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1/*
2 * Copyright (c) 2006 Oracle. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33#include <linux/kernel.h>
34#include <linux/in.h>
35#include <linux/device.h>
36#include <linux/dmapool.h>
37#include <linux/ratelimit.h>
38
39#include "rds_single_path.h"
40#include "rds.h"
41#include "ib.h"
42
43/*
44 * Convert IB-specific error message to RDS error message and call core
45 * completion handler.
46 */
47static void rds_ib_send_complete(struct rds_message *rm,
48 int wc_status,
49 void (*complete)(struct rds_message *rm, int status))
50{
51 int notify_status;
52
53 switch (wc_status) {
54 case IB_WC_WR_FLUSH_ERR:
55 return;
56
57 case IB_WC_SUCCESS:
58 notify_status = RDS_RDMA_SUCCESS;
59 break;
60
61 case IB_WC_REM_ACCESS_ERR:
62 notify_status = RDS_RDMA_REMOTE_ERROR;
63 break;
64
65 default:
66 notify_status = RDS_RDMA_OTHER_ERROR;
67 break;
68 }
69 complete(rm, notify_status);
70}
71
72static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
73 struct rm_rdma_op *op,
74 int wc_status)
75{
76 if (op->op_mapped) {
77 ib_dma_unmap_sg(ic->i_cm_id->device,
78 op->op_sg, op->op_nents,
79 op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
80 op->op_mapped = 0;
81 }
82
83 /* If the user asked for a completion notification on this
84 * message, we can implement three different semantics:
85 * 1. Notify when we received the ACK on the RDS message
86 * that was queued with the RDMA. This provides reliable
87 * notification of RDMA status at the expense of a one-way
88 * packet delay.
89 * 2. Notify when the IB stack gives us the completion event for
90 * the RDMA operation.
91 * 3. Notify when the IB stack gives us the completion event for
92 * the accompanying RDS messages.
93 * Here, we implement approach #3. To implement approach #2,
94 * we would need to take an event for the rdma WR. To implement #1,
95 * don't call rds_rdma_send_complete at all, and fall back to the notify
96 * handling in the ACK processing code.
97 *
98 * Note: There's no need to explicitly sync any RDMA buffers using
99 * ib_dma_sync_sg_for_cpu - the completion for the RDMA
100 * operation itself unmapped the RDMA buffers, which takes care
101 * of synching.
102 */
103 rds_ib_send_complete(container_of(op, struct rds_message, rdma),
104 wc_status, rds_rdma_send_complete);
105
106 if (op->op_write)
107 rds_stats_add(s_send_rdma_bytes, op->op_bytes);
108 else
109 rds_stats_add(s_recv_rdma_bytes, op->op_bytes);
110}
111
112static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
113 struct rm_atomic_op *op,
114 int wc_status)
115{
116 /* unmap atomic recvbuf */
117 if (op->op_mapped) {
118 ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1,
119 DMA_FROM_DEVICE);
120 op->op_mapped = 0;
121 }
122
123 rds_ib_send_complete(container_of(op, struct rds_message, atomic),
124 wc_status, rds_atomic_send_complete);
125
126 if (op->op_type == RDS_ATOMIC_TYPE_CSWP)
127 rds_ib_stats_inc(s_ib_atomic_cswp);
128 else
129 rds_ib_stats_inc(s_ib_atomic_fadd);
130}
131
132static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
133 struct rm_data_op *op,
134 int wc_status)
135{
136 struct rds_message *rm = container_of(op, struct rds_message, data);
137
138 if (op->op_nents)
139 ib_dma_unmap_sg(ic->i_cm_id->device,
140 op->op_sg, op->op_nents,
141 DMA_TO_DEVICE);
142
143 if (rm->rdma.op_active && rm->data.op_notify)
144 rds_ib_send_unmap_rdma(ic, &rm->rdma, wc_status);
145}
146
147/*
148 * Unmap the resources associated with a struct send_work.
149 *
150 * Returns the rm for no good reason other than it is unobtainable
151 * other than by switching on wr.opcode, currently, and the caller,
152 * the event handler, needs it.
153 */
154static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic,
155 struct rds_ib_send_work *send,
156 int wc_status)
157{
158 struct rds_message *rm = NULL;
159
160 /* In the error case, wc.opcode sometimes contains garbage */
161 switch (send->s_wr.opcode) {
162 case IB_WR_SEND:
163 if (send->s_op) {
164 rm = container_of(send->s_op, struct rds_message, data);
165 rds_ib_send_unmap_data(ic, send->s_op, wc_status);
166 }
167 break;
168 case IB_WR_RDMA_WRITE:
169 case IB_WR_RDMA_READ:
170 if (send->s_op) {
171 rm = container_of(send->s_op, struct rds_message, rdma);
172 rds_ib_send_unmap_rdma(ic, send->s_op, wc_status);
173 }
174 break;
175 case IB_WR_ATOMIC_FETCH_AND_ADD:
176 case IB_WR_ATOMIC_CMP_AND_SWP:
177 if (send->s_op) {
178 rm = container_of(send->s_op, struct rds_message, atomic);
179 rds_ib_send_unmap_atomic(ic, send->s_op, wc_status);
180 }
181 break;
182 default:
183 printk_ratelimited(KERN_NOTICE
184 "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
185 __func__, send->s_wr.opcode);
186 break;
187 }
188
189 send->s_wr.opcode = 0xdead;
190
191 return rm;
192}
193
194void rds_ib_send_init_ring(struct rds_ib_connection *ic)
195{
196 struct rds_ib_send_work *send;
197 u32 i;
198
199 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
200 struct ib_sge *sge;
201
202 send->s_op = NULL;
203
204 send->s_wr.wr_id = i;
205 send->s_wr.sg_list = send->s_sge;
206 send->s_wr.ex.imm_data = 0;
207
208 sge = &send->s_sge[0];
209 sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
210 sge->length = sizeof(struct rds_header);
211 sge->lkey = ic->i_pd->local_dma_lkey;
212
213 send->s_sge[1].lkey = ic->i_pd->local_dma_lkey;
214 }
215}
216
217void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
218{
219 struct rds_ib_send_work *send;
220 u32 i;
221
222 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
223 if (send->s_op && send->s_wr.opcode != 0xdead)
224 rds_ib_send_unmap_op(ic, send, IB_WC_WR_FLUSH_ERR);
225 }
226}
227
228/*
229 * The only fast path caller always has a non-zero nr, so we don't
230 * bother testing nr before performing the atomic sub.
231 */
232static void rds_ib_sub_signaled(struct rds_ib_connection *ic, int nr)
233{
234 if ((atomic_sub_return(nr, &ic->i_signaled_sends) == 0) &&
235 waitqueue_active(&rds_ib_ring_empty_wait))
236 wake_up(&rds_ib_ring_empty_wait);
237 BUG_ON(atomic_read(&ic->i_signaled_sends) < 0);
238}
239
240/*
241 * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
242 * operations performed in the send path. As the sender allocs and potentially
243 * unallocs the next free entry in the ring it doesn't alter which is
244 * the next to be freed, which is what this is concerned with.
245 */
246void rds_ib_send_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc)
247{
248 struct rds_message *rm = NULL;
249 struct rds_connection *conn = ic->conn;
250 struct rds_ib_send_work *send;
251 u32 completed;
252 u32 oldest;
253 u32 i = 0;
254 int nr_sig = 0;
255
256
257 rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
258 (unsigned long long)wc->wr_id, wc->status,
259 ib_wc_status_msg(wc->status), wc->byte_len,
260 be32_to_cpu(wc->ex.imm_data));
261 rds_ib_stats_inc(s_ib_tx_cq_event);
262
263 if (wc->wr_id == RDS_IB_ACK_WR_ID) {
264 if (time_after(jiffies, ic->i_ack_queued + HZ / 2))
265 rds_ib_stats_inc(s_ib_tx_stalled);
266 rds_ib_ack_send_complete(ic);
267 return;
268 }
269
270 oldest = rds_ib_ring_oldest(&ic->i_send_ring);
271
272 completed = rds_ib_ring_completed(&ic->i_send_ring, wc->wr_id, oldest);
273
274 for (i = 0; i < completed; i++) {
275 send = &ic->i_sends[oldest];
276 if (send->s_wr.send_flags & IB_SEND_SIGNALED)
277 nr_sig++;
278
279 rm = rds_ib_send_unmap_op(ic, send, wc->status);
280
281 if (time_after(jiffies, send->s_queued + HZ / 2))
282 rds_ib_stats_inc(s_ib_tx_stalled);
283
284 if (send->s_op) {
285 if (send->s_op == rm->m_final_op) {
286 /* If anyone waited for this message to get
287 * flushed out, wake them up now
288 */
289 rds_message_unmapped(rm);
290 }
291 rds_message_put(rm);
292 send->s_op = NULL;
293 }
294
295 oldest = (oldest + 1) % ic->i_send_ring.w_nr;
296 }
297
298 rds_ib_ring_free(&ic->i_send_ring, completed);
299 rds_ib_sub_signaled(ic, nr_sig);
300 nr_sig = 0;
301
302 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
303 test_bit(0, &conn->c_map_queued))
304 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
305
306 /* We expect errors as the qp is drained during shutdown */
307 if (wc->status != IB_WC_SUCCESS && rds_conn_up(conn)) {
308 rds_ib_conn_error(conn, "send completion on <%pI4,%pI4> had status %u (%s), disconnecting and reconnecting\n",
309 &conn->c_laddr, &conn->c_faddr, wc->status,
310 ib_wc_status_msg(wc->status));
311 }
312}
313
314/*
315 * This is the main function for allocating credits when sending
316 * messages.
317 *
318 * Conceptually, we have two counters:
319 * - send credits: this tells us how many WRs we're allowed
320 * to submit without overruning the receiver's queue. For
321 * each SEND WR we post, we decrement this by one.
322 *
323 * - posted credits: this tells us how many WRs we recently
324 * posted to the receive queue. This value is transferred
325 * to the peer as a "credit update" in a RDS header field.
326 * Every time we transmit credits to the peer, we subtract
327 * the amount of transferred credits from this counter.
328 *
329 * It is essential that we avoid situations where both sides have
330 * exhausted their send credits, and are unable to send new credits
331 * to the peer. We achieve this by requiring that we send at least
332 * one credit update to the peer before exhausting our credits.
333 * When new credits arrive, we subtract one credit that is withheld
334 * until we've posted new buffers and are ready to transmit these
335 * credits (see rds_ib_send_add_credits below).
336 *
337 * The RDS send code is essentially single-threaded; rds_send_xmit
338 * sets RDS_IN_XMIT to ensure exclusive access to the send ring.
339 * However, the ACK sending code is independent and can race with
340 * message SENDs.
341 *
342 * In the send path, we need to update the counters for send credits
343 * and the counter of posted buffers atomically - when we use the
344 * last available credit, we cannot allow another thread to race us
345 * and grab the posted credits counter. Hence, we have to use a
346 * spinlock to protect the credit counter, or use atomics.
347 *
348 * Spinlocks shared between the send and the receive path are bad,
349 * because they create unnecessary delays. An early implementation
350 * using a spinlock showed a 5% degradation in throughput at some
351 * loads.
352 *
353 * This implementation avoids spinlocks completely, putting both
354 * counters into a single atomic, and updating that atomic using
355 * atomic_add (in the receive path, when receiving fresh credits),
356 * and using atomic_cmpxchg when updating the two counters.
357 */
358int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
359 u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
360{
361 unsigned int avail, posted, got = 0, advertise;
362 long oldval, newval;
363
364 *adv_credits = 0;
365 if (!ic->i_flowctl)
366 return wanted;
367
368try_again:
369 advertise = 0;
370 oldval = newval = atomic_read(&ic->i_credits);
371 posted = IB_GET_POST_CREDITS(oldval);
372 avail = IB_GET_SEND_CREDITS(oldval);
373
374 rdsdebug("wanted=%u credits=%u posted=%u\n",
375 wanted, avail, posted);
376
377 /* The last credit must be used to send a credit update. */
378 if (avail && !posted)
379 avail--;
380
381 if (avail < wanted) {
382 struct rds_connection *conn = ic->i_cm_id->context;
383
384 /* Oops, there aren't that many credits left! */
385 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
386 got = avail;
387 } else {
388 /* Sometimes you get what you want, lalala. */
389 got = wanted;
390 }
391 newval -= IB_SET_SEND_CREDITS(got);
392
393 /*
394 * If need_posted is non-zero, then the caller wants
395 * the posted regardless of whether any send credits are
396 * available.
397 */
398 if (posted && (got || need_posted)) {
399 advertise = min_t(unsigned int, posted, max_posted);
400 newval -= IB_SET_POST_CREDITS(advertise);
401 }
402
403 /* Finally bill everything */
404 if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
405 goto try_again;
406
407 *adv_credits = advertise;
408 return got;
409}
410
411void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
412{
413 struct rds_ib_connection *ic = conn->c_transport_data;
414
415 if (credits == 0)
416 return;
417
418 rdsdebug("credits=%u current=%u%s\n",
419 credits,
420 IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
421 test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
422
423 atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
424 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
425 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
426
427 WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
428
429 rds_ib_stats_inc(s_ib_rx_credit_updates);
430}
431
432void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
433{
434 struct rds_ib_connection *ic = conn->c_transport_data;
435
436 if (posted == 0)
437 return;
438
439 atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
440
441 /* Decide whether to send an update to the peer now.
442 * If we would send a credit update for every single buffer we
443 * post, we would end up with an ACK storm (ACK arrives,
444 * consumes buffer, we refill the ring, send ACK to remote
445 * advertising the newly posted buffer... ad inf)
446 *
447 * Performance pretty much depends on how often we send
448 * credit updates - too frequent updates mean lots of ACKs.
449 * Too infrequent updates, and the peer will run out of
450 * credits and has to throttle.
451 * For the time being, 16 seems to be a good compromise.
452 */
453 if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
454 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
455}
456
457static inline int rds_ib_set_wr_signal_state(struct rds_ib_connection *ic,
458 struct rds_ib_send_work *send,
459 bool notify)
460{
461 /*
462 * We want to delay signaling completions just enough to get
463 * the batching benefits but not so much that we create dead time
464 * on the wire.
465 */
466 if (ic->i_unsignaled_wrs-- == 0 || notify) {
467 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
468 send->s_wr.send_flags |= IB_SEND_SIGNALED;
469 return 1;
470 }
471 return 0;
472}
473
474/*
475 * This can be called multiple times for a given message. The first time
476 * we see a message we map its scatterlist into the IB device so that
477 * we can provide that mapped address to the IB scatter gather entries
478 * in the IB work requests. We translate the scatterlist into a series
479 * of work requests that fragment the message. These work requests complete
480 * in order so we pass ownership of the message to the completion handler
481 * once we send the final fragment.
482 *
483 * The RDS core uses the c_send_lock to only enter this function once
484 * per connection. This makes sure that the tx ring alloc/unalloc pairs
485 * don't get out of sync and confuse the ring.
486 */
487int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
488 unsigned int hdr_off, unsigned int sg, unsigned int off)
489{
490 struct rds_ib_connection *ic = conn->c_transport_data;
491 struct ib_device *dev = ic->i_cm_id->device;
492 struct rds_ib_send_work *send = NULL;
493 struct rds_ib_send_work *first;
494 struct rds_ib_send_work *prev;
495 struct ib_send_wr *failed_wr;
496 struct scatterlist *scat;
497 u32 pos;
498 u32 i;
499 u32 work_alloc;
500 u32 credit_alloc = 0;
501 u32 posted;
502 u32 adv_credits = 0;
503 int send_flags = 0;
504 int bytes_sent = 0;
505 int ret;
506 int flow_controlled = 0;
507 int nr_sig = 0;
508
509 BUG_ON(off % RDS_FRAG_SIZE);
510 BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
511
512 /* Do not send cong updates to IB loopback */
513 if (conn->c_loopback
514 && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
515 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
516 scat = &rm->data.op_sg[sg];
517 ret = max_t(int, RDS_CONG_MAP_BYTES, scat->length);
518 return sizeof(struct rds_header) + ret;
519 }
520
521 /* FIXME we may overallocate here */
522 if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
523 i = 1;
524 else
525 i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
526
527 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
528 if (work_alloc == 0) {
529 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
530 rds_ib_stats_inc(s_ib_tx_ring_full);
531 ret = -ENOMEM;
532 goto out;
533 }
534
535 if (ic->i_flowctl) {
536 credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
537 adv_credits += posted;
538 if (credit_alloc < work_alloc) {
539 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
540 work_alloc = credit_alloc;
541 flow_controlled = 1;
542 }
543 if (work_alloc == 0) {
544 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
545 rds_ib_stats_inc(s_ib_tx_throttle);
546 ret = -ENOMEM;
547 goto out;
548 }
549 }
550
551 /* map the message the first time we see it */
552 if (!ic->i_data_op) {
553 if (rm->data.op_nents) {
554 rm->data.op_count = ib_dma_map_sg(dev,
555 rm->data.op_sg,
556 rm->data.op_nents,
557 DMA_TO_DEVICE);
558 rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
559 if (rm->data.op_count == 0) {
560 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
561 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
562 ret = -ENOMEM; /* XXX ? */
563 goto out;
564 }
565 } else {
566 rm->data.op_count = 0;
567 }
568
569 rds_message_addref(rm);
570 rm->data.op_dmasg = 0;
571 rm->data.op_dmaoff = 0;
572 ic->i_data_op = &rm->data;
573
574 /* Finalize the header */
575 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
576 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
577 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
578 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
579
580 /* If it has a RDMA op, tell the peer we did it. This is
581 * used by the peer to release use-once RDMA MRs. */
582 if (rm->rdma.op_active) {
583 struct rds_ext_header_rdma ext_hdr;
584
585 ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
586 rds_message_add_extension(&rm->m_inc.i_hdr,
587 RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
588 }
589 if (rm->m_rdma_cookie) {
590 rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
591 rds_rdma_cookie_key(rm->m_rdma_cookie),
592 rds_rdma_cookie_offset(rm->m_rdma_cookie));
593 }
594
595 /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
596 * we should not do this unless we have a chance of at least
597 * sticking the header into the send ring. Which is why we
598 * should call rds_ib_ring_alloc first. */
599 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
600 rds_message_make_checksum(&rm->m_inc.i_hdr);
601
602 /*
603 * Update adv_credits since we reset the ACK_REQUIRED bit.
604 */
605 if (ic->i_flowctl) {
606 rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
607 adv_credits += posted;
608 BUG_ON(adv_credits > 255);
609 }
610 }
611
612 /* Sometimes you want to put a fence between an RDMA
613 * READ and the following SEND.
614 * We could either do this all the time
615 * or when requested by the user. Right now, we let
616 * the application choose.
617 */
618 if (rm->rdma.op_active && rm->rdma.op_fence)
619 send_flags = IB_SEND_FENCE;
620
621 /* Each frag gets a header. Msgs may be 0 bytes */
622 send = &ic->i_sends[pos];
623 first = send;
624 prev = NULL;
625 scat = &ic->i_data_op->op_sg[rm->data.op_dmasg];
626 i = 0;
627 do {
628 unsigned int len = 0;
629
630 /* Set up the header */
631 send->s_wr.send_flags = send_flags;
632 send->s_wr.opcode = IB_WR_SEND;
633 send->s_wr.num_sge = 1;
634 send->s_wr.next = NULL;
635 send->s_queued = jiffies;
636 send->s_op = NULL;
637
638 send->s_sge[0].addr = ic->i_send_hdrs_dma
639 + (pos * sizeof(struct rds_header));
640 send->s_sge[0].length = sizeof(struct rds_header);
641
642 memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
643
644 /* Set up the data, if present */
645 if (i < work_alloc
646 && scat != &rm->data.op_sg[rm->data.op_count]) {
647 len = min(RDS_FRAG_SIZE,
648 ib_sg_dma_len(dev, scat) - rm->data.op_dmaoff);
649 send->s_wr.num_sge = 2;
650
651 send->s_sge[1].addr = ib_sg_dma_address(dev, scat);
652 send->s_sge[1].addr += rm->data.op_dmaoff;
653 send->s_sge[1].length = len;
654
655 bytes_sent += len;
656 rm->data.op_dmaoff += len;
657 if (rm->data.op_dmaoff == ib_sg_dma_len(dev, scat)) {
658 scat++;
659 rm->data.op_dmasg++;
660 rm->data.op_dmaoff = 0;
661 }
662 }
663
664 rds_ib_set_wr_signal_state(ic, send, false);
665
666 /*
667 * Always signal the last one if we're stopping due to flow control.
668 */
669 if (ic->i_flowctl && flow_controlled && i == (work_alloc - 1)) {
670 rds_ib_set_wr_signal_state(ic, send, true);
671 send->s_wr.send_flags |= IB_SEND_SOLICITED;
672 }
673
674 if (send->s_wr.send_flags & IB_SEND_SIGNALED)
675 nr_sig++;
676
677 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
678 &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
679
680 if (ic->i_flowctl && adv_credits) {
681 struct rds_header *hdr = &ic->i_send_hdrs[pos];
682
683 /* add credit and redo the header checksum */
684 hdr->h_credit = adv_credits;
685 rds_message_make_checksum(hdr);
686 adv_credits = 0;
687 rds_ib_stats_inc(s_ib_tx_credit_updates);
688 }
689
690 if (prev)
691 prev->s_wr.next = &send->s_wr;
692 prev = send;
693
694 pos = (pos + 1) % ic->i_send_ring.w_nr;
695 send = &ic->i_sends[pos];
696 i++;
697
698 } while (i < work_alloc
699 && scat != &rm->data.op_sg[rm->data.op_count]);
700
701 /* Account the RDS header in the number of bytes we sent, but just once.
702 * The caller has no concept of fragmentation. */
703 if (hdr_off == 0)
704 bytes_sent += sizeof(struct rds_header);
705
706 /* if we finished the message then send completion owns it */
707 if (scat == &rm->data.op_sg[rm->data.op_count]) {
708 prev->s_op = ic->i_data_op;
709 prev->s_wr.send_flags |= IB_SEND_SOLICITED;
710 if (!(prev->s_wr.send_flags & IB_SEND_SIGNALED))
711 nr_sig += rds_ib_set_wr_signal_state(ic, prev, true);
712 ic->i_data_op = NULL;
713 }
714
715 /* Put back wrs & credits we didn't use */
716 if (i < work_alloc) {
717 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
718 work_alloc = i;
719 }
720 if (ic->i_flowctl && i < credit_alloc)
721 rds_ib_send_add_credits(conn, credit_alloc - i);
722
723 if (nr_sig)
724 atomic_add(nr_sig, &ic->i_signaled_sends);
725
726 /* XXX need to worry about failed_wr and partial sends. */
727 failed_wr = &first->s_wr;
728 ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
729 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
730 first, &first->s_wr, ret, failed_wr);
731 BUG_ON(failed_wr != &first->s_wr);
732 if (ret) {
733 printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 "
734 "returned %d\n", &conn->c_faddr, ret);
735 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
736 rds_ib_sub_signaled(ic, nr_sig);
737 if (prev->s_op) {
738 ic->i_data_op = prev->s_op;
739 prev->s_op = NULL;
740 }
741
742 rds_ib_conn_error(ic->conn, "ib_post_send failed\n");
743 goto out;
744 }
745
746 ret = bytes_sent;
747out:
748 BUG_ON(adv_credits);
749 return ret;
750}
751
752/*
753 * Issue atomic operation.
754 * A simplified version of the rdma case, we always map 1 SG, and
755 * only 8 bytes, for the return value from the atomic operation.
756 */
757int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
758{
759 struct rds_ib_connection *ic = conn->c_transport_data;
760 struct rds_ib_send_work *send = NULL;
761 struct ib_send_wr *failed_wr;
762 struct rds_ib_device *rds_ibdev;
763 u32 pos;
764 u32 work_alloc;
765 int ret;
766 int nr_sig = 0;
767
768 rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
769
770 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
771 if (work_alloc != 1) {
772 rds_ib_stats_inc(s_ib_tx_ring_full);
773 ret = -ENOMEM;
774 goto out;
775 }
776
777 /* address of send request in ring */
778 send = &ic->i_sends[pos];
779 send->s_queued = jiffies;
780
781 if (op->op_type == RDS_ATOMIC_TYPE_CSWP) {
782 send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP;
783 send->s_atomic_wr.compare_add = op->op_m_cswp.compare;
784 send->s_atomic_wr.swap = op->op_m_cswp.swap;
785 send->s_atomic_wr.compare_add_mask = op->op_m_cswp.compare_mask;
786 send->s_atomic_wr.swap_mask = op->op_m_cswp.swap_mask;
787 } else { /* FADD */
788 send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD;
789 send->s_atomic_wr.compare_add = op->op_m_fadd.add;
790 send->s_atomic_wr.swap = 0;
791 send->s_atomic_wr.compare_add_mask = op->op_m_fadd.nocarry_mask;
792 send->s_atomic_wr.swap_mask = 0;
793 }
794 send->s_wr.send_flags = 0;
795 nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify);
796 send->s_atomic_wr.wr.num_sge = 1;
797 send->s_atomic_wr.wr.next = NULL;
798 send->s_atomic_wr.remote_addr = op->op_remote_addr;
799 send->s_atomic_wr.rkey = op->op_rkey;
800 send->s_op = op;
801 rds_message_addref(container_of(send->s_op, struct rds_message, atomic));
802
803 /* map 8 byte retval buffer to the device */
804 ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE);
805 rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret);
806 if (ret != 1) {
807 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
808 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
809 ret = -ENOMEM; /* XXX ? */
810 goto out;
811 }
812
813 /* Convert our struct scatterlist to struct ib_sge */
814 send->s_sge[0].addr = ib_sg_dma_address(ic->i_cm_id->device, op->op_sg);
815 send->s_sge[0].length = ib_sg_dma_len(ic->i_cm_id->device, op->op_sg);
816 send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
817
818 rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
819 send->s_sge[0].addr, send->s_sge[0].length);
820
821 if (nr_sig)
822 atomic_add(nr_sig, &ic->i_signaled_sends);
823
824 failed_wr = &send->s_atomic_wr.wr;
825 ret = ib_post_send(ic->i_cm_id->qp, &send->s_atomic_wr.wr, &failed_wr);
826 rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
827 send, &send->s_atomic_wr, ret, failed_wr);
828 BUG_ON(failed_wr != &send->s_atomic_wr.wr);
829 if (ret) {
830 printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI4 "
831 "returned %d\n", &conn->c_faddr, ret);
832 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
833 rds_ib_sub_signaled(ic, nr_sig);
834 goto out;
835 }
836
837 if (unlikely(failed_wr != &send->s_atomic_wr.wr)) {
838 printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
839 BUG_ON(failed_wr != &send->s_atomic_wr.wr);
840 }
841
842out:
843 return ret;
844}
845
846int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
847{
848 struct rds_ib_connection *ic = conn->c_transport_data;
849 struct rds_ib_send_work *send = NULL;
850 struct rds_ib_send_work *first;
851 struct rds_ib_send_work *prev;
852 struct ib_send_wr *failed_wr;
853 struct scatterlist *scat;
854 unsigned long len;
855 u64 remote_addr = op->op_remote_addr;
856 u32 max_sge = ic->rds_ibdev->max_sge;
857 u32 pos;
858 u32 work_alloc;
859 u32 i;
860 u32 j;
861 int sent;
862 int ret;
863 int num_sge;
864 int nr_sig = 0;
865
866 /* map the op the first time we see it */
867 if (!op->op_mapped) {
868 op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
869 op->op_sg, op->op_nents, (op->op_write) ?
870 DMA_TO_DEVICE : DMA_FROM_DEVICE);
871 rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
872 if (op->op_count == 0) {
873 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
874 ret = -ENOMEM; /* XXX ? */
875 goto out;
876 }
877
878 op->op_mapped = 1;
879 }
880
881 /*
882 * Instead of knowing how to return a partial rdma read/write we insist that there
883 * be enough work requests to send the entire message.
884 */
885 i = ceil(op->op_count, max_sge);
886
887 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
888 if (work_alloc != i) {
889 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
890 rds_ib_stats_inc(s_ib_tx_ring_full);
891 ret = -ENOMEM;
892 goto out;
893 }
894
895 send = &ic->i_sends[pos];
896 first = send;
897 prev = NULL;
898 scat = &op->op_sg[0];
899 sent = 0;
900 num_sge = op->op_count;
901
902 for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
903 send->s_wr.send_flags = 0;
904 send->s_queued = jiffies;
905 send->s_op = NULL;
906
907 nr_sig += rds_ib_set_wr_signal_state(ic, send, op->op_notify);
908
909 send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
910 send->s_rdma_wr.remote_addr = remote_addr;
911 send->s_rdma_wr.rkey = op->op_rkey;
912
913 if (num_sge > max_sge) {
914 send->s_rdma_wr.wr.num_sge = max_sge;
915 num_sge -= max_sge;
916 } else {
917 send->s_rdma_wr.wr.num_sge = num_sge;
918 }
919
920 send->s_rdma_wr.wr.next = NULL;
921
922 if (prev)
923 prev->s_rdma_wr.wr.next = &send->s_rdma_wr.wr;
924
925 for (j = 0; j < send->s_rdma_wr.wr.num_sge &&
926 scat != &op->op_sg[op->op_count]; j++) {
927 len = ib_sg_dma_len(ic->i_cm_id->device, scat);
928 send->s_sge[j].addr =
929 ib_sg_dma_address(ic->i_cm_id->device, scat);
930 send->s_sge[j].length = len;
931 send->s_sge[j].lkey = ic->i_pd->local_dma_lkey;
932
933 sent += len;
934 rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
935
936 remote_addr += len;
937 scat++;
938 }
939
940 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
941 &send->s_rdma_wr.wr,
942 send->s_rdma_wr.wr.num_sge,
943 send->s_rdma_wr.wr.next);
944
945 prev = send;
946 if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
947 send = ic->i_sends;
948 }
949
950 /* give a reference to the last op */
951 if (scat == &op->op_sg[op->op_count]) {
952 prev->s_op = op;
953 rds_message_addref(container_of(op, struct rds_message, rdma));
954 }
955
956 if (i < work_alloc) {
957 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
958 work_alloc = i;
959 }
960
961 if (nr_sig)
962 atomic_add(nr_sig, &ic->i_signaled_sends);
963
964 failed_wr = &first->s_rdma_wr.wr;
965 ret = ib_post_send(ic->i_cm_id->qp, &first->s_rdma_wr.wr, &failed_wr);
966 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
967 first, &first->s_rdma_wr.wr, ret, failed_wr);
968 BUG_ON(failed_wr != &first->s_rdma_wr.wr);
969 if (ret) {
970 printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 "
971 "returned %d\n", &conn->c_faddr, ret);
972 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
973 rds_ib_sub_signaled(ic, nr_sig);
974 goto out;
975 }
976
977 if (unlikely(failed_wr != &first->s_rdma_wr.wr)) {
978 printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
979 BUG_ON(failed_wr != &first->s_rdma_wr.wr);
980 }
981
982
983out:
984 return ret;
985}
986
987void rds_ib_xmit_path_complete(struct rds_conn_path *cp)
988{
989 struct rds_connection *conn = cp->cp_conn;
990 struct rds_ib_connection *ic = conn->c_transport_data;
991
992 /* We may have a pending ACK or window update we were unable
993 * to send previously (due to flow control). Try again. */
994 rds_ib_attempt_ack(ic);
995}
1/*
2 * Copyright (c) 2006, 2019 Oracle and/or its affiliates. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33#include <linux/kernel.h>
34#include <linux/in.h>
35#include <linux/device.h>
36#include <linux/dmapool.h>
37#include <linux/ratelimit.h>
38
39#include "rds_single_path.h"
40#include "rds.h"
41#include "ib.h"
42#include "ib_mr.h"
43
44/*
45 * Convert IB-specific error message to RDS error message and call core
46 * completion handler.
47 */
48static void rds_ib_send_complete(struct rds_message *rm,
49 int wc_status,
50 void (*complete)(struct rds_message *rm, int status))
51{
52 int notify_status;
53
54 switch (wc_status) {
55 case IB_WC_WR_FLUSH_ERR:
56 return;
57
58 case IB_WC_SUCCESS:
59 notify_status = RDS_RDMA_SUCCESS;
60 break;
61
62 case IB_WC_REM_ACCESS_ERR:
63 notify_status = RDS_RDMA_REMOTE_ERROR;
64 break;
65
66 default:
67 notify_status = RDS_RDMA_OTHER_ERROR;
68 break;
69 }
70 complete(rm, notify_status);
71}
72
73static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
74 struct rm_data_op *op,
75 int wc_status)
76{
77 if (op->op_nents)
78 ib_dma_unmap_sg(ic->i_cm_id->device,
79 op->op_sg, op->op_nents,
80 DMA_TO_DEVICE);
81}
82
83static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
84 struct rm_rdma_op *op,
85 int wc_status)
86{
87 if (op->op_mapped) {
88 ib_dma_unmap_sg(ic->i_cm_id->device,
89 op->op_sg, op->op_nents,
90 op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
91 op->op_mapped = 0;
92 }
93
94 /* If the user asked for a completion notification on this
95 * message, we can implement three different semantics:
96 * 1. Notify when we received the ACK on the RDS message
97 * that was queued with the RDMA. This provides reliable
98 * notification of RDMA status at the expense of a one-way
99 * packet delay.
100 * 2. Notify when the IB stack gives us the completion event for
101 * the RDMA operation.
102 * 3. Notify when the IB stack gives us the completion event for
103 * the accompanying RDS messages.
104 * Here, we implement approach #3. To implement approach #2,
105 * we would need to take an event for the rdma WR. To implement #1,
106 * don't call rds_rdma_send_complete at all, and fall back to the notify
107 * handling in the ACK processing code.
108 *
109 * Note: There's no need to explicitly sync any RDMA buffers using
110 * ib_dma_sync_sg_for_cpu - the completion for the RDMA
111 * operation itself unmapped the RDMA buffers, which takes care
112 * of synching.
113 */
114 rds_ib_send_complete(container_of(op, struct rds_message, rdma),
115 wc_status, rds_rdma_send_complete);
116
117 if (op->op_write)
118 rds_stats_add(s_send_rdma_bytes, op->op_bytes);
119 else
120 rds_stats_add(s_recv_rdma_bytes, op->op_bytes);
121}
122
123static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
124 struct rm_atomic_op *op,
125 int wc_status)
126{
127 /* unmap atomic recvbuf */
128 if (op->op_mapped) {
129 ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1,
130 DMA_FROM_DEVICE);
131 op->op_mapped = 0;
132 }
133
134 rds_ib_send_complete(container_of(op, struct rds_message, atomic),
135 wc_status, rds_atomic_send_complete);
136
137 if (op->op_type == RDS_ATOMIC_TYPE_CSWP)
138 rds_ib_stats_inc(s_ib_atomic_cswp);
139 else
140 rds_ib_stats_inc(s_ib_atomic_fadd);
141}
142
143/*
144 * Unmap the resources associated with a struct send_work.
145 *
146 * Returns the rm for no good reason other than it is unobtainable
147 * other than by switching on wr.opcode, currently, and the caller,
148 * the event handler, needs it.
149 */
150static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic,
151 struct rds_ib_send_work *send,
152 int wc_status)
153{
154 struct rds_message *rm = NULL;
155
156 /* In the error case, wc.opcode sometimes contains garbage */
157 switch (send->s_wr.opcode) {
158 case IB_WR_SEND:
159 if (send->s_op) {
160 rm = container_of(send->s_op, struct rds_message, data);
161 rds_ib_send_unmap_data(ic, send->s_op, wc_status);
162 }
163 break;
164 case IB_WR_RDMA_WRITE:
165 case IB_WR_RDMA_READ:
166 if (send->s_op) {
167 rm = container_of(send->s_op, struct rds_message, rdma);
168 rds_ib_send_unmap_rdma(ic, send->s_op, wc_status);
169 }
170 break;
171 case IB_WR_ATOMIC_FETCH_AND_ADD:
172 case IB_WR_ATOMIC_CMP_AND_SWP:
173 if (send->s_op) {
174 rm = container_of(send->s_op, struct rds_message, atomic);
175 rds_ib_send_unmap_atomic(ic, send->s_op, wc_status);
176 }
177 break;
178 default:
179 printk_ratelimited(KERN_NOTICE
180 "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
181 __func__, send->s_wr.opcode);
182 break;
183 }
184
185 send->s_wr.opcode = 0xdead;
186
187 return rm;
188}
189
190void rds_ib_send_init_ring(struct rds_ib_connection *ic)
191{
192 struct rds_ib_send_work *send;
193 u32 i;
194
195 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
196 struct ib_sge *sge;
197
198 send->s_op = NULL;
199
200 send->s_wr.wr_id = i;
201 send->s_wr.sg_list = send->s_sge;
202 send->s_wr.ex.imm_data = 0;
203
204 sge = &send->s_sge[0];
205 sge->addr = ic->i_send_hdrs_dma[i];
206
207 sge->length = sizeof(struct rds_header);
208 sge->lkey = ic->i_pd->local_dma_lkey;
209
210 send->s_sge[1].lkey = ic->i_pd->local_dma_lkey;
211 }
212}
213
214void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
215{
216 struct rds_ib_send_work *send;
217 u32 i;
218
219 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
220 if (send->s_op && send->s_wr.opcode != 0xdead)
221 rds_ib_send_unmap_op(ic, send, IB_WC_WR_FLUSH_ERR);
222 }
223}
224
225/*
226 * The only fast path caller always has a non-zero nr, so we don't
227 * bother testing nr before performing the atomic sub.
228 */
229static void rds_ib_sub_signaled(struct rds_ib_connection *ic, int nr)
230{
231 if ((atomic_sub_return(nr, &ic->i_signaled_sends) == 0) &&
232 waitqueue_active(&rds_ib_ring_empty_wait))
233 wake_up(&rds_ib_ring_empty_wait);
234 BUG_ON(atomic_read(&ic->i_signaled_sends) < 0);
235}
236
237/*
238 * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
239 * operations performed in the send path. As the sender allocs and potentially
240 * unallocs the next free entry in the ring it doesn't alter which is
241 * the next to be freed, which is what this is concerned with.
242 */
243void rds_ib_send_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc)
244{
245 struct rds_message *rm = NULL;
246 struct rds_connection *conn = ic->conn;
247 struct rds_ib_send_work *send;
248 u32 completed;
249 u32 oldest;
250 u32 i = 0;
251 int nr_sig = 0;
252
253
254 rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
255 (unsigned long long)wc->wr_id, wc->status,
256 ib_wc_status_msg(wc->status), wc->byte_len,
257 be32_to_cpu(wc->ex.imm_data));
258 rds_ib_stats_inc(s_ib_tx_cq_event);
259
260 if (wc->wr_id == RDS_IB_ACK_WR_ID) {
261 if (time_after(jiffies, ic->i_ack_queued + HZ / 2))
262 rds_ib_stats_inc(s_ib_tx_stalled);
263 rds_ib_ack_send_complete(ic);
264 return;
265 }
266
267 oldest = rds_ib_ring_oldest(&ic->i_send_ring);
268
269 completed = rds_ib_ring_completed(&ic->i_send_ring, wc->wr_id, oldest);
270
271 for (i = 0; i < completed; i++) {
272 send = &ic->i_sends[oldest];
273 if (send->s_wr.send_flags & IB_SEND_SIGNALED)
274 nr_sig++;
275
276 rm = rds_ib_send_unmap_op(ic, send, wc->status);
277
278 if (time_after(jiffies, send->s_queued + HZ / 2))
279 rds_ib_stats_inc(s_ib_tx_stalled);
280
281 if (send->s_op) {
282 if (send->s_op == rm->m_final_op) {
283 /* If anyone waited for this message to get
284 * flushed out, wake them up now
285 */
286 rds_message_unmapped(rm);
287 }
288 rds_message_put(rm);
289 send->s_op = NULL;
290 }
291
292 oldest = (oldest + 1) % ic->i_send_ring.w_nr;
293 }
294
295 rds_ib_ring_free(&ic->i_send_ring, completed);
296 rds_ib_sub_signaled(ic, nr_sig);
297
298 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
299 test_bit(0, &conn->c_map_queued))
300 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
301
302 /* We expect errors as the qp is drained during shutdown */
303 if (wc->status != IB_WC_SUCCESS && rds_conn_up(conn)) {
304 rds_ib_conn_error(conn, "send completion on <%pI6c,%pI6c,%d> had status %u (%s), vendor err 0x%x, disconnecting and reconnecting\n",
305 &conn->c_laddr, &conn->c_faddr,
306 conn->c_tos, wc->status,
307 ib_wc_status_msg(wc->status), wc->vendor_err);
308 }
309}
310
311/*
312 * This is the main function for allocating credits when sending
313 * messages.
314 *
315 * Conceptually, we have two counters:
316 * - send credits: this tells us how many WRs we're allowed
317 * to submit without overruning the receiver's queue. For
318 * each SEND WR we post, we decrement this by one.
319 *
320 * - posted credits: this tells us how many WRs we recently
321 * posted to the receive queue. This value is transferred
322 * to the peer as a "credit update" in a RDS header field.
323 * Every time we transmit credits to the peer, we subtract
324 * the amount of transferred credits from this counter.
325 *
326 * It is essential that we avoid situations where both sides have
327 * exhausted their send credits, and are unable to send new credits
328 * to the peer. We achieve this by requiring that we send at least
329 * one credit update to the peer before exhausting our credits.
330 * When new credits arrive, we subtract one credit that is withheld
331 * until we've posted new buffers and are ready to transmit these
332 * credits (see rds_ib_send_add_credits below).
333 *
334 * The RDS send code is essentially single-threaded; rds_send_xmit
335 * sets RDS_IN_XMIT to ensure exclusive access to the send ring.
336 * However, the ACK sending code is independent and can race with
337 * message SENDs.
338 *
339 * In the send path, we need to update the counters for send credits
340 * and the counter of posted buffers atomically - when we use the
341 * last available credit, we cannot allow another thread to race us
342 * and grab the posted credits counter. Hence, we have to use a
343 * spinlock to protect the credit counter, or use atomics.
344 *
345 * Spinlocks shared between the send and the receive path are bad,
346 * because they create unnecessary delays. An early implementation
347 * using a spinlock showed a 5% degradation in throughput at some
348 * loads.
349 *
350 * This implementation avoids spinlocks completely, putting both
351 * counters into a single atomic, and updating that atomic using
352 * atomic_add (in the receive path, when receiving fresh credits),
353 * and using atomic_cmpxchg when updating the two counters.
354 */
355int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
356 u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
357{
358 unsigned int avail, posted, got = 0, advertise;
359 long oldval, newval;
360
361 *adv_credits = 0;
362 if (!ic->i_flowctl)
363 return wanted;
364
365try_again:
366 advertise = 0;
367 oldval = newval = atomic_read(&ic->i_credits);
368 posted = IB_GET_POST_CREDITS(oldval);
369 avail = IB_GET_SEND_CREDITS(oldval);
370
371 rdsdebug("wanted=%u credits=%u posted=%u\n",
372 wanted, avail, posted);
373
374 /* The last credit must be used to send a credit update. */
375 if (avail && !posted)
376 avail--;
377
378 if (avail < wanted) {
379 struct rds_connection *conn = ic->i_cm_id->context;
380
381 /* Oops, there aren't that many credits left! */
382 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
383 got = avail;
384 } else {
385 /* Sometimes you get what you want, lalala. */
386 got = wanted;
387 }
388 newval -= IB_SET_SEND_CREDITS(got);
389
390 /*
391 * If need_posted is non-zero, then the caller wants
392 * the posted regardless of whether any send credits are
393 * available.
394 */
395 if (posted && (got || need_posted)) {
396 advertise = min_t(unsigned int, posted, max_posted);
397 newval -= IB_SET_POST_CREDITS(advertise);
398 }
399
400 /* Finally bill everything */
401 if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
402 goto try_again;
403
404 *adv_credits = advertise;
405 return got;
406}
407
408void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
409{
410 struct rds_ib_connection *ic = conn->c_transport_data;
411
412 if (credits == 0)
413 return;
414
415 rdsdebug("credits=%u current=%u%s\n",
416 credits,
417 IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
418 test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
419
420 atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
421 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
422 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
423
424 WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
425
426 rds_ib_stats_inc(s_ib_rx_credit_updates);
427}
428
429void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
430{
431 struct rds_ib_connection *ic = conn->c_transport_data;
432
433 if (posted == 0)
434 return;
435
436 atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
437
438 /* Decide whether to send an update to the peer now.
439 * If we would send a credit update for every single buffer we
440 * post, we would end up with an ACK storm (ACK arrives,
441 * consumes buffer, we refill the ring, send ACK to remote
442 * advertising the newly posted buffer... ad inf)
443 *
444 * Performance pretty much depends on how often we send
445 * credit updates - too frequent updates mean lots of ACKs.
446 * Too infrequent updates, and the peer will run out of
447 * credits and has to throttle.
448 * For the time being, 16 seems to be a good compromise.
449 */
450 if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
451 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
452}
453
454static inline int rds_ib_set_wr_signal_state(struct rds_ib_connection *ic,
455 struct rds_ib_send_work *send,
456 bool notify)
457{
458 /*
459 * We want to delay signaling completions just enough to get
460 * the batching benefits but not so much that we create dead time
461 * on the wire.
462 */
463 if (ic->i_unsignaled_wrs-- == 0 || notify) {
464 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
465 send->s_wr.send_flags |= IB_SEND_SIGNALED;
466 return 1;
467 }
468 return 0;
469}
470
471/*
472 * This can be called multiple times for a given message. The first time
473 * we see a message we map its scatterlist into the IB device so that
474 * we can provide that mapped address to the IB scatter gather entries
475 * in the IB work requests. We translate the scatterlist into a series
476 * of work requests that fragment the message. These work requests complete
477 * in order so we pass ownership of the message to the completion handler
478 * once we send the final fragment.
479 *
480 * The RDS core uses the c_send_lock to only enter this function once
481 * per connection. This makes sure that the tx ring alloc/unalloc pairs
482 * don't get out of sync and confuse the ring.
483 */
484int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
485 unsigned int hdr_off, unsigned int sg, unsigned int off)
486{
487 struct rds_ib_connection *ic = conn->c_transport_data;
488 struct ib_device *dev = ic->i_cm_id->device;
489 struct rds_ib_send_work *send = NULL;
490 struct rds_ib_send_work *first;
491 struct rds_ib_send_work *prev;
492 const struct ib_send_wr *failed_wr;
493 struct scatterlist *scat;
494 u32 pos;
495 u32 i;
496 u32 work_alloc;
497 u32 credit_alloc = 0;
498 u32 posted;
499 u32 adv_credits = 0;
500 int send_flags = 0;
501 int bytes_sent = 0;
502 int ret;
503 int flow_controlled = 0;
504 int nr_sig = 0;
505
506 BUG_ON(off % RDS_FRAG_SIZE);
507 BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
508
509 /* Do not send cong updates to IB loopback */
510 if (conn->c_loopback
511 && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
512 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
513 scat = &rm->data.op_sg[sg];
514 ret = max_t(int, RDS_CONG_MAP_BYTES, scat->length);
515 return sizeof(struct rds_header) + ret;
516 }
517
518 /* FIXME we may overallocate here */
519 if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
520 i = 1;
521 else
522 i = DIV_ROUND_UP(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
523
524 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
525 if (work_alloc == 0) {
526 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
527 rds_ib_stats_inc(s_ib_tx_ring_full);
528 ret = -ENOMEM;
529 goto out;
530 }
531
532 if (ic->i_flowctl) {
533 credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
534 adv_credits += posted;
535 if (credit_alloc < work_alloc) {
536 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
537 work_alloc = credit_alloc;
538 flow_controlled = 1;
539 }
540 if (work_alloc == 0) {
541 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
542 rds_ib_stats_inc(s_ib_tx_throttle);
543 ret = -ENOMEM;
544 goto out;
545 }
546 }
547
548 /* map the message the first time we see it */
549 if (!ic->i_data_op) {
550 if (rm->data.op_nents) {
551 rm->data.op_count = ib_dma_map_sg(dev,
552 rm->data.op_sg,
553 rm->data.op_nents,
554 DMA_TO_DEVICE);
555 rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
556 if (rm->data.op_count == 0) {
557 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
558 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
559 ret = -ENOMEM; /* XXX ? */
560 goto out;
561 }
562 } else {
563 rm->data.op_count = 0;
564 }
565
566 rds_message_addref(rm);
567 rm->data.op_dmasg = 0;
568 rm->data.op_dmaoff = 0;
569 ic->i_data_op = &rm->data;
570
571 /* Finalize the header */
572 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
573 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
574 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
575 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
576
577 /* If it has a RDMA op, tell the peer we did it. This is
578 * used by the peer to release use-once RDMA MRs. */
579 if (rm->rdma.op_active) {
580 struct rds_ext_header_rdma ext_hdr;
581
582 ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
583 rds_message_add_extension(&rm->m_inc.i_hdr,
584 RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
585 }
586 if (rm->m_rdma_cookie) {
587 rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
588 rds_rdma_cookie_key(rm->m_rdma_cookie),
589 rds_rdma_cookie_offset(rm->m_rdma_cookie));
590 }
591
592 /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
593 * we should not do this unless we have a chance of at least
594 * sticking the header into the send ring. Which is why we
595 * should call rds_ib_ring_alloc first. */
596 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
597 rds_message_make_checksum(&rm->m_inc.i_hdr);
598
599 /*
600 * Update adv_credits since we reset the ACK_REQUIRED bit.
601 */
602 if (ic->i_flowctl) {
603 rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
604 adv_credits += posted;
605 BUG_ON(adv_credits > 255);
606 }
607 }
608
609 /* Sometimes you want to put a fence between an RDMA
610 * READ and the following SEND.
611 * We could either do this all the time
612 * or when requested by the user. Right now, we let
613 * the application choose.
614 */
615 if (rm->rdma.op_active && rm->rdma.op_fence)
616 send_flags = IB_SEND_FENCE;
617
618 /* Each frag gets a header. Msgs may be 0 bytes */
619 send = &ic->i_sends[pos];
620 first = send;
621 prev = NULL;
622 scat = &ic->i_data_op->op_sg[rm->data.op_dmasg];
623 i = 0;
624 do {
625 unsigned int len = 0;
626
627 /* Set up the header */
628 send->s_wr.send_flags = send_flags;
629 send->s_wr.opcode = IB_WR_SEND;
630 send->s_wr.num_sge = 1;
631 send->s_wr.next = NULL;
632 send->s_queued = jiffies;
633 send->s_op = NULL;
634
635 send->s_sge[0].addr = ic->i_send_hdrs_dma[pos];
636
637 send->s_sge[0].length = sizeof(struct rds_header);
638 send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
639
640 ib_dma_sync_single_for_cpu(ic->rds_ibdev->dev,
641 ic->i_send_hdrs_dma[pos],
642 sizeof(struct rds_header),
643 DMA_TO_DEVICE);
644 memcpy(ic->i_send_hdrs[pos], &rm->m_inc.i_hdr,
645 sizeof(struct rds_header));
646
647
648 /* Set up the data, if present */
649 if (i < work_alloc
650 && scat != &rm->data.op_sg[rm->data.op_count]) {
651 len = min(RDS_FRAG_SIZE,
652 sg_dma_len(scat) - rm->data.op_dmaoff);
653 send->s_wr.num_sge = 2;
654
655 send->s_sge[1].addr = sg_dma_address(scat);
656 send->s_sge[1].addr += rm->data.op_dmaoff;
657 send->s_sge[1].length = len;
658 send->s_sge[1].lkey = ic->i_pd->local_dma_lkey;
659
660 bytes_sent += len;
661 rm->data.op_dmaoff += len;
662 if (rm->data.op_dmaoff == sg_dma_len(scat)) {
663 scat++;
664 rm->data.op_dmasg++;
665 rm->data.op_dmaoff = 0;
666 }
667 }
668
669 rds_ib_set_wr_signal_state(ic, send, false);
670
671 /*
672 * Always signal the last one if we're stopping due to flow control.
673 */
674 if (ic->i_flowctl && flow_controlled && i == (work_alloc - 1)) {
675 rds_ib_set_wr_signal_state(ic, send, true);
676 send->s_wr.send_flags |= IB_SEND_SOLICITED;
677 }
678
679 if (send->s_wr.send_flags & IB_SEND_SIGNALED)
680 nr_sig++;
681
682 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
683 &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
684
685 if (ic->i_flowctl && adv_credits) {
686 struct rds_header *hdr = ic->i_send_hdrs[pos];
687
688 /* add credit and redo the header checksum */
689 hdr->h_credit = adv_credits;
690 rds_message_make_checksum(hdr);
691 adv_credits = 0;
692 rds_ib_stats_inc(s_ib_tx_credit_updates);
693 }
694 ib_dma_sync_single_for_device(ic->rds_ibdev->dev,
695 ic->i_send_hdrs_dma[pos],
696 sizeof(struct rds_header),
697 DMA_TO_DEVICE);
698
699 if (prev)
700 prev->s_wr.next = &send->s_wr;
701 prev = send;
702
703 pos = (pos + 1) % ic->i_send_ring.w_nr;
704 send = &ic->i_sends[pos];
705 i++;
706
707 } while (i < work_alloc
708 && scat != &rm->data.op_sg[rm->data.op_count]);
709
710 /* Account the RDS header in the number of bytes we sent, but just once.
711 * The caller has no concept of fragmentation. */
712 if (hdr_off == 0)
713 bytes_sent += sizeof(struct rds_header);
714
715 /* if we finished the message then send completion owns it */
716 if (scat == &rm->data.op_sg[rm->data.op_count]) {
717 prev->s_op = ic->i_data_op;
718 prev->s_wr.send_flags |= IB_SEND_SOLICITED;
719 if (!(prev->s_wr.send_flags & IB_SEND_SIGNALED))
720 nr_sig += rds_ib_set_wr_signal_state(ic, prev, true);
721 ic->i_data_op = NULL;
722 }
723
724 /* Put back wrs & credits we didn't use */
725 if (i < work_alloc) {
726 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
727 work_alloc = i;
728 }
729 if (ic->i_flowctl && i < credit_alloc)
730 rds_ib_send_add_credits(conn, credit_alloc - i);
731
732 if (nr_sig)
733 atomic_add(nr_sig, &ic->i_signaled_sends);
734
735 /* XXX need to worry about failed_wr and partial sends. */
736 failed_wr = &first->s_wr;
737 ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
738 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
739 first, &first->s_wr, ret, failed_wr);
740 BUG_ON(failed_wr != &first->s_wr);
741 if (ret) {
742 printk(KERN_WARNING "RDS/IB: ib_post_send to %pI6c "
743 "returned %d\n", &conn->c_faddr, ret);
744 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
745 rds_ib_sub_signaled(ic, nr_sig);
746 if (prev->s_op) {
747 ic->i_data_op = prev->s_op;
748 prev->s_op = NULL;
749 }
750
751 rds_ib_conn_error(ic->conn, "ib_post_send failed\n");
752 goto out;
753 }
754
755 ret = bytes_sent;
756out:
757 BUG_ON(adv_credits);
758 return ret;
759}
760
761/*
762 * Issue atomic operation.
763 * A simplified version of the rdma case, we always map 1 SG, and
764 * only 8 bytes, for the return value from the atomic operation.
765 */
766int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
767{
768 struct rds_ib_connection *ic = conn->c_transport_data;
769 struct rds_ib_send_work *send = NULL;
770 const struct ib_send_wr *failed_wr;
771 u32 pos;
772 u32 work_alloc;
773 int ret;
774 int nr_sig = 0;
775
776 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
777 if (work_alloc != 1) {
778 rds_ib_stats_inc(s_ib_tx_ring_full);
779 ret = -ENOMEM;
780 goto out;
781 }
782
783 /* address of send request in ring */
784 send = &ic->i_sends[pos];
785 send->s_queued = jiffies;
786
787 if (op->op_type == RDS_ATOMIC_TYPE_CSWP) {
788 send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP;
789 send->s_atomic_wr.compare_add = op->op_m_cswp.compare;
790 send->s_atomic_wr.swap = op->op_m_cswp.swap;
791 send->s_atomic_wr.compare_add_mask = op->op_m_cswp.compare_mask;
792 send->s_atomic_wr.swap_mask = op->op_m_cswp.swap_mask;
793 } else { /* FADD */
794 send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD;
795 send->s_atomic_wr.compare_add = op->op_m_fadd.add;
796 send->s_atomic_wr.swap = 0;
797 send->s_atomic_wr.compare_add_mask = op->op_m_fadd.nocarry_mask;
798 send->s_atomic_wr.swap_mask = 0;
799 }
800 send->s_wr.send_flags = 0;
801 nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify);
802 send->s_atomic_wr.wr.num_sge = 1;
803 send->s_atomic_wr.wr.next = NULL;
804 send->s_atomic_wr.remote_addr = op->op_remote_addr;
805 send->s_atomic_wr.rkey = op->op_rkey;
806 send->s_op = op;
807 rds_message_addref(container_of(send->s_op, struct rds_message, atomic));
808
809 /* map 8 byte retval buffer to the device */
810 ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE);
811 rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret);
812 if (ret != 1) {
813 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
814 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
815 ret = -ENOMEM; /* XXX ? */
816 goto out;
817 }
818
819 /* Convert our struct scatterlist to struct ib_sge */
820 send->s_sge[0].addr = sg_dma_address(op->op_sg);
821 send->s_sge[0].length = sg_dma_len(op->op_sg);
822 send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
823
824 rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
825 send->s_sge[0].addr, send->s_sge[0].length);
826
827 if (nr_sig)
828 atomic_add(nr_sig, &ic->i_signaled_sends);
829
830 failed_wr = &send->s_atomic_wr.wr;
831 ret = ib_post_send(ic->i_cm_id->qp, &send->s_atomic_wr.wr, &failed_wr);
832 rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
833 send, &send->s_atomic_wr, ret, failed_wr);
834 BUG_ON(failed_wr != &send->s_atomic_wr.wr);
835 if (ret) {
836 printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI6c "
837 "returned %d\n", &conn->c_faddr, ret);
838 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
839 rds_ib_sub_signaled(ic, nr_sig);
840 goto out;
841 }
842
843 if (unlikely(failed_wr != &send->s_atomic_wr.wr)) {
844 printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
845 BUG_ON(failed_wr != &send->s_atomic_wr.wr);
846 }
847
848out:
849 return ret;
850}
851
852int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
853{
854 struct rds_ib_connection *ic = conn->c_transport_data;
855 struct rds_ib_send_work *send = NULL;
856 struct rds_ib_send_work *first;
857 struct rds_ib_send_work *prev;
858 const struct ib_send_wr *failed_wr;
859 struct scatterlist *scat;
860 unsigned long len;
861 u64 remote_addr = op->op_remote_addr;
862 u32 max_sge = ic->rds_ibdev->max_sge;
863 u32 pos;
864 u32 work_alloc;
865 u32 i;
866 u32 j;
867 int sent;
868 int ret;
869 int num_sge;
870 int nr_sig = 0;
871 u64 odp_addr = op->op_odp_addr;
872 u32 odp_lkey = 0;
873
874 /* map the op the first time we see it */
875 if (!op->op_odp_mr) {
876 if (!op->op_mapped) {
877 op->op_count =
878 ib_dma_map_sg(ic->i_cm_id->device, op->op_sg,
879 op->op_nents,
880 (op->op_write) ? DMA_TO_DEVICE :
881 DMA_FROM_DEVICE);
882 rdsdebug("ic %p mapping op %p: %d\n", ic, op,
883 op->op_count);
884 if (op->op_count == 0) {
885 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
886 ret = -ENOMEM; /* XXX ? */
887 goto out;
888 }
889 op->op_mapped = 1;
890 }
891 } else {
892 op->op_count = op->op_nents;
893 odp_lkey = rds_ib_get_lkey(op->op_odp_mr->r_trans_private);
894 }
895
896 /*
897 * Instead of knowing how to return a partial rdma read/write we insist that there
898 * be enough work requests to send the entire message.
899 */
900 i = DIV_ROUND_UP(op->op_count, max_sge);
901
902 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
903 if (work_alloc != i) {
904 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
905 rds_ib_stats_inc(s_ib_tx_ring_full);
906 ret = -ENOMEM;
907 goto out;
908 }
909
910 send = &ic->i_sends[pos];
911 first = send;
912 prev = NULL;
913 scat = &op->op_sg[0];
914 sent = 0;
915 num_sge = op->op_count;
916
917 for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
918 send->s_wr.send_flags = 0;
919 send->s_queued = jiffies;
920 send->s_op = NULL;
921
922 if (!op->op_notify)
923 nr_sig += rds_ib_set_wr_signal_state(ic, send,
924 op->op_notify);
925
926 send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
927 send->s_rdma_wr.remote_addr = remote_addr;
928 send->s_rdma_wr.rkey = op->op_rkey;
929
930 if (num_sge > max_sge) {
931 send->s_rdma_wr.wr.num_sge = max_sge;
932 num_sge -= max_sge;
933 } else {
934 send->s_rdma_wr.wr.num_sge = num_sge;
935 }
936
937 send->s_rdma_wr.wr.next = NULL;
938
939 if (prev)
940 prev->s_rdma_wr.wr.next = &send->s_rdma_wr.wr;
941
942 for (j = 0; j < send->s_rdma_wr.wr.num_sge &&
943 scat != &op->op_sg[op->op_count]; j++) {
944 len = sg_dma_len(scat);
945 if (!op->op_odp_mr) {
946 send->s_sge[j].addr = sg_dma_address(scat);
947 send->s_sge[j].lkey = ic->i_pd->local_dma_lkey;
948 } else {
949 send->s_sge[j].addr = odp_addr;
950 send->s_sge[j].lkey = odp_lkey;
951 }
952 send->s_sge[j].length = len;
953
954 sent += len;
955 rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
956
957 remote_addr += len;
958 odp_addr += len;
959 scat++;
960 }
961
962 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
963 &send->s_rdma_wr.wr,
964 send->s_rdma_wr.wr.num_sge,
965 send->s_rdma_wr.wr.next);
966
967 prev = send;
968 if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
969 send = ic->i_sends;
970 }
971
972 /* give a reference to the last op */
973 if (scat == &op->op_sg[op->op_count]) {
974 prev->s_op = op;
975 rds_message_addref(container_of(op, struct rds_message, rdma));
976 }
977
978 if (i < work_alloc) {
979 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
980 work_alloc = i;
981 }
982
983 if (nr_sig)
984 atomic_add(nr_sig, &ic->i_signaled_sends);
985
986 failed_wr = &first->s_rdma_wr.wr;
987 ret = ib_post_send(ic->i_cm_id->qp, &first->s_rdma_wr.wr, &failed_wr);
988 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
989 first, &first->s_rdma_wr.wr, ret, failed_wr);
990 BUG_ON(failed_wr != &first->s_rdma_wr.wr);
991 if (ret) {
992 printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI6c "
993 "returned %d\n", &conn->c_faddr, ret);
994 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
995 rds_ib_sub_signaled(ic, nr_sig);
996 goto out;
997 }
998
999 if (unlikely(failed_wr != &first->s_rdma_wr.wr)) {
1000 printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
1001 BUG_ON(failed_wr != &first->s_rdma_wr.wr);
1002 }
1003
1004
1005out:
1006 return ret;
1007}
1008
1009void rds_ib_xmit_path_complete(struct rds_conn_path *cp)
1010{
1011 struct rds_connection *conn = cp->cp_conn;
1012 struct rds_ib_connection *ic = conn->c_transport_data;
1013
1014 /* We may have a pending ACK or window update we were unable
1015 * to send previously (due to flow control). Try again. */
1016 rds_ib_attempt_ack(ic);
1017}