xref: /openbmc/linux/drivers/infiniband/hw/qib/qib_qp.c (revision baa7eb025ab14f3cba2e35c0a8648f9c9f01d24f)
1 /*
2  * Copyright (c) 2006, 2007, 2008, 2009, 2010 QLogic Corporation.
3  * All rights reserved.
4  * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
5  *
6  * This software is available to you under a choice of one of two
7  * licenses.  You may choose to be licensed under the terms of the GNU
8  * General Public License (GPL) Version 2, available from the file
9  * COPYING in the main directory of this source tree, or the
10  * OpenIB.org BSD license below:
11  *
12  *     Redistribution and use in source and binary forms, with or
13  *     without modification, are permitted provided that the following
14  *     conditions are met:
15  *
16  *      - Redistributions of source code must retain the above
17  *        copyright notice, this list of conditions and the following
18  *        disclaimer.
19  *
20  *      - Redistributions in binary form must reproduce the above
21  *        copyright notice, this list of conditions and the following
22  *        disclaimer in the documentation and/or other materials
23  *        provided with the distribution.
24  *
25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
26  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
27  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
28  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
29  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
30  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
31  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
32  * SOFTWARE.
33  */
34 
35 #include <linux/err.h>
36 #include <linux/vmalloc.h>
37 
38 #include "qib.h"
39 
40 #define BITS_PER_PAGE           (PAGE_SIZE*BITS_PER_BYTE)
41 #define BITS_PER_PAGE_MASK      (BITS_PER_PAGE-1)
42 
43 static inline unsigned mk_qpn(struct qib_qpn_table *qpt,
44 			      struct qpn_map *map, unsigned off)
45 {
46 	return (map - qpt->map) * BITS_PER_PAGE + off;
47 }
48 
49 static inline unsigned find_next_offset(struct qib_qpn_table *qpt,
50 					struct qpn_map *map, unsigned off,
51 					unsigned r)
52 {
53 	if (qpt->mask) {
54 		off++;
55 		if ((off & qpt->mask) >> 1 != r)
56 			off = ((off & qpt->mask) ?
57 				(off | qpt->mask) + 1 : off) | (r << 1);
58 	} else
59 		off = find_next_zero_bit(map->page, BITS_PER_PAGE, off);
60 	return off;
61 }
62 
63 /*
64  * Convert the AETH credit code into the number of credits.
65  */
66 static u32 credit_table[31] = {
67 	0,                      /* 0 */
68 	1,                      /* 1 */
69 	2,                      /* 2 */
70 	3,                      /* 3 */
71 	4,                      /* 4 */
72 	6,                      /* 5 */
73 	8,                      /* 6 */
74 	12,                     /* 7 */
75 	16,                     /* 8 */
76 	24,                     /* 9 */
77 	32,                     /* A */
78 	48,                     /* B */
79 	64,                     /* C */
80 	96,                     /* D */
81 	128,                    /* E */
82 	192,                    /* F */
83 	256,                    /* 10 */
84 	384,                    /* 11 */
85 	512,                    /* 12 */
86 	768,                    /* 13 */
87 	1024,                   /* 14 */
88 	1536,                   /* 15 */
89 	2048,                   /* 16 */
90 	3072,                   /* 17 */
91 	4096,                   /* 18 */
92 	6144,                   /* 19 */
93 	8192,                   /* 1A */
94 	12288,                  /* 1B */
95 	16384,                  /* 1C */
96 	24576,                  /* 1D */
97 	32768                   /* 1E */
98 };
99 
100 static void get_map_page(struct qib_qpn_table *qpt, struct qpn_map *map)
101 {
102 	unsigned long page = get_zeroed_page(GFP_KERNEL);
103 
104 	/*
105 	 * Free the page if someone raced with us installing it.
106 	 */
107 
108 	spin_lock(&qpt->lock);
109 	if (map->page)
110 		free_page(page);
111 	else
112 		map->page = (void *)page;
113 	spin_unlock(&qpt->lock);
114 }
115 
116 /*
117  * Allocate the next available QPN or
118  * zero/one for QP type IB_QPT_SMI/IB_QPT_GSI.
119  */
120 static int alloc_qpn(struct qib_devdata *dd, struct qib_qpn_table *qpt,
121 		     enum ib_qp_type type, u8 port)
122 {
123 	u32 i, offset, max_scan, qpn;
124 	struct qpn_map *map;
125 	u32 ret;
126 	int r;
127 
128 	if (type == IB_QPT_SMI || type == IB_QPT_GSI) {
129 		unsigned n;
130 
131 		ret = type == IB_QPT_GSI;
132 		n = 1 << (ret + 2 * (port - 1));
133 		spin_lock(&qpt->lock);
134 		if (qpt->flags & n)
135 			ret = -EINVAL;
136 		else
137 			qpt->flags |= n;
138 		spin_unlock(&qpt->lock);
139 		goto bail;
140 	}
141 
142 	r = smp_processor_id();
143 	if (r >= dd->n_krcv_queues)
144 		r %= dd->n_krcv_queues;
145 	qpn = qpt->last + 1;
146 	if (qpn >= QPN_MAX)
147 		qpn = 2;
148 	if (qpt->mask && ((qpn & qpt->mask) >> 1) != r)
149 		qpn = ((qpn & qpt->mask) ? (qpn | qpt->mask) + 1 : qpn) |
150 			(r << 1);
151 	offset = qpn & BITS_PER_PAGE_MASK;
152 	map = &qpt->map[qpn / BITS_PER_PAGE];
153 	max_scan = qpt->nmaps - !offset;
154 	for (i = 0;;) {
155 		if (unlikely(!map->page)) {
156 			get_map_page(qpt, map);
157 			if (unlikely(!map->page))
158 				break;
159 		}
160 		do {
161 			if (!test_and_set_bit(offset, map->page)) {
162 				qpt->last = qpn;
163 				ret = qpn;
164 				goto bail;
165 			}
166 			offset = find_next_offset(qpt, map, offset, r);
167 			qpn = mk_qpn(qpt, map, offset);
168 			/*
169 			 * This test differs from alloc_pidmap().
170 			 * If find_next_offset() does find a zero
171 			 * bit, we don't need to check for QPN
172 			 * wrapping around past our starting QPN.
173 			 * We just need to be sure we don't loop
174 			 * forever.
175 			 */
176 		} while (offset < BITS_PER_PAGE && qpn < QPN_MAX);
177 		/*
178 		 * In order to keep the number of pages allocated to a
179 		 * minimum, we scan the all existing pages before increasing
180 		 * the size of the bitmap table.
181 		 */
182 		if (++i > max_scan) {
183 			if (qpt->nmaps == QPNMAP_ENTRIES)
184 				break;
185 			map = &qpt->map[qpt->nmaps++];
186 			offset = qpt->mask ? (r << 1) : 0;
187 		} else if (map < &qpt->map[qpt->nmaps]) {
188 			++map;
189 			offset = qpt->mask ? (r << 1) : 0;
190 		} else {
191 			map = &qpt->map[0];
192 			offset = qpt->mask ? (r << 1) : 2;
193 		}
194 		qpn = mk_qpn(qpt, map, offset);
195 	}
196 
197 	ret = -ENOMEM;
198 
199 bail:
200 	return ret;
201 }
202 
203 static void free_qpn(struct qib_qpn_table *qpt, u32 qpn)
204 {
205 	struct qpn_map *map;
206 
207 	map = qpt->map + qpn / BITS_PER_PAGE;
208 	if (map->page)
209 		clear_bit(qpn & BITS_PER_PAGE_MASK, map->page);
210 }
211 
212 /*
213  * Put the QP into the hash table.
214  * The hash table holds a reference to the QP.
215  */
216 static void insert_qp(struct qib_ibdev *dev, struct qib_qp *qp)
217 {
218 	struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
219 	unsigned n = qp->ibqp.qp_num % dev->qp_table_size;
220 	unsigned long flags;
221 
222 	spin_lock_irqsave(&dev->qpt_lock, flags);
223 
224 	if (qp->ibqp.qp_num == 0)
225 		ibp->qp0 = qp;
226 	else if (qp->ibqp.qp_num == 1)
227 		ibp->qp1 = qp;
228 	else {
229 		qp->next = dev->qp_table[n];
230 		dev->qp_table[n] = qp;
231 	}
232 	atomic_inc(&qp->refcount);
233 
234 	spin_unlock_irqrestore(&dev->qpt_lock, flags);
235 }
236 
237 /*
238  * Remove the QP from the table so it can't be found asynchronously by
239  * the receive interrupt routine.
240  */
241 static void remove_qp(struct qib_ibdev *dev, struct qib_qp *qp)
242 {
243 	struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
244 	struct qib_qp *q, **qpp;
245 	unsigned long flags;
246 
247 	qpp = &dev->qp_table[qp->ibqp.qp_num % dev->qp_table_size];
248 
249 	spin_lock_irqsave(&dev->qpt_lock, flags);
250 
251 	if (ibp->qp0 == qp) {
252 		ibp->qp0 = NULL;
253 		atomic_dec(&qp->refcount);
254 	} else if (ibp->qp1 == qp) {
255 		ibp->qp1 = NULL;
256 		atomic_dec(&qp->refcount);
257 	} else
258 		for (; (q = *qpp) != NULL; qpp = &q->next)
259 			if (q == qp) {
260 				*qpp = qp->next;
261 				qp->next = NULL;
262 				atomic_dec(&qp->refcount);
263 				break;
264 			}
265 
266 	spin_unlock_irqrestore(&dev->qpt_lock, flags);
267 }
268 
269 /**
270  * qib_free_all_qps - check for QPs still in use
271  * @qpt: the QP table to empty
272  *
273  * There should not be any QPs still in use.
274  * Free memory for table.
275  */
276 unsigned qib_free_all_qps(struct qib_devdata *dd)
277 {
278 	struct qib_ibdev *dev = &dd->verbs_dev;
279 	unsigned long flags;
280 	struct qib_qp *qp;
281 	unsigned n, qp_inuse = 0;
282 
283 	for (n = 0; n < dd->num_pports; n++) {
284 		struct qib_ibport *ibp = &dd->pport[n].ibport_data;
285 
286 		if (!qib_mcast_tree_empty(ibp))
287 			qp_inuse++;
288 		if (ibp->qp0)
289 			qp_inuse++;
290 		if (ibp->qp1)
291 			qp_inuse++;
292 	}
293 
294 	spin_lock_irqsave(&dev->qpt_lock, flags);
295 	for (n = 0; n < dev->qp_table_size; n++) {
296 		qp = dev->qp_table[n];
297 		dev->qp_table[n] = NULL;
298 
299 		for (; qp; qp = qp->next)
300 			qp_inuse++;
301 	}
302 	spin_unlock_irqrestore(&dev->qpt_lock, flags);
303 
304 	return qp_inuse;
305 }
306 
307 /**
308  * qib_lookup_qpn - return the QP with the given QPN
309  * @qpt: the QP table
310  * @qpn: the QP number to look up
311  *
312  * The caller is responsible for decrementing the QP reference count
313  * when done.
314  */
315 struct qib_qp *qib_lookup_qpn(struct qib_ibport *ibp, u32 qpn)
316 {
317 	struct qib_ibdev *dev = &ppd_from_ibp(ibp)->dd->verbs_dev;
318 	unsigned long flags;
319 	struct qib_qp *qp;
320 
321 	spin_lock_irqsave(&dev->qpt_lock, flags);
322 
323 	if (qpn == 0)
324 		qp = ibp->qp0;
325 	else if (qpn == 1)
326 		qp = ibp->qp1;
327 	else
328 		for (qp = dev->qp_table[qpn % dev->qp_table_size]; qp;
329 		     qp = qp->next)
330 			if (qp->ibqp.qp_num == qpn)
331 				break;
332 	if (qp)
333 		atomic_inc(&qp->refcount);
334 
335 	spin_unlock_irqrestore(&dev->qpt_lock, flags);
336 	return qp;
337 }
338 
339 /**
340  * qib_reset_qp - initialize the QP state to the reset state
341  * @qp: the QP to reset
342  * @type: the QP type
343  */
344 static void qib_reset_qp(struct qib_qp *qp, enum ib_qp_type type)
345 {
346 	qp->remote_qpn = 0;
347 	qp->qkey = 0;
348 	qp->qp_access_flags = 0;
349 	atomic_set(&qp->s_dma_busy, 0);
350 	qp->s_flags &= QIB_S_SIGNAL_REQ_WR;
351 	qp->s_hdrwords = 0;
352 	qp->s_wqe = NULL;
353 	qp->s_draining = 0;
354 	qp->s_next_psn = 0;
355 	qp->s_last_psn = 0;
356 	qp->s_sending_psn = 0;
357 	qp->s_sending_hpsn = 0;
358 	qp->s_psn = 0;
359 	qp->r_psn = 0;
360 	qp->r_msn = 0;
361 	if (type == IB_QPT_RC) {
362 		qp->s_state = IB_OPCODE_RC_SEND_LAST;
363 		qp->r_state = IB_OPCODE_RC_SEND_LAST;
364 	} else {
365 		qp->s_state = IB_OPCODE_UC_SEND_LAST;
366 		qp->r_state = IB_OPCODE_UC_SEND_LAST;
367 	}
368 	qp->s_ack_state = IB_OPCODE_RC_ACKNOWLEDGE;
369 	qp->r_nak_state = 0;
370 	qp->r_aflags = 0;
371 	qp->r_flags = 0;
372 	qp->s_head = 0;
373 	qp->s_tail = 0;
374 	qp->s_cur = 0;
375 	qp->s_acked = 0;
376 	qp->s_last = 0;
377 	qp->s_ssn = 1;
378 	qp->s_lsn = 0;
379 	qp->s_mig_state = IB_MIG_MIGRATED;
380 	memset(qp->s_ack_queue, 0, sizeof(qp->s_ack_queue));
381 	qp->r_head_ack_queue = 0;
382 	qp->s_tail_ack_queue = 0;
383 	qp->s_num_rd_atomic = 0;
384 	if (qp->r_rq.wq) {
385 		qp->r_rq.wq->head = 0;
386 		qp->r_rq.wq->tail = 0;
387 	}
388 	qp->r_sge.num_sge = 0;
389 }
390 
391 static void clear_mr_refs(struct qib_qp *qp, int clr_sends)
392 {
393 	unsigned n;
394 
395 	if (test_and_clear_bit(QIB_R_REWIND_SGE, &qp->r_aflags))
396 		while (qp->s_rdma_read_sge.num_sge) {
397 			atomic_dec(&qp->s_rdma_read_sge.sge.mr->refcount);
398 			if (--qp->s_rdma_read_sge.num_sge)
399 				qp->s_rdma_read_sge.sge =
400 					*qp->s_rdma_read_sge.sg_list++;
401 		}
402 
403 	while (qp->r_sge.num_sge) {
404 		atomic_dec(&qp->r_sge.sge.mr->refcount);
405 		if (--qp->r_sge.num_sge)
406 			qp->r_sge.sge = *qp->r_sge.sg_list++;
407 	}
408 
409 	if (clr_sends) {
410 		while (qp->s_last != qp->s_head) {
411 			struct qib_swqe *wqe = get_swqe_ptr(qp, qp->s_last);
412 			unsigned i;
413 
414 			for (i = 0; i < wqe->wr.num_sge; i++) {
415 				struct qib_sge *sge = &wqe->sg_list[i];
416 
417 				atomic_dec(&sge->mr->refcount);
418 			}
419 			if (qp->ibqp.qp_type == IB_QPT_UD ||
420 			    qp->ibqp.qp_type == IB_QPT_SMI ||
421 			    qp->ibqp.qp_type == IB_QPT_GSI)
422 				atomic_dec(&to_iah(wqe->wr.wr.ud.ah)->refcount);
423 			if (++qp->s_last >= qp->s_size)
424 				qp->s_last = 0;
425 		}
426 		if (qp->s_rdma_mr) {
427 			atomic_dec(&qp->s_rdma_mr->refcount);
428 			qp->s_rdma_mr = NULL;
429 		}
430 	}
431 
432 	if (qp->ibqp.qp_type != IB_QPT_RC)
433 		return;
434 
435 	for (n = 0; n < ARRAY_SIZE(qp->s_ack_queue); n++) {
436 		struct qib_ack_entry *e = &qp->s_ack_queue[n];
437 
438 		if (e->opcode == IB_OPCODE_RC_RDMA_READ_REQUEST &&
439 		    e->rdma_sge.mr) {
440 			atomic_dec(&e->rdma_sge.mr->refcount);
441 			e->rdma_sge.mr = NULL;
442 		}
443 	}
444 }
445 
446 /**
447  * qib_error_qp - put a QP into the error state
448  * @qp: the QP to put into the error state
449  * @err: the receive completion error to signal if a RWQE is active
450  *
451  * Flushes both send and receive work queues.
452  * Returns true if last WQE event should be generated.
453  * The QP r_lock and s_lock should be held and interrupts disabled.
454  * If we are already in error state, just return.
455  */
456 int qib_error_qp(struct qib_qp *qp, enum ib_wc_status err)
457 {
458 	struct qib_ibdev *dev = to_idev(qp->ibqp.device);
459 	struct ib_wc wc;
460 	int ret = 0;
461 
462 	if (qp->state == IB_QPS_ERR || qp->state == IB_QPS_RESET)
463 		goto bail;
464 
465 	qp->state = IB_QPS_ERR;
466 
467 	if (qp->s_flags & (QIB_S_TIMER | QIB_S_WAIT_RNR)) {
468 		qp->s_flags &= ~(QIB_S_TIMER | QIB_S_WAIT_RNR);
469 		del_timer(&qp->s_timer);
470 	}
471 	spin_lock(&dev->pending_lock);
472 	if (!list_empty(&qp->iowait) && !(qp->s_flags & QIB_S_BUSY)) {
473 		qp->s_flags &= ~QIB_S_ANY_WAIT_IO;
474 		list_del_init(&qp->iowait);
475 	}
476 	spin_unlock(&dev->pending_lock);
477 
478 	if (!(qp->s_flags & QIB_S_BUSY)) {
479 		qp->s_hdrwords = 0;
480 		if (qp->s_rdma_mr) {
481 			atomic_dec(&qp->s_rdma_mr->refcount);
482 			qp->s_rdma_mr = NULL;
483 		}
484 		if (qp->s_tx) {
485 			qib_put_txreq(qp->s_tx);
486 			qp->s_tx = NULL;
487 		}
488 	}
489 
490 	/* Schedule the sending tasklet to drain the send work queue. */
491 	if (qp->s_last != qp->s_head)
492 		qib_schedule_send(qp);
493 
494 	clear_mr_refs(qp, 0);
495 
496 	memset(&wc, 0, sizeof(wc));
497 	wc.qp = &qp->ibqp;
498 	wc.opcode = IB_WC_RECV;
499 
500 	if (test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags)) {
501 		wc.wr_id = qp->r_wr_id;
502 		wc.status = err;
503 		qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc, 1);
504 	}
505 	wc.status = IB_WC_WR_FLUSH_ERR;
506 
507 	if (qp->r_rq.wq) {
508 		struct qib_rwq *wq;
509 		u32 head;
510 		u32 tail;
511 
512 		spin_lock(&qp->r_rq.lock);
513 
514 		/* sanity check pointers before trusting them */
515 		wq = qp->r_rq.wq;
516 		head = wq->head;
517 		if (head >= qp->r_rq.size)
518 			head = 0;
519 		tail = wq->tail;
520 		if (tail >= qp->r_rq.size)
521 			tail = 0;
522 		while (tail != head) {
523 			wc.wr_id = get_rwqe_ptr(&qp->r_rq, tail)->wr_id;
524 			if (++tail >= qp->r_rq.size)
525 				tail = 0;
526 			qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc, 1);
527 		}
528 		wq->tail = tail;
529 
530 		spin_unlock(&qp->r_rq.lock);
531 	} else if (qp->ibqp.event_handler)
532 		ret = 1;
533 
534 bail:
535 	return ret;
536 }
537 
538 /**
539  * qib_modify_qp - modify the attributes of a queue pair
540  * @ibqp: the queue pair who's attributes we're modifying
541  * @attr: the new attributes
542  * @attr_mask: the mask of attributes to modify
543  * @udata: user data for libibverbs.so
544  *
545  * Returns 0 on success, otherwise returns an errno.
546  */
547 int qib_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
548 		  int attr_mask, struct ib_udata *udata)
549 {
550 	struct qib_ibdev *dev = to_idev(ibqp->device);
551 	struct qib_qp *qp = to_iqp(ibqp);
552 	enum ib_qp_state cur_state, new_state;
553 	struct ib_event ev;
554 	int lastwqe = 0;
555 	int mig = 0;
556 	int ret;
557 	u32 pmtu = 0; /* for gcc warning only */
558 
559 	spin_lock_irq(&qp->r_lock);
560 	spin_lock(&qp->s_lock);
561 
562 	cur_state = attr_mask & IB_QP_CUR_STATE ?
563 		attr->cur_qp_state : qp->state;
564 	new_state = attr_mask & IB_QP_STATE ? attr->qp_state : cur_state;
565 
566 	if (!ib_modify_qp_is_ok(cur_state, new_state, ibqp->qp_type,
567 				attr_mask))
568 		goto inval;
569 
570 	if (attr_mask & IB_QP_AV) {
571 		if (attr->ah_attr.dlid >= QIB_MULTICAST_LID_BASE)
572 			goto inval;
573 		if (qib_check_ah(qp->ibqp.device, &attr->ah_attr))
574 			goto inval;
575 	}
576 
577 	if (attr_mask & IB_QP_ALT_PATH) {
578 		if (attr->alt_ah_attr.dlid >= QIB_MULTICAST_LID_BASE)
579 			goto inval;
580 		if (qib_check_ah(qp->ibqp.device, &attr->alt_ah_attr))
581 			goto inval;
582 		if (attr->alt_pkey_index >= qib_get_npkeys(dd_from_dev(dev)))
583 			goto inval;
584 	}
585 
586 	if (attr_mask & IB_QP_PKEY_INDEX)
587 		if (attr->pkey_index >= qib_get_npkeys(dd_from_dev(dev)))
588 			goto inval;
589 
590 	if (attr_mask & IB_QP_MIN_RNR_TIMER)
591 		if (attr->min_rnr_timer > 31)
592 			goto inval;
593 
594 	if (attr_mask & IB_QP_PORT)
595 		if (qp->ibqp.qp_type == IB_QPT_SMI ||
596 		    qp->ibqp.qp_type == IB_QPT_GSI ||
597 		    attr->port_num == 0 ||
598 		    attr->port_num > ibqp->device->phys_port_cnt)
599 			goto inval;
600 
601 	if (attr_mask & IB_QP_DEST_QPN)
602 		if (attr->dest_qp_num > QIB_QPN_MASK)
603 			goto inval;
604 
605 	if (attr_mask & IB_QP_RETRY_CNT)
606 		if (attr->retry_cnt > 7)
607 			goto inval;
608 
609 	if (attr_mask & IB_QP_RNR_RETRY)
610 		if (attr->rnr_retry > 7)
611 			goto inval;
612 
613 	/*
614 	 * Don't allow invalid path_mtu values.  OK to set greater
615 	 * than the active mtu (or even the max_cap, if we have tuned
616 	 * that to a small mtu.  We'll set qp->path_mtu
617 	 * to the lesser of requested attribute mtu and active,
618 	 * for packetizing messages.
619 	 * Note that the QP port has to be set in INIT and MTU in RTR.
620 	 */
621 	if (attr_mask & IB_QP_PATH_MTU) {
622 		struct qib_devdata *dd = dd_from_dev(dev);
623 		int mtu, pidx = qp->port_num - 1;
624 
625 		mtu = ib_mtu_enum_to_int(attr->path_mtu);
626 		if (mtu == -1)
627 			goto inval;
628 		if (mtu > dd->pport[pidx].ibmtu) {
629 			switch (dd->pport[pidx].ibmtu) {
630 			case 4096:
631 				pmtu = IB_MTU_4096;
632 				break;
633 			case 2048:
634 				pmtu = IB_MTU_2048;
635 				break;
636 			case 1024:
637 				pmtu = IB_MTU_1024;
638 				break;
639 			case 512:
640 				pmtu = IB_MTU_512;
641 				break;
642 			case 256:
643 				pmtu = IB_MTU_256;
644 				break;
645 			default:
646 				pmtu = IB_MTU_2048;
647 			}
648 		} else
649 			pmtu = attr->path_mtu;
650 	}
651 
652 	if (attr_mask & IB_QP_PATH_MIG_STATE) {
653 		if (attr->path_mig_state == IB_MIG_REARM) {
654 			if (qp->s_mig_state == IB_MIG_ARMED)
655 				goto inval;
656 			if (new_state != IB_QPS_RTS)
657 				goto inval;
658 		} else if (attr->path_mig_state == IB_MIG_MIGRATED) {
659 			if (qp->s_mig_state == IB_MIG_REARM)
660 				goto inval;
661 			if (new_state != IB_QPS_RTS && new_state != IB_QPS_SQD)
662 				goto inval;
663 			if (qp->s_mig_state == IB_MIG_ARMED)
664 				mig = 1;
665 		} else
666 			goto inval;
667 	}
668 
669 	if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC)
670 		if (attr->max_dest_rd_atomic > QIB_MAX_RDMA_ATOMIC)
671 			goto inval;
672 
673 	switch (new_state) {
674 	case IB_QPS_RESET:
675 		if (qp->state != IB_QPS_RESET) {
676 			qp->state = IB_QPS_RESET;
677 			spin_lock(&dev->pending_lock);
678 			if (!list_empty(&qp->iowait))
679 				list_del_init(&qp->iowait);
680 			spin_unlock(&dev->pending_lock);
681 			qp->s_flags &= ~(QIB_S_TIMER | QIB_S_ANY_WAIT);
682 			spin_unlock(&qp->s_lock);
683 			spin_unlock_irq(&qp->r_lock);
684 			/* Stop the sending work queue and retry timer */
685 			cancel_work_sync(&qp->s_work);
686 			del_timer_sync(&qp->s_timer);
687 			wait_event(qp->wait_dma, !atomic_read(&qp->s_dma_busy));
688 			if (qp->s_tx) {
689 				qib_put_txreq(qp->s_tx);
690 				qp->s_tx = NULL;
691 			}
692 			remove_qp(dev, qp);
693 			wait_event(qp->wait, !atomic_read(&qp->refcount));
694 			spin_lock_irq(&qp->r_lock);
695 			spin_lock(&qp->s_lock);
696 			clear_mr_refs(qp, 1);
697 			qib_reset_qp(qp, ibqp->qp_type);
698 		}
699 		break;
700 
701 	case IB_QPS_RTR:
702 		/* Allow event to retrigger if QP set to RTR more than once */
703 		qp->r_flags &= ~QIB_R_COMM_EST;
704 		qp->state = new_state;
705 		break;
706 
707 	case IB_QPS_SQD:
708 		qp->s_draining = qp->s_last != qp->s_cur;
709 		qp->state = new_state;
710 		break;
711 
712 	case IB_QPS_SQE:
713 		if (qp->ibqp.qp_type == IB_QPT_RC)
714 			goto inval;
715 		qp->state = new_state;
716 		break;
717 
718 	case IB_QPS_ERR:
719 		lastwqe = qib_error_qp(qp, IB_WC_WR_FLUSH_ERR);
720 		break;
721 
722 	default:
723 		qp->state = new_state;
724 		break;
725 	}
726 
727 	if (attr_mask & IB_QP_PKEY_INDEX)
728 		qp->s_pkey_index = attr->pkey_index;
729 
730 	if (attr_mask & IB_QP_PORT)
731 		qp->port_num = attr->port_num;
732 
733 	if (attr_mask & IB_QP_DEST_QPN)
734 		qp->remote_qpn = attr->dest_qp_num;
735 
736 	if (attr_mask & IB_QP_SQ_PSN) {
737 		qp->s_next_psn = attr->sq_psn & QIB_PSN_MASK;
738 		qp->s_psn = qp->s_next_psn;
739 		qp->s_sending_psn = qp->s_next_psn;
740 		qp->s_last_psn = qp->s_next_psn - 1;
741 		qp->s_sending_hpsn = qp->s_last_psn;
742 	}
743 
744 	if (attr_mask & IB_QP_RQ_PSN)
745 		qp->r_psn = attr->rq_psn & QIB_PSN_MASK;
746 
747 	if (attr_mask & IB_QP_ACCESS_FLAGS)
748 		qp->qp_access_flags = attr->qp_access_flags;
749 
750 	if (attr_mask & IB_QP_AV) {
751 		qp->remote_ah_attr = attr->ah_attr;
752 		qp->s_srate = attr->ah_attr.static_rate;
753 	}
754 
755 	if (attr_mask & IB_QP_ALT_PATH) {
756 		qp->alt_ah_attr = attr->alt_ah_attr;
757 		qp->s_alt_pkey_index = attr->alt_pkey_index;
758 	}
759 
760 	if (attr_mask & IB_QP_PATH_MIG_STATE) {
761 		qp->s_mig_state = attr->path_mig_state;
762 		if (mig) {
763 			qp->remote_ah_attr = qp->alt_ah_attr;
764 			qp->port_num = qp->alt_ah_attr.port_num;
765 			qp->s_pkey_index = qp->s_alt_pkey_index;
766 		}
767 	}
768 
769 	if (attr_mask & IB_QP_PATH_MTU)
770 		qp->path_mtu = pmtu;
771 
772 	if (attr_mask & IB_QP_RETRY_CNT) {
773 		qp->s_retry_cnt = attr->retry_cnt;
774 		qp->s_retry = attr->retry_cnt;
775 	}
776 
777 	if (attr_mask & IB_QP_RNR_RETRY) {
778 		qp->s_rnr_retry_cnt = attr->rnr_retry;
779 		qp->s_rnr_retry = attr->rnr_retry;
780 	}
781 
782 	if (attr_mask & IB_QP_MIN_RNR_TIMER)
783 		qp->r_min_rnr_timer = attr->min_rnr_timer;
784 
785 	if (attr_mask & IB_QP_TIMEOUT)
786 		qp->timeout = attr->timeout;
787 
788 	if (attr_mask & IB_QP_QKEY)
789 		qp->qkey = attr->qkey;
790 
791 	if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC)
792 		qp->r_max_rd_atomic = attr->max_dest_rd_atomic;
793 
794 	if (attr_mask & IB_QP_MAX_QP_RD_ATOMIC)
795 		qp->s_max_rd_atomic = attr->max_rd_atomic;
796 
797 	spin_unlock(&qp->s_lock);
798 	spin_unlock_irq(&qp->r_lock);
799 
800 	if (cur_state == IB_QPS_RESET && new_state == IB_QPS_INIT)
801 		insert_qp(dev, qp);
802 
803 	if (lastwqe) {
804 		ev.device = qp->ibqp.device;
805 		ev.element.qp = &qp->ibqp;
806 		ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
807 		qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
808 	}
809 	if (mig) {
810 		ev.device = qp->ibqp.device;
811 		ev.element.qp = &qp->ibqp;
812 		ev.event = IB_EVENT_PATH_MIG;
813 		qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
814 	}
815 	ret = 0;
816 	goto bail;
817 
818 inval:
819 	spin_unlock(&qp->s_lock);
820 	spin_unlock_irq(&qp->r_lock);
821 	ret = -EINVAL;
822 
823 bail:
824 	return ret;
825 }
826 
827 int qib_query_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
828 		 int attr_mask, struct ib_qp_init_attr *init_attr)
829 {
830 	struct qib_qp *qp = to_iqp(ibqp);
831 
832 	attr->qp_state = qp->state;
833 	attr->cur_qp_state = attr->qp_state;
834 	attr->path_mtu = qp->path_mtu;
835 	attr->path_mig_state = qp->s_mig_state;
836 	attr->qkey = qp->qkey;
837 	attr->rq_psn = qp->r_psn & QIB_PSN_MASK;
838 	attr->sq_psn = qp->s_next_psn & QIB_PSN_MASK;
839 	attr->dest_qp_num = qp->remote_qpn;
840 	attr->qp_access_flags = qp->qp_access_flags;
841 	attr->cap.max_send_wr = qp->s_size - 1;
842 	attr->cap.max_recv_wr = qp->ibqp.srq ? 0 : qp->r_rq.size - 1;
843 	attr->cap.max_send_sge = qp->s_max_sge;
844 	attr->cap.max_recv_sge = qp->r_rq.max_sge;
845 	attr->cap.max_inline_data = 0;
846 	attr->ah_attr = qp->remote_ah_attr;
847 	attr->alt_ah_attr = qp->alt_ah_attr;
848 	attr->pkey_index = qp->s_pkey_index;
849 	attr->alt_pkey_index = qp->s_alt_pkey_index;
850 	attr->en_sqd_async_notify = 0;
851 	attr->sq_draining = qp->s_draining;
852 	attr->max_rd_atomic = qp->s_max_rd_atomic;
853 	attr->max_dest_rd_atomic = qp->r_max_rd_atomic;
854 	attr->min_rnr_timer = qp->r_min_rnr_timer;
855 	attr->port_num = qp->port_num;
856 	attr->timeout = qp->timeout;
857 	attr->retry_cnt = qp->s_retry_cnt;
858 	attr->rnr_retry = qp->s_rnr_retry_cnt;
859 	attr->alt_port_num = qp->alt_ah_attr.port_num;
860 	attr->alt_timeout = qp->alt_timeout;
861 
862 	init_attr->event_handler = qp->ibqp.event_handler;
863 	init_attr->qp_context = qp->ibqp.qp_context;
864 	init_attr->send_cq = qp->ibqp.send_cq;
865 	init_attr->recv_cq = qp->ibqp.recv_cq;
866 	init_attr->srq = qp->ibqp.srq;
867 	init_attr->cap = attr->cap;
868 	if (qp->s_flags & QIB_S_SIGNAL_REQ_WR)
869 		init_attr->sq_sig_type = IB_SIGNAL_REQ_WR;
870 	else
871 		init_attr->sq_sig_type = IB_SIGNAL_ALL_WR;
872 	init_attr->qp_type = qp->ibqp.qp_type;
873 	init_attr->port_num = qp->port_num;
874 	return 0;
875 }
876 
877 /**
878  * qib_compute_aeth - compute the AETH (syndrome + MSN)
879  * @qp: the queue pair to compute the AETH for
880  *
881  * Returns the AETH.
882  */
883 __be32 qib_compute_aeth(struct qib_qp *qp)
884 {
885 	u32 aeth = qp->r_msn & QIB_MSN_MASK;
886 
887 	if (qp->ibqp.srq) {
888 		/*
889 		 * Shared receive queues don't generate credits.
890 		 * Set the credit field to the invalid value.
891 		 */
892 		aeth |= QIB_AETH_CREDIT_INVAL << QIB_AETH_CREDIT_SHIFT;
893 	} else {
894 		u32 min, max, x;
895 		u32 credits;
896 		struct qib_rwq *wq = qp->r_rq.wq;
897 		u32 head;
898 		u32 tail;
899 
900 		/* sanity check pointers before trusting them */
901 		head = wq->head;
902 		if (head >= qp->r_rq.size)
903 			head = 0;
904 		tail = wq->tail;
905 		if (tail >= qp->r_rq.size)
906 			tail = 0;
907 		/*
908 		 * Compute the number of credits available (RWQEs).
909 		 * XXX Not holding the r_rq.lock here so there is a small
910 		 * chance that the pair of reads are not atomic.
911 		 */
912 		credits = head - tail;
913 		if ((int)credits < 0)
914 			credits += qp->r_rq.size;
915 		/*
916 		 * Binary search the credit table to find the code to
917 		 * use.
918 		 */
919 		min = 0;
920 		max = 31;
921 		for (;;) {
922 			x = (min + max) / 2;
923 			if (credit_table[x] == credits)
924 				break;
925 			if (credit_table[x] > credits)
926 				max = x;
927 			else if (min == x)
928 				break;
929 			else
930 				min = x;
931 		}
932 		aeth |= x << QIB_AETH_CREDIT_SHIFT;
933 	}
934 	return cpu_to_be32(aeth);
935 }
936 
937 /**
938  * qib_create_qp - create a queue pair for a device
939  * @ibpd: the protection domain who's device we create the queue pair for
940  * @init_attr: the attributes of the queue pair
941  * @udata: user data for libibverbs.so
942  *
943  * Returns the queue pair on success, otherwise returns an errno.
944  *
945  * Called by the ib_create_qp() core verbs function.
946  */
947 struct ib_qp *qib_create_qp(struct ib_pd *ibpd,
948 			    struct ib_qp_init_attr *init_attr,
949 			    struct ib_udata *udata)
950 {
951 	struct qib_qp *qp;
952 	int err;
953 	struct qib_swqe *swq = NULL;
954 	struct qib_ibdev *dev;
955 	struct qib_devdata *dd;
956 	size_t sz;
957 	size_t sg_list_sz;
958 	struct ib_qp *ret;
959 
960 	if (init_attr->cap.max_send_sge > ib_qib_max_sges ||
961 	    init_attr->cap.max_send_wr > ib_qib_max_qp_wrs) {
962 		ret = ERR_PTR(-EINVAL);
963 		goto bail;
964 	}
965 
966 	/* Check receive queue parameters if no SRQ is specified. */
967 	if (!init_attr->srq) {
968 		if (init_attr->cap.max_recv_sge > ib_qib_max_sges ||
969 		    init_attr->cap.max_recv_wr > ib_qib_max_qp_wrs) {
970 			ret = ERR_PTR(-EINVAL);
971 			goto bail;
972 		}
973 		if (init_attr->cap.max_send_sge +
974 		    init_attr->cap.max_send_wr +
975 		    init_attr->cap.max_recv_sge +
976 		    init_attr->cap.max_recv_wr == 0) {
977 			ret = ERR_PTR(-EINVAL);
978 			goto bail;
979 		}
980 	}
981 
982 	switch (init_attr->qp_type) {
983 	case IB_QPT_SMI:
984 	case IB_QPT_GSI:
985 		if (init_attr->port_num == 0 ||
986 		    init_attr->port_num > ibpd->device->phys_port_cnt) {
987 			ret = ERR_PTR(-EINVAL);
988 			goto bail;
989 		}
990 	case IB_QPT_UC:
991 	case IB_QPT_RC:
992 	case IB_QPT_UD:
993 		sz = sizeof(struct qib_sge) *
994 			init_attr->cap.max_send_sge +
995 			sizeof(struct qib_swqe);
996 		swq = vmalloc((init_attr->cap.max_send_wr + 1) * sz);
997 		if (swq == NULL) {
998 			ret = ERR_PTR(-ENOMEM);
999 			goto bail;
1000 		}
1001 		sz = sizeof(*qp);
1002 		sg_list_sz = 0;
1003 		if (init_attr->srq) {
1004 			struct qib_srq *srq = to_isrq(init_attr->srq);
1005 
1006 			if (srq->rq.max_sge > 1)
1007 				sg_list_sz = sizeof(*qp->r_sg_list) *
1008 					(srq->rq.max_sge - 1);
1009 		} else if (init_attr->cap.max_recv_sge > 1)
1010 			sg_list_sz = sizeof(*qp->r_sg_list) *
1011 				(init_attr->cap.max_recv_sge - 1);
1012 		qp = kzalloc(sz + sg_list_sz, GFP_KERNEL);
1013 		if (!qp) {
1014 			ret = ERR_PTR(-ENOMEM);
1015 			goto bail_swq;
1016 		}
1017 		if (init_attr->srq)
1018 			sz = 0;
1019 		else {
1020 			qp->r_rq.size = init_attr->cap.max_recv_wr + 1;
1021 			qp->r_rq.max_sge = init_attr->cap.max_recv_sge;
1022 			sz = (sizeof(struct ib_sge) * qp->r_rq.max_sge) +
1023 				sizeof(struct qib_rwqe);
1024 			qp->r_rq.wq = vmalloc_user(sizeof(struct qib_rwq) +
1025 						   qp->r_rq.size * sz);
1026 			if (!qp->r_rq.wq) {
1027 				ret = ERR_PTR(-ENOMEM);
1028 				goto bail_qp;
1029 			}
1030 		}
1031 
1032 		/*
1033 		 * ib_create_qp() will initialize qp->ibqp
1034 		 * except for qp->ibqp.qp_num.
1035 		 */
1036 		spin_lock_init(&qp->r_lock);
1037 		spin_lock_init(&qp->s_lock);
1038 		spin_lock_init(&qp->r_rq.lock);
1039 		atomic_set(&qp->refcount, 0);
1040 		init_waitqueue_head(&qp->wait);
1041 		init_waitqueue_head(&qp->wait_dma);
1042 		init_timer(&qp->s_timer);
1043 		qp->s_timer.data = (unsigned long)qp;
1044 		INIT_WORK(&qp->s_work, qib_do_send);
1045 		INIT_LIST_HEAD(&qp->iowait);
1046 		INIT_LIST_HEAD(&qp->rspwait);
1047 		qp->state = IB_QPS_RESET;
1048 		qp->s_wq = swq;
1049 		qp->s_size = init_attr->cap.max_send_wr + 1;
1050 		qp->s_max_sge = init_attr->cap.max_send_sge;
1051 		if (init_attr->sq_sig_type == IB_SIGNAL_REQ_WR)
1052 			qp->s_flags = QIB_S_SIGNAL_REQ_WR;
1053 		dev = to_idev(ibpd->device);
1054 		dd = dd_from_dev(dev);
1055 		err = alloc_qpn(dd, &dev->qpn_table, init_attr->qp_type,
1056 				init_attr->port_num);
1057 		if (err < 0) {
1058 			ret = ERR_PTR(err);
1059 			vfree(qp->r_rq.wq);
1060 			goto bail_qp;
1061 		}
1062 		qp->ibqp.qp_num = err;
1063 		qp->port_num = init_attr->port_num;
1064 		qp->processor_id = smp_processor_id();
1065 		qib_reset_qp(qp, init_attr->qp_type);
1066 		break;
1067 
1068 	default:
1069 		/* Don't support raw QPs */
1070 		ret = ERR_PTR(-ENOSYS);
1071 		goto bail;
1072 	}
1073 
1074 	init_attr->cap.max_inline_data = 0;
1075 
1076 	/*
1077 	 * Return the address of the RWQ as the offset to mmap.
1078 	 * See qib_mmap() for details.
1079 	 */
1080 	if (udata && udata->outlen >= sizeof(__u64)) {
1081 		if (!qp->r_rq.wq) {
1082 			__u64 offset = 0;
1083 
1084 			err = ib_copy_to_udata(udata, &offset,
1085 					       sizeof(offset));
1086 			if (err) {
1087 				ret = ERR_PTR(err);
1088 				goto bail_ip;
1089 			}
1090 		} else {
1091 			u32 s = sizeof(struct qib_rwq) + qp->r_rq.size * sz;
1092 
1093 			qp->ip = qib_create_mmap_info(dev, s,
1094 						      ibpd->uobject->context,
1095 						      qp->r_rq.wq);
1096 			if (!qp->ip) {
1097 				ret = ERR_PTR(-ENOMEM);
1098 				goto bail_ip;
1099 			}
1100 
1101 			err = ib_copy_to_udata(udata, &(qp->ip->offset),
1102 					       sizeof(qp->ip->offset));
1103 			if (err) {
1104 				ret = ERR_PTR(err);
1105 				goto bail_ip;
1106 			}
1107 		}
1108 	}
1109 
1110 	spin_lock(&dev->n_qps_lock);
1111 	if (dev->n_qps_allocated == ib_qib_max_qps) {
1112 		spin_unlock(&dev->n_qps_lock);
1113 		ret = ERR_PTR(-ENOMEM);
1114 		goto bail_ip;
1115 	}
1116 
1117 	dev->n_qps_allocated++;
1118 	spin_unlock(&dev->n_qps_lock);
1119 
1120 	if (qp->ip) {
1121 		spin_lock_irq(&dev->pending_lock);
1122 		list_add(&qp->ip->pending_mmaps, &dev->pending_mmaps);
1123 		spin_unlock_irq(&dev->pending_lock);
1124 	}
1125 
1126 	ret = &qp->ibqp;
1127 	goto bail;
1128 
1129 bail_ip:
1130 	if (qp->ip)
1131 		kref_put(&qp->ip->ref, qib_release_mmap_info);
1132 	else
1133 		vfree(qp->r_rq.wq);
1134 	free_qpn(&dev->qpn_table, qp->ibqp.qp_num);
1135 bail_qp:
1136 	kfree(qp);
1137 bail_swq:
1138 	vfree(swq);
1139 bail:
1140 	return ret;
1141 }
1142 
1143 /**
1144  * qib_destroy_qp - destroy a queue pair
1145  * @ibqp: the queue pair to destroy
1146  *
1147  * Returns 0 on success.
1148  *
1149  * Note that this can be called while the QP is actively sending or
1150  * receiving!
1151  */
1152 int qib_destroy_qp(struct ib_qp *ibqp)
1153 {
1154 	struct qib_qp *qp = to_iqp(ibqp);
1155 	struct qib_ibdev *dev = to_idev(ibqp->device);
1156 
1157 	/* Make sure HW and driver activity is stopped. */
1158 	spin_lock_irq(&qp->s_lock);
1159 	if (qp->state != IB_QPS_RESET) {
1160 		qp->state = IB_QPS_RESET;
1161 		spin_lock(&dev->pending_lock);
1162 		if (!list_empty(&qp->iowait))
1163 			list_del_init(&qp->iowait);
1164 		spin_unlock(&dev->pending_lock);
1165 		qp->s_flags &= ~(QIB_S_TIMER | QIB_S_ANY_WAIT);
1166 		spin_unlock_irq(&qp->s_lock);
1167 		cancel_work_sync(&qp->s_work);
1168 		del_timer_sync(&qp->s_timer);
1169 		wait_event(qp->wait_dma, !atomic_read(&qp->s_dma_busy));
1170 		if (qp->s_tx) {
1171 			qib_put_txreq(qp->s_tx);
1172 			qp->s_tx = NULL;
1173 		}
1174 		remove_qp(dev, qp);
1175 		wait_event(qp->wait, !atomic_read(&qp->refcount));
1176 		clear_mr_refs(qp, 1);
1177 	} else
1178 		spin_unlock_irq(&qp->s_lock);
1179 
1180 	/* all user's cleaned up, mark it available */
1181 	free_qpn(&dev->qpn_table, qp->ibqp.qp_num);
1182 	spin_lock(&dev->n_qps_lock);
1183 	dev->n_qps_allocated--;
1184 	spin_unlock(&dev->n_qps_lock);
1185 
1186 	if (qp->ip)
1187 		kref_put(&qp->ip->ref, qib_release_mmap_info);
1188 	else
1189 		vfree(qp->r_rq.wq);
1190 	vfree(qp->s_wq);
1191 	kfree(qp);
1192 	return 0;
1193 }
1194 
1195 /**
1196  * qib_init_qpn_table - initialize the QP number table for a device
1197  * @qpt: the QPN table
1198  */
1199 void qib_init_qpn_table(struct qib_devdata *dd, struct qib_qpn_table *qpt)
1200 {
1201 	spin_lock_init(&qpt->lock);
1202 	qpt->last = 1;          /* start with QPN 2 */
1203 	qpt->nmaps = 1;
1204 	qpt->mask = dd->qpn_mask;
1205 }
1206 
1207 /**
1208  * qib_free_qpn_table - free the QP number table for a device
1209  * @qpt: the QPN table
1210  */
1211 void qib_free_qpn_table(struct qib_qpn_table *qpt)
1212 {
1213 	int i;
1214 
1215 	for (i = 0; i < ARRAY_SIZE(qpt->map); i++)
1216 		if (qpt->map[i].page)
1217 			free_page((unsigned long) qpt->map[i].page);
1218 }
1219 
1220 /**
1221  * qib_get_credit - flush the send work queue of a QP
1222  * @qp: the qp who's send work queue to flush
1223  * @aeth: the Acknowledge Extended Transport Header
1224  *
1225  * The QP s_lock should be held.
1226  */
1227 void qib_get_credit(struct qib_qp *qp, u32 aeth)
1228 {
1229 	u32 credit = (aeth >> QIB_AETH_CREDIT_SHIFT) & QIB_AETH_CREDIT_MASK;
1230 
1231 	/*
1232 	 * If the credit is invalid, we can send
1233 	 * as many packets as we like.  Otherwise, we have to
1234 	 * honor the credit field.
1235 	 */
1236 	if (credit == QIB_AETH_CREDIT_INVAL) {
1237 		if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT)) {
1238 			qp->s_flags |= QIB_S_UNLIMITED_CREDIT;
1239 			if (qp->s_flags & QIB_S_WAIT_SSN_CREDIT) {
1240 				qp->s_flags &= ~QIB_S_WAIT_SSN_CREDIT;
1241 				qib_schedule_send(qp);
1242 			}
1243 		}
1244 	} else if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT)) {
1245 		/* Compute new LSN (i.e., MSN + credit) */
1246 		credit = (aeth + credit_table[credit]) & QIB_MSN_MASK;
1247 		if (qib_cmp24(credit, qp->s_lsn) > 0) {
1248 			qp->s_lsn = credit;
1249 			if (qp->s_flags & QIB_S_WAIT_SSN_CREDIT) {
1250 				qp->s_flags &= ~QIB_S_WAIT_SSN_CREDIT;
1251 				qib_schedule_send(qp);
1252 			}
1253 		}
1254 	}
1255 }
1256