 	    pmsg->cp_version == RPCRDMA_CMP_VERSION) {
569 		newxprt->sc_snd_w_inv = pmsg->cp_flags &
570 					RPCRDMA_CMP_F_SND_W_INV_OK;
571 
572 		dprintk("svcrdma: client send_size %u, recv_size %u "
573 			"remote inv %ssupported\n",
574 			rpcrdma_decode_buffer_size(pmsg->cp_send_size),
575 			rpcrdma_decode_buffer_size(pmsg->cp_recv_size),
576 			newxprt->sc_snd_w_inv ? "" : "un");
577 	}
578 }
579 
580 /*
581  * This function handles the CONNECT_REQUEST event on a listening
582  * endpoint. It is passed the cma_id for the _new_ connection. The context in
583  * this cma_id is inherited from the listening cma_id and is the svc_xprt
584  * structure for the listening endpoint.
585  *
586  * This function creates a new xprt for the new connection and enqueues it on
587  * the accept queue for the listent xprt. When the listen thread is kicked, it
588  * will call the recvfrom method on the listen xprt which will accept the new
589  * connection.
590  */
591 static void handle_connect_req(struct rdma_cm_id *new_cma_id,
592 			       struct rdma_conn_param *param)
593 {
594 	struct svcxprt_rdma *listen_xprt = new_cma_id->context;
595 	struct svcxprt_rdma *newxprt;
596 	struct sockaddr *sa;
597 
598 	/* Create a new transport */
599 	newxprt = rdma_create_xprt(listen_xprt->sc_xprt.xpt_server, 0);
600 	if (!newxprt) {
601 		dprintk("svcrdma: failed to create new transport\n");
602 		return;
603 	}
604 	newxprt->sc_cm_id = new_cma_id;
605 	new_cma_id->context = newxprt;
606 	dprintk("svcrdma: Creating newxprt=%p, cm_id=%p, listenxprt=%p\n",
607 		newxprt, newxprt->sc_cm_id, listen_xprt);
608 	svc_rdma_parse_connect_private(newxprt, param);
609 
610 	/* Save client advertised inbound read limit for use later in accept. */
611 	newxprt->sc_ord = param->initiator_depth;
612 
613 	/* Set the local and remote addresses in the transport */
614 	sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.dst_addr;
615 	svc_xprt_set_remote(&newxprt->sc_xprt, sa, svc_addr_len(sa));
616 	sa = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.src_addr;
617 	svc_xprt_set_local(&newxprt->sc_xprt, sa, svc_addr_len(sa));
618 
619 	/*
620 	 * Enqueue the new transport on the accept queue of the listening
621 	 * transport
622 	 */
623 	spin_lock_bh(&listen_xprt->sc_lock);
624 	list_add_tail(&newxprt->sc_accept_q, &listen_xprt->sc_accept_q);
625 	spin_unlock_bh(&listen_xprt->sc_lock);
626 
627 	set_bit(XPT_CONN, &listen_xprt->sc_xprt.xpt_flags);
628 	svc_xprt_enqueue(&listen_xprt->sc_xprt);
629 }
630 
631 /*
632  * Handles events generated on the listening endpoint. These events will be
633  * either be incoming connect requests or adapter removal  events.
634  */
635 static int rdma_listen_handler(struct rdma_cm_id *cma_id,
636 			       struct rdma_cm_event *event)
637 {
638 	struct svcxprt_rdma *xprt = cma_id->context;
639 	int ret = 0;
640 
641 	switch (event->event) {
642 	case RDMA_CM_EVENT_CONNECT_REQUEST:
643 		dprintk("svcrdma: Connect request on cma_id=%p, xprt = %p, "
644 			"event = %s (%d)\n", cma_id, cma_id->context,
645 			rdma_event_msg(event->event), event->event);
646 		handle_connect_req(cma_id, &event->param.conn);
647 		break;
648 
649 	case RDMA_CM_EVENT_ESTABLISHED:
650 		/* Accept complete */
651 		dprintk("svcrdma: Connection completed on LISTEN xprt=%p, "
652 			"cm_id=%p\n", xprt, cma_id);
653 		break;
654 
655 	case RDMA_CM_EVENT_DEVICE_REMOVAL:
656 		dprintk("svcrdma: Device removal xprt=%p, cm_id=%p\n",
657 			xprt, cma_id);
658 		if (xprt)
659 			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
660 		break;
661 
662 	default:
663 		dprintk("svcrdma: Unexpected event on listening endpoint %p, "
664 			"event = %s (%d)\n", cma_id,
665 			rdma_event_msg(event->event), event->event);
666 		break;
667 	}
668 
669 	return ret;
670 }
671 
672 static int rdma_cma_handler(struct rdma_cm_id *cma_id,
673 			    struct rdma_cm_event *event)
674 {
675 	struct svc_xprt *xprt = cma_id->context;
676 	struct svcxprt_rdma *rdma =
677 		container_of(xprt, struct svcxprt_rdma, sc_xprt);
678 	switch (event->event) {
679 	case RDMA_CM_EVENT_ESTABLISHED:
680 		/* Accept complete */
681 		svc_xprt_get(xprt);
682 		dprintk("svcrdma: Connection completed on DTO xprt=%p, "
683 			"cm_id=%p\n", xprt, cma_id);
684 		clear_bit(RDMAXPRT_CONN_PENDING, &rdma->sc_flags);
685 		svc_xprt_enqueue(xprt);
686 		break;
687 	case RDMA_CM_EVENT_DISCONNECTED:
688 		dprintk("svcrdma: Disconnect on DTO xprt=%p, cm_id=%p\n",
689 			xprt, cma_id);
690 		if (xprt) {
691 			set_bit(XPT_CLOSE, &xprt->xpt_flags);
692 			svc_xprt_enqueue(xprt);
693 			svc_xprt_put(xprt);
694 		}
695 		break;
696 	case RDMA_CM_EVENT_DEVICE_REMOVAL:
697 		dprintk("svcrdma: Device removal cma_id=%p, xprt = %p, "
698 			"event = %s (%d)\n", cma_id, xprt,
699 			rdma_event_msg(event->event), event->event);
700 		if (xprt) {
701 			set_bit(XPT_CLOSE, &xprt->xpt_flags);
702 			svc_xprt_enqueue(xprt);
703 			svc_xprt_put(xprt);
704 		}
705 		break;
706 	default:
707 		dprintk("svcrdma: Unexpected event on DTO endpoint %p, "
708 			"event = %s (%d)\n", cma_id,
709 			rdma_event_msg(event->event), event->event);
710 		break;
711 	}
712 	return 0;
713 }
714 
715 /*
716  * Create a listening RDMA service endpoint.
717  */
718 static struct svc_xprt *svc_rdma_create(struct svc_serv *serv,
719 					struct net *net,
720 					struct sockaddr *sa, int salen,
721 					int flags)
722 {
723 	struct rdma_cm_id *listen_id;
724 	struct svcxprt_rdma *cma_xprt;
725 	int ret;
726 
727 	dprintk("svcrdma: Creating RDMA socket\n");
728 	if ((sa->sa_family != AF_INET) && (sa->sa_family != AF_INET6)) {
729 		dprintk("svcrdma: Address family %d is not supported.\n", sa->sa_family);
730 		return ERR_PTR(-EAFNOSUPPORT);
731 	}
732 	cma_xprt = rdma_create_xprt(serv, 1);
733 	if (!cma_xprt)
734 		return ERR_PTR(-ENOMEM);
735 
736 	listen_id = rdma_create_id(&init_net, rdma_listen_handler, cma_xprt,
737 				   RDMA_PS_TCP, IB_QPT_RC);
738 	if (IS_ERR(listen_id)) {
739 		ret = PTR_ERR(listen_id);
740 		dprintk("svcrdma: rdma_create_id failed = %d\n", ret);
741 		goto err0;
742 	}
743 
744 	/* Allow both IPv4 and IPv6 sockets to bind a single port
745 	 * at the same time.
746 	 */
747 #if IS_ENABLED(CONFIG_IPV6)
748 	ret = rdma_set_afonly(listen_id, 1);
749 	if (ret) {
750 		dprintk("svcrdma: rdma_set_afonly failed = %d\n", ret);
751 		goto err1;
752 	}
753 #endif
754 	ret = rdma_bind_addr(listen_id, sa);
755 	if (ret) {
756 		dprintk("svcrdma: rdma_bind_addr failed = %d\n", ret);
757 		goto err1;
758 	}
759 	cma_xprt->sc_cm_id = listen_id;
760 
761 	ret = rdma_listen(listen_id, RPCRDMA_LISTEN_BACKLOG);
762 	if (ret) {
763 		dprintk("svcrdma: rdma_listen failed = %d\n", ret);
764 		goto err1;
765 	}
766 
767 	/*
768 	 * We need to use the address from the cm_id in case the
769 	 * caller specified 0 for the port number.
770 	 */
771 	sa = (struct sockaddr *)&cma_xprt->sc_cm_id->route.addr.src_addr;
772 	svc_xprt_set_local(&cma_xprt->sc_xprt, sa, salen);
773 
774 	return &cma_xprt->sc_xprt;
775 
776  err1:
777 	rdma_destroy_id(listen_id);
778  err0:
779 	kfree(cma_xprt);
780 	return ERR_PTR(ret);
781 }
782 
783 static struct svc_rdma_fastreg_mr *rdma_alloc_frmr(struct svcxprt_rdma *xprt)
784 {
785 	struct ib_mr *mr;
786 	struct scatterlist *sg;
787 	struct svc_rdma_fastreg_mr *frmr;
788 	u32 num_sg;
789 
790 	frmr = kmalloc(sizeof(*frmr), GFP_KERNEL);
791 	if (!frmr)
792 		goto err;
793 
794 	num_sg = min_t(u32, RPCSVC_MAXPAGES, xprt->sc_frmr_pg_list_len);
795 	mr = ib_alloc_mr(xprt->sc_pd, IB_MR_TYPE_MEM_REG, num_sg);
796 	if (IS_ERR(mr))
797 		goto err_free_frmr;
798 
799 	sg = kcalloc(RPCSVC_MAXPAGES, sizeof(*sg), GFP_KERNEL);
800 	if (!sg)
801 		goto err_free_mr;
802 
803 	sg_init_table(sg, RPCSVC_MAXPAGES);
804 
805 	frmr->mr = mr;
806 	frmr->sg = sg;
807 	INIT_LIST_HEAD(&frmr->frmr_list);
808 	return frmr;
809 
810  err_free_mr:
811 	ib_dereg_mr(mr);
812  err_free_frmr:
813 	kfree(frmr);
814  err:
815 	return ERR_PTR(-ENOMEM);
816 }
817 
818 static void rdma_dealloc_frmr_q(struct svcxprt_rdma *xprt)
819 {
820 	struct svc_rdma_fastreg_mr *frmr;
821 
822 	while (!list_empty(&xprt->sc_frmr_q)) {
823 		frmr = list_entry(xprt->sc_frmr_q.next,
824 				  struct svc_rdma_fastreg_mr, frmr_list);
825 		list_del_init(&frmr->frmr_list);
826 		kfree(frmr->sg);
827 		ib_dereg_mr(frmr->mr);
828 		kfree(frmr);
829 	}
830 }
831 
832 struct svc_rdma_fastreg_mr *svc_rdma_get_frmr(struct svcxprt_rdma *rdma)
833 {
834 	struct svc_rdma_fastreg_mr *frmr = NULL;
835 
836 	spin_lock(&rdma->sc_frmr_q_lock);
837 	if (!list_empty(&rdma->sc_frmr_q)) {
838 		frmr = list_entry(rdma->sc_frmr_q.next,
839 				  struct svc_rdma_fastreg_mr, frmr_list);
840 		list_del_init(&frmr->frmr_list);
841 		frmr->sg_nents = 0;
842 	}
843 	spin_unlock(&rdma->sc_frmr_q_lock);
844 	if (frmr)
845 		return frmr;
846 
847 	return rdma_alloc_frmr(rdma);
848 }
849 
850 void svc_rdma_put_frmr(struct svcxprt_rdma *rdma,
851 		       struct svc_rdma_fastreg_mr *frmr)
852 {
853 	if (frmr) {
854 		ib_dma_unmap_sg(rdma->sc_cm_id->device,
855 				frmr->sg, frmr->sg_nents, frmr->direction);
856 		spin_lock(&rdma->sc_frmr_q_lock);
857 		WARN_ON_ONCE(!list_empty(&frmr->frmr_list));
858 		list_add(&frmr->frmr_list, &rdma->sc_frmr_q);
859 		spin_unlock(&rdma->sc_frmr_q_lock);
860 	}
861 }
862 
863 /*
864  * This is the xpo_recvfrom function for listening endpoints. Its
865  * purpose is to accept incoming connections. The CMA callback handler
866  * has already created a new transport and attached it to the new CMA
867  * ID.
868  *
869  * There is a queue of pending connections hung on the listening
870  * transport. This queue contains the new svc_xprt structure. This
871  * function takes svc_xprt structures off the accept_q and completes
872  * the connection.
873  */
874 static struct svc_xprt *svc_rdma_accept(struct svc_xprt *xprt)
875 {
876 	struct svcxprt_rdma *listen_rdma;
877 	struct svcxprt_rdma *newxprt = NULL;
878 	struct rdma_conn_param conn_param;
879 	struct rpcrdma_connect_private pmsg;
880 	struct ib_qp_init_attr qp_attr;
881 	struct ib_device *dev;
882 	struct sockaddr *sap;
883 	unsigned int i;
884 	int ret = 0;
885 
886 	listen_rdma = container_of(xprt, struct svcxprt_rdma, sc_xprt);
887 	clear_bit(XPT_CONN, &xprt->xpt_flags);
888 	/* Get the next entry off the accept list */
889 	spin_lock_bh(&listen_rdma->sc_lock);
890 	if (!list_empty(&listen_rdma->sc_accept_q)) {
891 		newxprt = list_entry(listen_rdma->sc_accept_q.next,
892 				     struct svcxprt_rdma, sc_accept_q);
893 		list_del_init(&newxprt->sc_accept_q);
894 	}
895 	if (!list_empty(&listen_rdma->sc_accept_q))
896 		set_bit(XPT_CONN, &listen_rdma->sc_xprt.xpt_flags);
897 	spin_unlock_bh(&listen_rdma->sc_lock);
898 	if (!newxprt)
899 		return NULL;
900 
901 	dprintk("svcrdma: newxprt from accept queue = %p, cm_id=%p\n",
902 		newxprt, newxprt->sc_cm_id);
903 
904 	dev = newxprt->sc_cm_id->device;
905 	newxprt->sc_port_num = newxprt->sc_cm_id->port_num;
906 
907 	/* Qualify the transport resource defaults with the
908 	 * capabilities of this particular device */
909 	newxprt->sc_max_sge = min((size_t)dev->attrs.max_sge,
910 				  (size_t)RPCSVC_MAXPAGES);
911 	newxprt->sc_max_sge_rd = min_t(size_t, dev->attrs.max_sge_rd,
912 				       RPCSVC_MAXPAGES);
913 	newxprt->sc_max_req_size = svcrdma_max_req_size;
914 	newxprt->sc_max_requests = min_t(u32, dev->attrs.max_qp_wr,
915 					 svcrdma_max_requests);
916 	newxprt->sc_fc_credits = cpu_to_be32(newxprt->sc_max_requests);
917 	newxprt->sc_max_bc_requests = min_t(u32, dev->attrs.max_qp_wr,
918 					    svcrdma_max_bc_requests);
919 	newxprt->sc_rq_depth = newxprt->sc_max_requests +
920 			       newxprt->sc_max_bc_requests;
921 	newxprt->sc_sq_depth = newxprt->sc_rq_depth;
922 	atomic_set(&newxprt->sc_sq_avail, newxprt->sc_sq_depth);
923 
924 	if (!svc_rdma_prealloc_ctxts(newxprt))
925 		goto errout;
926 
927 	/*
928 	 * Limit ORD based on client limit, local device limit, and
929 	 * configured svcrdma limit.
930 	 */
931 	newxprt->sc_ord = min_t(size_t, dev->attrs.max_qp_rd_atom, newxprt->sc_ord);
932 	newxprt->sc_ord = min_t(size_t,	svcrdma_ord, newxprt->sc_ord);
933 
934 	newxprt->sc_pd = ib_alloc_pd(dev, 0);
935 	if (IS_ERR(newxprt->sc_pd)) {
936 		dprintk("svcrdma: error creating PD for connect request\n");
937 		goto errout;
938 	}
939 	newxprt->sc_sq_cq = ib_alloc_cq(dev, newxprt, newxprt->sc_sq_depth,
940 					0, IB_POLL_WORKQUEUE);
941 	if (IS_ERR(newxprt->sc_sq_cq)) {
942 		dprintk("svcrdma: error creating SQ CQ for connect request\n");
943 		goto errout;
944 	}
945 	newxprt->sc_rq_cq = ib_alloc_cq(dev, newxprt, newxprt->sc_rq_depth,
946 					0, IB_POLL_WORKQUEUE);
947 	if (IS_ERR(newxprt->sc_rq_cq)) {
948 		dprintk("svcrdma: error creating RQ CQ for connect request\n");
949 		goto errout;
950 	}
951 
952 	memset(&qp_attr, 0, sizeof qp_attr);
953 	qp_attr.event_handler = qp_event_handler;
954 	qp_attr.qp_context = &newxprt->sc_xprt;
955 	qp_attr.port_num = newxprt->sc_cm_id->port_num;
956 	qp_attr.cap.max_rdma_ctxs = newxprt->sc_max_requests;
957 	qp_attr.cap.max_send_wr = newxprt->sc_sq_depth;
958 	qp_attr.cap.max_recv_wr = newxprt->sc_rq_depth;
959 	qp_attr.cap.max_send_sge = newxprt->sc_max_sge;
960 	qp_attr.cap.max_recv_sge = newxprt->sc_max_sge;
961 	qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
962 	qp_attr.qp_type = IB_QPT_RC;
963 	qp_attr.send_cq = newxprt->sc_sq_cq;
964 	qp_attr.recv_cq = newxprt->sc_rq_cq;
965 	dprintk("svcrdma: newxprt->sc_cm_id=%p, newxprt->sc_pd=%p\n",
966 		newxprt->sc_cm_id, newxprt->sc_pd);
967 	dprintk("    cap.max_send_wr = %d, cap.max_recv_wr = %d\n",
968 		qp_attr.cap.max_send_wr, qp_attr.cap.max_recv_wr);
969 	dprintk("    cap.max_send_sge = %d, cap.max_recv_sge = %d\n",
970 		qp_attr.cap.max_send_sge, qp_attr.cap.max_recv_sge);
971 
972 	ret = rdma_create_qp(newxprt->sc_cm_id, newxprt->sc_pd, &qp_attr);
973 	if (ret) {
974 		dprintk("svcrdma: failed to create QP, ret=%d\n", ret);
975 		goto errout;
976 	}
977 	newxprt->sc_qp = newxprt->sc_cm_id->qp;
978 
979 	/*
980 	 * Use the most secure set of MR resources based on the
981 	 * transport type and available memory management features in
982 	 * the device. Here's the table implemented below:
983 	 *
984 	 *		Fast	Global	DMA	Remote WR
985 	 *		Reg	LKEY	MR	Access
986 	 *		Sup'd	Sup'd	Needed	Needed
987 	 *
988 	 * IWARP	N	N	Y	Y
989 	 *		N	Y	Y	Y
990 	 *		Y	N	Y	N
991 	 *		Y	Y	N	-
992 	 *
993 	 * IB		N	N	Y	N
994 	 *		N	Y	N	-
995 	 *		Y	N	Y	N
996 	 *		Y	Y	N	-
997 	 *
998 	 * NB:	iWARP requires remote write access for the data sink
999 	 *	of an RDMA_READ. IB does not.
1000 	 */
1001 	newxprt->sc_reader = rdma_read_chunk_lcl;
1002 	if (dev->attrs.device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS) {
1003 		newxprt->sc_frmr_pg_list_len =
1004 			dev->attrs.max_fast_reg_page_list_len;
1005 		newxprt->sc_dev_caps |= SVCRDMA_DEVCAP_FAST_REG;
1006 		newxprt->sc_reader = rdma_read_chunk_frmr;
1007 	} else
1008 		newxprt->sc_snd_w_inv = false;
1009 
1010 	/*
1011 	 * Determine if a DMA MR is required and if so, what privs are required
1012 	 */
1013 	if (!rdma_protocol_iwarp(dev, newxprt->sc_cm_id->port_num) &&
1014 	    !rdma_ib_or_roce(dev, newxprt->sc_cm_id->port_num))
1015 		goto errout;
1016 
1017 	if (rdma_protocol_iwarp(dev, newxprt->sc_cm_id->port_num))
1018 		newxprt->sc_dev_caps |= SVCRDMA_DEVCAP_READ_W_INV;
1019 
1020 	/* Post receive buffers */
1021 	for (i = 0; i < newxprt->sc_max_requests; i++) {
1022 		ret = svc_rdma_post_recv(newxprt, GFP_KERNEL);
1023 		if (ret) {
1024 			dprintk("svcrdma: failure posting receive buffers\n");
1025 			goto errout;
1026 		}
1027 	}
1028 
1029 	/* Swap out the handler */
1030 	newxprt->sc_cm_id->event_handler = rdma_cma_handler;
1031 
1032 	/* Construct RDMA-CM private message */
1033 	pmsg.cp_magic = rpcrdma_cmp_magic;
1034 	pmsg.cp_version = RPCRDMA_CMP_VERSION;
1035 	pmsg.cp_flags = 0;
1036 	pmsg.cp_send_size = pmsg.cp_recv_size =
1037 		rpcrdma_encode_buffer_size(newxprt->sc_max_req_size);
1038 
1039 	/* Accept Connection */
1040 	set_bit(RDMAXPRT_CONN_PENDING, &newxprt->sc_flags);
1041 	memset(&conn_param, 0, sizeof conn_param);
1042 	conn_param.responder_resources = 0;
1043 	conn_param.initiator_depth = newxprt->sc_ord;
1044 	conn_param.private_data = &pmsg;
1045 	conn_param.private_data_len = sizeof(pmsg);
1046 	ret = rdma_accept(newxprt->sc_cm_id, &conn_param);
1047 	if (ret) {
1048 		dprintk("svcrdma: failed to accept new connection, ret=%d\n",
1049 		       ret);
1050 		goto errout;
1051 	}
1052 
1053 	dprintk("svcrdma: new connection %p accepted:\n", newxprt);
1054 	sap = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.src_addr;
1055 	dprintk("    local address   : %pIS:%u\n", sap, rpc_get_port(sap));
1056 	sap = (struct sockaddr *)&newxprt->sc_cm_id->route.addr.dst_addr;
1057 	dprintk("    remote address  : %pIS:%u\n", sap, rpc_get_port(sap));
1058 	dprintk("    max_sge         : %d\n", newxprt->sc_max_sge);
1059 	dprintk("    max_sge_rd      : %d\n", newxprt->sc_max_sge_rd);
1060 	dprintk("    sq_depth        : %d\n", newxprt->sc_sq_depth);
1061 	dprintk("    max_requests    : %d\n", newxprt->sc_max_requests);
1062 	dprintk("    ord             : %d\n", newxprt->sc_ord);
1063 
1064 	return &newxprt->sc_xprt;
1065 
1066  errout:
1067 	dprintk("svcrdma: failure accepting new connection rc=%d.\n", ret);
1068 	/* Take a reference in case the DTO handler runs */
1069 	svc_xprt_get(&newxprt->sc_xprt);
1070 	if (newxprt->sc_qp && !IS_ERR(newxprt->sc_qp))
1071 		ib_destroy_qp(newxprt->sc_qp);
1072 	rdma_destroy_id(newxprt->sc_cm_id);
1073 	/* This call to put will destroy the transport */
1074 	svc_xprt_put(&newxprt->sc_xprt);
1075 	return NULL;
1076 }
1077 
1078 static void svc_rdma_release_rqst(struct svc_rqst *rqstp)
1079 {
1080 }
1081 
1082 /*
1083  * When connected, an svc_xprt has at least two references:
1084  *
1085  * - A reference held by the cm_id between the ESTABLISHED and
1086  *   DISCONNECTED events. If the remote peer disconnected first, this
1087  *   reference could be gone.
1088  *
1089  * - A reference held by the svc_recv code that called this function
1090  *   as part of close processing.
1091  *
1092  * At a minimum one references should still be held.
1093  */
1094 static void svc_rdma_detach(struct svc_xprt *xprt)
1095 {
1096 	struct svcxprt_rdma *rdma =
1097 		container_of(xprt, struct svcxprt_rdma, sc_xprt);
1098 	dprintk("svc: svc_rdma_detach(%p)\n", xprt);
1099 
1100 	/* Disconnect and flush posted WQE */
1101 	rdma_disconnect(rdma->sc_cm_id);
1102 }
1103 
1104 static void __svc_rdma_free(struct work_struct *work)
1105 {
1106 	struct svcxprt_rdma *rdma =
1107 		container_of(work, struct svcxprt_rdma, sc_work);
1108 	struct svc_xprt *xprt = &rdma->sc_xprt;
1109 
1110 	dprintk("svcrdma: %s(%p)\n", __func__, rdma);
1111 
1112 	if (rdma->sc_qp && !IS_ERR(rdma->sc_qp))
1113 		ib_drain_qp(rdma->sc_qp);
1114 
1115 	/* We should only be called from kref_put */
1116 	if (kref_read(&xprt->xpt_ref) != 0)
1117 		pr_err("svcrdma: sc_xprt still in use? (%d)\n",
1118 		       kref_read(&xprt->xpt_ref));
1119 
1120 	/*
1121 	 * Destroy queued, but not processed read completions. Note
1122 	 * that this cleanup has to be done before destroying the
1123 	 * cm_id because the device ptr is needed to unmap the dma in
1124 	 * svc_rdma_put_context.
1125 	 */
1126 	while (!list_empty(&rdma->sc_read_complete_q)) {
1127 		struct svc_rdma_op_ctxt *ctxt;
1128 		ctxt = list_first_entry(&rdma->sc_read_complete_q,
1129 					struct svc_rdma_op_ctxt, list);
1130 		list_del(&ctxt->list);
1131 		svc_rdma_put_context(ctxt, 1);
1132 	}
1133 
1134 	/* Destroy queued, but not processed recv completions */
1135 	while (!list_empty(&rdma->sc_rq_dto_q)) {
1136 		struct svc_rdma_op_ctxt *ctxt;
1137 		ctxt = list_first_entry(&rdma->sc_rq_dto_q,
1138 					struct svc_rdma_op_ctxt, list);
1139 		list_del(&ctxt->list);
1140 		svc_rdma_put_context(ctxt, 1);
1141 	}
1142 
1143 	/* Warn if we leaked a resource or under-referenced */
1144 	if (rdma->sc_ctxt_used != 0)
1145 		pr_err("svcrdma: ctxt still in use? (%d)\n",
1146 		       rdma->sc_ctxt_used);
1147 
1148 	/* Final put of backchannel client transport */
1149 	if (xprt->xpt_bc_xprt) {
1150 		xprt_put(xprt->xpt_bc_xprt);
1151 		xprt->xpt_bc_xprt = NULL;
1152 	}
1153 
1154 	rdma_dealloc_frmr_q(rdma);
1155 	svc_rdma_destroy_rw_ctxts(rdma);
1156 	svc_rdma_destroy_ctxts(rdma);
1157 
1158 	/* Destroy the QP if present (not a listener) */
1159 	if (rdma->sc_qp && !IS_ERR(rdma->sc_qp))
1160 		ib_destroy_qp(rdma->sc_qp);
1161 
1162 	if (rdma->sc_sq_cq && !IS_ERR(rdma->sc_sq_cq))
1163 		ib_free_cq(rdma->sc_sq_cq);
1164 
1165 	if (rdma->sc_rq_cq && !IS_ERR(rdma->sc_rq_cq))
1166 		ib_free_cq(rdma->sc_rq_cq);
1167 
1168 	if (rdma->sc_pd && !IS_ERR(rdma->sc_pd))
1169 		ib_dealloc_pd(rdma->sc_pd);
1170 
1171 	/* Destroy the CM ID */
1172 	rdma_destroy_id(rdma->sc_cm_id);
1173 
1174 	kfree(rdma);
1175 }
1176 
1177 static void svc_rdma_free(struct svc_xprt *xprt)
1178 {
1179 	struct svcxprt_rdma *rdma =
1180 		container_of(xprt, struct svcxprt_rdma, sc_xprt);
1181 	INIT_WORK(&rdma->sc_work, __svc_rdma_free);
1182 	queue_work(svc_rdma_wq, &rdma->sc_work);
1183 }
1184 
1185 static int svc_rdma_has_wspace(struct svc_xprt *xprt)
1186 {
1187 	struct svcxprt_rdma *rdma =
1188 		container_of(xprt, struct svcxprt_rdma, sc_xprt);
1189 
1190 	/*
1191 	 * If there are already waiters on the SQ,
1192 	 * return false.
1193 	 */
1194 	if (waitqueue_active(&rdma->sc_send_wait))
1195 		return 0;
1196 
1197 	/* Otherwise return true. */
1198 	return 1;
1199 }
1200 
1201 static int svc_rdma_secure_port(struct svc_rqst *rqstp)
1202 {
1203 	return 1;
1204 }
1205 
1206 static void svc_rdma_kill_temp_xprt(struct svc_xprt *xprt)
1207 {
1208 }
1209 
1210 int svc_rdma_send(struct svcxprt_rdma *xprt, struct ib_send_wr *wr)
1211 {
1212 	struct ib_send_wr *bad_wr, *n_wr;
1213 	int wr_count;
1214 	int i;
1215 	int ret;
1216 
1217 	if (test_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags))
1218 		return -ENOTCONN;
1219 
1220 	wr_count = 1;
1221 	for (n_wr = wr->next; n_wr; n_wr = n_wr->next)
1222 		wr_count++;
1223 
1224 	/* If the SQ is full, wait until an SQ entry is available */
1225 	while (1) {
1226 		if ((atomic_sub_return(wr_count, &xprt->sc_sq_avail) < 0)) {
1227 			atomic_inc(&rdma_stat_sq_starve);
1228 
1229 			/* Wait until SQ WR available if SQ still full */
1230 			atomic_add(wr_count, &xprt->sc_sq_avail);
1231 			wait_event(xprt->sc_send_wait,
1232 				   atomic_read(&xprt->sc_sq_avail) > wr_count);
1233 			if (test_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags))
1234 				return -ENOTCONN;
1235 			continue;
1236 		}
1237 		/* Take a transport ref for each WR posted */
1238 		for (i = 0; i < wr_count; i++)
1239 			svc_xprt_get(&xprt->sc_xprt);
1240 
1241 		/* Bump used SQ WR count and post */
1242 		ret = ib_post_send(xprt->sc_qp, wr, &bad_wr);
1243 		if (ret) {
1244 			set_bit(XPT_CLOSE, &xprt->sc_xprt.xpt_flags);
1245 			for (i = 0; i < wr_count; i ++)
1246 				svc_xprt_put(&xprt->sc_xprt);
1247 			dprintk("svcrdma: failed to post SQ WR rc=%d\n", ret);
1248 			dprintk("    sc_sq_avail=%d, sc_sq_depth=%d\n",
1249 				atomic_read(&xprt->sc_sq_avail),
1250 				xprt->sc_sq_depth);
1251 			wake_up(&xprt->sc_send_wait);
1252 		}
1253 		break;
1254 	}
1255 	return ret;
1256 }
1257