894afac26f3b433da854f7d1b05ab11c435d9dc0
[pandora-kernel.git] / drivers / infiniband / hw / qib / qib_rc.c
1 /*
2  * Copyright (c) 2006, 2007, 2008, 2009 QLogic Corporation. All rights reserved.
3  * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
4  *
5  * This software is available to you under a choice of one of two
6  * licenses.  You may choose to be licensed under the terms of the GNU
7  * General Public License (GPL) Version 2, available from the file
8  * COPYING in the main directory of this source tree, or the
9  * OpenIB.org BSD license below:
10  *
11  *     Redistribution and use in source and binary forms, with or
12  *     without modification, are permitted provided that the following
13  *     conditions are met:
14  *
15  *      - Redistributions of source code must retain the above
16  *        copyright notice, this list of conditions and the following
17  *        disclaimer.
18  *
19  *      - Redistributions in binary form must reproduce the above
20  *        copyright notice, this list of conditions and the following
21  *        disclaimer in the documentation and/or other materials
22  *        provided with the distribution.
23  *
24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
28  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
29  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
30  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31  * SOFTWARE.
32  */
33
34 #include <linux/io.h>
35
36 #include "qib.h"
37
38 /* cut down ridiculously long IB macro names */
39 #define OP(x) IB_OPCODE_RC_##x
40
41 static void rc_timeout(unsigned long arg);
42
43 static u32 restart_sge(struct qib_sge_state *ss, struct qib_swqe *wqe,
44                        u32 psn, u32 pmtu)
45 {
46         u32 len;
47
48         len = ((psn - wqe->psn) & QIB_PSN_MASK) * pmtu;
49         ss->sge = wqe->sg_list[0];
50         ss->sg_list = wqe->sg_list + 1;
51         ss->num_sge = wqe->wr.num_sge;
52         ss->total_len = wqe->length;
53         qib_skip_sge(ss, len, 0);
54         return wqe->length - len;
55 }
56
57 static void start_timer(struct qib_qp *qp)
58 {
59         qp->s_flags |= QIB_S_TIMER;
60         qp->s_timer.function = rc_timeout;
61         /* 4.096 usec. * (1 << qp->timeout) */
62         qp->s_timer.expires = jiffies + qp->timeout_jiffies;
63         add_timer(&qp->s_timer);
64 }
65
66 /**
67  * qib_make_rc_ack - construct a response packet (ACK, NAK, or RDMA read)
68  * @dev: the device for this QP
69  * @qp: a pointer to the QP
70  * @ohdr: a pointer to the IB header being constructed
71  * @pmtu: the path MTU
72  *
73  * Return 1 if constructed; otherwise, return 0.
74  * Note that we are in the responder's side of the QP context.
75  * Note the QP s_lock must be held.
76  */
77 static int qib_make_rc_ack(struct qib_ibdev *dev, struct qib_qp *qp,
78                            struct qib_other_headers *ohdr, u32 pmtu)
79 {
80         struct qib_ack_entry *e;
81         u32 hwords;
82         u32 len;
83         u32 bth0;
84         u32 bth2;
85
86         /* Don't send an ACK if we aren't supposed to. */
87         if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK))
88                 goto bail;
89
90         /* header size in 32-bit words LRH+BTH = (8+12)/4. */
91         hwords = 5;
92
93         switch (qp->s_ack_state) {
94         case OP(RDMA_READ_RESPONSE_LAST):
95         case OP(RDMA_READ_RESPONSE_ONLY):
96                 e = &qp->s_ack_queue[qp->s_tail_ack_queue];
97                 if (e->rdma_sge.mr) {
98                         atomic_dec(&e->rdma_sge.mr->refcount);
99                         e->rdma_sge.mr = NULL;
100                 }
101                 /* FALLTHROUGH */
102         case OP(ATOMIC_ACKNOWLEDGE):
103                 /*
104                  * We can increment the tail pointer now that the last
105                  * response has been sent instead of only being
106                  * constructed.
107                  */
108                 if (++qp->s_tail_ack_queue > QIB_MAX_RDMA_ATOMIC)
109                         qp->s_tail_ack_queue = 0;
110                 /* FALLTHROUGH */
111         case OP(SEND_ONLY):
112         case OP(ACKNOWLEDGE):
113                 /* Check for no next entry in the queue. */
114                 if (qp->r_head_ack_queue == qp->s_tail_ack_queue) {
115                         if (qp->s_flags & QIB_S_ACK_PENDING)
116                                 goto normal;
117                         goto bail;
118                 }
119
120                 e = &qp->s_ack_queue[qp->s_tail_ack_queue];
121                 if (e->opcode == OP(RDMA_READ_REQUEST)) {
122                         /*
123                          * If a RDMA read response is being resent and
124                          * we haven't seen the duplicate request yet,
125                          * then stop sending the remaining responses the
126                          * responder has seen until the requester resends it.
127                          */
128                         len = e->rdma_sge.sge_length;
129                         if (len && !e->rdma_sge.mr) {
130                                 qp->s_tail_ack_queue = qp->r_head_ack_queue;
131                                 goto bail;
132                         }
133                         /* Copy SGE state in case we need to resend */
134                         qp->s_rdma_mr = e->rdma_sge.mr;
135                         if (qp->s_rdma_mr)
136                                 atomic_inc(&qp->s_rdma_mr->refcount);
137                         qp->s_ack_rdma_sge.sge = e->rdma_sge;
138                         qp->s_ack_rdma_sge.num_sge = 1;
139                         qp->s_cur_sge = &qp->s_ack_rdma_sge;
140                         if (len > pmtu) {
141                                 len = pmtu;
142                                 qp->s_ack_state = OP(RDMA_READ_RESPONSE_FIRST);
143                         } else {
144                                 qp->s_ack_state = OP(RDMA_READ_RESPONSE_ONLY);
145                                 e->sent = 1;
146                         }
147                         ohdr->u.aeth = qib_compute_aeth(qp);
148                         hwords++;
149                         qp->s_ack_rdma_psn = e->psn;
150                         bth2 = qp->s_ack_rdma_psn++ & QIB_PSN_MASK;
151                 } else {
152                         /* COMPARE_SWAP or FETCH_ADD */
153                         qp->s_cur_sge = NULL;
154                         len = 0;
155                         qp->s_ack_state = OP(ATOMIC_ACKNOWLEDGE);
156                         ohdr->u.at.aeth = qib_compute_aeth(qp);
157                         ohdr->u.at.atomic_ack_eth[0] =
158                                 cpu_to_be32(e->atomic_data >> 32);
159                         ohdr->u.at.atomic_ack_eth[1] =
160                                 cpu_to_be32(e->atomic_data);
161                         hwords += sizeof(ohdr->u.at) / sizeof(u32);
162                         bth2 = e->psn & QIB_PSN_MASK;
163                         e->sent = 1;
164                 }
165                 bth0 = qp->s_ack_state << 24;
166                 break;
167
168         case OP(RDMA_READ_RESPONSE_FIRST):
169                 qp->s_ack_state = OP(RDMA_READ_RESPONSE_MIDDLE);
170                 /* FALLTHROUGH */
171         case OP(RDMA_READ_RESPONSE_MIDDLE):
172                 qp->s_cur_sge = &qp->s_ack_rdma_sge;
173                 qp->s_rdma_mr = qp->s_ack_rdma_sge.sge.mr;
174                 if (qp->s_rdma_mr)
175                         atomic_inc(&qp->s_rdma_mr->refcount);
176                 len = qp->s_ack_rdma_sge.sge.sge_length;
177                 if (len > pmtu)
178                         len = pmtu;
179                 else {
180                         ohdr->u.aeth = qib_compute_aeth(qp);
181                         hwords++;
182                         qp->s_ack_state = OP(RDMA_READ_RESPONSE_LAST);
183                         e = &qp->s_ack_queue[qp->s_tail_ack_queue];
184                         e->sent = 1;
185                 }
186                 bth0 = qp->s_ack_state << 24;
187                 bth2 = qp->s_ack_rdma_psn++ & QIB_PSN_MASK;
188                 break;
189
190         default:
191 normal:
192                 /*
193                  * Send a regular ACK.
194                  * Set the s_ack_state so we wait until after sending
195                  * the ACK before setting s_ack_state to ACKNOWLEDGE
196                  * (see above).
197                  */
198                 qp->s_ack_state = OP(SEND_ONLY);
199                 qp->s_flags &= ~QIB_S_ACK_PENDING;
200                 qp->s_cur_sge = NULL;
201                 if (qp->s_nak_state)
202                         ohdr->u.aeth =
203                                 cpu_to_be32((qp->r_msn & QIB_MSN_MASK) |
204                                             (qp->s_nak_state <<
205                                              QIB_AETH_CREDIT_SHIFT));
206                 else
207                         ohdr->u.aeth = qib_compute_aeth(qp);
208                 hwords++;
209                 len = 0;
210                 bth0 = OP(ACKNOWLEDGE) << 24;
211                 bth2 = qp->s_ack_psn & QIB_PSN_MASK;
212         }
213         qp->s_rdma_ack_cnt++;
214         qp->s_hdrwords = hwords;
215         qp->s_cur_size = len;
216         qib_make_ruc_header(qp, ohdr, bth0, bth2);
217         return 1;
218
219 bail:
220         qp->s_ack_state = OP(ACKNOWLEDGE);
221         qp->s_flags &= ~(QIB_S_RESP_PENDING | QIB_S_ACK_PENDING);
222         return 0;
223 }
224
225 /**
226  * qib_make_rc_req - construct a request packet (SEND, RDMA r/w, ATOMIC)
227  * @qp: a pointer to the QP
228  *
229  * Return 1 if constructed; otherwise, return 0.
230  */
231 int qib_make_rc_req(struct qib_qp *qp)
232 {
233         struct qib_ibdev *dev = to_idev(qp->ibqp.device);
234         struct qib_other_headers *ohdr;
235         struct qib_sge_state *ss;
236         struct qib_swqe *wqe;
237         u32 hwords;
238         u32 len;
239         u32 bth0;
240         u32 bth2;
241         u32 pmtu = qp->pmtu;
242         char newreq;
243         unsigned long flags;
244         int ret = 0;
245         int delta;
246
247         ohdr = &qp->s_hdr.u.oth;
248         if (qp->remote_ah_attr.ah_flags & IB_AH_GRH)
249                 ohdr = &qp->s_hdr.u.l.oth;
250
251         /*
252          * The lock is needed to synchronize between the sending tasklet,
253          * the receive interrupt handler, and timeout resends.
254          */
255         spin_lock_irqsave(&qp->s_lock, flags);
256
257         /* Sending responses has higher priority over sending requests. */
258         if ((qp->s_flags & QIB_S_RESP_PENDING) &&
259             qib_make_rc_ack(dev, qp, ohdr, pmtu))
260                 goto done;
261
262         if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_SEND_OK)) {
263                 if (!(ib_qib_state_ops[qp->state] & QIB_FLUSH_SEND))
264                         goto bail;
265                 /* We are in the error state, flush the work request. */
266                 if (qp->s_last == qp->s_head)
267                         goto bail;
268                 /* If DMAs are in progress, we can't flush immediately. */
269                 if (atomic_read(&qp->s_dma_busy)) {
270                         qp->s_flags |= QIB_S_WAIT_DMA;
271                         goto bail;
272                 }
273                 wqe = get_swqe_ptr(qp, qp->s_last);
274                 qib_send_complete(qp, wqe, qp->s_last != qp->s_acked ?
275                         IB_WC_SUCCESS : IB_WC_WR_FLUSH_ERR);
276                 /* will get called again */
277                 goto done;
278         }
279
280         if (qp->s_flags & (QIB_S_WAIT_RNR | QIB_S_WAIT_ACK))
281                 goto bail;
282
283         if (qib_cmp24(qp->s_psn, qp->s_sending_hpsn) <= 0) {
284                 if (qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) <= 0) {
285                         qp->s_flags |= QIB_S_WAIT_PSN;
286                         goto bail;
287                 }
288                 qp->s_sending_psn = qp->s_psn;
289                 qp->s_sending_hpsn = qp->s_psn - 1;
290         }
291
292         /* header size in 32-bit words LRH+BTH = (8+12)/4. */
293         hwords = 5;
294         bth0 = 0;
295
296         /* Send a request. */
297         wqe = get_swqe_ptr(qp, qp->s_cur);
298         switch (qp->s_state) {
299         default:
300                 if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_NEXT_SEND_OK))
301                         goto bail;
302                 /*
303                  * Resend an old request or start a new one.
304                  *
305                  * We keep track of the current SWQE so that
306                  * we don't reset the "furthest progress" state
307                  * if we need to back up.
308                  */
309                 newreq = 0;
310                 if (qp->s_cur == qp->s_tail) {
311                         /* Check if send work queue is empty. */
312                         if (qp->s_tail == qp->s_head)
313                                 goto bail;
314                         /*
315                          * If a fence is requested, wait for previous
316                          * RDMA read and atomic operations to finish.
317                          */
318                         if ((wqe->wr.send_flags & IB_SEND_FENCE) &&
319                             qp->s_num_rd_atomic) {
320                                 qp->s_flags |= QIB_S_WAIT_FENCE;
321                                 goto bail;
322                         }
323                         wqe->psn = qp->s_next_psn;
324                         newreq = 1;
325                 }
326                 /*
327                  * Note that we have to be careful not to modify the
328                  * original work request since we may need to resend
329                  * it.
330                  */
331                 len = wqe->length;
332                 ss = &qp->s_sge;
333                 bth2 = qp->s_psn & QIB_PSN_MASK;
334                 switch (wqe->wr.opcode) {
335                 case IB_WR_SEND:
336                 case IB_WR_SEND_WITH_IMM:
337                         /* If no credit, return. */
338                         if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT) &&
339                             qib_cmp24(wqe->ssn, qp->s_lsn + 1) > 0) {
340                                 qp->s_flags |= QIB_S_WAIT_SSN_CREDIT;
341                                 goto bail;
342                         }
343                         wqe->lpsn = wqe->psn;
344                         if (len > pmtu) {
345                                 wqe->lpsn += (len - 1) / pmtu;
346                                 qp->s_state = OP(SEND_FIRST);
347                                 len = pmtu;
348                                 break;
349                         }
350                         if (wqe->wr.opcode == IB_WR_SEND)
351                                 qp->s_state = OP(SEND_ONLY);
352                         else {
353                                 qp->s_state = OP(SEND_ONLY_WITH_IMMEDIATE);
354                                 /* Immediate data comes after the BTH */
355                                 ohdr->u.imm_data = wqe->wr.ex.imm_data;
356                                 hwords += 1;
357                         }
358                         if (wqe->wr.send_flags & IB_SEND_SOLICITED)
359                                 bth0 |= IB_BTH_SOLICITED;
360                         bth2 |= IB_BTH_REQ_ACK;
361                         if (++qp->s_cur == qp->s_size)
362                                 qp->s_cur = 0;
363                         break;
364
365                 case IB_WR_RDMA_WRITE:
366                         if (newreq && !(qp->s_flags & QIB_S_UNLIMITED_CREDIT))
367                                 qp->s_lsn++;
368                         /* FALLTHROUGH */
369                 case IB_WR_RDMA_WRITE_WITH_IMM:
370                         /* If no credit, return. */
371                         if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT) &&
372                             qib_cmp24(wqe->ssn, qp->s_lsn + 1) > 0) {
373                                 qp->s_flags |= QIB_S_WAIT_SSN_CREDIT;
374                                 goto bail;
375                         }
376                         ohdr->u.rc.reth.vaddr =
377                                 cpu_to_be64(wqe->wr.wr.rdma.remote_addr);
378                         ohdr->u.rc.reth.rkey =
379                                 cpu_to_be32(wqe->wr.wr.rdma.rkey);
380                         ohdr->u.rc.reth.length = cpu_to_be32(len);
381                         hwords += sizeof(struct ib_reth) / sizeof(u32);
382                         wqe->lpsn = wqe->psn;
383                         if (len > pmtu) {
384                                 wqe->lpsn += (len - 1) / pmtu;
385                                 qp->s_state = OP(RDMA_WRITE_FIRST);
386                                 len = pmtu;
387                                 break;
388                         }
389                         if (wqe->wr.opcode == IB_WR_RDMA_WRITE)
390                                 qp->s_state = OP(RDMA_WRITE_ONLY);
391                         else {
392                                 qp->s_state =
393                                         OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE);
394                                 /* Immediate data comes after RETH */
395                                 ohdr->u.rc.imm_data = wqe->wr.ex.imm_data;
396                                 hwords += 1;
397                                 if (wqe->wr.send_flags & IB_SEND_SOLICITED)
398                                         bth0 |= IB_BTH_SOLICITED;
399                         }
400                         bth2 |= IB_BTH_REQ_ACK;
401                         if (++qp->s_cur == qp->s_size)
402                                 qp->s_cur = 0;
403                         break;
404
405                 case IB_WR_RDMA_READ:
406                         /*
407                          * Don't allow more operations to be started
408                          * than the QP limits allow.
409                          */
410                         if (newreq) {
411                                 if (qp->s_num_rd_atomic >=
412                                     qp->s_max_rd_atomic) {
413                                         qp->s_flags |= QIB_S_WAIT_RDMAR;
414                                         goto bail;
415                                 }
416                                 qp->s_num_rd_atomic++;
417                                 if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT))
418                                         qp->s_lsn++;
419                                 /*
420                                  * Adjust s_next_psn to count the
421                                  * expected number of responses.
422                                  */
423                                 if (len > pmtu)
424                                         qp->s_next_psn += (len - 1) / pmtu;
425                                 wqe->lpsn = qp->s_next_psn++;
426                         }
427                         ohdr->u.rc.reth.vaddr =
428                                 cpu_to_be64(wqe->wr.wr.rdma.remote_addr);
429                         ohdr->u.rc.reth.rkey =
430                                 cpu_to_be32(wqe->wr.wr.rdma.rkey);
431                         ohdr->u.rc.reth.length = cpu_to_be32(len);
432                         qp->s_state = OP(RDMA_READ_REQUEST);
433                         hwords += sizeof(ohdr->u.rc.reth) / sizeof(u32);
434                         ss = NULL;
435                         len = 0;
436                         bth2 |= IB_BTH_REQ_ACK;
437                         if (++qp->s_cur == qp->s_size)
438                                 qp->s_cur = 0;
439                         break;
440
441                 case IB_WR_ATOMIC_CMP_AND_SWP:
442                 case IB_WR_ATOMIC_FETCH_AND_ADD:
443                         /*
444                          * Don't allow more operations to be started
445                          * than the QP limits allow.
446                          */
447                         if (newreq) {
448                                 if (qp->s_num_rd_atomic >=
449                                     qp->s_max_rd_atomic) {
450                                         qp->s_flags |= QIB_S_WAIT_RDMAR;
451                                         goto bail;
452                                 }
453                                 qp->s_num_rd_atomic++;
454                                 if (!(qp->s_flags & QIB_S_UNLIMITED_CREDIT))
455                                         qp->s_lsn++;
456                                 wqe->lpsn = wqe->psn;
457                         }
458                         if (wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP) {
459                                 qp->s_state = OP(COMPARE_SWAP);
460                                 ohdr->u.atomic_eth.swap_data = cpu_to_be64(
461                                         wqe->wr.wr.atomic.swap);
462                                 ohdr->u.atomic_eth.compare_data = cpu_to_be64(
463                                         wqe->wr.wr.atomic.compare_add);
464                         } else {
465                                 qp->s_state = OP(FETCH_ADD);
466                                 ohdr->u.atomic_eth.swap_data = cpu_to_be64(
467                                         wqe->wr.wr.atomic.compare_add);
468                                 ohdr->u.atomic_eth.compare_data = 0;
469                         }
470                         ohdr->u.atomic_eth.vaddr[0] = cpu_to_be32(
471                                 wqe->wr.wr.atomic.remote_addr >> 32);
472                         ohdr->u.atomic_eth.vaddr[1] = cpu_to_be32(
473                                 wqe->wr.wr.atomic.remote_addr);
474                         ohdr->u.atomic_eth.rkey = cpu_to_be32(
475                                 wqe->wr.wr.atomic.rkey);
476                         hwords += sizeof(struct ib_atomic_eth) / sizeof(u32);
477                         ss = NULL;
478                         len = 0;
479                         bth2 |= IB_BTH_REQ_ACK;
480                         if (++qp->s_cur == qp->s_size)
481                                 qp->s_cur = 0;
482                         break;
483
484                 default:
485                         goto bail;
486                 }
487                 qp->s_sge.sge = wqe->sg_list[0];
488                 qp->s_sge.sg_list = wqe->sg_list + 1;
489                 qp->s_sge.num_sge = wqe->wr.num_sge;
490                 qp->s_sge.total_len = wqe->length;
491                 qp->s_len = wqe->length;
492                 if (newreq) {
493                         qp->s_tail++;
494                         if (qp->s_tail >= qp->s_size)
495                                 qp->s_tail = 0;
496                 }
497                 if (wqe->wr.opcode == IB_WR_RDMA_READ)
498                         qp->s_psn = wqe->lpsn + 1;
499                 else {
500                         qp->s_psn++;
501                         if (qib_cmp24(qp->s_psn, qp->s_next_psn) > 0)
502                                 qp->s_next_psn = qp->s_psn;
503                 }
504                 break;
505
506         case OP(RDMA_READ_RESPONSE_FIRST):
507                 /*
508                  * qp->s_state is normally set to the opcode of the
509                  * last packet constructed for new requests and therefore
510                  * is never set to RDMA read response.
511                  * RDMA_READ_RESPONSE_FIRST is used by the ACK processing
512                  * thread to indicate a SEND needs to be restarted from an
513                  * earlier PSN without interferring with the sending thread.
514                  * See qib_restart_rc().
515                  */
516                 qp->s_len = restart_sge(&qp->s_sge, wqe, qp->s_psn, pmtu);
517                 /* FALLTHROUGH */
518         case OP(SEND_FIRST):
519                 qp->s_state = OP(SEND_MIDDLE);
520                 /* FALLTHROUGH */
521         case OP(SEND_MIDDLE):
522                 bth2 = qp->s_psn++ & QIB_PSN_MASK;
523                 if (qib_cmp24(qp->s_psn, qp->s_next_psn) > 0)
524                         qp->s_next_psn = qp->s_psn;
525                 ss = &qp->s_sge;
526                 len = qp->s_len;
527                 if (len > pmtu) {
528                         len = pmtu;
529                         break;
530                 }
531                 if (wqe->wr.opcode == IB_WR_SEND)
532                         qp->s_state = OP(SEND_LAST);
533                 else {
534                         qp->s_state = OP(SEND_LAST_WITH_IMMEDIATE);
535                         /* Immediate data comes after the BTH */
536                         ohdr->u.imm_data = wqe->wr.ex.imm_data;
537                         hwords += 1;
538                 }
539                 if (wqe->wr.send_flags & IB_SEND_SOLICITED)
540                         bth0 |= IB_BTH_SOLICITED;
541                 bth2 |= IB_BTH_REQ_ACK;
542                 qp->s_cur++;
543                 if (qp->s_cur >= qp->s_size)
544                         qp->s_cur = 0;
545                 break;
546
547         case OP(RDMA_READ_RESPONSE_LAST):
548                 /*
549                  * qp->s_state is normally set to the opcode of the
550                  * last packet constructed for new requests and therefore
551                  * is never set to RDMA read response.
552                  * RDMA_READ_RESPONSE_LAST is used by the ACK processing
553                  * thread to indicate a RDMA write needs to be restarted from
554                  * an earlier PSN without interferring with the sending thread.
555                  * See qib_restart_rc().
556                  */
557                 qp->s_len = restart_sge(&qp->s_sge, wqe, qp->s_psn, pmtu);
558                 /* FALLTHROUGH */
559         case OP(RDMA_WRITE_FIRST):
560                 qp->s_state = OP(RDMA_WRITE_MIDDLE);
561                 /* FALLTHROUGH */
562         case OP(RDMA_WRITE_MIDDLE):
563                 bth2 = qp->s_psn++ & QIB_PSN_MASK;
564                 if (qib_cmp24(qp->s_psn, qp->s_next_psn) > 0)
565                         qp->s_next_psn = qp->s_psn;
566                 ss = &qp->s_sge;
567                 len = qp->s_len;
568                 if (len > pmtu) {
569                         len = pmtu;
570                         break;
571                 }
572                 if (wqe->wr.opcode == IB_WR_RDMA_WRITE)
573                         qp->s_state = OP(RDMA_WRITE_LAST);
574                 else {
575                         qp->s_state = OP(RDMA_WRITE_LAST_WITH_IMMEDIATE);
576                         /* Immediate data comes after the BTH */
577                         ohdr->u.imm_data = wqe->wr.ex.imm_data;
578                         hwords += 1;
579                         if (wqe->wr.send_flags & IB_SEND_SOLICITED)
580                                 bth0 |= IB_BTH_SOLICITED;
581                 }
582                 bth2 |= IB_BTH_REQ_ACK;
583                 qp->s_cur++;
584                 if (qp->s_cur >= qp->s_size)
585                         qp->s_cur = 0;
586                 break;
587
588         case OP(RDMA_READ_RESPONSE_MIDDLE):
589                 /*
590                  * qp->s_state is normally set to the opcode of the
591                  * last packet constructed for new requests and therefore
592                  * is never set to RDMA read response.
593                  * RDMA_READ_RESPONSE_MIDDLE is used by the ACK processing
594                  * thread to indicate a RDMA read needs to be restarted from
595                  * an earlier PSN without interferring with the sending thread.
596                  * See qib_restart_rc().
597                  */
598                 len = ((qp->s_psn - wqe->psn) & QIB_PSN_MASK) * pmtu;
599                 ohdr->u.rc.reth.vaddr =
600                         cpu_to_be64(wqe->wr.wr.rdma.remote_addr + len);
601                 ohdr->u.rc.reth.rkey =
602                         cpu_to_be32(wqe->wr.wr.rdma.rkey);
603                 ohdr->u.rc.reth.length = cpu_to_be32(wqe->length - len);
604                 qp->s_state = OP(RDMA_READ_REQUEST);
605                 hwords += sizeof(ohdr->u.rc.reth) / sizeof(u32);
606                 bth2 = (qp->s_psn & QIB_PSN_MASK) | IB_BTH_REQ_ACK;
607                 qp->s_psn = wqe->lpsn + 1;
608                 ss = NULL;
609                 len = 0;
610                 qp->s_cur++;
611                 if (qp->s_cur == qp->s_size)
612                         qp->s_cur = 0;
613                 break;
614         }
615         qp->s_sending_hpsn = bth2;
616         delta = (((int) bth2 - (int) wqe->psn) << 8) >> 8;
617         if (delta && delta % QIB_PSN_CREDIT == 0)
618                 bth2 |= IB_BTH_REQ_ACK;
619         if (qp->s_flags & QIB_S_SEND_ONE) {
620                 qp->s_flags &= ~QIB_S_SEND_ONE;
621                 qp->s_flags |= QIB_S_WAIT_ACK;
622                 bth2 |= IB_BTH_REQ_ACK;
623         }
624         qp->s_len -= len;
625         qp->s_hdrwords = hwords;
626         qp->s_cur_sge = ss;
627         qp->s_cur_size = len;
628         qib_make_ruc_header(qp, ohdr, bth0 | (qp->s_state << 24), bth2);
629 done:
630         ret = 1;
631         goto unlock;
632
633 bail:
634         qp->s_flags &= ~QIB_S_BUSY;
635 unlock:
636         spin_unlock_irqrestore(&qp->s_lock, flags);
637         return ret;
638 }
639
640 /**
641  * qib_send_rc_ack - Construct an ACK packet and send it
642  * @qp: a pointer to the QP
643  *
644  * This is called from qib_rc_rcv() and qib_kreceive().
645  * Note that RDMA reads and atomics are handled in the
646  * send side QP state and tasklet.
647  */
648 void qib_send_rc_ack(struct qib_qp *qp)
649 {
650         struct qib_devdata *dd = dd_from_ibdev(qp->ibqp.device);
651         struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
652         struct qib_pportdata *ppd = ppd_from_ibp(ibp);
653         u64 pbc;
654         u16 lrh0;
655         u32 bth0;
656         u32 hwords;
657         u32 pbufn;
658         u32 __iomem *piobuf;
659         struct qib_ib_header hdr;
660         struct qib_other_headers *ohdr;
661         u32 control;
662         unsigned long flags;
663
664         spin_lock_irqsave(&qp->s_lock, flags);
665
666         if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK))
667                 goto unlock;
668
669         /* Don't send ACK or NAK if a RDMA read or atomic is pending. */
670         if ((qp->s_flags & QIB_S_RESP_PENDING) || qp->s_rdma_ack_cnt)
671                 goto queue_ack;
672
673         /* Construct the header with s_lock held so APM doesn't change it. */
674         ohdr = &hdr.u.oth;
675         lrh0 = QIB_LRH_BTH;
676         /* header size in 32-bit words LRH+BTH+AETH = (8+12+4)/4. */
677         hwords = 6;
678         if (unlikely(qp->remote_ah_attr.ah_flags & IB_AH_GRH)) {
679                 hwords += qib_make_grh(ibp, &hdr.u.l.grh,
680                                        &qp->remote_ah_attr.grh, hwords, 0);
681                 ohdr = &hdr.u.l.oth;
682                 lrh0 = QIB_LRH_GRH;
683         }
684         /* read pkey_index w/o lock (its atomic) */
685         bth0 = qib_get_pkey(ibp, qp->s_pkey_index) | (OP(ACKNOWLEDGE) << 24);
686         if (qp->s_mig_state == IB_MIG_MIGRATED)
687                 bth0 |= IB_BTH_MIG_REQ;
688         if (qp->r_nak_state)
689                 ohdr->u.aeth = cpu_to_be32((qp->r_msn & QIB_MSN_MASK) |
690                                             (qp->r_nak_state <<
691                                              QIB_AETH_CREDIT_SHIFT));
692         else
693                 ohdr->u.aeth = qib_compute_aeth(qp);
694         lrh0 |= ibp->sl_to_vl[qp->remote_ah_attr.sl] << 12 |
695                 qp->remote_ah_attr.sl << 4;
696         hdr.lrh[0] = cpu_to_be16(lrh0);
697         hdr.lrh[1] = cpu_to_be16(qp->remote_ah_attr.dlid);
698         hdr.lrh[2] = cpu_to_be16(hwords + SIZE_OF_CRC);
699         hdr.lrh[3] = cpu_to_be16(ppd->lid | qp->remote_ah_attr.src_path_bits);
700         ohdr->bth[0] = cpu_to_be32(bth0);
701         ohdr->bth[1] = cpu_to_be32(qp->remote_qpn);
702         ohdr->bth[2] = cpu_to_be32(qp->r_ack_psn & QIB_PSN_MASK);
703
704         spin_unlock_irqrestore(&qp->s_lock, flags);
705
706         /* Don't try to send ACKs if the link isn't ACTIVE */
707         if (!(ppd->lflags & QIBL_LINKACTIVE))
708                 goto done;
709
710         control = dd->f_setpbc_control(ppd, hwords + SIZE_OF_CRC,
711                                        qp->s_srate, lrh0 >> 12);
712         /* length is + 1 for the control dword */
713         pbc = ((u64) control << 32) | (hwords + 1);
714
715         piobuf = dd->f_getsendbuf(ppd, pbc, &pbufn);
716         if (!piobuf) {
717                 /*
718                  * We are out of PIO buffers at the moment.
719                  * Pass responsibility for sending the ACK to the
720                  * send tasklet so that when a PIO buffer becomes
721                  * available, the ACK is sent ahead of other outgoing
722                  * packets.
723                  */
724                 spin_lock_irqsave(&qp->s_lock, flags);
725                 goto queue_ack;
726         }
727
728         /*
729          * Write the pbc.
730          * We have to flush after the PBC for correctness
731          * on some cpus or WC buffer can be written out of order.
732          */
733         writeq(pbc, piobuf);
734
735         if (dd->flags & QIB_PIO_FLUSH_WC) {
736                 u32 *hdrp = (u32 *) &hdr;
737
738                 qib_flush_wc();
739                 qib_pio_copy(piobuf + 2, hdrp, hwords - 1);
740                 qib_flush_wc();
741                 __raw_writel(hdrp[hwords - 1], piobuf + hwords + 1);
742         } else
743                 qib_pio_copy(piobuf + 2, (u32 *) &hdr, hwords);
744
745         if (dd->flags & QIB_USE_SPCL_TRIG) {
746                 u32 spcl_off = (pbufn >= dd->piobcnt2k) ? 2047 : 1023;
747
748                 qib_flush_wc();
749                 __raw_writel(0xaebecede, piobuf + spcl_off);
750         }
751
752         qib_flush_wc();
753         qib_sendbuf_done(dd, pbufn);
754
755         ibp->n_unicast_xmit++;
756         goto done;
757
758 queue_ack:
759         if (ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK) {
760                 ibp->n_rc_qacks++;
761                 qp->s_flags |= QIB_S_ACK_PENDING | QIB_S_RESP_PENDING;
762                 qp->s_nak_state = qp->r_nak_state;
763                 qp->s_ack_psn = qp->r_ack_psn;
764
765                 /* Schedule the send tasklet. */
766                 qib_schedule_send(qp);
767         }
768 unlock:
769         spin_unlock_irqrestore(&qp->s_lock, flags);
770 done:
771         return;
772 }
773
774 /**
775  * reset_psn - reset the QP state to send starting from PSN
776  * @qp: the QP
777  * @psn: the packet sequence number to restart at
778  *
779  * This is called from qib_rc_rcv() to process an incoming RC ACK
780  * for the given QP.
781  * Called at interrupt level with the QP s_lock held.
782  */
783 static void reset_psn(struct qib_qp *qp, u32 psn)
784 {
785         u32 n = qp->s_acked;
786         struct qib_swqe *wqe = get_swqe_ptr(qp, n);
787         u32 opcode;
788
789         qp->s_cur = n;
790
791         /*
792          * If we are starting the request from the beginning,
793          * let the normal send code handle initialization.
794          */
795         if (qib_cmp24(psn, wqe->psn) <= 0) {
796                 qp->s_state = OP(SEND_LAST);
797                 goto done;
798         }
799
800         /* Find the work request opcode corresponding to the given PSN. */
801         opcode = wqe->wr.opcode;
802         for (;;) {
803                 int diff;
804
805                 if (++n == qp->s_size)
806                         n = 0;
807                 if (n == qp->s_tail)
808                         break;
809                 wqe = get_swqe_ptr(qp, n);
810                 diff = qib_cmp24(psn, wqe->psn);
811                 if (diff < 0)
812                         break;
813                 qp->s_cur = n;
814                 /*
815                  * If we are starting the request from the beginning,
816                  * let the normal send code handle initialization.
817                  */
818                 if (diff == 0) {
819                         qp->s_state = OP(SEND_LAST);
820                         goto done;
821                 }
822                 opcode = wqe->wr.opcode;
823         }
824
825         /*
826          * Set the state to restart in the middle of a request.
827          * Don't change the s_sge, s_cur_sge, or s_cur_size.
828          * See qib_make_rc_req().
829          */
830         switch (opcode) {
831         case IB_WR_SEND:
832         case IB_WR_SEND_WITH_IMM:
833                 qp->s_state = OP(RDMA_READ_RESPONSE_FIRST);
834                 break;
835
836         case IB_WR_RDMA_WRITE:
837         case IB_WR_RDMA_WRITE_WITH_IMM:
838                 qp->s_state = OP(RDMA_READ_RESPONSE_LAST);
839                 break;
840
841         case IB_WR_RDMA_READ:
842                 qp->s_state = OP(RDMA_READ_RESPONSE_MIDDLE);
843                 break;
844
845         default:
846                 /*
847                  * This case shouldn't happen since its only
848                  * one PSN per req.
849                  */
850                 qp->s_state = OP(SEND_LAST);
851         }
852 done:
853         qp->s_psn = psn;
854         /*
855          * Set QIB_S_WAIT_PSN as qib_rc_complete() may start the timer
856          * asynchronously before the send tasklet can get scheduled.
857          * Doing it in qib_make_rc_req() is too late.
858          */
859         if ((qib_cmp24(qp->s_psn, qp->s_sending_hpsn) <= 0) &&
860             (qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) <= 0))
861                 qp->s_flags |= QIB_S_WAIT_PSN;
862 }
863
864 /*
865  * Back up requester to resend the last un-ACKed request.
866  * The QP r_lock and s_lock should be held and interrupts disabled.
867  */
868 static void qib_restart_rc(struct qib_qp *qp, u32 psn, int wait)
869 {
870         struct qib_swqe *wqe = get_swqe_ptr(qp, qp->s_acked);
871         struct qib_ibport *ibp;
872
873         if (qp->s_retry == 0) {
874                 if (qp->s_mig_state == IB_MIG_ARMED) {
875                         qib_migrate_qp(qp);
876                         qp->s_retry = qp->s_retry_cnt;
877                 } else if (qp->s_last == qp->s_acked) {
878                         qib_send_complete(qp, wqe, IB_WC_RETRY_EXC_ERR);
879                         qib_error_qp(qp, IB_WC_WR_FLUSH_ERR);
880                         return;
881                 } else /* XXX need to handle delayed completion */
882                         return;
883         } else
884                 qp->s_retry--;
885
886         ibp = to_iport(qp->ibqp.device, qp->port_num);
887         if (wqe->wr.opcode == IB_WR_RDMA_READ)
888                 ibp->n_rc_resends++;
889         else
890                 ibp->n_rc_resends += (qp->s_psn - psn) & QIB_PSN_MASK;
891
892         qp->s_flags &= ~(QIB_S_WAIT_FENCE | QIB_S_WAIT_RDMAR |
893                          QIB_S_WAIT_SSN_CREDIT | QIB_S_WAIT_PSN |
894                          QIB_S_WAIT_ACK);
895         if (wait)
896                 qp->s_flags |= QIB_S_SEND_ONE;
897         reset_psn(qp, psn);
898 }
899
900 /*
901  * This is called from s_timer for missing responses.
902  */
903 static void rc_timeout(unsigned long arg)
904 {
905         struct qib_qp *qp = (struct qib_qp *)arg;
906         struct qib_ibport *ibp;
907         unsigned long flags;
908
909         spin_lock_irqsave(&qp->r_lock, flags);
910         spin_lock(&qp->s_lock);
911         if (qp->s_flags & QIB_S_TIMER) {
912                 ibp = to_iport(qp->ibqp.device, qp->port_num);
913                 ibp->n_rc_timeouts++;
914                 qp->s_flags &= ~QIB_S_TIMER;
915                 del_timer(&qp->s_timer);
916                 qib_restart_rc(qp, qp->s_last_psn + 1, 1);
917                 qib_schedule_send(qp);
918         }
919         spin_unlock(&qp->s_lock);
920         spin_unlock_irqrestore(&qp->r_lock, flags);
921 }
922
923 /*
924  * This is called from s_timer for RNR timeouts.
925  */
926 void qib_rc_rnr_retry(unsigned long arg)
927 {
928         struct qib_qp *qp = (struct qib_qp *)arg;
929         unsigned long flags;
930
931         spin_lock_irqsave(&qp->s_lock, flags);
932         if (qp->s_flags & QIB_S_WAIT_RNR) {
933                 qp->s_flags &= ~QIB_S_WAIT_RNR;
934                 del_timer(&qp->s_timer);
935                 qib_schedule_send(qp);
936         }
937         spin_unlock_irqrestore(&qp->s_lock, flags);
938 }
939
940 /*
941  * Set qp->s_sending_psn to the next PSN after the given one.
942  * This would be psn+1 except when RDMA reads are present.
943  */
944 static void reset_sending_psn(struct qib_qp *qp, u32 psn)
945 {
946         struct qib_swqe *wqe;
947         u32 n = qp->s_last;
948
949         /* Find the work request corresponding to the given PSN. */
950         for (;;) {
951                 wqe = get_swqe_ptr(qp, n);
952                 if (qib_cmp24(psn, wqe->lpsn) <= 0) {
953                         if (wqe->wr.opcode == IB_WR_RDMA_READ)
954                                 qp->s_sending_psn = wqe->lpsn + 1;
955                         else
956                                 qp->s_sending_psn = psn + 1;
957                         break;
958                 }
959                 if (++n == qp->s_size)
960                         n = 0;
961                 if (n == qp->s_tail)
962                         break;
963         }
964 }
965
966 /*
967  * This should be called with the QP s_lock held and interrupts disabled.
968  */
969 void qib_rc_send_complete(struct qib_qp *qp, struct qib_ib_header *hdr)
970 {
971         struct qib_other_headers *ohdr;
972         struct qib_swqe *wqe;
973         struct ib_wc wc;
974         unsigned i;
975         u32 opcode;
976         u32 psn;
977
978         if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_OR_FLUSH_SEND))
979                 return;
980
981         /* Find out where the BTH is */
982         if ((be16_to_cpu(hdr->lrh[0]) & 3) == QIB_LRH_BTH)
983                 ohdr = &hdr->u.oth;
984         else
985                 ohdr = &hdr->u.l.oth;
986
987         opcode = be32_to_cpu(ohdr->bth[0]) >> 24;
988         if (opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
989             opcode <= OP(ATOMIC_ACKNOWLEDGE)) {
990                 WARN_ON(!qp->s_rdma_ack_cnt);
991                 qp->s_rdma_ack_cnt--;
992                 return;
993         }
994
995         psn = be32_to_cpu(ohdr->bth[2]);
996         reset_sending_psn(qp, psn);
997
998         /*
999          * Start timer after a packet requesting an ACK has been sent and
1000          * there are still requests that haven't been acked.
1001          */
1002         if ((psn & IB_BTH_REQ_ACK) && qp->s_acked != qp->s_tail &&
1003             !(qp->s_flags & (QIB_S_TIMER | QIB_S_WAIT_RNR | QIB_S_WAIT_PSN)) &&
1004             (ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK))
1005                 start_timer(qp);
1006
1007         while (qp->s_last != qp->s_acked) {
1008                 wqe = get_swqe_ptr(qp, qp->s_last);
1009                 if (qib_cmp24(wqe->lpsn, qp->s_sending_psn) >= 0 &&
1010                     qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) <= 0)
1011                         break;
1012                 for (i = 0; i < wqe->wr.num_sge; i++) {
1013                         struct qib_sge *sge = &wqe->sg_list[i];
1014
1015                         atomic_dec(&sge->mr->refcount);
1016                 }
1017                 /* Post a send completion queue entry if requested. */
1018                 if (!(qp->s_flags & QIB_S_SIGNAL_REQ_WR) ||
1019                     (wqe->wr.send_flags & IB_SEND_SIGNALED)) {
1020                         memset(&wc, 0, sizeof wc);
1021                         wc.wr_id = wqe->wr.wr_id;
1022                         wc.status = IB_WC_SUCCESS;
1023                         wc.opcode = ib_qib_wc_opcode[wqe->wr.opcode];
1024                         wc.byte_len = wqe->length;
1025                         wc.qp = &qp->ibqp;
1026                         qib_cq_enter(to_icq(qp->ibqp.send_cq), &wc, 0);
1027                 }
1028                 if (++qp->s_last >= qp->s_size)
1029                         qp->s_last = 0;
1030         }
1031         /*
1032          * If we were waiting for sends to complete before resending,
1033          * and they are now complete, restart sending.
1034          */
1035         if (qp->s_flags & QIB_S_WAIT_PSN &&
1036             qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) > 0) {
1037                 qp->s_flags &= ~QIB_S_WAIT_PSN;
1038                 qp->s_sending_psn = qp->s_psn;
1039                 qp->s_sending_hpsn = qp->s_psn - 1;
1040                 qib_schedule_send(qp);
1041         }
1042 }
1043
1044 static inline void update_last_psn(struct qib_qp *qp, u32 psn)
1045 {
1046         qp->s_last_psn = psn;
1047 }
1048
1049 /*
1050  * Generate a SWQE completion.
1051  * This is similar to qib_send_complete but has to check to be sure
1052  * that the SGEs are not being referenced if the SWQE is being resent.
1053  */
1054 static struct qib_swqe *do_rc_completion(struct qib_qp *qp,
1055                                          struct qib_swqe *wqe,
1056                                          struct qib_ibport *ibp)
1057 {
1058         struct ib_wc wc;
1059         unsigned i;
1060
1061         /*
1062          * Don't decrement refcount and don't generate a
1063          * completion if the SWQE is being resent until the send
1064          * is finished.
1065          */
1066         if (qib_cmp24(wqe->lpsn, qp->s_sending_psn) < 0 ||
1067             qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) > 0) {
1068                 for (i = 0; i < wqe->wr.num_sge; i++) {
1069                         struct qib_sge *sge = &wqe->sg_list[i];
1070
1071                         atomic_dec(&sge->mr->refcount);
1072                 }
1073                 /* Post a send completion queue entry if requested. */
1074                 if (!(qp->s_flags & QIB_S_SIGNAL_REQ_WR) ||
1075                     (wqe->wr.send_flags & IB_SEND_SIGNALED)) {
1076                         memset(&wc, 0, sizeof wc);
1077                         wc.wr_id = wqe->wr.wr_id;
1078                         wc.status = IB_WC_SUCCESS;
1079                         wc.opcode = ib_qib_wc_opcode[wqe->wr.opcode];
1080                         wc.byte_len = wqe->length;
1081                         wc.qp = &qp->ibqp;
1082                         qib_cq_enter(to_icq(qp->ibqp.send_cq), &wc, 0);
1083                 }
1084                 if (++qp->s_last >= qp->s_size)
1085                         qp->s_last = 0;
1086         } else
1087                 ibp->n_rc_delayed_comp++;
1088
1089         qp->s_retry = qp->s_retry_cnt;
1090         update_last_psn(qp, wqe->lpsn);
1091
1092         /*
1093          * If we are completing a request which is in the process of
1094          * being resent, we can stop resending it since we know the
1095          * responder has already seen it.
1096          */
1097         if (qp->s_acked == qp->s_cur) {
1098                 if (++qp->s_cur >= qp->s_size)
1099                         qp->s_cur = 0;
1100                 qp->s_acked = qp->s_cur;
1101                 wqe = get_swqe_ptr(qp, qp->s_cur);
1102                 if (qp->s_acked != qp->s_tail) {
1103                         qp->s_state = OP(SEND_LAST);
1104                         qp->s_psn = wqe->psn;
1105                 }
1106         } else {
1107                 if (++qp->s_acked >= qp->s_size)
1108                         qp->s_acked = 0;
1109                 if (qp->state == IB_QPS_SQD && qp->s_acked == qp->s_cur)
1110                         qp->s_draining = 0;
1111                 wqe = get_swqe_ptr(qp, qp->s_acked);
1112         }
1113         return wqe;
1114 }
1115
1116 /**
1117  * do_rc_ack - process an incoming RC ACK
1118  * @qp: the QP the ACK came in on
1119  * @psn: the packet sequence number of the ACK
1120  * @opcode: the opcode of the request that resulted in the ACK
1121  *
1122  * This is called from qib_rc_rcv_resp() to process an incoming RC ACK
1123  * for the given QP.
1124  * Called at interrupt level with the QP s_lock held.
1125  * Returns 1 if OK, 0 if current operation should be aborted (NAK).
1126  */
1127 static int do_rc_ack(struct qib_qp *qp, u32 aeth, u32 psn, int opcode,
1128                      u64 val, struct qib_ctxtdata *rcd)
1129 {
1130         struct qib_ibport *ibp;
1131         enum ib_wc_status status;
1132         struct qib_swqe *wqe;
1133         int ret = 0;
1134         u32 ack_psn;
1135         int diff;
1136
1137         /* Remove QP from retry timer */
1138         if (qp->s_flags & (QIB_S_TIMER | QIB_S_WAIT_RNR)) {
1139                 qp->s_flags &= ~(QIB_S_TIMER | QIB_S_WAIT_RNR);
1140                 del_timer(&qp->s_timer);
1141         }
1142
1143         /*
1144          * Note that NAKs implicitly ACK outstanding SEND and RDMA write
1145          * requests and implicitly NAK RDMA read and atomic requests issued
1146          * before the NAK'ed request.  The MSN won't include the NAK'ed
1147          * request but will include an ACK'ed request(s).
1148          */
1149         ack_psn = psn;
1150         if (aeth >> 29)
1151                 ack_psn--;
1152         wqe = get_swqe_ptr(qp, qp->s_acked);
1153         ibp = to_iport(qp->ibqp.device, qp->port_num);
1154
1155         /*
1156          * The MSN might be for a later WQE than the PSN indicates so
1157          * only complete WQEs that the PSN finishes.
1158          */
1159         while ((diff = qib_cmp24(ack_psn, wqe->lpsn)) >= 0) {
1160                 /*
1161                  * RDMA_READ_RESPONSE_ONLY is a special case since
1162                  * we want to generate completion events for everything
1163                  * before the RDMA read, copy the data, then generate
1164                  * the completion for the read.
1165                  */
1166                 if (wqe->wr.opcode == IB_WR_RDMA_READ &&
1167                     opcode == OP(RDMA_READ_RESPONSE_ONLY) &&
1168                     diff == 0) {
1169                         ret = 1;
1170                         goto bail;
1171                 }
1172                 /*
1173                  * If this request is a RDMA read or atomic, and the ACK is
1174                  * for a later operation, this ACK NAKs the RDMA read or
1175                  * atomic.  In other words, only a RDMA_READ_LAST or ONLY
1176                  * can ACK a RDMA read and likewise for atomic ops.  Note
1177                  * that the NAK case can only happen if relaxed ordering is
1178                  * used and requests are sent after an RDMA read or atomic
1179                  * is sent but before the response is received.
1180                  */
1181                 if ((wqe->wr.opcode == IB_WR_RDMA_READ &&
1182                      (opcode != OP(RDMA_READ_RESPONSE_LAST) || diff != 0)) ||
1183                     ((wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
1184                       wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) &&
1185                      (opcode != OP(ATOMIC_ACKNOWLEDGE) || diff != 0))) {
1186                         /* Retry this request. */
1187                         if (!(qp->r_flags & QIB_R_RDMAR_SEQ)) {
1188                                 qp->r_flags |= QIB_R_RDMAR_SEQ;
1189                                 qib_restart_rc(qp, qp->s_last_psn + 1, 0);
1190                                 if (list_empty(&qp->rspwait)) {
1191                                         qp->r_flags |= QIB_R_RSP_SEND;
1192                                         atomic_inc(&qp->refcount);
1193                                         list_add_tail(&qp->rspwait,
1194                                                       &rcd->qp_wait_list);
1195                                 }
1196                         }
1197                         /*
1198                          * No need to process the ACK/NAK since we are
1199                          * restarting an earlier request.
1200                          */
1201                         goto bail;
1202                 }
1203                 if (wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
1204                     wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD) {
1205                         u64 *vaddr = wqe->sg_list[0].vaddr;
1206                         *vaddr = val;
1207                 }
1208                 if (qp->s_num_rd_atomic &&
1209                     (wqe->wr.opcode == IB_WR_RDMA_READ ||
1210                      wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
1211                      wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD)) {
1212                         qp->s_num_rd_atomic--;
1213                         /* Restart sending task if fence is complete */
1214                         if ((qp->s_flags & QIB_S_WAIT_FENCE) &&
1215                             !qp->s_num_rd_atomic) {
1216                                 qp->s_flags &= ~(QIB_S_WAIT_FENCE |
1217                                                  QIB_S_WAIT_ACK);
1218                                 qib_schedule_send(qp);
1219                         } else if (qp->s_flags & QIB_S_WAIT_RDMAR) {
1220                                 qp->s_flags &= ~(QIB_S_WAIT_RDMAR |
1221                                                  QIB_S_WAIT_ACK);
1222                                 qib_schedule_send(qp);
1223                         }
1224                 }
1225                 wqe = do_rc_completion(qp, wqe, ibp);
1226                 if (qp->s_acked == qp->s_tail)
1227                         break;
1228         }
1229
1230         switch (aeth >> 29) {
1231         case 0:         /* ACK */
1232                 ibp->n_rc_acks++;
1233                 if (qp->s_acked != qp->s_tail) {
1234                         /*
1235                          * We are expecting more ACKs so
1236                          * reset the retransmit timer.
1237                          */
1238                         start_timer(qp);
1239                         /*
1240                          * We can stop resending the earlier packets and
1241                          * continue with the next packet the receiver wants.
1242                          */
1243                         if (qib_cmp24(qp->s_psn, psn) <= 0)
1244                                 reset_psn(qp, psn + 1);
1245                 } else if (qib_cmp24(qp->s_psn, psn) <= 0) {
1246                         qp->s_state = OP(SEND_LAST);
1247                         qp->s_psn = psn + 1;
1248                 }
1249                 if (qp->s_flags & QIB_S_WAIT_ACK) {
1250                         qp->s_flags &= ~QIB_S_WAIT_ACK;
1251                         qib_schedule_send(qp);
1252                 }
1253                 qib_get_credit(qp, aeth);
1254                 qp->s_rnr_retry = qp->s_rnr_retry_cnt;
1255                 qp->s_retry = qp->s_retry_cnt;
1256                 update_last_psn(qp, psn);
1257                 ret = 1;
1258                 goto bail;
1259
1260         case 1:         /* RNR NAK */
1261                 ibp->n_rnr_naks++;
1262                 if (qp->s_acked == qp->s_tail)
1263                         goto bail;
1264                 if (qp->s_flags & QIB_S_WAIT_RNR)
1265                         goto bail;
1266                 if (qp->s_rnr_retry == 0) {
1267                         status = IB_WC_RNR_RETRY_EXC_ERR;
1268                         goto class_b;
1269                 }
1270                 if (qp->s_rnr_retry_cnt < 7)
1271                         qp->s_rnr_retry--;
1272
1273                 /* The last valid PSN is the previous PSN. */
1274                 update_last_psn(qp, psn - 1);
1275
1276                 ibp->n_rc_resends += (qp->s_psn - psn) & QIB_PSN_MASK;
1277
1278                 reset_psn(qp, psn);
1279
1280                 qp->s_flags &= ~(QIB_S_WAIT_SSN_CREDIT | QIB_S_WAIT_ACK);
1281                 qp->s_flags |= QIB_S_WAIT_RNR;
1282                 qp->s_timer.function = qib_rc_rnr_retry;
1283                 qp->s_timer.expires = jiffies + usecs_to_jiffies(
1284                         ib_qib_rnr_table[(aeth >> QIB_AETH_CREDIT_SHIFT) &
1285                                            QIB_AETH_CREDIT_MASK]);
1286                 add_timer(&qp->s_timer);
1287                 goto bail;
1288
1289         case 3:         /* NAK */
1290                 if (qp->s_acked == qp->s_tail)
1291                         goto bail;
1292                 /* The last valid PSN is the previous PSN. */
1293                 update_last_psn(qp, psn - 1);
1294                 switch ((aeth >> QIB_AETH_CREDIT_SHIFT) &
1295                         QIB_AETH_CREDIT_MASK) {
1296                 case 0: /* PSN sequence error */
1297                         ibp->n_seq_naks++;
1298                         /*
1299                          * Back up to the responder's expected PSN.
1300                          * Note that we might get a NAK in the middle of an
1301                          * RDMA READ response which terminates the RDMA
1302                          * READ.
1303                          */
1304                         qib_restart_rc(qp, psn, 0);
1305                         qib_schedule_send(qp);
1306                         break;
1307
1308                 case 1: /* Invalid Request */
1309                         status = IB_WC_REM_INV_REQ_ERR;
1310                         ibp->n_other_naks++;
1311                         goto class_b;
1312
1313                 case 2: /* Remote Access Error */
1314                         status = IB_WC_REM_ACCESS_ERR;
1315                         ibp->n_other_naks++;
1316                         goto class_b;
1317
1318                 case 3: /* Remote Operation Error */
1319                         status = IB_WC_REM_OP_ERR;
1320                         ibp->n_other_naks++;
1321 class_b:
1322                         if (qp->s_last == qp->s_acked) {
1323                                 qib_send_complete(qp, wqe, status);
1324                                 qib_error_qp(qp, IB_WC_WR_FLUSH_ERR);
1325                         }
1326                         break;
1327
1328                 default:
1329                         /* Ignore other reserved NAK error codes */
1330                         goto reserved;
1331                 }
1332                 qp->s_retry = qp->s_retry_cnt;
1333                 qp->s_rnr_retry = qp->s_rnr_retry_cnt;
1334                 goto bail;
1335
1336         default:                /* 2: reserved */
1337 reserved:
1338                 /* Ignore reserved NAK codes. */
1339                 goto bail;
1340         }
1341
1342 bail:
1343         return ret;
1344 }
1345
1346 /*
1347  * We have seen an out of sequence RDMA read middle or last packet.
1348  * This ACKs SENDs and RDMA writes up to the first RDMA read or atomic SWQE.
1349  */
1350 static void rdma_seq_err(struct qib_qp *qp, struct qib_ibport *ibp, u32 psn,
1351                          struct qib_ctxtdata *rcd)
1352 {
1353         struct qib_swqe *wqe;
1354
1355         /* Remove QP from retry timer */
1356         if (qp->s_flags & (QIB_S_TIMER | QIB_S_WAIT_RNR)) {
1357                 qp->s_flags &= ~(QIB_S_TIMER | QIB_S_WAIT_RNR);
1358                 del_timer(&qp->s_timer);
1359         }
1360
1361         wqe = get_swqe_ptr(qp, qp->s_acked);
1362
1363         while (qib_cmp24(psn, wqe->lpsn) > 0) {
1364                 if (wqe->wr.opcode == IB_WR_RDMA_READ ||
1365                     wqe->wr.opcode == IB_WR_ATOMIC_CMP_AND_SWP ||
1366                     wqe->wr.opcode == IB_WR_ATOMIC_FETCH_AND_ADD)
1367                         break;
1368                 wqe = do_rc_completion(qp, wqe, ibp);
1369         }
1370
1371         ibp->n_rdma_seq++;
1372         qp->r_flags |= QIB_R_RDMAR_SEQ;
1373         qib_restart_rc(qp, qp->s_last_psn + 1, 0);
1374         if (list_empty(&qp->rspwait)) {
1375                 qp->r_flags |= QIB_R_RSP_SEND;
1376                 atomic_inc(&qp->refcount);
1377                 list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
1378         }
1379 }
1380
1381 /**
1382  * qib_rc_rcv_resp - process an incoming RC response packet
1383  * @ibp: the port this packet came in on
1384  * @ohdr: the other headers for this packet
1385  * @data: the packet data
1386  * @tlen: the packet length
1387  * @qp: the QP for this packet
1388  * @opcode: the opcode for this packet
1389  * @psn: the packet sequence number for this packet
1390  * @hdrsize: the header length
1391  * @pmtu: the path MTU
1392  *
1393  * This is called from qib_rc_rcv() to process an incoming RC response
1394  * packet for the given QP.
1395  * Called at interrupt level.
1396  */
1397 static void qib_rc_rcv_resp(struct qib_ibport *ibp,
1398                             struct qib_other_headers *ohdr,
1399                             void *data, u32 tlen,
1400                             struct qib_qp *qp,
1401                             u32 opcode,
1402                             u32 psn, u32 hdrsize, u32 pmtu,
1403                             struct qib_ctxtdata *rcd)
1404 {
1405         struct qib_swqe *wqe;
1406         struct qib_pportdata *ppd = ppd_from_ibp(ibp);
1407         enum ib_wc_status status;
1408         unsigned long flags;
1409         int diff;
1410         u32 pad;
1411         u32 aeth;
1412         u64 val;
1413
1414         if (opcode != OP(RDMA_READ_RESPONSE_MIDDLE)) {
1415                 /*
1416                  * If ACK'd PSN on SDMA busy list try to make progress to
1417                  * reclaim SDMA credits.
1418                  */
1419                 if ((qib_cmp24(psn, qp->s_sending_psn) >= 0) &&
1420                     (qib_cmp24(qp->s_sending_psn, qp->s_sending_hpsn) <= 0)) {
1421
1422                         /*
1423                          * If send tasklet not running attempt to progress
1424                          * SDMA queue.
1425                          */
1426                         if (!(qp->s_flags & QIB_S_BUSY)) {
1427                                 /* Acquire SDMA Lock */
1428                                 spin_lock_irqsave(&ppd->sdma_lock, flags);
1429                                 /* Invoke sdma make progress */
1430                                 qib_sdma_make_progress(ppd);
1431                                 /* Release SDMA Lock */
1432                                 spin_unlock_irqrestore(&ppd->sdma_lock, flags);
1433                         }
1434                 }
1435         }
1436
1437         spin_lock_irqsave(&qp->s_lock, flags);
1438         if (!(ib_qib_state_ops[qp->state] & QIB_PROCESS_RECV_OK))
1439                 goto ack_done;
1440
1441         /* Ignore invalid responses. */
1442         if (qib_cmp24(psn, qp->s_next_psn) >= 0)
1443                 goto ack_done;
1444
1445         /* Ignore duplicate responses. */
1446         diff = qib_cmp24(psn, qp->s_last_psn);
1447         if (unlikely(diff <= 0)) {
1448                 /* Update credits for "ghost" ACKs */
1449                 if (diff == 0 && opcode == OP(ACKNOWLEDGE)) {
1450                         aeth = be32_to_cpu(ohdr->u.aeth);
1451                         if ((aeth >> 29) == 0)
1452                                 qib_get_credit(qp, aeth);
1453                 }
1454                 goto ack_done;
1455         }
1456
1457         /*
1458          * Skip everything other than the PSN we expect, if we are waiting
1459          * for a reply to a restarted RDMA read or atomic op.
1460          */
1461         if (qp->r_flags & QIB_R_RDMAR_SEQ) {
1462                 if (qib_cmp24(psn, qp->s_last_psn + 1) != 0)
1463                         goto ack_done;
1464                 qp->r_flags &= ~QIB_R_RDMAR_SEQ;
1465         }
1466
1467         if (unlikely(qp->s_acked == qp->s_tail))
1468                 goto ack_done;
1469         wqe = get_swqe_ptr(qp, qp->s_acked);
1470         status = IB_WC_SUCCESS;
1471
1472         switch (opcode) {
1473         case OP(ACKNOWLEDGE):
1474         case OP(ATOMIC_ACKNOWLEDGE):
1475         case OP(RDMA_READ_RESPONSE_FIRST):
1476                 aeth = be32_to_cpu(ohdr->u.aeth);
1477                 if (opcode == OP(ATOMIC_ACKNOWLEDGE)) {
1478                         __be32 *p = ohdr->u.at.atomic_ack_eth;
1479
1480                         val = ((u64) be32_to_cpu(p[0]) << 32) |
1481                                 be32_to_cpu(p[1]);
1482                 } else
1483                         val = 0;
1484                 if (!do_rc_ack(qp, aeth, psn, opcode, val, rcd) ||
1485                     opcode != OP(RDMA_READ_RESPONSE_FIRST))
1486                         goto ack_done;
1487                 hdrsize += 4;
1488                 wqe = get_swqe_ptr(qp, qp->s_acked);
1489                 if (unlikely(wqe->wr.opcode != IB_WR_RDMA_READ))
1490                         goto ack_op_err;
1491                 /*
1492                  * If this is a response to a resent RDMA read, we
1493                  * have to be careful to copy the data to the right
1494                  * location.
1495                  */
1496                 qp->s_rdma_read_len = restart_sge(&qp->s_rdma_read_sge,
1497                                                   wqe, psn, pmtu);
1498                 goto read_middle;
1499
1500         case OP(RDMA_READ_RESPONSE_MIDDLE):
1501                 /* no AETH, no ACK */
1502                 if (unlikely(qib_cmp24(psn, qp->s_last_psn + 1)))
1503                         goto ack_seq_err;
1504                 if (unlikely(wqe->wr.opcode != IB_WR_RDMA_READ))
1505                         goto ack_op_err;
1506 read_middle:
1507                 if (unlikely(tlen != (hdrsize + pmtu + 4)))
1508                         goto ack_len_err;
1509                 if (unlikely(pmtu >= qp->s_rdma_read_len))
1510                         goto ack_len_err;
1511
1512                 /*
1513                  * We got a response so update the timeout.
1514                  * 4.096 usec. * (1 << qp->timeout)
1515                  */
1516                 qp->s_flags |= QIB_S_TIMER;
1517                 mod_timer(&qp->s_timer, jiffies + qp->timeout_jiffies);
1518                 if (qp->s_flags & QIB_S_WAIT_ACK) {
1519                         qp->s_flags &= ~QIB_S_WAIT_ACK;
1520                         qib_schedule_send(qp);
1521                 }
1522
1523                 if (opcode == OP(RDMA_READ_RESPONSE_MIDDLE))
1524                         qp->s_retry = qp->s_retry_cnt;
1525
1526                 /*
1527                  * Update the RDMA receive state but do the copy w/o
1528                  * holding the locks and blocking interrupts.
1529                  */
1530                 qp->s_rdma_read_len -= pmtu;
1531                 update_last_psn(qp, psn);
1532                 spin_unlock_irqrestore(&qp->s_lock, flags);
1533                 qib_copy_sge(&qp->s_rdma_read_sge, data, pmtu, 0);
1534                 goto bail;
1535
1536         case OP(RDMA_READ_RESPONSE_ONLY):
1537                 aeth = be32_to_cpu(ohdr->u.aeth);
1538                 if (!do_rc_ack(qp, aeth, psn, opcode, 0, rcd))
1539                         goto ack_done;
1540                 /* Get the number of bytes the message was padded by. */
1541                 pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
1542                 /*
1543                  * Check that the data size is >= 0 && <= pmtu.
1544                  * Remember to account for the AETH header (4) and
1545                  * ICRC (4).
1546                  */
1547                 if (unlikely(tlen < (hdrsize + pad + 8)))
1548                         goto ack_len_err;
1549                 /*
1550                  * If this is a response to a resent RDMA read, we
1551                  * have to be careful to copy the data to the right
1552                  * location.
1553                  */
1554                 wqe = get_swqe_ptr(qp, qp->s_acked);
1555                 qp->s_rdma_read_len = restart_sge(&qp->s_rdma_read_sge,
1556                                                   wqe, psn, pmtu);
1557                 goto read_last;
1558
1559         case OP(RDMA_READ_RESPONSE_LAST):
1560                 /* ACKs READ req. */
1561                 if (unlikely(qib_cmp24(psn, qp->s_last_psn + 1)))
1562                         goto ack_seq_err;
1563                 if (unlikely(wqe->wr.opcode != IB_WR_RDMA_READ))
1564                         goto ack_op_err;
1565                 /* Get the number of bytes the message was padded by. */
1566                 pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
1567                 /*
1568                  * Check that the data size is >= 1 && <= pmtu.
1569                  * Remember to account for the AETH header (4) and
1570                  * ICRC (4).
1571                  */
1572                 if (unlikely(tlen <= (hdrsize + pad + 8)))
1573                         goto ack_len_err;
1574 read_last:
1575                 tlen -= hdrsize + pad + 8;
1576                 if (unlikely(tlen != qp->s_rdma_read_len))
1577                         goto ack_len_err;
1578                 aeth = be32_to_cpu(ohdr->u.aeth);
1579                 qib_copy_sge(&qp->s_rdma_read_sge, data, tlen, 0);
1580                 WARN_ON(qp->s_rdma_read_sge.num_sge);
1581                 (void) do_rc_ack(qp, aeth, psn,
1582                                  OP(RDMA_READ_RESPONSE_LAST), 0, rcd);
1583                 goto ack_done;
1584         }
1585
1586 ack_op_err:
1587         status = IB_WC_LOC_QP_OP_ERR;
1588         goto ack_err;
1589
1590 ack_seq_err:
1591         rdma_seq_err(qp, ibp, psn, rcd);
1592         goto ack_done;
1593
1594 ack_len_err:
1595         status = IB_WC_LOC_LEN_ERR;
1596 ack_err:
1597         if (qp->s_last == qp->s_acked) {
1598                 qib_send_complete(qp, wqe, status);
1599                 qib_error_qp(qp, IB_WC_WR_FLUSH_ERR);
1600         }
1601 ack_done:
1602         spin_unlock_irqrestore(&qp->s_lock, flags);
1603 bail:
1604         return;
1605 }
1606
1607 /**
1608  * qib_rc_rcv_error - process an incoming duplicate or error RC packet
1609  * @ohdr: the other headers for this packet
1610  * @data: the packet data
1611  * @qp: the QP for this packet
1612  * @opcode: the opcode for this packet
1613  * @psn: the packet sequence number for this packet
1614  * @diff: the difference between the PSN and the expected PSN
1615  *
1616  * This is called from qib_rc_rcv() to process an unexpected
1617  * incoming RC packet for the given QP.
1618  * Called at interrupt level.
1619  * Return 1 if no more processing is needed; otherwise return 0 to
1620  * schedule a response to be sent.
1621  */
1622 static int qib_rc_rcv_error(struct qib_other_headers *ohdr,
1623                             void *data,
1624                             struct qib_qp *qp,
1625                             u32 opcode,
1626                             u32 psn,
1627                             int diff,
1628                             struct qib_ctxtdata *rcd)
1629 {
1630         struct qib_ibport *ibp = to_iport(qp->ibqp.device, qp->port_num);
1631         struct qib_ack_entry *e;
1632         unsigned long flags;
1633         u8 i, prev;
1634         int old_req;
1635
1636         if (diff > 0) {
1637                 /*
1638                  * Packet sequence error.
1639                  * A NAK will ACK earlier sends and RDMA writes.
1640                  * Don't queue the NAK if we already sent one.
1641                  */
1642                 if (!qp->r_nak_state) {
1643                         ibp->n_rc_seqnak++;
1644                         qp->r_nak_state = IB_NAK_PSN_ERROR;
1645                         /* Use the expected PSN. */
1646                         qp->r_ack_psn = qp->r_psn;
1647                         /*
1648                          * Wait to send the sequence NAK until all packets
1649                          * in the receive queue have been processed.
1650                          * Otherwise, we end up propagating congestion.
1651                          */
1652                         if (list_empty(&qp->rspwait)) {
1653                                 qp->r_flags |= QIB_R_RSP_NAK;
1654                                 atomic_inc(&qp->refcount);
1655                                 list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
1656                         }
1657                 }
1658                 goto done;
1659         }
1660
1661         /*
1662          * Handle a duplicate request.  Don't re-execute SEND, RDMA
1663          * write or atomic op.  Don't NAK errors, just silently drop
1664          * the duplicate request.  Note that r_sge, r_len, and
1665          * r_rcv_len may be in use so don't modify them.
1666          *
1667          * We are supposed to ACK the earliest duplicate PSN but we
1668          * can coalesce an outstanding duplicate ACK.  We have to
1669          * send the earliest so that RDMA reads can be restarted at
1670          * the requester's expected PSN.
1671          *
1672          * First, find where this duplicate PSN falls within the
1673          * ACKs previously sent.
1674          * old_req is true if there is an older response that is scheduled
1675          * to be sent before sending this one.
1676          */
1677         e = NULL;
1678         old_req = 1;
1679         ibp->n_rc_dupreq++;
1680
1681         spin_lock_irqsave(&qp->s_lock, flags);
1682
1683         for (i = qp->r_head_ack_queue; ; i = prev) {
1684                 if (i == qp->s_tail_ack_queue)
1685                         old_req = 0;
1686                 if (i)
1687                         prev = i - 1;
1688                 else
1689                         prev = QIB_MAX_RDMA_ATOMIC;
1690                 if (prev == qp->r_head_ack_queue) {
1691                         e = NULL;
1692                         break;
1693                 }
1694                 e = &qp->s_ack_queue[prev];
1695                 if (!e->opcode) {
1696                         e = NULL;
1697                         break;
1698                 }
1699                 if (qib_cmp24(psn, e->psn) >= 0) {
1700                         if (prev == qp->s_tail_ack_queue &&
1701                             qib_cmp24(psn, e->lpsn) <= 0)
1702                                 old_req = 0;
1703                         break;
1704                 }
1705         }
1706         switch (opcode) {
1707         case OP(RDMA_READ_REQUEST): {
1708                 struct ib_reth *reth;
1709                 u32 offset;
1710                 u32 len;
1711
1712                 /*
1713                  * If we didn't find the RDMA read request in the ack queue,
1714                  * we can ignore this request.
1715                  */
1716                 if (!e || e->opcode != OP(RDMA_READ_REQUEST))
1717                         goto unlock_done;
1718                 /* RETH comes after BTH */
1719                 reth = &ohdr->u.rc.reth;
1720                 /*
1721                  * Address range must be a subset of the original
1722                  * request and start on pmtu boundaries.
1723                  * We reuse the old ack_queue slot since the requester
1724                  * should not back up and request an earlier PSN for the
1725                  * same request.
1726                  */
1727                 offset = ((psn - e->psn) & QIB_PSN_MASK) *
1728                         qp->pmtu;
1729                 len = be32_to_cpu(reth->length);
1730                 if (unlikely(offset + len != e->rdma_sge.sge_length))
1731                         goto unlock_done;
1732                 if (e->rdma_sge.mr) {
1733                         atomic_dec(&e->rdma_sge.mr->refcount);
1734                         e->rdma_sge.mr = NULL;
1735                 }
1736                 if (len != 0) {
1737                         u32 rkey = be32_to_cpu(reth->rkey);
1738                         u64 vaddr = be64_to_cpu(reth->vaddr);
1739                         int ok;
1740
1741                         ok = qib_rkey_ok(qp, &e->rdma_sge, len, vaddr, rkey,
1742                                          IB_ACCESS_REMOTE_READ);
1743                         if (unlikely(!ok))
1744                                 goto unlock_done;
1745                 } else {
1746                         e->rdma_sge.vaddr = NULL;
1747                         e->rdma_sge.length = 0;
1748                         e->rdma_sge.sge_length = 0;
1749                 }
1750                 e->psn = psn;
1751                 if (old_req)
1752                         goto unlock_done;
1753                 qp->s_tail_ack_queue = prev;
1754                 break;
1755         }
1756
1757         case OP(COMPARE_SWAP):
1758         case OP(FETCH_ADD): {
1759                 /*
1760                  * If we didn't find the atomic request in the ack queue
1761                  * or the send tasklet is already backed up to send an
1762                  * earlier entry, we can ignore this request.
1763                  */
1764                 if (!e || e->opcode != (u8) opcode || old_req)
1765                         goto unlock_done;
1766                 qp->s_tail_ack_queue = prev;
1767                 break;
1768         }
1769
1770         default:
1771                 /*
1772                  * Ignore this operation if it doesn't request an ACK
1773                  * or an earlier RDMA read or atomic is going to be resent.
1774                  */
1775                 if (!(psn & IB_BTH_REQ_ACK) || old_req)
1776                         goto unlock_done;
1777                 /*
1778                  * Resend the most recent ACK if this request is
1779                  * after all the previous RDMA reads and atomics.
1780                  */
1781                 if (i == qp->r_head_ack_queue) {
1782                         spin_unlock_irqrestore(&qp->s_lock, flags);
1783                         qp->r_nak_state = 0;
1784                         qp->r_ack_psn = qp->r_psn - 1;
1785                         goto send_ack;
1786                 }
1787                 /*
1788                  * Try to send a simple ACK to work around a Mellanox bug
1789                  * which doesn't accept a RDMA read response or atomic
1790                  * response as an ACK for earlier SENDs or RDMA writes.
1791                  */
1792                 if (!(qp->s_flags & QIB_S_RESP_PENDING)) {
1793                         spin_unlock_irqrestore(&qp->s_lock, flags);
1794                         qp->r_nak_state = 0;
1795                         qp->r_ack_psn = qp->s_ack_queue[i].psn - 1;
1796                         goto send_ack;
1797                 }
1798                 /*
1799                  * Resend the RDMA read or atomic op which
1800                  * ACKs this duplicate request.
1801                  */
1802                 qp->s_tail_ack_queue = i;
1803                 break;
1804         }
1805         qp->s_ack_state = OP(ACKNOWLEDGE);
1806         qp->s_flags |= QIB_S_RESP_PENDING;
1807         qp->r_nak_state = 0;
1808         qib_schedule_send(qp);
1809
1810 unlock_done:
1811         spin_unlock_irqrestore(&qp->s_lock, flags);
1812 done:
1813         return 1;
1814
1815 send_ack:
1816         return 0;
1817 }
1818
1819 void qib_rc_error(struct qib_qp *qp, enum ib_wc_status err)
1820 {
1821         unsigned long flags;
1822         int lastwqe;
1823
1824         spin_lock_irqsave(&qp->s_lock, flags);
1825         lastwqe = qib_error_qp(qp, err);
1826         spin_unlock_irqrestore(&qp->s_lock, flags);
1827
1828         if (lastwqe) {
1829                 struct ib_event ev;
1830
1831                 ev.device = qp->ibqp.device;
1832                 ev.element.qp = &qp->ibqp;
1833                 ev.event = IB_EVENT_QP_LAST_WQE_REACHED;
1834                 qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
1835         }
1836 }
1837
1838 static inline void qib_update_ack_queue(struct qib_qp *qp, unsigned n)
1839 {
1840         unsigned next;
1841
1842         next = n + 1;
1843         if (next > QIB_MAX_RDMA_ATOMIC)
1844                 next = 0;
1845         qp->s_tail_ack_queue = next;
1846         qp->s_ack_state = OP(ACKNOWLEDGE);
1847 }
1848
1849 /**
1850  * qib_rc_rcv - process an incoming RC packet
1851  * @rcd: the context pointer
1852  * @hdr: the header of this packet
1853  * @has_grh: true if the header has a GRH
1854  * @data: the packet data
1855  * @tlen: the packet length
1856  * @qp: the QP for this packet
1857  *
1858  * This is called from qib_qp_rcv() to process an incoming RC packet
1859  * for the given QP.
1860  * Called at interrupt level.
1861  */
1862 void qib_rc_rcv(struct qib_ctxtdata *rcd, struct qib_ib_header *hdr,
1863                 int has_grh, void *data, u32 tlen, struct qib_qp *qp)
1864 {
1865         struct qib_ibport *ibp = &rcd->ppd->ibport_data;
1866         struct qib_other_headers *ohdr;
1867         u32 opcode;
1868         u32 hdrsize;
1869         u32 psn;
1870         u32 pad;
1871         struct ib_wc wc;
1872         u32 pmtu = qp->pmtu;
1873         int diff;
1874         struct ib_reth *reth;
1875         unsigned long flags;
1876         int ret;
1877
1878         /* Check for GRH */
1879         if (!has_grh) {
1880                 ohdr = &hdr->u.oth;
1881                 hdrsize = 8 + 12;       /* LRH + BTH */
1882         } else {
1883                 ohdr = &hdr->u.l.oth;
1884                 hdrsize = 8 + 40 + 12;  /* LRH + GRH + BTH */
1885         }
1886
1887         opcode = be32_to_cpu(ohdr->bth[0]);
1888         if (qib_ruc_check_hdr(ibp, hdr, has_grh, qp, opcode))
1889                 return;
1890
1891         psn = be32_to_cpu(ohdr->bth[2]);
1892         opcode >>= 24;
1893
1894         /*
1895          * Process responses (ACKs) before anything else.  Note that the
1896          * packet sequence number will be for something in the send work
1897          * queue rather than the expected receive packet sequence number.
1898          * In other words, this QP is the requester.
1899          */
1900         if (opcode >= OP(RDMA_READ_RESPONSE_FIRST) &&
1901             opcode <= OP(ATOMIC_ACKNOWLEDGE)) {
1902                 qib_rc_rcv_resp(ibp, ohdr, data, tlen, qp, opcode, psn,
1903                                 hdrsize, pmtu, rcd);
1904                 return;
1905         }
1906
1907         /* Compute 24 bits worth of difference. */
1908         diff = qib_cmp24(psn, qp->r_psn);
1909         if (unlikely(diff)) {
1910                 if (qib_rc_rcv_error(ohdr, data, qp, opcode, psn, diff, rcd))
1911                         return;
1912                 goto send_ack;
1913         }
1914
1915         /* Check for opcode sequence errors. */
1916         switch (qp->r_state) {
1917         case OP(SEND_FIRST):
1918         case OP(SEND_MIDDLE):
1919                 if (opcode == OP(SEND_MIDDLE) ||
1920                     opcode == OP(SEND_LAST) ||
1921                     opcode == OP(SEND_LAST_WITH_IMMEDIATE))
1922                         break;
1923                 goto nack_inv;
1924
1925         case OP(RDMA_WRITE_FIRST):
1926         case OP(RDMA_WRITE_MIDDLE):
1927                 if (opcode == OP(RDMA_WRITE_MIDDLE) ||
1928                     opcode == OP(RDMA_WRITE_LAST) ||
1929                     opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
1930                         break;
1931                 goto nack_inv;
1932
1933         default:
1934                 if (opcode == OP(SEND_MIDDLE) ||
1935                     opcode == OP(SEND_LAST) ||
1936                     opcode == OP(SEND_LAST_WITH_IMMEDIATE) ||
1937                     opcode == OP(RDMA_WRITE_MIDDLE) ||
1938                     opcode == OP(RDMA_WRITE_LAST) ||
1939                     opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE))
1940                         goto nack_inv;
1941                 /*
1942                  * Note that it is up to the requester to not send a new
1943                  * RDMA read or atomic operation before receiving an ACK
1944                  * for the previous operation.
1945                  */
1946                 break;
1947         }
1948
1949         if (qp->state == IB_QPS_RTR && !(qp->r_flags & QIB_R_COMM_EST)) {
1950                 qp->r_flags |= QIB_R_COMM_EST;
1951                 if (qp->ibqp.event_handler) {
1952                         struct ib_event ev;
1953
1954                         ev.device = qp->ibqp.device;
1955                         ev.element.qp = &qp->ibqp;
1956                         ev.event = IB_EVENT_COMM_EST;
1957                         qp->ibqp.event_handler(&ev, qp->ibqp.qp_context);
1958                 }
1959         }
1960
1961         /* OK, process the packet. */
1962         switch (opcode) {
1963         case OP(SEND_FIRST):
1964                 ret = qib_get_rwqe(qp, 0);
1965                 if (ret < 0)
1966                         goto nack_op_err;
1967                 if (!ret)
1968                         goto rnr_nak;
1969                 qp->r_rcv_len = 0;
1970                 /* FALLTHROUGH */
1971         case OP(SEND_MIDDLE):
1972         case OP(RDMA_WRITE_MIDDLE):
1973 send_middle:
1974                 /* Check for invalid length PMTU or posted rwqe len. */
1975                 if (unlikely(tlen != (hdrsize + pmtu + 4)))
1976                         goto nack_inv;
1977                 qp->r_rcv_len += pmtu;
1978                 if (unlikely(qp->r_rcv_len > qp->r_len))
1979                         goto nack_inv;
1980                 qib_copy_sge(&qp->r_sge, data, pmtu, 1);
1981                 break;
1982
1983         case OP(RDMA_WRITE_LAST_WITH_IMMEDIATE):
1984                 /* consume RWQE */
1985                 ret = qib_get_rwqe(qp, 1);
1986                 if (ret < 0)
1987                         goto nack_op_err;
1988                 if (!ret)
1989                         goto rnr_nak;
1990                 goto send_last_imm;
1991
1992         case OP(SEND_ONLY):
1993         case OP(SEND_ONLY_WITH_IMMEDIATE):
1994                 ret = qib_get_rwqe(qp, 0);
1995                 if (ret < 0)
1996                         goto nack_op_err;
1997                 if (!ret)
1998                         goto rnr_nak;
1999                 qp->r_rcv_len = 0;
2000                 if (opcode == OP(SEND_ONLY))
2001                         goto no_immediate_data;
2002                 /* FALLTHROUGH for SEND_ONLY_WITH_IMMEDIATE */
2003         case OP(SEND_LAST_WITH_IMMEDIATE):
2004 send_last_imm:
2005                 wc.ex.imm_data = ohdr->u.imm_data;
2006                 hdrsize += 4;
2007                 wc.wc_flags = IB_WC_WITH_IMM;
2008                 goto send_last;
2009         case OP(SEND_LAST):
2010         case OP(RDMA_WRITE_LAST):
2011 no_immediate_data:
2012                 wc.wc_flags = 0;
2013                 wc.ex.imm_data = 0;
2014 send_last:
2015                 /* Get the number of bytes the message was padded by. */
2016                 pad = (be32_to_cpu(ohdr->bth[0]) >> 20) & 3;
2017                 /* Check for invalid length. */
2018                 /* XXX LAST len should be >= 1 */
2019                 if (unlikely(tlen < (hdrsize + pad + 4)))
2020                         goto nack_inv;
2021                 /* Don't count the CRC. */
2022                 tlen -= (hdrsize + pad + 4);
2023                 wc.byte_len = tlen + qp->r_rcv_len;
2024                 if (unlikely(wc.byte_len > qp->r_len))
2025                         goto nack_inv;
2026                 qib_copy_sge(&qp->r_sge, data, tlen, 1);
2027                 while (qp->r_sge.num_sge) {
2028                         atomic_dec(&qp->r_sge.sge.mr->refcount);
2029                         if (--qp->r_sge.num_sge)
2030                                 qp->r_sge.sge = *qp->r_sge.sg_list++;
2031                 }
2032                 qp->r_msn++;
2033                 if (!test_and_clear_bit(QIB_R_WRID_VALID, &qp->r_aflags))
2034                         break;
2035                 wc.wr_id = qp->r_wr_id;
2036                 wc.status = IB_WC_SUCCESS;
2037                 if (opcode == OP(RDMA_WRITE_LAST_WITH_IMMEDIATE) ||
2038                     opcode == OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE))
2039                         wc.opcode = IB_WC_RECV_RDMA_WITH_IMM;
2040                 else
2041                         wc.opcode = IB_WC_RECV;
2042                 wc.qp = &qp->ibqp;
2043                 wc.src_qp = qp->remote_qpn;
2044                 wc.slid = qp->remote_ah_attr.dlid;
2045                 wc.sl = qp->remote_ah_attr.sl;
2046                 /* zero fields that are N/A */
2047                 wc.vendor_err = 0;
2048                 wc.pkey_index = 0;
2049                 wc.dlid_path_bits = 0;
2050                 wc.port_num = 0;
2051                 wc.csum_ok = 0;
2052                 /* Signal completion event if the solicited bit is set. */
2053                 qib_cq_enter(to_icq(qp->ibqp.recv_cq), &wc,
2054                              (ohdr->bth[0] &
2055                               cpu_to_be32(IB_BTH_SOLICITED)) != 0);
2056                 break;
2057
2058         case OP(RDMA_WRITE_FIRST):
2059         case OP(RDMA_WRITE_ONLY):
2060         case OP(RDMA_WRITE_ONLY_WITH_IMMEDIATE):
2061                 if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_WRITE)))
2062                         goto nack_inv;
2063                 /* consume RWQE */
2064                 reth = &ohdr->u.rc.reth;
2065                 hdrsize += sizeof(*reth);
2066                 qp->r_len = be32_to_cpu(reth->length);
2067                 qp->r_rcv_len = 0;
2068                 qp->r_sge.sg_list = NULL;
2069                 if (qp->r_len != 0) {
2070                         u32 rkey = be32_to_cpu(reth->rkey);
2071                         u64 vaddr = be64_to_cpu(reth->vaddr);
2072                         int ok;
2073
2074                         /* Check rkey & NAK */
2075                         ok = qib_rkey_ok(qp, &qp->r_sge.sge, qp->r_len, vaddr,
2076                                          rkey, IB_ACCESS_REMOTE_WRITE);
2077                         if (unlikely(!ok))
2078                                 goto nack_acc;
2079                         qp->r_sge.num_sge = 1;
2080                 } else {
2081                         qp->r_sge.num_sge = 0;
2082                         qp->r_sge.sge.mr = NULL;
2083                         qp->r_sge.sge.vaddr = NULL;
2084                         qp->r_sge.sge.length = 0;
2085                         qp->r_sge.sge.sge_length = 0;
2086                 }
2087                 if (opcode == OP(RDMA_WRITE_FIRST))
2088                         goto send_middle;
2089                 else if (opcode == OP(RDMA_WRITE_ONLY))
2090                         goto no_immediate_data;
2091                 ret = qib_get_rwqe(qp, 1);
2092                 if (ret < 0)
2093                         goto nack_op_err;
2094                 if (!ret)
2095                         goto rnr_nak;
2096                 wc.ex.imm_data = ohdr->u.rc.imm_data;
2097                 hdrsize += 4;
2098                 wc.wc_flags = IB_WC_WITH_IMM;
2099                 goto send_last;
2100
2101         case OP(RDMA_READ_REQUEST): {
2102                 struct qib_ack_entry *e;
2103                 u32 len;
2104                 u8 next;
2105
2106                 if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_READ)))
2107                         goto nack_inv;
2108                 next = qp->r_head_ack_queue + 1;
2109                 /* s_ack_queue is size QIB_MAX_RDMA_ATOMIC+1 so use > not >= */
2110                 if (next > QIB_MAX_RDMA_ATOMIC)
2111                         next = 0;
2112                 spin_lock_irqsave(&qp->s_lock, flags);
2113                 if (unlikely(next == qp->s_tail_ack_queue)) {
2114                         if (!qp->s_ack_queue[next].sent)
2115                                 goto nack_inv_unlck;
2116                         qib_update_ack_queue(qp, next);
2117                 }
2118                 e = &qp->s_ack_queue[qp->r_head_ack_queue];
2119                 if (e->opcode == OP(RDMA_READ_REQUEST) && e->rdma_sge.mr) {
2120                         atomic_dec(&e->rdma_sge.mr->refcount);
2121                         e->rdma_sge.mr = NULL;
2122                 }
2123                 reth = &ohdr->u.rc.reth;
2124                 len = be32_to_cpu(reth->length);
2125                 if (len) {
2126                         u32 rkey = be32_to_cpu(reth->rkey);
2127                         u64 vaddr = be64_to_cpu(reth->vaddr);
2128                         int ok;
2129
2130                         /* Check rkey & NAK */
2131                         ok = qib_rkey_ok(qp, &e->rdma_sge, len, vaddr,
2132                                          rkey, IB_ACCESS_REMOTE_READ);
2133                         if (unlikely(!ok))
2134                                 goto nack_acc_unlck;
2135                         /*
2136                          * Update the next expected PSN.  We add 1 later
2137                          * below, so only add the remainder here.
2138                          */
2139                         if (len > pmtu)
2140                                 qp->r_psn += (len - 1) / pmtu;
2141                 } else {
2142                         e->rdma_sge.mr = NULL;
2143                         e->rdma_sge.vaddr = NULL;
2144                         e->rdma_sge.length = 0;
2145                         e->rdma_sge.sge_length = 0;
2146                 }
2147                 e->opcode = opcode;
2148                 e->sent = 0;
2149                 e->psn = psn;
2150                 e->lpsn = qp->r_psn;
2151                 /*
2152                  * We need to increment the MSN here instead of when we
2153                  * finish sending the result since a duplicate request would
2154                  * increment it more than once.
2155                  */
2156                 qp->r_msn++;
2157                 qp->r_psn++;
2158                 qp->r_state = opcode;
2159                 qp->r_nak_state = 0;
2160                 qp->r_head_ack_queue = next;
2161
2162                 /* Schedule the send tasklet. */
2163                 qp->s_flags |= QIB_S_RESP_PENDING;
2164                 qib_schedule_send(qp);
2165
2166                 goto sunlock;
2167         }
2168
2169         case OP(COMPARE_SWAP):
2170         case OP(FETCH_ADD): {
2171                 struct ib_atomic_eth *ateth;
2172                 struct qib_ack_entry *e;
2173                 u64 vaddr;
2174                 atomic64_t *maddr;
2175                 u64 sdata;
2176                 u32 rkey;
2177                 u8 next;
2178
2179                 if (unlikely(!(qp->qp_access_flags & IB_ACCESS_REMOTE_ATOMIC)))
2180                         goto nack_inv;
2181                 next = qp->r_head_ack_queue + 1;
2182                 if (next > QIB_MAX_RDMA_ATOMIC)
2183                         next = 0;
2184                 spin_lock_irqsave(&qp->s_lock, flags);
2185                 if (unlikely(next == qp->s_tail_ack_queue)) {
2186                         if (!qp->s_ack_queue[next].sent)
2187                                 goto nack_inv_unlck;
2188                         qib_update_ack_queue(qp, next);
2189                 }
2190                 e = &qp->s_ack_queue[qp->r_head_ack_queue];
2191                 if (e->opcode == OP(RDMA_READ_REQUEST) && e->rdma_sge.mr) {
2192                         atomic_dec(&e->rdma_sge.mr->refcount);
2193                         e->rdma_sge.mr = NULL;
2194                 }
2195                 ateth = &ohdr->u.atomic_eth;
2196                 vaddr = ((u64) be32_to_cpu(ateth->vaddr[0]) << 32) |
2197                         be32_to_cpu(ateth->vaddr[1]);
2198                 if (unlikely(vaddr & (sizeof(u64) - 1)))
2199                         goto nack_inv_unlck;
2200                 rkey = be32_to_cpu(ateth->rkey);
2201                 /* Check rkey & NAK */
2202                 if (unlikely(!qib_rkey_ok(qp, &qp->r_sge.sge, sizeof(u64),
2203                                           vaddr, rkey,
2204                                           IB_ACCESS_REMOTE_ATOMIC)))
2205                         goto nack_acc_unlck;
2206                 /* Perform atomic OP and save result. */
2207                 maddr = (atomic64_t *) qp->r_sge.sge.vaddr;
2208                 sdata = be64_to_cpu(ateth->swap_data);
2209                 e->atomic_data = (opcode == OP(FETCH_ADD)) ?
2210                         (u64) atomic64_add_return(sdata, maddr) - sdata :
2211                         (u64) cmpxchg((u64 *) qp->r_sge.sge.vaddr,
2212                                       be64_to_cpu(ateth->compare_data),
2213                                       sdata);
2214                 atomic_dec(&qp->r_sge.sge.mr->refcount);
2215                 qp->r_sge.num_sge = 0;
2216                 e->opcode = opcode;
2217                 e->sent = 0;
2218                 e->psn = psn;
2219                 e->lpsn = psn;
2220                 qp->r_msn++;
2221                 qp->r_psn++;
2222                 qp->r_state = opcode;
2223                 qp->r_nak_state = 0;
2224                 qp->r_head_ack_queue = next;
2225
2226                 /* Schedule the send tasklet. */
2227                 qp->s_flags |= QIB_S_RESP_PENDING;
2228                 qib_schedule_send(qp);
2229
2230                 goto sunlock;
2231         }
2232
2233         default:
2234                 /* NAK unknown opcodes. */
2235                 goto nack_inv;
2236         }
2237         qp->r_psn++;
2238         qp->r_state = opcode;
2239         qp->r_ack_psn = psn;
2240         qp->r_nak_state = 0;
2241         /* Send an ACK if requested or required. */
2242         if (psn & (1 << 31))
2243                 goto send_ack;
2244         return;
2245
2246 rnr_nak:
2247         qp->r_nak_state = IB_RNR_NAK | qp->r_min_rnr_timer;
2248         qp->r_ack_psn = qp->r_psn;
2249         /* Queue RNR NAK for later */
2250         if (list_empty(&qp->rspwait)) {
2251                 qp->r_flags |= QIB_R_RSP_NAK;
2252                 atomic_inc(&qp->refcount);
2253                 list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
2254         }
2255         return;
2256
2257 nack_op_err:
2258         qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
2259         qp->r_nak_state = IB_NAK_REMOTE_OPERATIONAL_ERROR;
2260         qp->r_ack_psn = qp->r_psn;
2261         /* Queue NAK for later */
2262         if (list_empty(&qp->rspwait)) {
2263                 qp->r_flags |= QIB_R_RSP_NAK;
2264                 atomic_inc(&qp->refcount);
2265                 list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
2266         }
2267         return;
2268
2269 nack_inv_unlck:
2270         spin_unlock_irqrestore(&qp->s_lock, flags);
2271 nack_inv:
2272         qib_rc_error(qp, IB_WC_LOC_QP_OP_ERR);
2273         qp->r_nak_state = IB_NAK_INVALID_REQUEST;
2274         qp->r_ack_psn = qp->r_psn;
2275         /* Queue NAK for later */
2276         if (list_empty(&qp->rspwait)) {
2277                 qp->r_flags |= QIB_R_RSP_NAK;
2278                 atomic_inc(&qp->refcount);
2279                 list_add_tail(&qp->rspwait, &rcd->qp_wait_list);
2280         }
2281         return;
2282
2283 nack_acc_unlck:
2284         spin_unlock_irqrestore(&qp->s_lock, flags);
2285 nack_acc:
2286         qib_rc_error(qp, IB_WC_LOC_PROT_ERR);
2287         qp->r_nak_state = IB_NAK_REMOTE_ACCESS_ERROR;
2288         qp->r_ack_psn = qp->r_psn;
2289 send_ack:
2290         qib_send_rc_ack(qp);
2291         return;
2292
2293 sunlock:
2294         spin_unlock_irqrestore(&qp->s_lock, flags);
2295 }