xref: /openbmc/linux/net/9p/trans_rdma.c (revision b627b4ed) 
1 /*
2  * linux/fs/9p/trans_rdma.c
3  *
4  * RDMA transport layer based on the trans_fd.c implementation.
5  *
6  *  Copyright (C) 2008 by Tom Tucker <tom@opengridcomputing.com>
7  *  Copyright (C) 2006 by Russ Cox <rsc@swtch.com>
8  *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
9  *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
10  *  Copyright (C) 1997-2002 by Ron Minnich <rminnich@sarnoff.com>
11  *
12  *  This program is free software; you can redistribute it and/or modify
13  *  it under the terms of the GNU General Public License version 2
14  *  as published by the Free Software Foundation.
15  *
16  *  This program is distributed in the hope that it will be useful,
17  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
18  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19  *  GNU General Public License for more details.
20  *
21  *  You should have received a copy of the GNU General Public License
22  *  along with this program; if not, write to:
23  *  Free Software Foundation
24  *  51 Franklin Street, Fifth Floor
25  *  Boston, MA  02111-1301  USA
26  *
27  */
28 
29 #include <linux/in.h>
30 #include <linux/module.h>
31 #include <linux/net.h>
32 #include <linux/ipv6.h>
33 #include <linux/kthread.h>
34 #include <linux/errno.h>
35 #include <linux/kernel.h>
36 #include <linux/un.h>
37 #include <linux/uaccess.h>
38 #include <linux/inet.h>
39 #include <linux/idr.h>
40 #include <linux/file.h>
41 #include <linux/parser.h>
42 #include <linux/semaphore.h>
43 #include <net/9p/9p.h>
44 #include <net/9p/client.h>
45 #include <net/9p/transport.h>
46 #include <rdma/ib_verbs.h>
47 #include <rdma/rdma_cm.h>
48 
49 #define P9_PORT			5640
50 #define P9_RDMA_SQ_DEPTH	32
51 #define P9_RDMA_RQ_DEPTH	32
52 #define P9_RDMA_SEND_SGE	4
53 #define P9_RDMA_RECV_SGE	4
54 #define P9_RDMA_IRD		0
55 #define P9_RDMA_ORD		0
56 #define P9_RDMA_TIMEOUT		30000		/* 30 seconds */
57 #define P9_RDMA_MAXSIZE		(4*4096)	/* Min SGE is 4, so we can
58 						 * safely advertise a maxsize
59 						 * of 64k */
60 
61 #define P9_RDMA_MAX_SGE (P9_RDMA_MAXSIZE >> PAGE_SHIFT)
62 /**
63  * struct p9_trans_rdma - RDMA transport instance
64  *
65  * @state: tracks the transport state machine for connection setup and tear down
66  * @cm_id: The RDMA CM ID
67  * @pd: Protection Domain pointer
68  * @qp: Queue Pair pointer
69  * @cq: Completion Queue pointer
70  * @lkey: The local access only memory region key
71  * @timeout: Number of uSecs to wait for connection management events
72  * @sq_depth: The depth of the Send Queue
73  * @sq_sem: Semaphore for the SQ
74  * @rq_depth: The depth of the Receive Queue.
75  * @addr: The remote peer's address
76  * @req_lock: Protects the active request list
77  * @send_wait: Wait list when the SQ fills up
78  * @cm_done: Completion event for connection management tracking
79  */
80 struct p9_trans_rdma {
81 	enum {
82 		P9_RDMA_INIT,
83 		P9_RDMA_ADDR_RESOLVED,
84 		P9_RDMA_ROUTE_RESOLVED,
85 		P9_RDMA_CONNECTED,
86 		P9_RDMA_FLUSHING,
87 		P9_RDMA_CLOSING,
88 		P9_RDMA_CLOSED,
89 	} state;
90 	struct rdma_cm_id *cm_id;
91 	struct ib_pd *pd;
92 	struct ib_qp *qp;
93 	struct ib_cq *cq;
94 	struct ib_mr *dma_mr;
95 	u32 lkey;
96 	long timeout;
97 	int sq_depth;
98 	struct semaphore sq_sem;
99 	int rq_depth;
100 	atomic_t rq_count;
101 	struct sockaddr_in addr;
102 	spinlock_t req_lock;
103 
104 	struct completion cm_done;
105 };
106 
107 /**
108  * p9_rdma_context - Keeps track of in-process WR
109  *
110  * @wc_op: The original WR op for when the CQE completes in error.
111  * @busa: Bus address to unmap when the WR completes
112  * @req: Keeps track of requests (send)
113  * @rc: Keepts track of replies (receive)
114  */
115 struct p9_rdma_req;
116 struct p9_rdma_context {
117 	enum ib_wc_opcode wc_op;
118 	dma_addr_t busa;
119 	union {
120 		struct p9_req_t *req;
121 		struct p9_fcall *rc;
122 	};
123 };
124 
125 /**
126  * p9_rdma_opts - Collection of mount options
127  * @port: port of connection
128  * @sq_depth: The requested depth of the SQ. This really doesn't need
129  * to be any deeper than the number of threads used in the client
130  * @rq_depth: The depth of the RQ. Should be greater than or equal to SQ depth
131  * @timeout: Time to wait in msecs for CM events
132  */
133 struct p9_rdma_opts {
134 	short port;
135 	int sq_depth;
136 	int rq_depth;
137 	long timeout;
138 };
139 
140 /*
141  * Option Parsing (code inspired by NFS code)
142  */
143 enum {
144 	/* Options that take integer arguments */
145 	Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout, Opt_err,
146 };
147 
148 static match_table_t tokens = {
149 	{Opt_port, "port=%u"},
150 	{Opt_sq_depth, "sq=%u"},
151 	{Opt_rq_depth, "rq=%u"},
152 	{Opt_timeout, "timeout=%u"},
153 	{Opt_err, NULL},
154 };
155 
156 /**
157  * parse_options - parse mount options into session structure
158  * @options: options string passed from mount
159  * @opts: transport-specific structure to parse options into
160  *
161  * Returns 0 upon success, -ERRNO upon failure
162  */
163 static int parse_opts(char *params, struct p9_rdma_opts *opts)
164 {
165 	char *p;
166 	substring_t args[MAX_OPT_ARGS];
167 	int option;
168 	char *options;
169 	int ret;
170 
171 	opts->port = P9_PORT;
172 	opts->sq_depth = P9_RDMA_SQ_DEPTH;
173 	opts->rq_depth = P9_RDMA_RQ_DEPTH;
174 	opts->timeout = P9_RDMA_TIMEOUT;
175 
176 	if (!params)
177 		return 0;
178 
179 	options = kstrdup(params, GFP_KERNEL);
180 	if (!options) {
181 		P9_DPRINTK(P9_DEBUG_ERROR,
182 			   "failed to allocate copy of option string\n");
183 		return -ENOMEM;
184 	}
185 
186 	while ((p = strsep(&options, ",")) != NULL) {
187 		int token;
188 		int r;
189 		if (!*p)
190 			continue;
191 		token = match_token(p, tokens, args);
192 		r = match_int(&args[0], &option);
193 		if (r < 0) {
194 			P9_DPRINTK(P9_DEBUG_ERROR,
195 				   "integer field, but no integer?\n");
196 			ret = r;
197 			continue;
198 		}
199 		switch (token) {
200 		case Opt_port:
201 			opts->port = option;
202 			break;
203 		case Opt_sq_depth:
204 			opts->sq_depth = option;
205 			break;
206 		case Opt_rq_depth:
207 			opts->rq_depth = option;
208 			break;
209 		case Opt_timeout:
210 			opts->timeout = option;
211 			break;
212 		default:
213 			continue;
214 		}
215 	}
216 	/* RQ must be at least as large as the SQ */
217 	opts->rq_depth = max(opts->rq_depth, opts->sq_depth);
218 	kfree(options);
219 	return 0;
220 }
221 
222 static int
223 p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
224 {
225 	struct p9_client *c = id->context;
226 	struct p9_trans_rdma *rdma = c->trans;
227 	switch (event->event) {
228 	case RDMA_CM_EVENT_ADDR_RESOLVED:
229 		BUG_ON(rdma->state != P9_RDMA_INIT);
230 		rdma->state = P9_RDMA_ADDR_RESOLVED;
231 		break;
232 
233 	case RDMA_CM_EVENT_ROUTE_RESOLVED:
234 		BUG_ON(rdma->state != P9_RDMA_ADDR_RESOLVED);
235 		rdma->state = P9_RDMA_ROUTE_RESOLVED;
236 		break;
237 
238 	case RDMA_CM_EVENT_ESTABLISHED:
239 		BUG_ON(rdma->state != P9_RDMA_ROUTE_RESOLVED);
240 		rdma->state = P9_RDMA_CONNECTED;
241 		break;
242 
243 	case RDMA_CM_EVENT_DISCONNECTED:
244 		if (rdma)
245 			rdma->state = P9_RDMA_CLOSED;
246 		if (c)
247 			c->status = Disconnected;
248 		break;
249 
250 	case RDMA_CM_EVENT_TIMEWAIT_EXIT:
251 		break;
252 
253 	case RDMA_CM_EVENT_ADDR_CHANGE:
254 	case RDMA_CM_EVENT_ROUTE_ERROR:
255 	case RDMA_CM_EVENT_DEVICE_REMOVAL:
256 	case RDMA_CM_EVENT_MULTICAST_JOIN:
257 	case RDMA_CM_EVENT_MULTICAST_ERROR:
258 	case RDMA_CM_EVENT_REJECTED:
259 	case RDMA_CM_EVENT_CONNECT_REQUEST:
260 	case RDMA_CM_EVENT_CONNECT_RESPONSE:
261 	case RDMA_CM_EVENT_CONNECT_ERROR:
262 	case RDMA_CM_EVENT_ADDR_ERROR:
263 	case RDMA_CM_EVENT_UNREACHABLE:
264 		c->status = Disconnected;
265 		rdma_disconnect(rdma->cm_id);
266 		break;
267 	default:
268 		BUG();
269 	}
270 	complete(&rdma->cm_done);
271 	return 0;
272 }
273 
274 static void
275 handle_recv(struct p9_client *client, struct p9_trans_rdma *rdma,
276 	    struct p9_rdma_context *c, enum ib_wc_status status, u32 byte_len)
277 {
278 	struct p9_req_t *req;
279 	int err = 0;
280 	int16_t tag;
281 
282 	req = NULL;
283 	ib_dma_unmap_single(rdma->cm_id->device, c->busa, client->msize,
284 							 DMA_FROM_DEVICE);
285 
286 	if (status != IB_WC_SUCCESS)
287 		goto err_out;
288 
289 	err = p9_parse_header(c->rc, NULL, NULL, &tag, 1);
290 	if (err)
291 		goto err_out;
292 
293 	req = p9_tag_lookup(client, tag);
294 	if (!req)
295 		goto err_out;
296 
297 	req->rc = c->rc;
298 	p9_client_cb(client, req);
299 
300 	return;
301 
302  err_out:
303 	P9_DPRINTK(P9_DEBUG_ERROR, "req %p err %d status %d\n",
304 		   req, err, status);
305 	rdma->state = P9_RDMA_FLUSHING;
306 	client->status = Disconnected;
307 	return;
308 }
309 
310 static void
311 handle_send(struct p9_client *client, struct p9_trans_rdma *rdma,
312 	    struct p9_rdma_context *c, enum ib_wc_status status, u32 byte_len)
313 {
314 	ib_dma_unmap_single(rdma->cm_id->device,
315 			    c->busa, c->req->tc->size,
316 			    DMA_TO_DEVICE);
317 }
318 
319 static void qp_event_handler(struct ib_event *event, void *context)
320 {
321 	P9_DPRINTK(P9_DEBUG_ERROR, "QP event %d context %p\n", event->event,
322 								context);
323 }
324 
325 static void cq_comp_handler(struct ib_cq *cq, void *cq_context)
326 {
327 	struct p9_client *client = cq_context;
328 	struct p9_trans_rdma *rdma = client->trans;
329 	int ret;
330 	struct ib_wc wc;
331 
332 	ib_req_notify_cq(rdma->cq, IB_CQ_NEXT_COMP);
333 	while ((ret = ib_poll_cq(cq, 1, &wc)) > 0) {
334 		struct p9_rdma_context *c = (void *) (unsigned long) wc.wr_id;
335 
336 		switch (c->wc_op) {
337 		case IB_WC_RECV:
338 			atomic_dec(&rdma->rq_count);
339 			handle_recv(client, rdma, c, wc.status, wc.byte_len);
340 			break;
341 
342 		case IB_WC_SEND:
343 			handle_send(client, rdma, c, wc.status, wc.byte_len);
344 			up(&rdma->sq_sem);
345 			break;
346 
347 		default:
348 			printk(KERN_ERR "9prdma: unexpected completion type, "
349 			       "c->wc_op=%d, wc.opcode=%d, status=%d\n",
350 			       c->wc_op, wc.opcode, wc.status);
351 			break;
352 		}
353 		kfree(c);
354 	}
355 }
356 
357 static void cq_event_handler(struct ib_event *e, void *v)
358 {
359 	P9_DPRINTK(P9_DEBUG_ERROR, "CQ event %d context %p\n", e->event, v);
360 }
361 
362 static void rdma_destroy_trans(struct p9_trans_rdma *rdma)
363 {
364 	if (!rdma)
365 		return;
366 
367 	if (rdma->dma_mr && !IS_ERR(rdma->dma_mr))
368 		ib_dereg_mr(rdma->dma_mr);
369 
370 	if (rdma->qp && !IS_ERR(rdma->qp))
371 		ib_destroy_qp(rdma->qp);
372 
373 	if (rdma->pd && !IS_ERR(rdma->pd))
374 		ib_dealloc_pd(rdma->pd);
375 
376 	if (rdma->cq && !IS_ERR(rdma->cq))
377 		ib_destroy_cq(rdma->cq);
378 
379 	if (rdma->cm_id && !IS_ERR(rdma->cm_id))
380 		rdma_destroy_id(rdma->cm_id);
381 
382 	kfree(rdma);
383 }
384 
385 static int
386 post_recv(struct p9_client *client, struct p9_rdma_context *c)
387 {
388 	struct p9_trans_rdma *rdma = client->trans;
389 	struct ib_recv_wr wr, *bad_wr;
390 	struct ib_sge sge;
391 
392 	c->busa = ib_dma_map_single(rdma->cm_id->device,
393 				    c->rc->sdata, client->msize,
394 				    DMA_FROM_DEVICE);
395 	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
396 		goto error;
397 
398 	sge.addr = c->busa;
399 	sge.length = client->msize;
400 	sge.lkey = rdma->lkey;
401 
402 	wr.next = NULL;
403 	c->wc_op = IB_WC_RECV;
404 	wr.wr_id = (unsigned long) c;
405 	wr.sg_list = &sge;
406 	wr.num_sge = 1;
407 	return ib_post_recv(rdma->qp, &wr, &bad_wr);
408 
409  error:
410 	P9_DPRINTK(P9_DEBUG_ERROR, "EIO\n");
411 	return -EIO;
412 }
413 
414 static int rdma_request(struct p9_client *client, struct p9_req_t *req)
415 {
416 	struct p9_trans_rdma *rdma = client->trans;
417 	struct ib_send_wr wr, *bad_wr;
418 	struct ib_sge sge;
419 	int err = 0;
420 	unsigned long flags;
421 	struct p9_rdma_context *c = NULL;
422 	struct p9_rdma_context *rpl_context = NULL;
423 
424 	/* Allocate an fcall for the reply */
425 	rpl_context = kmalloc(sizeof *rpl_context, GFP_KERNEL);
426 	if (!rpl_context)
427 		goto err_close;
428 
429 	/*
430 	 * If the request has a buffer, steal it, otherwise
431 	 * allocate a new one.  Typically, requests should already
432 	 * have receive buffers allocated and just swap them around
433 	 */
434 	if (!req->rc) {
435 		req->rc = kmalloc(sizeof(struct p9_fcall)+client->msize,
436 								GFP_KERNEL);
437 		if (req->rc) {
438 			req->rc->sdata = (char *) req->rc +
439 						sizeof(struct p9_fcall);
440 			req->rc->capacity = client->msize;
441 		}
442 	}
443 	rpl_context->rc = req->rc;
444 	if (!rpl_context->rc) {
445 		kfree(rpl_context);
446 		goto err_close;
447 	}
448 
449 	/*
450 	 * Post a receive buffer for this request. We need to ensure
451 	 * there is a reply buffer available for every outstanding
452 	 * request. A flushed request can result in no reply for an
453 	 * outstanding request, so we must keep a count to avoid
454 	 * overflowing the RQ.
455 	 */
456 	if (atomic_inc_return(&rdma->rq_count) <= rdma->rq_depth) {
457 		err = post_recv(client, rpl_context);
458 		if (err) {
459 			kfree(rpl_context->rc);
460 			kfree(rpl_context);
461 			goto err_close;
462 		}
463 	} else
464 		atomic_dec(&rdma->rq_count);
465 
466 	/* remove posted receive buffer from request structure */
467 	req->rc = NULL;
468 
469 	/* Post the request */
470 	c = kmalloc(sizeof *c, GFP_KERNEL);
471 	if (!c)
472 		goto err_close;
473 	c->req = req;
474 
475 	c->busa = ib_dma_map_single(rdma->cm_id->device,
476 				    c->req->tc->sdata, c->req->tc->size,
477 				    DMA_TO_DEVICE);
478 	if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
479 		goto error;
480 
481 	sge.addr = c->busa;
482 	sge.length = c->req->tc->size;
483 	sge.lkey = rdma->lkey;
484 
485 	wr.next = NULL;
486 	c->wc_op = IB_WC_SEND;
487 	wr.wr_id = (unsigned long) c;
488 	wr.opcode = IB_WR_SEND;
489 	wr.send_flags = IB_SEND_SIGNALED;
490 	wr.sg_list = &sge;
491 	wr.num_sge = 1;
492 
493 	if (down_interruptible(&rdma->sq_sem))
494 		goto error;
495 
496 	return ib_post_send(rdma->qp, &wr, &bad_wr);
497 
498  error:
499 	P9_DPRINTK(P9_DEBUG_ERROR, "EIO\n");
500 	return -EIO;
501 
502  err_close:
503 	spin_lock_irqsave(&rdma->req_lock, flags);
504 	if (rdma->state < P9_RDMA_CLOSING) {
505 		rdma->state = P9_RDMA_CLOSING;
506 		spin_unlock_irqrestore(&rdma->req_lock, flags);
507 		rdma_disconnect(rdma->cm_id);
508 	} else
509 		spin_unlock_irqrestore(&rdma->req_lock, flags);
510 	return err;
511 }
512 
513 static void rdma_close(struct p9_client *client)
514 {
515 	struct p9_trans_rdma *rdma;
516 
517 	if (!client)
518 		return;
519 
520 	rdma = client->trans;
521 	if (!rdma)
522 		return;
523 
524 	client->status = Disconnected;
525 	rdma_disconnect(rdma->cm_id);
526 	rdma_destroy_trans(rdma);
527 }
528 
529 /**
530  * alloc_rdma - Allocate and initialize the rdma transport structure
531  * @opts: Mount options structure
532  */
533 static struct p9_trans_rdma *alloc_rdma(struct p9_rdma_opts *opts)
534 {
535 	struct p9_trans_rdma *rdma;
536 
537 	rdma = kzalloc(sizeof(struct p9_trans_rdma), GFP_KERNEL);
538 	if (!rdma)
539 		return NULL;
540 
541 	rdma->sq_depth = opts->sq_depth;
542 	rdma->rq_depth = opts->rq_depth;
543 	rdma->timeout = opts->timeout;
544 	spin_lock_init(&rdma->req_lock);
545 	init_completion(&rdma->cm_done);
546 	sema_init(&rdma->sq_sem, rdma->sq_depth);
547 	atomic_set(&rdma->rq_count, 0);
548 
549 	return rdma;
550 }
551 
552 /* its not clear to me we can do anything after send has been posted */
553 static int rdma_cancel(struct p9_client *client, struct p9_req_t *req)
554 {
555 	return 1;
556 }
557 
558 /**
559  * trans_create_rdma - Transport method for creating atransport instance
560  * @client: client instance
561  * @addr: IP address string
562  * @args: Mount options string
563  */
564 static int
565 rdma_create_trans(struct p9_client *client, const char *addr, char *args)
566 {
567 	int err;
568 	struct p9_rdma_opts opts;
569 	struct p9_trans_rdma *rdma;
570 	struct rdma_conn_param conn_param;
571 	struct ib_qp_init_attr qp_attr;
572 	struct ib_device_attr devattr;
573 
574 	/* Parse the transport specific mount options */
575 	err = parse_opts(args, &opts);
576 	if (err < 0)
577 		return err;
578 
579 	/* Create and initialize the RDMA transport structure */
580 	rdma = alloc_rdma(&opts);
581 	if (!rdma)
582 		return -ENOMEM;
583 
584 	/* Create the RDMA CM ID */
585 	rdma->cm_id = rdma_create_id(p9_cm_event_handler, client, RDMA_PS_TCP);
586 	if (IS_ERR(rdma->cm_id))
587 		goto error;
588 
589 	/* Associate the client with the transport */
590 	client->trans = rdma;
591 
592 	/* Resolve the server's address */
593 	rdma->addr.sin_family = AF_INET;
594 	rdma->addr.sin_addr.s_addr = in_aton(addr);
595 	rdma->addr.sin_port = htons(opts.port);
596 	err = rdma_resolve_addr(rdma->cm_id, NULL,
597 				(struct sockaddr *)&rdma->addr,
598 				rdma->timeout);
599 	if (err)
600 		goto error;
601 	err = wait_for_completion_interruptible(&rdma->cm_done);
602 	if (err || (rdma->state != P9_RDMA_ADDR_RESOLVED))
603 		goto error;
604 
605 	/* Resolve the route to the server */
606 	err = rdma_resolve_route(rdma->cm_id, rdma->timeout);
607 	if (err)
608 		goto error;
609 	err = wait_for_completion_interruptible(&rdma->cm_done);
610 	if (err || (rdma->state != P9_RDMA_ROUTE_RESOLVED))
611 		goto error;
612 
613 	/* Query the device attributes */
614 	err = ib_query_device(rdma->cm_id->device, &devattr);
615 	if (err)
616 		goto error;
617 
618 	/* Create the Completion Queue */
619 	rdma->cq = ib_create_cq(rdma->cm_id->device, cq_comp_handler,
620 				cq_event_handler, client,
621 				opts.sq_depth + opts.rq_depth + 1, 0);
622 	if (IS_ERR(rdma->cq))
623 		goto error;
624 	ib_req_notify_cq(rdma->cq, IB_CQ_NEXT_COMP);
625 
626 	/* Create the Protection Domain */
627 	rdma->pd = ib_alloc_pd(rdma->cm_id->device);
628 	if (IS_ERR(rdma->pd))
629 		goto error;
630 
631 	/* Cache the DMA lkey in the transport */
632 	rdma->dma_mr = NULL;
633 	if (devattr.device_cap_flags & IB_DEVICE_LOCAL_DMA_LKEY)
634 		rdma->lkey = rdma->cm_id->device->local_dma_lkey;
635 	else {
636 		rdma->dma_mr = ib_get_dma_mr(rdma->pd, IB_ACCESS_LOCAL_WRITE);
637 		if (IS_ERR(rdma->dma_mr))
638 			goto error;
639 		rdma->lkey = rdma->dma_mr->lkey;
640 	}
641 
642 	/* Create the Queue Pair */
643 	memset(&qp_attr, 0, sizeof qp_attr);
644 	qp_attr.event_handler = qp_event_handler;
645 	qp_attr.qp_context = client;
646 	qp_attr.cap.max_send_wr = opts.sq_depth;
647 	qp_attr.cap.max_recv_wr = opts.rq_depth;
648 	qp_attr.cap.max_send_sge = P9_RDMA_SEND_SGE;
649 	qp_attr.cap.max_recv_sge = P9_RDMA_RECV_SGE;
650 	qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
651 	qp_attr.qp_type = IB_QPT_RC;
652 	qp_attr.send_cq = rdma->cq;
653 	qp_attr.recv_cq = rdma->cq;
654 	err = rdma_create_qp(rdma->cm_id, rdma->pd, &qp_attr);
655 	if (err)
656 		goto error;
657 	rdma->qp = rdma->cm_id->qp;
658 
659 	/* Request a connection */
660 	memset(&conn_param, 0, sizeof(conn_param));
661 	conn_param.private_data = NULL;
662 	conn_param.private_data_len = 0;
663 	conn_param.responder_resources = P9_RDMA_IRD;
664 	conn_param.initiator_depth = P9_RDMA_ORD;
665 	err = rdma_connect(rdma->cm_id, &conn_param);
666 	if (err)
667 		goto error;
668 	err = wait_for_completion_interruptible(&rdma->cm_done);
669 	if (err || (rdma->state != P9_RDMA_CONNECTED))
670 		goto error;
671 
672 	client->status = Connected;
673 
674 	return 0;
675 
676 error:
677 	rdma_destroy_trans(rdma);
678 	return -ENOTCONN;
679 }
680 
681 static struct p9_trans_module p9_rdma_trans = {
682 	.name = "rdma",
683 	.maxsize = P9_RDMA_MAXSIZE,
684 	.def = 0,
685 	.owner = THIS_MODULE,
686 	.create = rdma_create_trans,
687 	.close = rdma_close,
688 	.request = rdma_request,
689 	.cancel = rdma_cancel,
690 };
691 
692 /**
693  * p9_trans_rdma_init - Register the 9P RDMA transport driver
694  */
695 static int __init p9_trans_rdma_init(void)
696 {
697 	v9fs_register_trans(&p9_rdma_trans);
698 	return 0;
699 }
700 
701 static void __exit p9_trans_rdma_exit(void)
702 {
703 	v9fs_unregister_trans(&p9_rdma_trans);
704 }
705 
706 module_init(p9_trans_rdma_init);
707 module_exit(p9_trans_rdma_exit);
708 
709 MODULE_AUTHOR("Tom Tucker <tom@opengridcomputing.com>");
710 MODULE_DESCRIPTION("RDMA Transport for 9P");
711 MODULE_LICENSE("Dual BSD/GPL");
712