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authorAndy Grover <andy.grover@oracle.com>2009-02-24 10:30:33 -0500
committerDavid S. Miller <davem@davemloft.net>2009-02-27 02:39:31 -0500
commit6a0979df32296c3ba75a346db47a18292a231c6e (patch)
tree4d8cff3575e6e12e1472c6b10f837663db23d3fc /net/rds
parent08b48a1ed84b19b602cbe979184ad06e7e1c025e (diff)
RDS/IB: Implement IB-specific datagram send.
Specific to IB is a credits-based flow control mechanism, in addition to the expected usage of the IB API to package outgoing data into work requests. Signed-off-by: Andy Grover <andy.grover@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/rds')
-rw-r--r--net/rds/ib_send.c874
1 files changed, 874 insertions, 0 deletions
diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c
new file mode 100644
index 000000000000..cb6c52cb1c4c
--- /dev/null
+++ b/net/rds/ib_send.c
@@ -0,0 +1,874 @@
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
38#include "rds.h"
39#include "rdma.h"
40#include "ib.h"
41
42static void rds_ib_send_rdma_complete(struct rds_message *rm,
43 int wc_status)
44{
45 int notify_status;
46
47 switch (wc_status) {
48 case IB_WC_WR_FLUSH_ERR:
49 return;
50
51 case IB_WC_SUCCESS:
52 notify_status = RDS_RDMA_SUCCESS;
53 break;
54
55 case IB_WC_REM_ACCESS_ERR:
56 notify_status = RDS_RDMA_REMOTE_ERROR;
57 break;
58
59 default:
60 notify_status = RDS_RDMA_OTHER_ERROR;
61 break;
62 }
63 rds_rdma_send_complete(rm, notify_status);
64}
65
66static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
67 struct rds_rdma_op *op)
68{
69 if (op->r_mapped) {
70 ib_dma_unmap_sg(ic->i_cm_id->device,
71 op->r_sg, op->r_nents,
72 op->r_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
73 op->r_mapped = 0;
74 }
75}
76
77static void rds_ib_send_unmap_rm(struct rds_ib_connection *ic,
78 struct rds_ib_send_work *send,
79 int wc_status)
80{
81 struct rds_message *rm = send->s_rm;
82
83 rdsdebug("ic %p send %p rm %p\n", ic, send, rm);
84
85 ib_dma_unmap_sg(ic->i_cm_id->device,
86 rm->m_sg, rm->m_nents,
87 DMA_TO_DEVICE);
88
89 if (rm->m_rdma_op != NULL) {
90 rds_ib_send_unmap_rdma(ic, rm->m_rdma_op);
91
92 /* If the user asked for a completion notification on this
93 * message, we can implement three different semantics:
94 * 1. Notify when we received the ACK on the RDS message
95 * that was queued with the RDMA. This provides reliable
96 * notification of RDMA status at the expense of a one-way
97 * packet delay.
98 * 2. Notify when the IB stack gives us the completion event for
99 * the RDMA operation.
100 * 3. Notify when the IB stack gives us the completion event for
101 * the accompanying RDS messages.
102 * Here, we implement approach #3. To implement approach #2,
103 * call rds_rdma_send_complete from the cq_handler. To implement #1,
104 * don't call rds_rdma_send_complete at all, and fall back to the notify
105 * handling in the ACK processing code.
106 *
107 * Note: There's no need to explicitly sync any RDMA buffers using
108 * ib_dma_sync_sg_for_cpu - the completion for the RDMA
109 * operation itself unmapped the RDMA buffers, which takes care
110 * of synching.
111 */
112 rds_ib_send_rdma_complete(rm, wc_status);
113
114 if (rm->m_rdma_op->r_write)
115 rds_stats_add(s_send_rdma_bytes, rm->m_rdma_op->r_bytes);
116 else
117 rds_stats_add(s_recv_rdma_bytes, rm->m_rdma_op->r_bytes);
118 }
119
120 /* If anyone waited for this message to get flushed out, wake
121 * them up now */
122 rds_message_unmapped(rm);
123
124 rds_message_put(rm);
125 send->s_rm = NULL;
126}
127
128void rds_ib_send_init_ring(struct rds_ib_connection *ic)
129{
130 struct rds_ib_send_work *send;
131 u32 i;
132
133 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
134 struct ib_sge *sge;
135
136 send->s_rm = NULL;
137 send->s_op = NULL;
138
139 send->s_wr.wr_id = i;
140 send->s_wr.sg_list = send->s_sge;
141 send->s_wr.num_sge = 1;
142 send->s_wr.opcode = IB_WR_SEND;
143 send->s_wr.send_flags = 0;
144 send->s_wr.ex.imm_data = 0;
145
146 sge = rds_ib_data_sge(ic, send->s_sge);
147 sge->lkey = ic->i_mr->lkey;
148
149 sge = rds_ib_header_sge(ic, send->s_sge);
150 sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
151 sge->length = sizeof(struct rds_header);
152 sge->lkey = ic->i_mr->lkey;
153 }
154}
155
156void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
157{
158 struct rds_ib_send_work *send;
159 u32 i;
160
161 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
162 if (send->s_wr.opcode == 0xdead)
163 continue;
164 if (send->s_rm)
165 rds_ib_send_unmap_rm(ic, send, IB_WC_WR_FLUSH_ERR);
166 if (send->s_op)
167 rds_ib_send_unmap_rdma(ic, send->s_op);
168 }
169}
170
171/*
172 * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
173 * operations performed in the send path. As the sender allocs and potentially
174 * unallocs the next free entry in the ring it doesn't alter which is
175 * the next to be freed, which is what this is concerned with.
176 */
177void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context)
178{
179 struct rds_connection *conn = context;
180 struct rds_ib_connection *ic = conn->c_transport_data;
181 struct ib_wc wc;
182 struct rds_ib_send_work *send;
183 u32 completed;
184 u32 oldest;
185 u32 i = 0;
186 int ret;
187
188 rdsdebug("cq %p conn %p\n", cq, conn);
189 rds_ib_stats_inc(s_ib_tx_cq_call);
190 ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
191 if (ret)
192 rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
193
194 while (ib_poll_cq(cq, 1, &wc) > 0) {
195 rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
196 (unsigned long long)wc.wr_id, wc.status, wc.byte_len,
197 be32_to_cpu(wc.ex.imm_data));
198 rds_ib_stats_inc(s_ib_tx_cq_event);
199
200 if (wc.wr_id == RDS_IB_ACK_WR_ID) {
201 if (ic->i_ack_queued + HZ/2 < jiffies)
202 rds_ib_stats_inc(s_ib_tx_stalled);
203 rds_ib_ack_send_complete(ic);
204 continue;
205 }
206
207 oldest = rds_ib_ring_oldest(&ic->i_send_ring);
208
209 completed = rds_ib_ring_completed(&ic->i_send_ring, wc.wr_id, oldest);
210
211 for (i = 0; i < completed; i++) {
212 send = &ic->i_sends[oldest];
213
214 /* In the error case, wc.opcode sometimes contains garbage */
215 switch (send->s_wr.opcode) {
216 case IB_WR_SEND:
217 if (send->s_rm)
218 rds_ib_send_unmap_rm(ic, send, wc.status);
219 break;
220 case IB_WR_RDMA_WRITE:
221 case IB_WR_RDMA_READ:
222 /* Nothing to be done - the SG list will be unmapped
223 * when the SEND completes. */
224 break;
225 default:
226 if (printk_ratelimit())
227 printk(KERN_NOTICE
228 "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
229 __func__, send->s_wr.opcode);
230 break;
231 }
232
233 send->s_wr.opcode = 0xdead;
234 send->s_wr.num_sge = 1;
235 if (send->s_queued + HZ/2 < jiffies)
236 rds_ib_stats_inc(s_ib_tx_stalled);
237
238 /* If a RDMA operation produced an error, signal this right
239 * away. If we don't, the subsequent SEND that goes with this
240 * RDMA will be canceled with ERR_WFLUSH, and the application
241 * never learn that the RDMA failed. */
242 if (unlikely(wc.status == IB_WC_REM_ACCESS_ERR && send->s_op)) {
243 struct rds_message *rm;
244
245 rm = rds_send_get_message(conn, send->s_op);
246 if (rm)
247 rds_ib_send_rdma_complete(rm, wc.status);
248 }
249
250 oldest = (oldest + 1) % ic->i_send_ring.w_nr;
251 }
252
253 rds_ib_ring_free(&ic->i_send_ring, completed);
254
255 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags)
256 || test_bit(0, &conn->c_map_queued))
257 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
258
259 /* We expect errors as the qp is drained during shutdown */
260 if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) {
261 rds_ib_conn_error(conn,
262 "send completion on %pI4 "
263 "had status %u, disconnecting and reconnecting\n",
264 &conn->c_faddr, wc.status);
265 }
266 }
267}
268
269/*
270 * This is the main function for allocating credits when sending
271 * messages.
272 *
273 * Conceptually, we have two counters:
274 * - send credits: this tells us how many WRs we're allowed
275 * to submit without overruning the reciever's queue. For
276 * each SEND WR we post, we decrement this by one.
277 *
278 * - posted credits: this tells us how many WRs we recently
279 * posted to the receive queue. This value is transferred
280 * to the peer as a "credit update" in a RDS header field.
281 * Every time we transmit credits to the peer, we subtract
282 * the amount of transferred credits from this counter.
283 *
284 * It is essential that we avoid situations where both sides have
285 * exhausted their send credits, and are unable to send new credits
286 * to the peer. We achieve this by requiring that we send at least
287 * one credit update to the peer before exhausting our credits.
288 * When new credits arrive, we subtract one credit that is withheld
289 * until we've posted new buffers and are ready to transmit these
290 * credits (see rds_ib_send_add_credits below).
291 *
292 * The RDS send code is essentially single-threaded; rds_send_xmit
293 * grabs c_send_lock to ensure exclusive access to the send ring.
294 * However, the ACK sending code is independent and can race with
295 * message SENDs.
296 *
297 * In the send path, we need to update the counters for send credits
298 * and the counter of posted buffers atomically - when we use the
299 * last available credit, we cannot allow another thread to race us
300 * and grab the posted credits counter. Hence, we have to use a
301 * spinlock to protect the credit counter, or use atomics.
302 *
303 * Spinlocks shared between the send and the receive path are bad,
304 * because they create unnecessary delays. An early implementation
305 * using a spinlock showed a 5% degradation in throughput at some
306 * loads.
307 *
308 * This implementation avoids spinlocks completely, putting both
309 * counters into a single atomic, and updating that atomic using
310 * atomic_add (in the receive path, when receiving fresh credits),
311 * and using atomic_cmpxchg when updating the two counters.
312 */
313int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
314 u32 wanted, u32 *adv_credits, int need_posted)
315{
316 unsigned int avail, posted, got = 0, advertise;
317 long oldval, newval;
318
319 *adv_credits = 0;
320 if (!ic->i_flowctl)
321 return wanted;
322
323try_again:
324 advertise = 0;
325 oldval = newval = atomic_read(&ic->i_credits);
326 posted = IB_GET_POST_CREDITS(oldval);
327 avail = IB_GET_SEND_CREDITS(oldval);
328
329 rdsdebug("rds_ib_send_grab_credits(%u): credits=%u posted=%u\n",
330 wanted, avail, posted);
331
332 /* The last credit must be used to send a credit update. */
333 if (avail && !posted)
334 avail--;
335
336 if (avail < wanted) {
337 struct rds_connection *conn = ic->i_cm_id->context;
338
339 /* Oops, there aren't that many credits left! */
340 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
341 got = avail;
342 } else {
343 /* Sometimes you get what you want, lalala. */
344 got = wanted;
345 }
346 newval -= IB_SET_SEND_CREDITS(got);
347
348 /*
349 * If need_posted is non-zero, then the caller wants
350 * the posted regardless of whether any send credits are
351 * available.
352 */
353 if (posted && (got || need_posted)) {
354 advertise = min_t(unsigned int, posted, RDS_MAX_ADV_CREDIT);
355 newval -= IB_SET_POST_CREDITS(advertise);
356 }
357
358 /* Finally bill everything */
359 if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
360 goto try_again;
361
362 *adv_credits = advertise;
363 return got;
364}
365
366void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
367{
368 struct rds_ib_connection *ic = conn->c_transport_data;
369
370 if (credits == 0)
371 return;
372
373 rdsdebug("rds_ib_send_add_credits(%u): current=%u%s\n",
374 credits,
375 IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
376 test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
377
378 atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
379 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
380 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
381
382 WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
383
384 rds_ib_stats_inc(s_ib_rx_credit_updates);
385}
386
387void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
388{
389 struct rds_ib_connection *ic = conn->c_transport_data;
390
391 if (posted == 0)
392 return;
393
394 atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
395
396 /* Decide whether to send an update to the peer now.
397 * If we would send a credit update for every single buffer we
398 * post, we would end up with an ACK storm (ACK arrives,
399 * consumes buffer, we refill the ring, send ACK to remote
400 * advertising the newly posted buffer... ad inf)
401 *
402 * Performance pretty much depends on how often we send
403 * credit updates - too frequent updates mean lots of ACKs.
404 * Too infrequent updates, and the peer will run out of
405 * credits and has to throttle.
406 * For the time being, 16 seems to be a good compromise.
407 */
408 if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
409 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
410}
411
412static inline void
413rds_ib_xmit_populate_wr(struct rds_ib_connection *ic,
414 struct rds_ib_send_work *send, unsigned int pos,
415 unsigned long buffer, unsigned int length,
416 int send_flags)
417{
418 struct ib_sge *sge;
419
420 WARN_ON(pos != send - ic->i_sends);
421
422 send->s_wr.send_flags = send_flags;
423 send->s_wr.opcode = IB_WR_SEND;
424 send->s_wr.num_sge = 2;
425 send->s_wr.next = NULL;
426 send->s_queued = jiffies;
427 send->s_op = NULL;
428
429 if (length != 0) {
430 sge = rds_ib_data_sge(ic, send->s_sge);
431 sge->addr = buffer;
432 sge->length = length;
433 sge->lkey = ic->i_mr->lkey;
434
435 sge = rds_ib_header_sge(ic, send->s_sge);
436 } else {
437 /* We're sending a packet with no payload. There is only
438 * one SGE */
439 send->s_wr.num_sge = 1;
440 sge = &send->s_sge[0];
441 }
442
443 sge->addr = ic->i_send_hdrs_dma + (pos * sizeof(struct rds_header));
444 sge->length = sizeof(struct rds_header);
445 sge->lkey = ic->i_mr->lkey;
446}
447
448/*
449 * This can be called multiple times for a given message. The first time
450 * we see a message we map its scatterlist into the IB device so that
451 * we can provide that mapped address to the IB scatter gather entries
452 * in the IB work requests. We translate the scatterlist into a series
453 * of work requests that fragment the message. These work requests complete
454 * in order so we pass ownership of the message to the completion handler
455 * once we send the final fragment.
456 *
457 * The RDS core uses the c_send_lock to only enter this function once
458 * per connection. This makes sure that the tx ring alloc/unalloc pairs
459 * don't get out of sync and confuse the ring.
460 */
461int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
462 unsigned int hdr_off, unsigned int sg, unsigned int off)
463{
464 struct rds_ib_connection *ic = conn->c_transport_data;
465 struct ib_device *dev = ic->i_cm_id->device;
466 struct rds_ib_send_work *send = NULL;
467 struct rds_ib_send_work *first;
468 struct rds_ib_send_work *prev;
469 struct ib_send_wr *failed_wr;
470 struct scatterlist *scat;
471 u32 pos;
472 u32 i;
473 u32 work_alloc;
474 u32 credit_alloc;
475 u32 posted;
476 u32 adv_credits = 0;
477 int send_flags = 0;
478 int sent;
479 int ret;
480 int flow_controlled = 0;
481
482 BUG_ON(off % RDS_FRAG_SIZE);
483 BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
484
485 /* FIXME we may overallocate here */
486 if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
487 i = 1;
488 else
489 i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
490
491 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
492 if (work_alloc == 0) {
493 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
494 rds_ib_stats_inc(s_ib_tx_ring_full);
495 ret = -ENOMEM;
496 goto out;
497 }
498
499 credit_alloc = work_alloc;
500 if (ic->i_flowctl) {
501 credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0);
502 adv_credits += posted;
503 if (credit_alloc < work_alloc) {
504 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
505 work_alloc = credit_alloc;
506 flow_controlled++;
507 }
508 if (work_alloc == 0) {
509 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
510 rds_ib_stats_inc(s_ib_tx_throttle);
511 ret = -ENOMEM;
512 goto out;
513 }
514 }
515
516 /* map the message the first time we see it */
517 if (ic->i_rm == NULL) {
518 /*
519 printk(KERN_NOTICE "rds_ib_xmit prep msg dport=%u flags=0x%x len=%d\n",
520 be16_to_cpu(rm->m_inc.i_hdr.h_dport),
521 rm->m_inc.i_hdr.h_flags,
522 be32_to_cpu(rm->m_inc.i_hdr.h_len));
523 */
524 if (rm->m_nents) {
525 rm->m_count = ib_dma_map_sg(dev,
526 rm->m_sg, rm->m_nents, DMA_TO_DEVICE);
527 rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->m_count);
528 if (rm->m_count == 0) {
529 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
530 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
531 ret = -ENOMEM; /* XXX ? */
532 goto out;
533 }
534 } else {
535 rm->m_count = 0;
536 }
537
538 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
539 ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes;
540 rds_message_addref(rm);
541 ic->i_rm = rm;
542
543 /* Finalize the header */
544 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
545 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
546 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
547 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
548
549 /* If it has a RDMA op, tell the peer we did it. This is
550 * used by the peer to release use-once RDMA MRs. */
551 if (rm->m_rdma_op) {
552 struct rds_ext_header_rdma ext_hdr;
553
554 ext_hdr.h_rdma_rkey = cpu_to_be32(rm->m_rdma_op->r_key);
555 rds_message_add_extension(&rm->m_inc.i_hdr,
556 RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
557 }
558 if (rm->m_rdma_cookie) {
559 rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
560 rds_rdma_cookie_key(rm->m_rdma_cookie),
561 rds_rdma_cookie_offset(rm->m_rdma_cookie));
562 }
563
564 /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
565 * we should not do this unless we have a chance of at least
566 * sticking the header into the send ring. Which is why we
567 * should call rds_ib_ring_alloc first. */
568 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
569 rds_message_make_checksum(&rm->m_inc.i_hdr);
570
571 /*
572 * Update adv_credits since we reset the ACK_REQUIRED bit.
573 */
574 rds_ib_send_grab_credits(ic, 0, &posted, 1);
575 adv_credits += posted;
576 BUG_ON(adv_credits > 255);
577 } else if (ic->i_rm != rm)
578 BUG();
579
580 send = &ic->i_sends[pos];
581 first = send;
582 prev = NULL;
583 scat = &rm->m_sg[sg];
584 sent = 0;
585 i = 0;
586
587 /* Sometimes you want to put a fence between an RDMA
588 * READ and the following SEND.
589 * We could either do this all the time
590 * or when requested by the user. Right now, we let
591 * the application choose.
592 */
593 if (rm->m_rdma_op && rm->m_rdma_op->r_fence)
594 send_flags = IB_SEND_FENCE;
595
596 /*
597 * We could be copying the header into the unused tail of the page.
598 * That would need to be changed in the future when those pages might
599 * be mapped userspace pages or page cache pages. So instead we always
600 * use a second sge and our long-lived ring of mapped headers. We send
601 * the header after the data so that the data payload can be aligned on
602 * the receiver.
603 */
604
605 /* handle a 0-len message */
606 if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) {
607 rds_ib_xmit_populate_wr(ic, send, pos, 0, 0, send_flags);
608 goto add_header;
609 }
610
611 /* if there's data reference it with a chain of work reqs */
612 for (; i < work_alloc && scat != &rm->m_sg[rm->m_count]; i++) {
613 unsigned int len;
614
615 send = &ic->i_sends[pos];
616
617 len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
618 rds_ib_xmit_populate_wr(ic, send, pos,
619 ib_sg_dma_address(dev, scat) + off, len,
620 send_flags);
621
622 /*
623 * We want to delay signaling completions just enough to get
624 * the batching benefits but not so much that we create dead time
625 * on the wire.
626 */
627 if (ic->i_unsignaled_wrs-- == 0) {
628 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
629 send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
630 }
631
632 ic->i_unsignaled_bytes -= len;
633 if (ic->i_unsignaled_bytes <= 0) {
634 ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes;
635 send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
636 }
637
638 /*
639 * Always signal the last one if we're stopping due to flow control.
640 */
641 if (flow_controlled && i == (work_alloc-1))
642 send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
643
644 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
645 &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
646
647 sent += len;
648 off += len;
649 if (off == ib_sg_dma_len(dev, scat)) {
650 scat++;
651 off = 0;
652 }
653
654add_header:
655 /* Tack on the header after the data. The header SGE should already
656 * have been set up to point to the right header buffer. */
657 memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
658
659 if (0) {
660 struct rds_header *hdr = &ic->i_send_hdrs[pos];
661
662 printk(KERN_NOTICE "send WR dport=%u flags=0x%x len=%d\n",
663 be16_to_cpu(hdr->h_dport),
664 hdr->h_flags,
665 be32_to_cpu(hdr->h_len));
666 }
667 if (adv_credits) {
668 struct rds_header *hdr = &ic->i_send_hdrs[pos];
669
670 /* add credit and redo the header checksum */
671 hdr->h_credit = adv_credits;
672 rds_message_make_checksum(hdr);
673 adv_credits = 0;
674 rds_ib_stats_inc(s_ib_tx_credit_updates);
675 }
676
677 if (prev)
678 prev->s_wr.next = &send->s_wr;
679 prev = send;
680
681 pos = (pos + 1) % ic->i_send_ring.w_nr;
682 }
683
684 /* Account the RDS header in the number of bytes we sent, but just once.
685 * The caller has no concept of fragmentation. */
686 if (hdr_off == 0)
687 sent += sizeof(struct rds_header);
688
689 /* if we finished the message then send completion owns it */
690 if (scat == &rm->m_sg[rm->m_count]) {
691 prev->s_rm = ic->i_rm;
692 prev->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
693 ic->i_rm = NULL;
694 }
695
696 if (i < work_alloc) {
697 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
698 work_alloc = i;
699 }
700 if (ic->i_flowctl && i < credit_alloc)
701 rds_ib_send_add_credits(conn, credit_alloc - i);
702
703 /* XXX need to worry about failed_wr and partial sends. */
704 failed_wr = &first->s_wr;
705 ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
706 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
707 first, &first->s_wr, ret, failed_wr);
708 BUG_ON(failed_wr != &first->s_wr);
709 if (ret) {
710 printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 "
711 "returned %d\n", &conn->c_faddr, ret);
712 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
713 if (prev->s_rm) {
714 ic->i_rm = prev->s_rm;
715 prev->s_rm = NULL;
716 }
717 /* Finesse this later */
718 BUG();
719 goto out;
720 }
721
722 ret = sent;
723out:
724 BUG_ON(adv_credits);
725 return ret;
726}
727
728int rds_ib_xmit_rdma(struct rds_connection *conn, struct rds_rdma_op *op)
729{
730 struct rds_ib_connection *ic = conn->c_transport_data;
731 struct rds_ib_send_work *send = NULL;
732 struct rds_ib_send_work *first;
733 struct rds_ib_send_work *prev;
734 struct ib_send_wr *failed_wr;
735 struct rds_ib_device *rds_ibdev;
736 struct scatterlist *scat;
737 unsigned long len;
738 u64 remote_addr = op->r_remote_addr;
739 u32 pos;
740 u32 work_alloc;
741 u32 i;
742 u32 j;
743 int sent;
744 int ret;
745 int num_sge;
746
747 rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
748
749 /* map the message the first time we see it */
750 if (!op->r_mapped) {
751 op->r_count = ib_dma_map_sg(ic->i_cm_id->device,
752 op->r_sg, op->r_nents, (op->r_write) ?
753 DMA_TO_DEVICE : DMA_FROM_DEVICE);
754 rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->r_count);
755 if (op->r_count == 0) {
756 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
757 ret = -ENOMEM; /* XXX ? */
758 goto out;
759 }
760
761 op->r_mapped = 1;
762 }
763
764 /*
765 * Instead of knowing how to return a partial rdma read/write we insist that there
766 * be enough work requests to send the entire message.
767 */
768 i = ceil(op->r_count, rds_ibdev->max_sge);
769
770 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
771 if (work_alloc != i) {
772 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
773 rds_ib_stats_inc(s_ib_tx_ring_full);
774 ret = -ENOMEM;
775 goto out;
776 }
777
778 send = &ic->i_sends[pos];
779 first = send;
780 prev = NULL;
781 scat = &op->r_sg[0];
782 sent = 0;
783 num_sge = op->r_count;
784
785 for (i = 0; i < work_alloc && scat != &op->r_sg[op->r_count]; i++) {
786 send->s_wr.send_flags = 0;
787 send->s_queued = jiffies;
788 /*
789 * We want to delay signaling completions just enough to get
790 * the batching benefits but not so much that we create dead time on the wire.
791 */
792 if (ic->i_unsignaled_wrs-- == 0) {
793 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
794 send->s_wr.send_flags = IB_SEND_SIGNALED;
795 }
796
797 send->s_wr.opcode = op->r_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
798 send->s_wr.wr.rdma.remote_addr = remote_addr;
799 send->s_wr.wr.rdma.rkey = op->r_key;
800 send->s_op = op;
801
802 if (num_sge > rds_ibdev->max_sge) {
803 send->s_wr.num_sge = rds_ibdev->max_sge;
804 num_sge -= rds_ibdev->max_sge;
805 } else {
806 send->s_wr.num_sge = num_sge;
807 }
808
809 send->s_wr.next = NULL;
810
811 if (prev)
812 prev->s_wr.next = &send->s_wr;
813
814 for (j = 0; j < send->s_wr.num_sge && scat != &op->r_sg[op->r_count]; j++) {
815 len = ib_sg_dma_len(ic->i_cm_id->device, scat);
816 send->s_sge[j].addr =
817 ib_sg_dma_address(ic->i_cm_id->device, scat);
818 send->s_sge[j].length = len;
819 send->s_sge[j].lkey = ic->i_mr->lkey;
820
821 sent += len;
822 rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
823
824 remote_addr += len;
825 scat++;
826 }
827
828 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
829 &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
830
831 prev = send;
832 if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
833 send = ic->i_sends;
834 }
835
836 /* if we finished the message then send completion owns it */
837 if (scat == &op->r_sg[op->r_count])
838 prev->s_wr.send_flags = IB_SEND_SIGNALED;
839
840 if (i < work_alloc) {
841 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
842 work_alloc = i;
843 }
844
845 failed_wr = &first->s_wr;
846 ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
847 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
848 first, &first->s_wr, ret, failed_wr);
849 BUG_ON(failed_wr != &first->s_wr);
850 if (ret) {
851 printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 "
852 "returned %d\n", &conn->c_faddr, ret);
853 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
854 goto out;
855 }
856
857 if (unlikely(failed_wr != &first->s_wr)) {
858 printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
859 BUG_ON(failed_wr != &first->s_wr);
860 }
861
862
863out:
864 return ret;
865}
866
867void rds_ib_xmit_complete(struct rds_connection *conn)
868{
869 struct rds_ib_connection *ic = conn->c_transport_data;
870
871 /* We may have a pending ACK or window update we were unable
872 * to send previously (due to flow control). Try again. */
873 rds_ib_attempt_ack(ic);
874}