summaryrefslogtreecommitdiff
path: root/net/smc/smc_llc.c
blob: 5800a6b43d830018ffc91a4272190508e8c9f233 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
// SPDX-License-Identifier: GPL-2.0
/*
 *  Shared Memory Communications over RDMA (SMC-R) and RoCE
 *
 *  Link Layer Control (LLC)
 *
 *  Copyright IBM Corp. 2016
 *
 *  Author(s):  Klaus Wacker <Klaus.Wacker@de.ibm.com>
 *              Ursula Braun <ubraun@linux.vnet.ibm.com>
 */

#include <net/tcp.h>
#include <rdma/ib_verbs.h>

#include "smc.h"
#include "smc_core.h"
#include "smc_clc.h"
#include "smc_llc.h"

#define SMC_LLC_DATA_LEN		40

struct smc_llc_hdr {
	struct smc_wr_rx_hdr common;
	u8 length;	/* 44 */
#if defined(__BIG_ENDIAN_BITFIELD)
	u8 reserved:4,
	   add_link_rej_rsn:4;
#elif defined(__LITTLE_ENDIAN_BITFIELD)
	u8 add_link_rej_rsn:4,
	   reserved:4;
#endif
	u8 flags;
};

#define SMC_LLC_FLAG_NO_RMBE_EYEC	0x03

struct smc_llc_msg_confirm_link {	/* type 0x01 */
	struct smc_llc_hdr hd;
	u8 sender_mac[ETH_ALEN];
	u8 sender_gid[SMC_GID_SIZE];
	u8 sender_qp_num[3];
	u8 link_num;
	u8 link_uid[SMC_LGR_ID_SIZE];
	u8 max_links;
	u8 reserved[9];
};

#define SMC_LLC_FLAG_ADD_LNK_REJ	0x40
#define SMC_LLC_REJ_RSN_NO_ALT_PATH	1

#define SMC_LLC_ADD_LNK_MAX_LINKS	2

struct smc_llc_msg_add_link {		/* type 0x02 */
	struct smc_llc_hdr hd;
	u8 sender_mac[ETH_ALEN];
	u8 reserved2[2];
	u8 sender_gid[SMC_GID_SIZE];
	u8 sender_qp_num[3];
	u8 link_num;
	u8 flags2;	/* QP mtu */
	u8 initial_psn[3];
	u8 reserved[8];
};

#define SMC_LLC_FLAG_DEL_LINK_ALL	0x40
#define SMC_LLC_FLAG_DEL_LINK_ORDERLY	0x20

struct smc_llc_msg_del_link {		/* type 0x04 */
	struct smc_llc_hdr hd;
	u8 link_num;
	__be32 reason;
	u8 reserved[35];
} __packed;			/* format defined in RFC7609 */

struct smc_llc_msg_test_link {		/* type 0x07 */
	struct smc_llc_hdr hd;
	u8 user_data[16];
	u8 reserved[24];
};

struct smc_rmb_rtoken {
	union {
		u8 num_rkeys;	/* first rtoken byte of CONFIRM LINK msg */
				/* is actually the num of rtokens, first */
				/* rtoken is always for the current link */
		u8 link_id;	/* link id of the rtoken */
	};
	__be32 rmb_key;
	__be64 rmb_vaddr;
} __packed;			/* format defined in RFC7609 */

#define SMC_LLC_RKEYS_PER_MSG	3

struct smc_llc_msg_confirm_rkey {	/* type 0x06 */
	struct smc_llc_hdr hd;
	struct smc_rmb_rtoken rtoken[SMC_LLC_RKEYS_PER_MSG];
	u8 reserved;
};

struct smc_llc_msg_confirm_rkey_cont {	/* type 0x08 */
	struct smc_llc_hdr hd;
	u8 num_rkeys;
	struct smc_rmb_rtoken rtoken[SMC_LLC_RKEYS_PER_MSG];
};

#define SMC_LLC_DEL_RKEY_MAX	8
#define SMC_LLC_FLAG_RKEY_NEG	0x20

struct smc_llc_msg_delete_rkey {	/* type 0x09 */
	struct smc_llc_hdr hd;
	u8 num_rkeys;
	u8 err_mask;
	u8 reserved[2];
	__be32 rkey[8];
	u8 reserved2[4];
};

union smc_llc_msg {
	struct smc_llc_msg_confirm_link confirm_link;
	struct smc_llc_msg_add_link add_link;
	struct smc_llc_msg_del_link delete_link;

	struct smc_llc_msg_confirm_rkey confirm_rkey;
	struct smc_llc_msg_confirm_rkey_cont confirm_rkey_cont;
	struct smc_llc_msg_delete_rkey delete_rkey;

	struct smc_llc_msg_test_link test_link;
	struct {
		struct smc_llc_hdr hdr;
		u8 data[SMC_LLC_DATA_LEN];
	} raw;
};

#define SMC_LLC_FLAG_RESP		0x80

/********************************** send *************************************/

struct smc_llc_tx_pend {
};

/* handler for send/transmission completion of an LLC msg */
static void smc_llc_tx_handler(struct smc_wr_tx_pend_priv *pend,
			       struct smc_link *link,
			       enum ib_wc_status wc_status)
{
	/* future work: handle wc_status error for recovery and failover */
}

/**
 * smc_llc_add_pending_send() - add LLC control message to pending WQE transmits
 * @link: Pointer to SMC link used for sending LLC control message.
 * @wr_buf: Out variable returning pointer to work request payload buffer.
 * @pend: Out variable returning pointer to private pending WR tracking.
 *	  It's the context the transmit complete handler will get.
 *
 * Reserves and pre-fills an entry for a pending work request send/tx.
 * Used by mid-level smc_llc_send_msg() to prepare for later actual send/tx.
 * Can sleep due to smc_get_ctrl_buf (if not in softirq context).
 *
 * Return: 0 on success, otherwise an error value.
 */
static int smc_llc_add_pending_send(struct smc_link *link,
				    struct smc_wr_buf **wr_buf,
				    struct smc_wr_tx_pend_priv **pend)
{
	int rc;

	rc = smc_wr_tx_get_free_slot(link, smc_llc_tx_handler, wr_buf, pend);
	if (rc < 0)
		return rc;
	BUILD_BUG_ON_MSG(
		sizeof(union smc_llc_msg) > SMC_WR_BUF_SIZE,
		"must increase SMC_WR_BUF_SIZE to at least sizeof(struct smc_llc_msg)");
	BUILD_BUG_ON_MSG(
		sizeof(union smc_llc_msg) != SMC_WR_TX_SIZE,
		"must adapt SMC_WR_TX_SIZE to sizeof(struct smc_llc_msg); if not all smc_wr upper layer protocols use the same message size any more, must start to set link->wr_tx_sges[i].length on each individual smc_wr_tx_send()");
	BUILD_BUG_ON_MSG(
		sizeof(struct smc_llc_tx_pend) > SMC_WR_TX_PEND_PRIV_SIZE,
		"must increase SMC_WR_TX_PEND_PRIV_SIZE to at least sizeof(struct smc_llc_tx_pend)");
	return 0;
}

/* high-level API to send LLC confirm link */
int smc_llc_send_confirm_link(struct smc_link *link, u8 mac[],
			      union ib_gid *gid,
			      enum smc_llc_reqresp reqresp)
{
	struct smc_link_group *lgr = container_of(link, struct smc_link_group,
						  lnk[SMC_SINGLE_LINK]);
	struct smc_llc_msg_confirm_link *confllc;
	struct smc_wr_tx_pend_priv *pend;
	struct smc_wr_buf *wr_buf;
	int rc;

	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
	if (rc)
		return rc;
	confllc = (struct smc_llc_msg_confirm_link *)wr_buf;
	memset(confllc, 0, sizeof(*confllc));
	confllc->hd.common.type = SMC_LLC_CONFIRM_LINK;
	confllc->hd.length = sizeof(struct smc_llc_msg_confirm_link);
	confllc->hd.flags |= SMC_LLC_FLAG_NO_RMBE_EYEC;
	if (reqresp == SMC_LLC_RESP)
		confllc->hd.flags |= SMC_LLC_FLAG_RESP;
	memcpy(confllc->sender_mac, mac, ETH_ALEN);
	memcpy(confllc->sender_gid, gid, SMC_GID_SIZE);
	hton24(confllc->sender_qp_num, link->roce_qp->qp_num);
	confllc->link_num = link->link_id;
	memcpy(confllc->link_uid, lgr->id, SMC_LGR_ID_SIZE);
	confllc->max_links = SMC_LLC_ADD_LNK_MAX_LINKS; /* enforce peer resp. */
	/* send llc message */
	rc = smc_wr_tx_send(link, pend);
	return rc;
}

/* send LLC confirm rkey request */
static int smc_llc_send_confirm_rkey(struct smc_link *link,
				     struct smc_buf_desc *rmb_desc)
{
	struct smc_llc_msg_confirm_rkey *rkeyllc;
	struct smc_wr_tx_pend_priv *pend;
	struct smc_wr_buf *wr_buf;
	int rc;

	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
	if (rc)
		return rc;
	rkeyllc = (struct smc_llc_msg_confirm_rkey *)wr_buf;
	memset(rkeyllc, 0, sizeof(*rkeyllc));
	rkeyllc->hd.common.type = SMC_LLC_CONFIRM_RKEY;
	rkeyllc->hd.length = sizeof(struct smc_llc_msg_confirm_rkey);
	rkeyllc->rtoken[0].rmb_key =
		htonl(rmb_desc->mr_rx[SMC_SINGLE_LINK]->rkey);
	rkeyllc->rtoken[0].rmb_vaddr = cpu_to_be64(
		(u64)sg_dma_address(rmb_desc->sgt[SMC_SINGLE_LINK].sgl));
	/* send llc message */
	rc = smc_wr_tx_send(link, pend);
	return rc;
}

/* prepare an add link message */
static void smc_llc_prep_add_link(struct smc_llc_msg_add_link *addllc,
				  struct smc_link *link, u8 mac[],
				  union ib_gid *gid,
				  enum smc_llc_reqresp reqresp)
{
	memset(addllc, 0, sizeof(*addllc));
	addllc->hd.common.type = SMC_LLC_ADD_LINK;
	addllc->hd.length = sizeof(struct smc_llc_msg_add_link);
	if (reqresp == SMC_LLC_RESP) {
		addllc->hd.flags |= SMC_LLC_FLAG_RESP;
		/* always reject more links for now */
		addllc->hd.flags |= SMC_LLC_FLAG_ADD_LNK_REJ;
		addllc->hd.add_link_rej_rsn = SMC_LLC_REJ_RSN_NO_ALT_PATH;
	}
	memcpy(addllc->sender_mac, mac, ETH_ALEN);
	memcpy(addllc->sender_gid, gid, SMC_GID_SIZE);
}

/* send ADD LINK request or response */
int smc_llc_send_add_link(struct smc_link *link, u8 mac[],
			  union ib_gid *gid,
			  enum smc_llc_reqresp reqresp)
{
	struct smc_llc_msg_add_link *addllc;
	struct smc_wr_tx_pend_priv *pend;
	struct smc_wr_buf *wr_buf;
	int rc;

	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
	if (rc)
		return rc;
	addllc = (struct smc_llc_msg_add_link *)wr_buf;
	smc_llc_prep_add_link(addllc, link, mac, gid, reqresp);
	/* send llc message */
	rc = smc_wr_tx_send(link, pend);
	return rc;
}

/* prepare a delete link message */
static void smc_llc_prep_delete_link(struct smc_llc_msg_del_link *delllc,
				     struct smc_link *link,
				     enum smc_llc_reqresp reqresp)
{
	memset(delllc, 0, sizeof(*delllc));
	delllc->hd.common.type = SMC_LLC_DELETE_LINK;
	delllc->hd.length = sizeof(struct smc_llc_msg_add_link);
	if (reqresp == SMC_LLC_RESP)
		delllc->hd.flags |= SMC_LLC_FLAG_RESP;
	/* DEL_LINK_ALL because only 1 link supported */
	delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ALL;
	delllc->hd.flags |= SMC_LLC_FLAG_DEL_LINK_ORDERLY;
	delllc->link_num = link->link_id;
}

/* send DELETE LINK request or response */
int smc_llc_send_delete_link(struct smc_link *link,
			     enum smc_llc_reqresp reqresp)
{
	struct smc_llc_msg_del_link *delllc;
	struct smc_wr_tx_pend_priv *pend;
	struct smc_wr_buf *wr_buf;
	int rc;

	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
	if (rc)
		return rc;
	delllc = (struct smc_llc_msg_del_link *)wr_buf;
	smc_llc_prep_delete_link(delllc, link, reqresp);
	/* send llc message */
	rc = smc_wr_tx_send(link, pend);
	return rc;
}

/* send LLC test link request */
static int smc_llc_send_test_link(struct smc_link *link, u8 user_data[16])
{
	struct smc_llc_msg_test_link *testllc;
	struct smc_wr_tx_pend_priv *pend;
	struct smc_wr_buf *wr_buf;
	int rc;

	rc = smc_llc_add_pending_send(link, &wr_buf, &pend);
	if (rc)
		return rc;
	testllc = (struct smc_llc_msg_test_link *)wr_buf;
	memset(testllc, 0, sizeof(*testllc));
	testllc->hd.common.type = SMC_LLC_TEST_LINK;
	testllc->hd.length = sizeof(struct smc_llc_msg_test_link);
	memcpy(testllc->user_data, user_data, sizeof(testllc->user_data));
	/* send llc message */
	rc = smc_wr_tx_send(link, pend);
	return rc;
}

struct smc_llc_send_work {
	struct work_struct work;
	struct smc_link *link;
	int llclen;
	union smc_llc_msg llcbuf;
};

/* worker that sends a prepared message */
static void smc_llc_send_message_work(struct work_struct *work)
{
	struct smc_llc_send_work *llcwrk = container_of(work,
						struct smc_llc_send_work, work);
	struct smc_wr_tx_pend_priv *pend;
	struct smc_wr_buf *wr_buf;
	int rc;

	if (llcwrk->link->state == SMC_LNK_INACTIVE)
		goto out;
	rc = smc_llc_add_pending_send(llcwrk->link, &wr_buf, &pend);
	if (rc)
		goto out;
	memcpy(wr_buf, &llcwrk->llcbuf, llcwrk->llclen);
	smc_wr_tx_send(llcwrk->link, pend);
out:
	kfree(llcwrk);
}

/* copy llcbuf and schedule an llc send on link */
static int smc_llc_send_message(struct smc_link *link, void *llcbuf, int llclen)
{
	struct smc_llc_send_work *wrk = kmalloc(sizeof(*wrk), GFP_ATOMIC);

	if (!wrk)
		return -ENOMEM;
	INIT_WORK(&wrk->work, smc_llc_send_message_work);
	wrk->link = link;
	wrk->llclen = llclen;
	memcpy(&wrk->llcbuf, llcbuf, llclen);
	queue_work(link->llc_wq, &wrk->work);
	return 0;
}

/********************************* receive ***********************************/

static void smc_llc_rx_confirm_link(struct smc_link *link,
				    struct smc_llc_msg_confirm_link *llc)
{
	struct smc_link_group *lgr;
	int conf_rc;

	lgr = container_of(link, struct smc_link_group, lnk[SMC_SINGLE_LINK]);

	/* RMBE eyecatchers are not supported */
	if (llc->hd.flags & SMC_LLC_FLAG_NO_RMBE_EYEC)
		conf_rc = 0;
	else
		conf_rc = ENOTSUPP;

	if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
		if (lgr->role == SMC_SERV &&
		    link->state == SMC_LNK_ACTIVATING) {
			link->llc_confirm_resp_rc = conf_rc;
			complete(&link->llc_confirm_resp);
		}
	} else {
		if (lgr->role == SMC_CLNT &&
		    link->state == SMC_LNK_ACTIVATING) {
			link->llc_confirm_rc = conf_rc;
			link->link_id = llc->link_num;
			complete(&link->llc_confirm);
		}
	}
}

static void smc_llc_rx_add_link(struct smc_link *link,
				struct smc_llc_msg_add_link *llc)
{
	struct smc_link_group *lgr = container_of(link, struct smc_link_group,
						  lnk[SMC_SINGLE_LINK]);

	if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
		if (link->state == SMC_LNK_ACTIVATING)
			complete(&link->llc_add_resp);
	} else {
		if (link->state == SMC_LNK_ACTIVATING) {
			complete(&link->llc_add);
			return;
		}

		if (lgr->role == SMC_SERV) {
			smc_llc_prep_add_link(llc, link,
					link->smcibdev->mac[link->ibport - 1],
					&link->smcibdev->gid[link->ibport - 1],
					SMC_LLC_REQ);

		} else {
			smc_llc_prep_add_link(llc, link,
					link->smcibdev->mac[link->ibport - 1],
					&link->smcibdev->gid[link->ibport - 1],
					SMC_LLC_RESP);
		}
		smc_llc_send_message(link, llc, sizeof(*llc));
	}
}

static void smc_llc_rx_delete_link(struct smc_link *link,
				   struct smc_llc_msg_del_link *llc)
{
	struct smc_link_group *lgr = container_of(link, struct smc_link_group,
						  lnk[SMC_SINGLE_LINK]);

	if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
		if (lgr->role == SMC_SERV)
			smc_lgr_terminate(lgr);
	} else {
		if (lgr->role == SMC_SERV) {
			smc_lgr_forget(lgr);
			smc_llc_prep_delete_link(llc, link, SMC_LLC_REQ);
			smc_llc_send_message(link, llc, sizeof(*llc));
		} else {
			smc_llc_prep_delete_link(llc, link, SMC_LLC_RESP);
			smc_llc_send_message(link, llc, sizeof(*llc));
			smc_lgr_terminate(lgr);
		}
	}
}

static void smc_llc_rx_test_link(struct smc_link *link,
				 struct smc_llc_msg_test_link *llc)
{
	if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
		if (link->state == SMC_LNK_ACTIVE)
			complete(&link->llc_testlink_resp);
	} else {
		llc->hd.flags |= SMC_LLC_FLAG_RESP;
		smc_llc_send_message(link, llc, sizeof(*llc));
	}
}

static void smc_llc_rx_confirm_rkey(struct smc_link *link,
				    struct smc_llc_msg_confirm_rkey *llc)
{
	struct smc_link_group *lgr;
	int rc;

	lgr = container_of(link, struct smc_link_group, lnk[SMC_SINGLE_LINK]);

	if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
		link->llc_confirm_rkey_rc = llc->hd.flags &
					    SMC_LLC_FLAG_RKEY_NEG;
		complete(&link->llc_confirm_rkey);
	} else {
		rc = smc_rtoken_add(lgr,
				    llc->rtoken[0].rmb_vaddr,
				    llc->rtoken[0].rmb_key);

		/* ignore rtokens for other links, we have only one link */

		llc->hd.flags |= SMC_LLC_FLAG_RESP;
		if (rc < 0)
			llc->hd.flags |= SMC_LLC_FLAG_RKEY_NEG;
		smc_llc_send_message(link, llc, sizeof(*llc));
	}
}

static void smc_llc_rx_confirm_rkey_cont(struct smc_link *link,
				      struct smc_llc_msg_confirm_rkey_cont *llc)
{
	if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
		/* unused as long as we don't send this type of msg */
	} else {
		/* ignore rtokens for other links, we have only one link */
		llc->hd.flags |= SMC_LLC_FLAG_RESP;
		smc_llc_send_message(link, llc, sizeof(*llc));
	}
}

static void smc_llc_rx_delete_rkey(struct smc_link *link,
				   struct smc_llc_msg_delete_rkey *llc)
{
	struct smc_link_group *lgr;
	u8 err_mask = 0;
	int i, max;

	lgr = container_of(link, struct smc_link_group, lnk[SMC_SINGLE_LINK]);

	if (llc->hd.flags & SMC_LLC_FLAG_RESP) {
		/* unused as long as we don't send this type of msg */
	} else {
		max = min_t(u8, llc->num_rkeys, SMC_LLC_DEL_RKEY_MAX);
		for (i = 0; i < max; i++) {
			if (smc_rtoken_delete(lgr, llc->rkey[i]))
				err_mask |= 1 << (SMC_LLC_DEL_RKEY_MAX - 1 - i);
		}

		if (err_mask) {
			llc->hd.flags |= SMC_LLC_FLAG_RKEY_NEG;
			llc->err_mask = err_mask;
		}

		llc->hd.flags |= SMC_LLC_FLAG_RESP;
		smc_llc_send_message(link, llc, sizeof(*llc));
	}
}

static void smc_llc_rx_handler(struct ib_wc *wc, void *buf)
{
	struct smc_link *link = (struct smc_link *)wc->qp->qp_context;
	union smc_llc_msg *llc = buf;

	if (wc->byte_len < sizeof(*llc))
		return; /* short message */
	if (llc->raw.hdr.length != sizeof(*llc))
		return; /* invalid message */
	if (link->state == SMC_LNK_INACTIVE)
		return; /* link not active, drop msg */

	switch (llc->raw.hdr.common.type) {
	case SMC_LLC_TEST_LINK:
		smc_llc_rx_test_link(link, &llc->test_link);
		break;
	case SMC_LLC_CONFIRM_LINK:
		smc_llc_rx_confirm_link(link, &llc->confirm_link);
		break;
	case SMC_LLC_ADD_LINK:
		smc_llc_rx_add_link(link, &llc->add_link);
		break;
	case SMC_LLC_DELETE_LINK:
		smc_llc_rx_delete_link(link, &llc->delete_link);
		break;
	case SMC_LLC_CONFIRM_RKEY:
		smc_llc_rx_confirm_rkey(link, &llc->confirm_rkey);
		break;
	case SMC_LLC_CONFIRM_RKEY_CONT:
		smc_llc_rx_confirm_rkey_cont(link, &llc->confirm_rkey_cont);
		break;
	case SMC_LLC_DELETE_RKEY:
		smc_llc_rx_delete_rkey(link, &llc->delete_rkey);
		break;
	}
}

/***************************** worker, utils *********************************/

static void smc_llc_testlink_work(struct work_struct *work)
{
	struct smc_link *link = container_of(to_delayed_work(work),
					     struct smc_link, llc_testlink_wrk);
	unsigned long next_interval;
	struct smc_link_group *lgr;
	unsigned long expire_time;
	u8 user_data[16] = { 0 };
	int rc;

	lgr = container_of(link, struct smc_link_group, lnk[SMC_SINGLE_LINK]);
	if (link->state != SMC_LNK_ACTIVE)
		return;		/* don't reschedule worker */
	expire_time = link->wr_rx_tstamp + link->llc_testlink_time;
	if (time_is_after_jiffies(expire_time)) {
		next_interval = expire_time - jiffies;
		goto out;
	}
	reinit_completion(&link->llc_testlink_resp);
	smc_llc_send_test_link(link, user_data);
	/* receive TEST LINK response over RoCE fabric */
	rc = wait_for_completion_interruptible_timeout(&link->llc_testlink_resp,
						       SMC_LLC_WAIT_TIME);
	if (rc <= 0) {
		smc_lgr_terminate(lgr);
		return;
	}
	next_interval = link->llc_testlink_time;
out:
	queue_delayed_work(link->llc_wq, &link->llc_testlink_wrk,
			   next_interval);
}

int smc_llc_link_init(struct smc_link *link)
{
	struct smc_link_group *lgr = container_of(link, struct smc_link_group,
						  lnk[SMC_SINGLE_LINK]);
	link->llc_wq = alloc_ordered_workqueue("llc_wq-%x:%x)", WQ_MEM_RECLAIM,
					       *((u32 *)lgr->id),
					       link->link_id);
	if (!link->llc_wq)
		return -ENOMEM;
	init_completion(&link->llc_confirm);
	init_completion(&link->llc_confirm_resp);
	init_completion(&link->llc_add);
	init_completion(&link->llc_add_resp);
	init_completion(&link->llc_confirm_rkey);
	init_completion(&link->llc_testlink_resp);
	INIT_DELAYED_WORK(&link->llc_testlink_wrk, smc_llc_testlink_work);
	return 0;
}

void smc_llc_link_active(struct smc_link *link, int testlink_time)
{
	link->state = SMC_LNK_ACTIVE;
	if (testlink_time) {
		link->llc_testlink_time = testlink_time * HZ;
		queue_delayed_work(link->llc_wq, &link->llc_testlink_wrk,
				   link->llc_testlink_time);
	}
}

/* called in tasklet context */
void smc_llc_link_inactive(struct smc_link *link)
{
	link->state = SMC_LNK_INACTIVE;
	cancel_delayed_work(&link->llc_testlink_wrk);
}

/* called in worker context */
void smc_llc_link_clear(struct smc_link *link)
{
	flush_workqueue(link->llc_wq);
	destroy_workqueue(link->llc_wq);
}

/* register a new rtoken at the remote peer */
int smc_llc_do_confirm_rkey(struct smc_link *link,
			    struct smc_buf_desc *rmb_desc)
{
	int rc;

	reinit_completion(&link->llc_confirm_rkey);
	smc_llc_send_confirm_rkey(link, rmb_desc);
	/* receive CONFIRM RKEY response from server over RoCE fabric */
	rc = wait_for_completion_interruptible_timeout(&link->llc_confirm_rkey,
						       SMC_LLC_WAIT_TIME);
	if (rc <= 0 || link->llc_confirm_rkey_rc)
		return -EFAULT;
	return 0;
}

/***************************** init, exit, misc ******************************/

static struct smc_wr_rx_handler smc_llc_rx_handlers[] = {
	{
		.handler	= smc_llc_rx_handler,
		.type		= SMC_LLC_CONFIRM_LINK
	},
	{
		.handler	= smc_llc_rx_handler,
		.type		= SMC_LLC_TEST_LINK
	},
	{
		.handler	= smc_llc_rx_handler,
		.type		= SMC_LLC_ADD_LINK
	},
	{
		.handler	= smc_llc_rx_handler,
		.type		= SMC_LLC_DELETE_LINK
	},
	{
		.handler	= smc_llc_rx_handler,
		.type		= SMC_LLC_CONFIRM_RKEY
	},
	{
		.handler	= smc_llc_rx_handler,
		.type		= SMC_LLC_CONFIRM_RKEY_CONT
	},
	{
		.handler	= smc_llc_rx_handler,
		.type		= SMC_LLC_DELETE_RKEY
	},
	{
		.handler	= NULL,
	}
};

int __init smc_llc_init(void)
{
	struct smc_wr_rx_handler *handler;
	int rc = 0;

	for (handler = smc_llc_rx_handlers; handler->handler; handler++) {
		INIT_HLIST_NODE(&handler->list);
		rc = smc_wr_rx_register_handler(handler);
		if (rc)
			break;
	}
	return rc;
}