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IB/qib: Fix for broken sparse warning fix
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1 /*
2  * Copyright (c) 2012 Intel Corporation.  All rights reserved.
3  * Copyright (c) 2006 - 2012 QLogic Corporation.  * 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 #include <linux/jhash.h>
38
39 #include "qib.h"
40
41 #define BITS_PER_PAGE           (PAGE_SIZE*BITS_PER_BYTE)
42 #define BITS_PER_PAGE_MASK      (BITS_PER_PAGE-1)
43
44 static inline unsigned mk_qpn(struct qib_qpn_table *qpt,
45                               struct qpn_map *map, unsigned off)
46 {
47         return (map - qpt->map) * BITS_PER_PAGE + off;
48 }
49
50 static inline unsigned find_next_offset(struct qib_qpn_table *qpt,
51                                         struct qpn_map *map, unsigned off,
52                                         unsigned n)
53 {
54         if (qpt->mask) {
55                 off++;
56                 if (((off & qpt->mask) >> 1) >= n)
57                         off = (off | qpt->mask) + 2;
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
127         if (type == IB_QPT_SMI || type == IB_QPT_GSI) {
128                 unsigned n;
129
130                 ret = type == IB_QPT_GSI;
131                 n = 1 << (ret + 2 * (port - 1));
132                 spin_lock(&qpt->lock);
133                 if (qpt->flags & n)
134                         ret = -EINVAL;
135                 else
136                         qpt->flags |= n;
137                 spin_unlock(&qpt->lock);
138                 goto bail;
139         }
140
141         qpn = qpt->last + 2;
142         if (qpn >= QPN_MAX)
143                 qpn = 2;
144         if (qpt->mask && ((qpn & qpt->mask) >> 1) >= dd->n_krcv_queues)
145                 qpn = (qpn | qpt->mask) + 2;
146         offset = qpn & BITS_PER_PAGE_MASK;
147         map = &qpt->map[qpn / BITS_PER_PAGE];
148         max_scan = qpt->nmaps - !offset;
149         for (i = 0;;) {
150                 if (unlikely(!map->page)) {
151                         get_map_page(qpt, map);
152                         if (unlikely(!map->page))
153                                 break;
154                 }
155                 do {
156                         if (!test_and_set_bit(offset, map->page)) {
157                                 qpt->last = qpn;
158                                 ret = qpn;
159                                 goto bail;
160                         }
161                         offset = find_next_offset(qpt, map, offset,
162                                 dd->n_krcv_queues);
163                         qpn = mk_qpn(qpt, map, offset);
164                         /*
165                          * This test differs from alloc_pidmap().
166                          * If find_next_offset() does find a zero
167                          * bit, we don't need to check for QPN
168                          * wrapping around past our starting QPN.
169                          * We just need to be sure we don't loop
170                          * forever.
171                          */
172                 } while (offset < BITS_PER_PAGE && qpn < QPN_MAX);
173                 /*
174                  * In order to keep the number of pages allocated to a
175                  * minimum, we scan the all existing pages before increasing
176                  * the size of the bitmap table.
177                  */
178                 if (++i > max_scan) {
179                         if (qpt->nmaps == QPNMAP_ENTRIES)
180                                 break;
181                         map = &qpt->map[qpt->nmaps++];
182                         offset = 0;
183                 } else if (map < &qpt->map[qpt->nmaps]) {
184                         ++map;
185                         offset = 0;
186                 } else {
187                         map = &qpt->map[0];
188                         offset = 2;
189                 }
190                 qpn = mk_qpn(qpt, map, offset);
191         }
192
193         ret = -ENOMEM;
194
195 bail:
196         return ret;
197 }
198
199 static void free_qpn(struct qib_qpn_table *qpt, u32 qpn)
200 {
201         struct qpn_map *map;
202
203         map = qpt->map + qpn / BITS_PER_PAGE;
204         if (map->page)
205                 clear_bit(qpn & BITS_PER_PAGE_MASK, map->page);
206 }
207
208 static inline unsigned qpn_hash(struct qib_ibdev *dev, u32 qpn)
209 {
210         return jhash_1word(qpn, dev->qp_rnd) &
211                 (dev->qp_table_size - 1);
212 }
213
214
215 /*
216  * Put the QP into the hash table.
217  * The hash table holds a reference to the QP.
218  */
219 static void insert_qp(struct qib_ibdev *dev, struct qib_qp *qp)
220 {
221         struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
222         unsigned long flags;
223         unsigned n = qpn_hash(dev, qp->ibqp.qp_num);
224
225         spin_lock_irqsave(&dev->qpt_lock, flags);
226         atomic_inc(&qp->refcount);
227
228         if (qp->ibqp.qp_num == 0)
229                 rcu_assign_pointer(ibp->qp0, qp);
230         else if (qp->ibqp.qp_num == 1)
231                 rcu_assign_pointer(ibp->qp1, qp);
232         else {
233                 qp->next = dev->qp_table[n];
234                 rcu_assign_pointer(dev->qp_table[n], qp);
235         }
236
237         spin_unlock_irqrestore(&dev->qpt_lock, flags);
238         synchronize_rcu();
239 }
240
241 /*
242  * Remove the QP from the table so it can't be found asynchronously by
243  * the receive interrupt routine.
244  */
245 static void remove_qp(struct qib_ibdev *dev, struct qib_qp *qp)
246 {
247         struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
248         unsigned n = qpn_hash(dev, qp->ibqp.qp_num);
249         unsigned long flags;
250
251         spin_lock_irqsave(&dev->qpt_lock, flags);
252
253         if (rcu_dereference_protected(ibp->qp0,
254                         lockdep_is_held(&dev->qpt_lock)) == qp) {
255                 atomic_dec(&qp->refcount);
256                 rcu_assign_pointer(ibp->qp0, NULL);
257         } else if (rcu_dereference_protected(ibp->qp1,
258                         lockdep_is_held(&dev->qpt_lock)) == qp) {
259                 atomic_dec(&qp->refcount);
260                 rcu_assign_pointer(ibp->qp1, NULL);
261         } else {
262                 struct qib_qp *q;
263                 struct qib_qp __rcu **qpp;
264
265                 qpp = &dev->qp_table[n];
266                 for (; (q = rcu_dereference_protected(*qpp,
267                                 lockdep_is_held(&dev->qpt_lock))) != NULL;
268                                 qpp = &q->next)
269                         if (q == qp) {
270                                 atomic_dec(&qp->refcount);
271                                 *qpp = qp->next;
272                                 rcu_assign_pointer(qp->next, NULL);
273                                 break;
274                         }
275         }
276
277         spin_unlock_irqrestore(&dev->qpt_lock, flags);
278         synchronize_rcu();
279 }
280
281 /**
282  * qib_free_all_qps - check for QPs still in use
283  * @qpt: the QP table to empty
284  *
285  * There should not be any QPs still in use.
286  * Free memory for table.
287  */
288 unsigned qib_free_all_qps(struct qib_devdata *dd)
289 {
290         struct qib_ibdev *dev = &dd->verbs_dev;
291         unsigned long flags;
292         struct qib_qp *qp;
293         unsigned n, qp_inuse = 0;
294
295         for (n = 0; n < dd->num_pports; n++) {
296                 struct qib_ibport *ibp = &dd->pport[n].ibport_data;
297
298                 if (!qib_mcast_tree_empty(ibp))
299                         qp_inuse++;
300                 rcu_read_lock();
301                 if (rcu_dereference(ibp->qp0))
302                         qp_inuse++;
303                 if (rcu_dereference(ibp->qp1))
304                         qp_inuse++;
305                 rcu_read_unlock();
306         }
307
308         spin_lock_irqsave(&dev->qpt_lock, flags);
309         for (n = 0; n < dev->qp_table_size; n++) {
310                 qp = rcu_dereference_protected(dev->qp_table[n],
311                         lockdep_is_held(&dev->qpt_lock));
312                 rcu_assign_pointer(dev->qp_table[n], NULL);
313
314                 for (; qp; qp = rcu_dereference_protected(qp->next,
315                                         lockdep_is_held(&dev->qpt_lock)))
316                         qp_inuse++;
317         }
318         spin_unlock_irqrestore(&dev->qpt_lock, flags);
319         synchronize_rcu();
320
321         return qp_inuse;
322 }
323
324 /**
325  * qib_lookup_qpn - return the QP with the given QPN
326  * @qpt: the QP table
327  * @qpn: the QP number to look up
328  *
329  * The caller is responsible for decrementing the QP reference count
330  * when done.
331  */
332 struct qib_qp *qib_lookup_qpn(struct qib_ibport *ibp, u32 qpn)
333 {
334         struct qib_qp *qp = NULL;
335
336         if (unlikely(qpn <= 1)) {
337                 rcu_read_lock();
338                 if (qpn == 0)
339                         qp = rcu_dereference(ibp->qp0);
340                 else
341                         qp = rcu_dereference(ibp->qp1);
342         } else {
343                 struct qib_ibdev *dev = &ppd_from_ibp(ibp)->dd->verbs_dev;
344                 unsigned n = qpn_hash(dev, qpn);
345
346                 rcu_read_lock();
347                 for (qp = rcu_dereference(dev->qp_table[n]); qp;
348                         qp = rcu_dereference(qp->next))
349                         if (qp->ibqp.qp_num == qpn)
350                                 break;
351         }
352         if (qp)
353                 if (unlikely(!atomic_inc_not_zero(&qp->refcount)))
354                         qp = NULL;
355
356         rcu_read_unlock();
357         return qp;
358 }
359
360 /**
361  * qib_reset_qp - initialize the QP state to the reset state
362  * @qp: the QP to reset
363  * @type: the QP type
364  */
365 static void qib_reset_qp(struct qib_qp *qp, enum ib_qp_type type)
366 {
367         qp->remote_qpn = 0;
368         qp->qkey = 0;
369         qp->qp_access_flags = 0;
370         atomic_set(&qp->s_dma_busy, 0);
371         qp->s_flags &= QIB_S_SIGNAL_REQ_WR;
372         qp->s_hdrwords = 0;
373         qp->s_wqe = NULL;
374         qp->s_draining = 0;
375         qp->s_next_psn = 0;
376         qp->s_last_psn = 0;
377         qp->s_sending_psn = 0;
378         qp->s_sending_hpsn = 0;
379         qp->s_psn = 0;
380         qp->r_psn = 0;
381         qp->r_msn = 0;
382         if (type == IB_QPT_RC) {
383                 qp->s_state = IB_OPCODE_RC_SEND_LAST;
384                 qp->r_state = IB_OPCODE_RC_SEND_LAST;
385         } else {
386                 qp->s_state = IB_OPCODE_UC_SEND_LAST;
387                 qp->r_state = IB_OPCODE_UC_SEND_LAST;
388         }
389         qp->s_ack_state = IB_OPCODE_RC_ACKNOWLEDGE;
390         qp->r_nak_state = 0;
391         qp->r_aflags = 0;
392         qp->r_flags = 0;
393         qp->s_head = 0;
394         qp->s_tail = 0;
395         qp->s_cur = 0;
396         qp->s_acked = 0;
397         qp->s_last = 0;
398         qp->s_ssn = 1;
399         qp->s_lsn = 0;
400         qp->s_mig_state = IB_MIG_MIGRATED;
401         memset(qp->s_ack_queue, 0, sizeof(qp->s_ack_queue));
402         qp->r_head_ack_queue = 0;
403         qp->s_tail_ack_queue = 0;
404         qp->s_num_rd_atomic = 0;
405         if (qp->r_rq.wq) {
406                 qp->r_rq.wq->head = 0;
407                 qp->r_rq.wq->tail = 0;
408         }
409         qp->r_sge.num_sge = 0;
410 }
411
412 static void clear_mr_refs(struct qib_qp *qp, int clr_sends)
413 {
414         unsigned n;
415
416         if (test_and_clear_bit(QIB_R_REWIND_SGE, &qp->r_aflags))
417                 qib_put_ss(&qp->s_rdma_read_sge);
418
419         qib_put_ss(&qp->r_sge);
420
421         if (clr_sends) {
422                 while (qp->s_last != qp->s_head) {
423                         struct qib_swqe *wqe = get_swqe_ptr(qp, qp->s_last);
424                         unsigned i;
425
426                         for (i = 0; i < wqe->wr.num_sge; i++) {
427                                 struct qib_sge *sge = &wqe->sg_list[i];
428
429                                 qib_put_mr(sge->mr);
430                         }
431                         if (qp->ibqp.qp_type == IB_QPT_UD ||
432                             qp->ibqp.qp_type == IB_QPT_SMI ||
433                             qp->ibqp.qp_type == IB_QPT_GSI)
434                                 atomic_dec(&to_iah(wqe->wr.wr.ud.ah)->refcount);
435                         if (++qp->s_last >= qp->s_size)
436                                 qp->s_last = 0;
437                 }
438                 if (qp->s_rdma_mr) {
439                         qib_put_mr(qp->s_rdma_mr);
440                         qp->s_rdma_mr = NULL;
441                 }
442         }
443
444         if (qp->ibqp.qp_type != IB_QPT_RC)
445                 return;
446
447         for (n = 0; n < ARRAY_SIZE(qp->s_ack_queue); n++) {
448                 struct qib_ack_entry *e = &qp->s_ack_queue[n];
449
450                 if (e->opcode == IB_OPCODE_RC_RDMA_READ_REQUEST &&
451                     e->rdma_sge.mr) {
452                         qib_put_mr(e->rdma_sge.mr);
453                         e->rdma_sge.mr = NULL;
454                 }
455         }
456 }
457
458 /**
459  * qib_error_qp - put a QP into the error state
460  * @qp: the QP to put into the error state
461  * @err: the receive completion error to signal if a RWQE is active
462  *
463  * Flushes both send and receive work queues.
464  * Returns true if last WQE event should be generated.
465  * The QP r_lock and s_lock should be held and interrupts disabled.
466  * If we are already in error state, just return.
467  */
468 int qib_error_qp(struct qib_qp *qp, enum ib_wc_status err)
469 {
470         struct qib_ibdev *dev = to_idev(qp->ibqp.device);
471         struct ib_wc wc;
472         int ret = 0;
473
474         if (qp->state == IB_QPS_ERR || qp->state == IB_QPS_RESET)
475                 goto bail;
476
477         qp->state = IB_QPS_ERR;
478
479         if (qp->s_flags & (QIB_S_TIMER | QIB_S_WAIT_RNR)) {
480                 qp->s_flags &= ~(QIB_S_TIMER | QIB_S_WAIT_RNR);
481                 del_timer(&qp->s_timer);
482         }
483
484         if (qp->s_flags & QIB_S_ANY_WAIT_SEND)
485                 qp->s_flags &= ~QIB_S_ANY_WAIT_SEND;
486
487         spin_lock(&dev->pending_lock);
488         if (!list_empty(&qp->iowait) && !(qp->s_flags & QIB_S_BUSY)) {
489                 qp->s_flags &= ~QIB_S_ANY_WAIT_IO;
490                 list_del_init(&qp->iowait);
491         }
492         spin_unlock(&dev->pending_lock);
493
494         if (!(qp->s_flags & QIB_S_BUSY)) {
495                 qp->s_hdrwords = 0;
496                 if (qp->s_rdma_mr) {
497                         qib_put_mr(qp->s_rdma_mr);
498                         qp->s_rdma_mr = NULL;
499                 }
500                 if (qp->s_tx) {
501                         qib_put_txreq(qp->s_tx);
502                         qp->s_tx = NULL;
503                 }
504         }
505
506         /* Schedule the sending tasklet to drain the send work queue. */
507         if (qp->s_last != qp->s_head)
508                 qib_schedule_send(qp);
509
510         clear_mr_refs(qp, 0);
511
512         memset(&wc, 0, sizeof(wc));
513         wc.qp = &qp->ibqp;
514         wc.opcode = IB_WC_RECV;
515
516         if (test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags)) {
517                 wc.wr_id = qp->r_wr_id;
518                 wc.status = err;
519                 qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc, 1);
520         }
521         wc.status = IB_WC_WR_FLUSH_ERR;
522
523         if (qp->r_rq.wq) {
524                 struct qib_rwq *wq;
525                 u32 head;
526                 u32 tail;
527
528                 spin_lock(&qp->r_rq.lock);
529
530                 /* sanity check pointers before trusting them */
531                 wq = qp->r_rq.wq;
532                 head = wq->head;
533                 if (head >= qp->r_rq.size)
534                         head = 0;
535                 tail = wq->tail;
536                 if (tail >= qp->r_rq.size)
537                         tail = 0;
538                 while (tail != head) {
539                         wc.wr_id = get_rwqe_ptr(&qp->r_rq, tail)->wr_id;
540                         if (++tail >= qp->r_rq.size)
541                                 tail = 0;
542                         qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc, 1);
543                 }
544                 wq->tail = tail;
545
546                 spin_unlock(&qp->r_rq.lock);
547         } else if (qp->ibqp.event_handler)
548                 ret = 1;
549
550 bail:
551         return ret;
552 }
553
554 /**
555  * qib_modify_qp - modify the attributes of a queue pair
556  * @ibqp: the queue pair who's attributes we're modifying
557  * @attr: the new attributes
558  * @attr_mask: the mask of attributes to modify
559  * @udata: user data for libibverbs.so
560  *
561  * Returns 0 on success, otherwise returns an errno.
562  */
563 int qib_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
564                   int attr_mask, struct ib_udata *udata)
565 {
566         struct qib_ibdev *dev = to_idev(ibqp->device);
567         struct qib_qp *qp = to_iqp(ibqp);
568         enum ib_qp_state cur_state, new_state;
569         struct ib_event ev;
570         int lastwqe = 0;
571         int mig = 0;
572         int ret;
573         u32 pmtu = 0; /* for gcc warning only */
574
575         spin_lock_irq(&qp->r_lock);
576         spin_lock(&qp->s_lock);
577
578         cur_state = attr_mask & IB_QP_CUR_STATE ?
579                 attr->cur_qp_state : qp->state;
580         new_state = attr_mask & IB_QP_STATE ? attr->qp_state : cur_state;
581
582         if (!ib_modify_qp_is_ok(cur_state, new_state, ibqp->qp_type,
583                                 attr_mask))
584                 goto inval;
585
586         if (attr_mask & IB_QP_AV) {
587                 if (attr->ah_attr.dlid >= QIB_MULTICAST_LID_BASE)
588                         goto inval;
589                 if (qib_check_ah(qp->ibqp.device, &attr->ah_attr))
590                         goto inval;
591         }
592
593         if (attr_mask & IB_QP_ALT_PATH) {
594                 if (attr->alt_ah_attr.dlid >= QIB_MULTICAST_LID_BASE)
595                         goto inval;
596                 if (qib_check_ah(qp->ibqp.device, &attr->alt_ah_attr))
597                         goto inval;
598                 if (attr->alt_pkey_index >= qib_get_npkeys(dd_from_dev(dev)))
599                         goto inval;
600         }
601
602         if (attr_mask & IB_QP_PKEY_INDEX)
603                 if (attr->pkey_index >= qib_get_npkeys(dd_from_dev(dev)))
604                         goto inval;
605
606         if (attr_mask & IB_QP_MIN_RNR_TIMER)
607                 if (attr->min_rnr_timer > 31)
608                         goto inval;
609
610         if (attr_mask & IB_QP_PORT)
611                 if (qp->ibqp.qp_type == IB_QPT_SMI ||
612                     qp->ibqp.qp_type == IB_QPT_GSI ||
613                     attr->port_num == 0 ||
614                     attr->port_num > ibqp->device->phys_port_cnt)
615                         goto inval;
616
617         if (attr_mask & IB_QP_DEST_QPN)
618                 if (attr->dest_qp_num > QIB_QPN_MASK)
619                         goto inval;
620
621         if (attr_mask & IB_QP_RETRY_CNT)
622                 if (attr->retry_cnt > 7)
623                         goto inval;
624
625         if (attr_mask & IB_QP_RNR_RETRY)
626                 if (attr->rnr_retry > 7)
627                         goto inval;
628
629         /*
630          * Don't allow invalid path_mtu values.  OK to set greater
631          * than the active mtu (or even the max_cap, if we have tuned
632          * that to a small mtu.  We'll set qp->path_mtu
633          * to the lesser of requested attribute mtu and active,
634          * for packetizing messages.
635          * Note that the QP port has to be set in INIT and MTU in RTR.
636          */
637         if (attr_mask & IB_QP_PATH_MTU) {
638                 struct qib_devdata *dd = dd_from_dev(dev);
639                 int mtu, pidx = qp->port_num - 1;
640
641                 mtu = ib_mtu_enum_to_int(attr->path_mtu);
642                 if (mtu == -1)
643                         goto inval;
644                 if (mtu > dd->pport[pidx].ibmtu) {
645                         switch (dd->pport[pidx].ibmtu) {
646                         case 4096:
647                                 pmtu = IB_MTU_4096;
648                                 break;
649                         case 2048:
650                                 pmtu = IB_MTU_2048;
651                                 break;
652                         case 1024:
653                                 pmtu = IB_MTU_1024;
654                                 break;
655                         case 512:
656                                 pmtu = IB_MTU_512;
657                                 break;
658                         case 256:
659                                 pmtu = IB_MTU_256;
660                                 break;
661                         default:
662                                 pmtu = IB_MTU_2048;
663                         }
664                 } else
665                         pmtu = attr->path_mtu;
666         }
667
668         if (attr_mask & IB_QP_PATH_MIG_STATE) {
669                 if (attr->path_mig_state == IB_MIG_REARM) {
670                         if (qp->s_mig_state == IB_MIG_ARMED)
671                                 goto inval;
672                         if (new_state != IB_QPS_RTS)
673                                 goto inval;
674                 } else if (attr->path_mig_state == IB_MIG_MIGRATED) {
675                         if (qp->s_mig_state == IB_MIG_REARM)
676                                 goto inval;
677                         if (new_state != IB_QPS_RTS && new_state != IB_QPS_SQD)
678                                 goto inval;
679                         if (qp->s_mig_state == IB_MIG_ARMED)
680                                 mig = 1;
681                 } else
682                         goto inval;
683         }
684
685         if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC)
686                 if (attr->max_dest_rd_atomic > QIB_MAX_RDMA_ATOMIC)
687                         goto inval;
688
689         switch (new_state) {
690         case IB_QPS_RESET:
691                 if (qp->state != IB_QPS_RESET) {
692                         qp->state = IB_QPS_RESET;
693                         spin_lock(&dev->pending_lock);
694                         if (!list_empty(&qp->iowait))
695                                 list_del_init(&qp->iowait);
696                         spin_unlock(&dev->pending_lock);
697                         qp->s_flags &= ~(QIB_S_TIMER | QIB_S_ANY_WAIT);
698                         spin_unlock(&qp->s_lock);
699                         spin_unlock_irq(&qp->r_lock);
700                         /* Stop the sending work queue and retry timer */
701                         cancel_work_sync(&qp->s_work);
702                         del_timer_sync(&qp->s_timer);
703                         wait_event(qp->wait_dma, !atomic_read(&qp->s_dma_busy));
704                         if (qp->s_tx) {
705                                 qib_put_txreq(qp->s_tx);
706                                 qp->s_tx = NULL;
707                         }
708                         remove_qp(dev, qp);
709                         wait_event(qp->wait, !atomic_read(&qp->refcount));
710                         spin_lock_irq(&qp->r_lock);
711                         spin_lock(&qp->s_lock);
712                         clear_mr_refs(qp, 1);
713                         qib_reset_qp(qp, ibqp->qp_type);
714                 }
715                 break;
716
717         case IB_QPS_RTR:
718                 /* Allow event to retrigger if QP set to RTR more than once */
719                 qp->r_flags &= ~QIB_R_COMM_EST;
720                 qp->state = new_state;
721                 break;
722
723         case IB_QPS_SQD:
724                 qp->s_draining = qp->s_last != qp->s_cur;
725                 qp->state = new_state;
726                 break;
727
728         case IB_QPS_SQE:
729                 if (qp->ibqp.qp_type == IB_QPT_RC)
730                         goto inval;
731                 qp->state = new_state;
732                 break;
733
734         case IB_QPS_ERR:
735                 lastwqe = qib_error_qp(qp, IB_WC_WR_FLUSH_ERR);
736                 break;
737
738         default:
739                 qp->state = new_state;
740                 break;
741         }
742
743         if (attr_mask & IB_QP_PKEY_INDEX)
744                 qp->s_pkey_index = attr->pkey_index;
745
746         if (attr_mask & IB_QP_PORT)
747                 qp->port_num = attr->port_num;
748
749         if (attr_mask & IB_QP_DEST_QPN)
750                 qp->remote_qpn = attr->dest_qp_num;
751
752         if (attr_mask & IB_QP_SQ_PSN) {
753                 qp->s_next_psn = attr->sq_psn & QIB_PSN_MASK;
754                 qp->s_psn = qp->s_next_psn;
755                 qp->s_sending_psn = qp->s_next_psn;
756                 qp->s_last_psn = qp->s_next_psn - 1;
757                 qp->s_sending_hpsn = qp->s_last_psn;
758         }
759
760         if (attr_mask & IB_QP_RQ_PSN)
761                 qp->r_psn = attr->rq_psn & QIB_PSN_MASK;
762
763         if (attr_mask & IB_QP_ACCESS_FLAGS)
764                 qp->qp_access_flags = attr->qp_access_flags;
765
766         if (attr_mask & IB_QP_AV) {
767                 qp->remote_ah_attr = attr->ah_attr;
768                 qp->s_srate = attr->ah_attr.static_rate;
769         }
770
771         if (attr_mask & IB_QP_ALT_PATH) {
772                 qp->alt_ah_attr = attr->alt_ah_attr;
773                 qp->s_alt_pkey_index = attr->alt_pkey_index;
774         }
775
776         if (attr_mask & IB_QP_PATH_MIG_STATE) {
777                 qp->s_mig_state = attr->path_mig_state;
778                 if (mig) {
779                         qp->remote_ah_attr = qp->alt_ah_attr;
780                         qp->port_num = qp->alt_ah_attr.port_num;
781                         qp->s_pkey_index = qp->s_alt_pkey_index;
782                 }
783         }
784
785         if (attr_mask & IB_QP_PATH_MTU) {
786                 qp->path_mtu = pmtu;
787                 qp->pmtu = ib_mtu_enum_to_int(pmtu);
788         }
789
790         if (attr_mask & IB_QP_RETRY_CNT) {
791                 qp->s_retry_cnt = attr->retry_cnt;
792                 qp->s_retry = attr->retry_cnt;
793         }
794
795         if (attr_mask & IB_QP_RNR_RETRY) {
796                 qp->s_rnr_retry_cnt = attr->rnr_retry;
797                 qp->s_rnr_retry = attr->rnr_retry;
798         }
799
800         if (attr_mask & IB_QP_MIN_RNR_TIMER)
801                 qp->r_min_rnr_timer = attr->min_rnr_timer;
802
803         if (attr_mask & IB_QP_TIMEOUT) {
804                 qp->timeout = attr->timeout;
805                 qp->timeout_jiffies =
806                         usecs_to_jiffies((4096UL * (1UL << qp->timeout)) /
807                                 1000UL);
808         }
809
810         if (attr_mask & IB_QP_QKEY)
811                 qp->qkey = attr->qkey;
812
813         if (attr_mask & IB_QP_MAX_DEST_RD_ATOMIC)
814                 qp->r_max_rd_atomic = attr->max_dest_rd_atomic;
815
816         if (attr_mask & IB_QP_MAX_QP_RD_ATOMIC)
817                 qp->s_max_rd_atomic = attr->max_rd_atomic;
818
819         spin_unlock(&qp->s_lock);
820         spin_unlock_irq(&qp->r_lock);
821
822         if (cur_state == IB_QPS_RESET && new_state == IB_QPS_INIT)
823                 insert_qp(dev, qp);
824
825         if (lastwqe) {
826                 ev.device = qp->ibqp.device;
827                 ev.element.qp = &qp->ibqp;
828                 ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
829                 qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
830         }
831         if (mig) {
832                 ev.device = qp->ibqp.device;
833                 ev.element.qp = &qp->ibqp;
834                 ev.event = IB_EVENT_PATH_MIG;
835                 qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
836         }
837         ret = 0;
838         goto bail;
839
840 inval:
841         spin_unlock(&qp->s_lock);
842         spin_unlock_irq(&qp->r_lock);
843         ret = -EINVAL;
844
845 bail:
846         return ret;
847 }
848
849 int qib_query_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
850                  int attr_mask, struct ib_qp_init_attr *init_attr)
851 {
852         struct qib_qp *qp = to_iqp(ibqp);
853
854         attr->qp_state = qp->state;
855         attr->cur_qp_state = attr->qp_state;
856         attr->path_mtu = qp->path_mtu;
857         attr->path_mig_state = qp->s_mig_state;
858         attr->qkey = qp->qkey;
859         attr->rq_psn = qp->r_psn & QIB_PSN_MASK;
860         attr->sq_psn = qp->s_next_psn & QIB_PSN_MASK;
861         attr->dest_qp_num = qp->remote_qpn;
862         attr->qp_access_flags = qp->qp_access_flags;
863         attr->cap.max_send_wr = qp->s_size - 1;
864         attr->cap.max_recv_wr = qp->ibqp.srq ? 0 : qp->r_rq.size - 1;
865         attr->cap.max_send_sge = qp->s_max_sge;
866         attr->cap.max_recv_sge = qp->r_rq.max_sge;
867         attr->cap.max_inline_data = 0;
868         attr->ah_attr = qp->remote_ah_attr;
869         attr->alt_ah_attr = qp->alt_ah_attr;
870         attr->pkey_index = qp->s_pkey_index;
871         attr->alt_pkey_index = qp->s_alt_pkey_index;
872         attr->en_sqd_async_notify = 0;
873         attr->sq_draining = qp->s_draining;
874         attr->max_rd_atomic = qp->s_max_rd_atomic;
875         attr->max_dest_rd_atomic = qp->r_max_rd_atomic;
876         attr->min_rnr_timer = qp->r_min_rnr_timer;
877         attr->port_num = qp->port_num;
878         attr->timeout = qp->timeout;
879         attr->retry_cnt = qp->s_retry_cnt;
880         attr->rnr_retry = qp->s_rnr_retry_cnt;
881         attr->alt_port_num = qp->alt_ah_attr.port_num;
882         attr->alt_timeout = qp->alt_timeout;
883
884         init_attr->event_handler = qp->ibqp.event_handler;
885         init_attr->qp_context = qp->ibqp.qp_context;
886         init_attr->send_cq = qp->ibqp.send_cq;
887         init_attr->recv_cq = qp->ibqp.recv_cq;
888         init_attr->srq = qp->ibqp.srq;
889         init_attr->cap = attr->cap;
890         if (qp->s_flags & QIB_S_SIGNAL_REQ_WR)
891                 init_attr->sq_sig_type = IB_SIGNAL_REQ_WR;
892         else
893                 init_attr->sq_sig_type = IB_SIGNAL_ALL_WR;
894         init_attr->qp_type = qp->ibqp.qp_type;
895         init_attr->port_num = qp->port_num;
896         return 0;
897 }
898
899 /**
900  * qib_compute_aeth - compute the AETH (syndrome + MSN)
901  * @qp: the queue pair to compute the AETH for
902  *
903  * Returns the AETH.
904  */
905 __be32 qib_compute_aeth(struct qib_qp *qp)
906 {
907         u32 aeth = qp->r_msn & QIB_MSN_MASK;
908
909         if (qp->ibqp.srq) {
910                 /*
911                  * Shared receive queues don't generate credits.
912                  * Set the credit field to the invalid value.
913                  */
914                 aeth |= QIB_AETH_CREDIT_INVAL << QIB_AETH_CREDIT_SHIFT;
915         } else {
916                 u32 min, max, x;
917                 u32 credits;
918                 struct qib_rwq *wq = qp->r_rq.wq;
919                 u32 head;
920                 u32 tail;
921
922                 /* sanity check pointers before trusting them */
923                 head = wq->head;
924                 if (head >= qp->r_rq.size)
925                         head = 0;
926                 tail = wq->tail;
927                 if (tail >= qp->r_rq.size)
928                         tail = 0;
929                 /*
930                  * Compute the number of credits available (RWQEs).
931                  * XXX Not holding the r_rq.lock here so there is a small
932                  * chance that the pair of reads are not atomic.
933                  */
934                 credits = head - tail;
935                 if ((int)credits < 0)
936                         credits += qp->r_rq.size;
937                 /*
938                  * Binary search the credit table to find the code to
939                  * use.
940                  */
941                 min = 0;
942                 max = 31;
943                 for (;;) {
944                         x = (min + max) / 2;
945                         if (credit_table[x] == credits)
946                                 break;
947                         if (credit_table[x] > credits)
948                                 max = x;
949                         else if (min == x)
950                                 break;
951                         else
952                                 min = x;
953                 }
954                 aeth |= x << QIB_AETH_CREDIT_SHIFT;
955         }
956         return cpu_to_be32(aeth);
957 }
958
959 /**
960  * qib_create_qp - create a queue pair for a device
961  * @ibpd: the protection domain who's device we create the queue pair for
962  * @init_attr: the attributes of the queue pair
963  * @udata: user data for libibverbs.so
964  *
965  * Returns the queue pair on success, otherwise returns an errno.
966  *
967  * Called by the ib_create_qp() core verbs function.
968  */
969 struct ib_qp *qib_create_qp(struct ib_pd *ibpd,
970                             struct ib_qp_init_attr *init_attr,
971                             struct ib_udata *udata)
972 {
973         struct qib_qp *qp;
974         int err;
975         struct qib_swqe *swq = NULL;
976         struct qib_ibdev *dev;
977         struct qib_devdata *dd;
978         size_t sz;
979         size_t sg_list_sz;
980         struct ib_qp *ret;
981
982         if (init_attr->cap.max_send_sge > ib_qib_max_sges ||
983             init_attr->cap.max_send_wr > ib_qib_max_qp_wrs) {
984                 ret = ERR_PTR(-EINVAL);
985                 goto bail;
986         }
987
988         /* Check receive queue parameters if no SRQ is specified. */
989         if (!init_attr->srq) {
990                 if (init_attr->cap.max_recv_sge > ib_qib_max_sges ||
991                     init_attr->cap.max_recv_wr > ib_qib_max_qp_wrs) {
992                         ret = ERR_PTR(-EINVAL);
993                         goto bail;
994                 }
995                 if (init_attr->cap.max_send_sge +
996                     init_attr->cap.max_send_wr +
997                     init_attr->cap.max_recv_sge +
998                     init_attr->cap.max_recv_wr == 0) {
999                         ret = ERR_PTR(-EINVAL);
1000                         goto bail;
1001                 }
1002         }
1003
1004         switch (init_attr->qp_type) {
1005         case IB_QPT_SMI:
1006         case IB_QPT_GSI:
1007                 if (init_attr->port_num == 0 ||
1008                     init_attr->port_num > ibpd->device->phys_port_cnt) {
1009                         ret = ERR_PTR(-EINVAL);
1010                         goto bail;
1011                 }
1012         case IB_QPT_UC:
1013         case IB_QPT_RC:
1014         case IB_QPT_UD:
1015                 sz = sizeof(struct qib_sge) *
1016                         init_attr->cap.max_send_sge +
1017                         sizeof(struct qib_swqe);
1018                 swq = vmalloc((init_attr->cap.max_send_wr + 1) * sz);
1019                 if (swq == NULL) {
1020                         ret = ERR_PTR(-ENOMEM);
1021                         goto bail;
1022                 }
1023                 sz = sizeof(*qp);
1024                 sg_list_sz = 0;
1025                 if (init_attr->srq) {
1026                         struct qib_srq *srq = to_isrq(init_attr->srq);
1027
1028                         if (srq->rq.max_sge > 1)
1029                                 sg_list_sz = sizeof(*qp->r_sg_list) *
1030                                         (srq->rq.max_sge - 1);
1031                 } else if (init_attr->cap.max_recv_sge > 1)
1032                         sg_list_sz = sizeof(*qp->r_sg_list) *
1033                                 (init_attr->cap.max_recv_sge - 1);
1034                 qp = kzalloc(sz + sg_list_sz, GFP_KERNEL);
1035                 if (!qp) {
1036                         ret = ERR_PTR(-ENOMEM);
1037                         goto bail_swq;
1038                 }
1039                 RCU_INIT_POINTER(qp->next, NULL);
1040                 qp->s_hdr = kzalloc(sizeof(*qp->s_hdr), GFP_KERNEL);
1041                 if (!qp->s_hdr) {
1042                         ret = ERR_PTR(-ENOMEM);
1043                         goto bail_qp;
1044                 }
1045                 qp->timeout_jiffies =
1046                         usecs_to_jiffies((4096UL * (1UL << qp->timeout)) /
1047                                 1000UL);
1048                 if (init_attr->srq)
1049                         sz = 0;
1050                 else {
1051                         qp->r_rq.size = init_attr->cap.max_recv_wr + 1;
1052                         qp->r_rq.max_sge = init_attr->cap.max_recv_sge;
1053                         sz = (sizeof(struct ib_sge) * qp->r_rq.max_sge) +
1054                                 sizeof(struct qib_rwqe);
1055                         qp->r_rq.wq = vmalloc_user(sizeof(struct qib_rwq) +
1056                                                    qp->r_rq.size * sz);
1057                         if (!qp->r_rq.wq) {
1058                                 ret = ERR_PTR(-ENOMEM);
1059                                 goto bail_qp;
1060                         }
1061                 }
1062
1063                 /*
1064                  * ib_create_qp() will initialize qp->ibqp
1065                  * except for qp->ibqp.qp_num.
1066                  */
1067                 spin_lock_init(&qp->r_lock);
1068                 spin_lock_init(&qp->s_lock);
1069                 spin_lock_init(&qp->r_rq.lock);
1070                 atomic_set(&qp->refcount, 0);
1071                 init_waitqueue_head(&qp->wait);
1072                 init_waitqueue_head(&qp->wait_dma);
1073                 init_timer(&qp->s_timer);
1074                 qp->s_timer.data = (unsigned long)qp;
1075                 INIT_WORK(&qp->s_work, qib_do_send);
1076                 INIT_LIST_HEAD(&qp->iowait);
1077                 INIT_LIST_HEAD(&qp->rspwait);
1078                 qp->state = IB_QPS_RESET;
1079                 qp->s_wq = swq;
1080                 qp->s_size = init_attr->cap.max_send_wr + 1;
1081                 qp->s_max_sge = init_attr->cap.max_send_sge;
1082                 if (init_attr->sq_sig_type == IB_SIGNAL_REQ_WR)
1083                         qp->s_flags = QIB_S_SIGNAL_REQ_WR;
1084                 dev = to_idev(ibpd->device);
1085                 dd = dd_from_dev(dev);
1086                 err = alloc_qpn(dd, &dev->qpn_table, init_attr->qp_type,
1087                                 init_attr->port_num);
1088                 if (err < 0) {
1089                         ret = ERR_PTR(err);
1090                         vfree(qp->r_rq.wq);
1091                         goto bail_qp;
1092                 }
1093                 qp->ibqp.qp_num = err;
1094                 qp->port_num = init_attr->port_num;
1095                 qib_reset_qp(qp, init_attr->qp_type);
1096                 break;
1097
1098         default:
1099                 /* Don't support raw QPs */
1100                 ret = ERR_PTR(-ENOSYS);
1101                 goto bail;
1102         }
1103
1104         init_attr->cap.max_inline_data = 0;
1105
1106         /*
1107          * Return the address of the RWQ as the offset to mmap.
1108          * See qib_mmap() for details.
1109          */
1110         if (udata && udata->outlen >= sizeof(__u64)) {
1111                 if (!qp->r_rq.wq) {
1112                         __u64 offset = 0;
1113
1114                         err = ib_copy_to_udata(udata, &offset,
1115                                                sizeof(offset));
1116                         if (err) {
1117                                 ret = ERR_PTR(err);
1118                                 goto bail_ip;
1119                         }
1120                 } else {
1121                         u32 s = sizeof(struct qib_rwq) + qp->r_rq.size * sz;
1122
1123                         qp->ip = qib_create_mmap_info(dev, s,
1124                                                       ibpd->uobject->context,
1125                                                       qp->r_rq.wq);
1126                         if (!qp->ip) {
1127                                 ret = ERR_PTR(-ENOMEM);
1128                                 goto bail_ip;
1129                         }
1130
1131                         err = ib_copy_to_udata(udata, &(qp->ip->offset),
1132                                                sizeof(qp->ip->offset));
1133                         if (err) {
1134                                 ret = ERR_PTR(err);
1135                                 goto bail_ip;
1136                         }
1137                 }
1138         }
1139
1140         spin_lock(&dev->n_qps_lock);
1141         if (dev->n_qps_allocated == ib_qib_max_qps) {
1142                 spin_unlock(&dev->n_qps_lock);
1143                 ret = ERR_PTR(-ENOMEM);
1144                 goto bail_ip;
1145         }
1146
1147         dev->n_qps_allocated++;
1148         spin_unlock(&dev->n_qps_lock);
1149
1150         if (qp->ip) {
1151                 spin_lock_irq(&dev->pending_lock);
1152                 list_add(&qp->ip->pending_mmaps, &dev->pending_mmaps);
1153                 spin_unlock_irq(&dev->pending_lock);
1154         }
1155
1156         ret = &qp->ibqp;
1157         goto bail;
1158
1159 bail_ip:
1160         if (qp->ip)
1161                 kref_put(&qp->ip->ref, qib_release_mmap_info);
1162         else
1163                 vfree(qp->r_rq.wq);
1164         free_qpn(&dev->qpn_table, qp->ibqp.qp_num);
1165 bail_qp:
1166         kfree(qp->s_hdr);
1167         kfree(qp);
1168 bail_swq:
1169         vfree(swq);
1170 bail:
1171         return ret;
1172 }
1173
1174 /**
1175  * qib_destroy_qp - destroy a queue pair
1176  * @ibqp: the queue pair to destroy
1177  *
1178  * Returns 0 on success.
1179  *
1180  * Note that this can be called while the QP is actively sending or
1181  * receiving!
1182  */
1183 int qib_destroy_qp(struct ib_qp *ibqp)
1184 {
1185         struct qib_qp *qp = to_iqp(ibqp);
1186         struct qib_ibdev *dev = to_idev(ibqp->device);
1187
1188         /* Make sure HW and driver activity is stopped. */
1189         spin_lock_irq(&qp->s_lock);
1190         if (qp->state != IB_QPS_RESET) {
1191                 qp->state = IB_QPS_RESET;
1192                 spin_lock(&dev->pending_lock);
1193                 if (!list_empty(&qp->iowait))
1194                         list_del_init(&qp->iowait);
1195                 spin_unlock(&dev->pending_lock);
1196                 qp->s_flags &= ~(QIB_S_TIMER | QIB_S_ANY_WAIT);
1197                 spin_unlock_irq(&qp->s_lock);
1198                 cancel_work_sync(&qp->s_work);
1199                 del_timer_sync(&qp->s_timer);
1200                 wait_event(qp->wait_dma, !atomic_read(&qp->s_dma_busy));
1201                 if (qp->s_tx) {
1202                         qib_put_txreq(qp->s_tx);
1203                         qp->s_tx = NULL;
1204                 }
1205                 remove_qp(dev, qp);
1206                 wait_event(qp->wait, !atomic_read(&qp->refcount));
1207                 clear_mr_refs(qp, 1);
1208         } else
1209                 spin_unlock_irq(&qp->s_lock);
1210
1211         /* all user's cleaned up, mark it available */
1212         free_qpn(&dev->qpn_table, qp->ibqp.qp_num);
1213         spin_lock(&dev->n_qps_lock);
1214         dev->n_qps_allocated--;
1215         spin_unlock(&dev->n_qps_lock);
1216
1217         if (qp->ip)
1218                 kref_put(&qp->ip->ref, qib_release_mmap_info);
1219         else
1220                 vfree(qp->r_rq.wq);
1221         vfree(qp->s_wq);
1222         kfree(qp->s_hdr);
1223         kfree(qp);
1224         return 0;
1225 }
1226
1227 /**
1228  * qib_init_qpn_table - initialize the QP number table for a device
1229  * @qpt: the QPN table
1230  */
1231 void qib_init_qpn_table(struct qib_devdata *dd, struct qib_qpn_table *qpt)
1232 {
1233         spin_lock_init(&qpt->lock);
1234         qpt->last = 1;          /* start with QPN 2 */
1235         qpt->nmaps = 1;
1236         qpt->mask = dd->qpn_mask;
1237 }
1238
1239 /**
1240  * qib_free_qpn_table - free the QP number table for a device
1241  * @qpt: the QPN table
1242  */
1243 void qib_free_qpn_table(struct qib_qpn_table *qpt)
1244 {
1245         int i;
1246
1247         for (i = 0; i < ARRAY_SIZE(qpt->map); i++)
1248                 if (qpt->map[i].page)
1249                         free_page((unsigned long) qpt->map[i].page);
1250 }
1251
1252 /**
1253  * qib_get_credit - flush the send work queue of a QP
1254  * @qp: the qp who's send work queue to flush
1255  * @aeth: the Acknowledge Extended Transport Header
1256  *
1257  * The QP s_lock should be held.
1258  */
1259 void qib_get_credit(struct qib_qp *qp, u32 aeth)
1260 {
1261         u32 credit = (aeth >> QIB_AETH_CREDIT_SHIFT) & QIB_AETH_CREDIT_MASK;
1262
1263         /*
1264          * If the credit is invalid, we can send
1265          * as many packets as we like.  Otherwise, we have to
1266          * honor the credit field.
1267          */
1268         if (credit == QIB_AETH_CREDIT_INVAL) {
1269                 if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT)) {
1270                         qp->s_flags |= QIB_S_UNLIMITED_CREDIT;
1271                         if (qp->s_flags & QIB_S_WAIT_SSN_CREDIT) {
1272                                 qp->s_flags &= ~QIB_S_WAIT_SSN_CREDIT;
1273                                 qib_schedule_send(qp);
1274                         }
1275                 }
1276         } else if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT)) {
1277                 /* Compute new LSN (i.e., MSN + credit) */
1278                 credit = (aeth + credit_table[credit]) & QIB_MSN_MASK;
1279                 if (qib_cmp24(credit, qp->s_lsn) > 0) {
1280                         qp->s_lsn = credit;
1281                         if (qp->s_flags & QIB_S_WAIT_SSN_CREDIT) {
1282                                 qp->s_flags &= ~QIB_S_WAIT_SSN_CREDIT;
1283                                 qib_schedule_send(qp);
1284                         }
1285                 }
1286         }
1287 }