71f373c421bc4d8b6a97f2be7201a2dc8c2290e8
[linux-2.6.git] / net / rds / ib_send.c
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 "ib.h"
40
41 static char *rds_ib_wc_status_strings[] = {
42 #define RDS_IB_WC_STATUS_STR(foo) \
43                 [IB_WC_##foo] = __stringify(IB_WC_##foo)
44         RDS_IB_WC_STATUS_STR(SUCCESS),
45         RDS_IB_WC_STATUS_STR(LOC_LEN_ERR),
46         RDS_IB_WC_STATUS_STR(LOC_QP_OP_ERR),
47         RDS_IB_WC_STATUS_STR(LOC_EEC_OP_ERR),
48         RDS_IB_WC_STATUS_STR(LOC_PROT_ERR),
49         RDS_IB_WC_STATUS_STR(WR_FLUSH_ERR),
50         RDS_IB_WC_STATUS_STR(MW_BIND_ERR),
51         RDS_IB_WC_STATUS_STR(BAD_RESP_ERR),
52         RDS_IB_WC_STATUS_STR(LOC_ACCESS_ERR),
53         RDS_IB_WC_STATUS_STR(REM_INV_REQ_ERR),
54         RDS_IB_WC_STATUS_STR(REM_ACCESS_ERR),
55         RDS_IB_WC_STATUS_STR(REM_OP_ERR),
56         RDS_IB_WC_STATUS_STR(RETRY_EXC_ERR),
57         RDS_IB_WC_STATUS_STR(RNR_RETRY_EXC_ERR),
58         RDS_IB_WC_STATUS_STR(LOC_RDD_VIOL_ERR),
59         RDS_IB_WC_STATUS_STR(REM_INV_RD_REQ_ERR),
60         RDS_IB_WC_STATUS_STR(REM_ABORT_ERR),
61         RDS_IB_WC_STATUS_STR(INV_EECN_ERR),
62         RDS_IB_WC_STATUS_STR(INV_EEC_STATE_ERR),
63         RDS_IB_WC_STATUS_STR(FATAL_ERR),
64         RDS_IB_WC_STATUS_STR(RESP_TIMEOUT_ERR),
65         RDS_IB_WC_STATUS_STR(GENERAL_ERR),
66 #undef RDS_IB_WC_STATUS_STR
67 };
68
69 char *rds_ib_wc_status_str(enum ib_wc_status status)
70 {
71         return rds_str_array(rds_ib_wc_status_strings,
72                              ARRAY_SIZE(rds_ib_wc_status_strings), status);
73 }
74
75 /*
76  * Convert IB-specific error message to RDS error message and call core
77  * completion handler.
78  */
79 static void rds_ib_send_complete(struct rds_message *rm,
80                                  int wc_status,
81                                  void (*complete)(struct rds_message *rm, int status))
82 {
83         int notify_status;
84
85         switch (wc_status) {
86         case IB_WC_WR_FLUSH_ERR:
87                 return;
88
89         case IB_WC_SUCCESS:
90                 notify_status = RDS_RDMA_SUCCESS;
91                 break;
92
93         case IB_WC_REM_ACCESS_ERR:
94                 notify_status = RDS_RDMA_REMOTE_ERROR;
95                 break;
96
97         default:
98                 notify_status = RDS_RDMA_OTHER_ERROR;
99                 break;
100         }
101         complete(rm, notify_status);
102 }
103
104 static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
105                                    struct rm_data_op *op,
106                                    int wc_status)
107 {
108         if (op->op_nents)
109                 ib_dma_unmap_sg(ic->i_cm_id->device,
110                                 op->op_sg, op->op_nents,
111                                 DMA_TO_DEVICE);
112 }
113
114 static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
115                                    struct rm_rdma_op *op,
116                                    int wc_status)
117 {
118         if (op->op_mapped) {
119                 ib_dma_unmap_sg(ic->i_cm_id->device,
120                                 op->op_sg, op->op_nents,
121                                 op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
122                 op->op_mapped = 0;
123         }
124
125         /* If the user asked for a completion notification on this
126          * message, we can implement three different semantics:
127          *  1.  Notify when we received the ACK on the RDS message
128          *      that was queued with the RDMA. This provides reliable
129          *      notification of RDMA status at the expense of a one-way
130          *      packet delay.
131          *  2.  Notify when the IB stack gives us the completion event for
132          *      the RDMA operation.
133          *  3.  Notify when the IB stack gives us the completion event for
134          *      the accompanying RDS messages.
135          * Here, we implement approach #3. To implement approach #2,
136          * we would need to take an event for the rdma WR. To implement #1,
137          * don't call rds_rdma_send_complete at all, and fall back to the notify
138          * handling in the ACK processing code.
139          *
140          * Note: There's no need to explicitly sync any RDMA buffers using
141          * ib_dma_sync_sg_for_cpu - the completion for the RDMA
142          * operation itself unmapped the RDMA buffers, which takes care
143          * of synching.
144          */
145         rds_ib_send_complete(container_of(op, struct rds_message, rdma),
146                              wc_status, rds_rdma_send_complete);
147
148         if (op->op_write)
149                 rds_stats_add(s_send_rdma_bytes, op->op_bytes);
150         else
151                 rds_stats_add(s_recv_rdma_bytes, op->op_bytes);
152 }
153
154 static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
155                                      struct rm_atomic_op *op,
156                                      int wc_status)
157 {
158         /* unmap atomic recvbuf */
159         if (op->op_mapped) {
160                 ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1,
161                                 DMA_FROM_DEVICE);
162                 op->op_mapped = 0;
163         }
164
165         rds_ib_send_complete(container_of(op, struct rds_message, atomic),
166                              wc_status, rds_atomic_send_complete);
167
168         if (op->op_type == RDS_ATOMIC_TYPE_CSWP)
169                 rds_ib_stats_inc(s_ib_atomic_cswp);
170         else
171                 rds_ib_stats_inc(s_ib_atomic_fadd);
172 }
173
174 /*
175  * Unmap the resources associated with a struct send_work.
176  *
177  * Returns the rm for no good reason other than it is unobtainable
178  * other than by switching on wr.opcode, currently, and the caller,
179  * the event handler, needs it.
180  */
181 static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic,
182                                                 struct rds_ib_send_work *send,
183                                                 int wc_status)
184 {
185         struct rds_message *rm = NULL;
186
187         /* In the error case, wc.opcode sometimes contains garbage */
188         switch (send->s_wr.opcode) {
189         case IB_WR_SEND:
190                 if (send->s_op) {
191                         rm = container_of(send->s_op, struct rds_message, data);
192                         rds_ib_send_unmap_data(ic, send->s_op, wc_status);
193                 }
194                 break;
195         case IB_WR_RDMA_WRITE:
196         case IB_WR_RDMA_READ:
197                 if (send->s_op) {
198                         rm = container_of(send->s_op, struct rds_message, rdma);
199                         rds_ib_send_unmap_rdma(ic, send->s_op, wc_status);
200                 }
201                 break;
202         case IB_WR_ATOMIC_FETCH_AND_ADD:
203         case IB_WR_ATOMIC_CMP_AND_SWP:
204                 if (send->s_op) {
205                         rm = container_of(send->s_op, struct rds_message, atomic);
206                         rds_ib_send_unmap_atomic(ic, send->s_op, wc_status);
207                 }
208                 break;
209         default:
210                 if (printk_ratelimit())
211                         printk(KERN_NOTICE
212                                "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
213                                __func__, send->s_wr.opcode);
214                 break;
215         }
216
217         send->s_wr.opcode = 0xdead;
218
219         return rm;
220 }
221
222 void rds_ib_send_init_ring(struct rds_ib_connection *ic)
223 {
224         struct rds_ib_send_work *send;
225         u32 i;
226
227         for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
228                 struct ib_sge *sge;
229
230                 send->s_op = NULL;
231
232                 send->s_wr.wr_id = i;
233                 send->s_wr.sg_list = send->s_sge;
234                 send->s_wr.ex.imm_data = 0;
235
236                 sge = &send->s_sge[0];
237                 sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
238                 sge->length = sizeof(struct rds_header);
239                 sge->lkey = ic->i_mr->lkey;
240
241                 send->s_sge[1].lkey = ic->i_mr->lkey;
242         }
243 }
244
245 void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
246 {
247         struct rds_ib_send_work *send;
248         u32 i;
249
250         for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
251                 if (send->s_op && send->s_wr.opcode != 0xdead)
252                         rds_ib_send_unmap_op(ic, send, IB_WC_WR_FLUSH_ERR);
253         }
254 }
255
256 /*
257  * The only fast path caller always has a non-zero nr, so we don't
258  * bother testing nr before performing the atomic sub.
259  */
260 static void rds_ib_sub_signaled(struct rds_ib_connection *ic, int nr)
261 {
262         if ((atomic_sub_return(nr, &ic->i_signaled_sends) == 0) &&
263             waitqueue_active(&rds_ib_ring_empty_wait))
264                 wake_up(&rds_ib_ring_empty_wait);
265         BUG_ON(atomic_read(&ic->i_signaled_sends) < 0);
266 }
267
268 /*
269  * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
270  * operations performed in the send path.  As the sender allocs and potentially
271  * unallocs the next free entry in the ring it doesn't alter which is
272  * the next to be freed, which is what this is concerned with.
273  */
274 void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context)
275 {
276         struct rds_connection *conn = context;
277         struct rds_ib_connection *ic = conn->c_transport_data;
278         struct rds_message *rm = NULL;
279         struct ib_wc wc;
280         struct rds_ib_send_work *send;
281         u32 completed;
282         u32 oldest;
283         u32 i = 0;
284         int ret;
285         int nr_sig = 0;
286
287         rdsdebug("cq %p conn %p\n", cq, conn);
288         rds_ib_stats_inc(s_ib_tx_cq_call);
289         ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
290         if (ret)
291                 rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
292
293         while (ib_poll_cq(cq, 1, &wc) > 0) {
294                 rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
295                          (unsigned long long)wc.wr_id, wc.status,
296                          rds_ib_wc_status_str(wc.status), wc.byte_len,
297                          be32_to_cpu(wc.ex.imm_data));
298                 rds_ib_stats_inc(s_ib_tx_cq_event);
299
300                 if (wc.wr_id == RDS_IB_ACK_WR_ID) {
301                         if (ic->i_ack_queued + HZ/2 < jiffies)
302                                 rds_ib_stats_inc(s_ib_tx_stalled);
303                         rds_ib_ack_send_complete(ic);
304                         continue;
305                 }
306
307                 oldest = rds_ib_ring_oldest(&ic->i_send_ring);
308
309                 completed = rds_ib_ring_completed(&ic->i_send_ring, wc.wr_id, oldest);
310
311                 for (i = 0; i < completed; i++) {
312                         send = &ic->i_sends[oldest];
313                         if (send->s_wr.send_flags & IB_SEND_SIGNALED)
314                                 nr_sig++;
315
316                         rm = rds_ib_send_unmap_op(ic, send, wc.status);
317
318                         if (send->s_queued + HZ/2 < jiffies)
319                                 rds_ib_stats_inc(s_ib_tx_stalled);
320
321                         if (send->s_op) {
322                                 if (send->s_op == rm->m_final_op) {
323                                         /* If anyone waited for this message to get flushed out, wake
324                                          * them up now */
325                                         rds_message_unmapped(rm);
326                                 }
327                                 rds_message_put(rm);
328                                 send->s_op = NULL;
329                         }
330
331                         oldest = (oldest + 1) % ic->i_send_ring.w_nr;
332                 }
333
334                 rds_ib_ring_free(&ic->i_send_ring, completed);
335                 rds_ib_sub_signaled(ic, nr_sig);
336                 nr_sig = 0;
337
338                 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
339                     test_bit(0, &conn->c_map_queued))
340                         queue_delayed_work(rds_wq, &conn->c_send_w, 0);
341
342                 /* We expect errors as the qp is drained during shutdown */
343                 if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) {
344                         rds_ib_conn_error(conn, "send completion on %pI4 had status "
345                                           "%u (%s), disconnecting and reconnecting\n",
346                                           &conn->c_faddr, wc.status,
347                                           rds_ib_wc_status_str(wc.status));
348                 }
349         }
350 }
351
352 /*
353  * This is the main function for allocating credits when sending
354  * messages.
355  *
356  * Conceptually, we have two counters:
357  *  -   send credits: this tells us how many WRs we're allowed
358  *      to submit without overruning the reciever's queue. For
359  *      each SEND WR we post, we decrement this by one.
360  *
361  *  -   posted credits: this tells us how many WRs we recently
362  *      posted to the receive queue. This value is transferred
363  *      to the peer as a "credit update" in a RDS header field.
364  *      Every time we transmit credits to the peer, we subtract
365  *      the amount of transferred credits from this counter.
366  *
367  * It is essential that we avoid situations where both sides have
368  * exhausted their send credits, and are unable to send new credits
369  * to the peer. We achieve this by requiring that we send at least
370  * one credit update to the peer before exhausting our credits.
371  * When new credits arrive, we subtract one credit that is withheld
372  * until we've posted new buffers and are ready to transmit these
373  * credits (see rds_ib_send_add_credits below).
374  *
375  * The RDS send code is essentially single-threaded; rds_send_xmit
376  * sets RDS_IN_XMIT to ensure exclusive access to the send ring.
377  * However, the ACK sending code is independent and can race with
378  * message SENDs.
379  *
380  * In the send path, we need to update the counters for send credits
381  * and the counter of posted buffers atomically - when we use the
382  * last available credit, we cannot allow another thread to race us
383  * and grab the posted credits counter.  Hence, we have to use a
384  * spinlock to protect the credit counter, or use atomics.
385  *
386  * Spinlocks shared between the send and the receive path are bad,
387  * because they create unnecessary delays. An early implementation
388  * using a spinlock showed a 5% degradation in throughput at some
389  * loads.
390  *
391  * This implementation avoids spinlocks completely, putting both
392  * counters into a single atomic, and updating that atomic using
393  * atomic_add (in the receive path, when receiving fresh credits),
394  * and using atomic_cmpxchg when updating the two counters.
395  */
396 int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
397                              u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
398 {
399         unsigned int avail, posted, got = 0, advertise;
400         long oldval, newval;
401
402         *adv_credits = 0;
403         if (!ic->i_flowctl)
404                 return wanted;
405
406 try_again:
407         advertise = 0;
408         oldval = newval = atomic_read(&ic->i_credits);
409         posted = IB_GET_POST_CREDITS(oldval);
410         avail = IB_GET_SEND_CREDITS(oldval);
411
412         rdsdebug("rds_ib_send_grab_credits(%u): credits=%u posted=%u\n",
413                         wanted, avail, posted);
414
415         /* The last credit must be used to send a credit update. */
416         if (avail && !posted)
417                 avail--;
418
419         if (avail < wanted) {
420                 struct rds_connection *conn = ic->i_cm_id->context;
421
422                 /* Oops, there aren't that many credits left! */
423                 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
424                 got = avail;
425         } else {
426                 /* Sometimes you get what you want, lalala. */
427                 got = wanted;
428         }
429         newval -= IB_SET_SEND_CREDITS(got);
430
431         /*
432          * If need_posted is non-zero, then the caller wants
433          * the posted regardless of whether any send credits are
434          * available.
435          */
436         if (posted && (got || need_posted)) {
437                 advertise = min_t(unsigned int, posted, max_posted);
438                 newval -= IB_SET_POST_CREDITS(advertise);
439         }
440
441         /* Finally bill everything */
442         if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
443                 goto try_again;
444
445         *adv_credits = advertise;
446         return got;
447 }
448
449 void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
450 {
451         struct rds_ib_connection *ic = conn->c_transport_data;
452
453         if (credits == 0)
454                 return;
455
456         rdsdebug("rds_ib_send_add_credits(%u): current=%u%s\n",
457                         credits,
458                         IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
459                         test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
460
461         atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
462         if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
463                 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
464
465         WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
466
467         rds_ib_stats_inc(s_ib_rx_credit_updates);
468 }
469
470 void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
471 {
472         struct rds_ib_connection *ic = conn->c_transport_data;
473
474         if (posted == 0)
475                 return;
476
477         atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
478
479         /* Decide whether to send an update to the peer now.
480          * If we would send a credit update for every single buffer we
481          * post, we would end up with an ACK storm (ACK arrives,
482          * consumes buffer, we refill the ring, send ACK to remote
483          * advertising the newly posted buffer... ad inf)
484          *
485          * Performance pretty much depends on how often we send
486          * credit updates - too frequent updates mean lots of ACKs.
487          * Too infrequent updates, and the peer will run out of
488          * credits and has to throttle.
489          * For the time being, 16 seems to be a good compromise.
490          */
491         if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
492                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
493 }
494
495 static inline int rds_ib_set_wr_signal_state(struct rds_ib_connection *ic,
496                                              struct rds_ib_send_work *send,
497                                              bool notify)
498 {
499         /*
500          * We want to delay signaling completions just enough to get
501          * the batching benefits but not so much that we create dead time
502          * on the wire.
503          */
504         if (ic->i_unsignaled_wrs-- == 0 || notify) {
505                 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
506                 send->s_wr.send_flags |= IB_SEND_SIGNALED;
507                 return 1;
508         }
509         return 0;
510 }
511
512 /*
513  * This can be called multiple times for a given message.  The first time
514  * we see a message we map its scatterlist into the IB device so that
515  * we can provide that mapped address to the IB scatter gather entries
516  * in the IB work requests.  We translate the scatterlist into a series
517  * of work requests that fragment the message.  These work requests complete
518  * in order so we pass ownership of the message to the completion handler
519  * once we send the final fragment.
520  *
521  * The RDS core uses the c_send_lock to only enter this function once
522  * per connection.  This makes sure that the tx ring alloc/unalloc pairs
523  * don't get out of sync and confuse the ring.
524  */
525 int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
526                 unsigned int hdr_off, unsigned int sg, unsigned int off)
527 {
528         struct rds_ib_connection *ic = conn->c_transport_data;
529         struct ib_device *dev = ic->i_cm_id->device;
530         struct rds_ib_send_work *send = NULL;
531         struct rds_ib_send_work *first;
532         struct rds_ib_send_work *prev;
533         struct ib_send_wr *failed_wr;
534         struct scatterlist *scat;
535         u32 pos;
536         u32 i;
537         u32 work_alloc;
538         u32 credit_alloc = 0;
539         u32 posted;
540         u32 adv_credits = 0;
541         int send_flags = 0;
542         int bytes_sent = 0;
543         int ret;
544         int flow_controlled = 0;
545         int nr_sig = 0;
546
547         BUG_ON(off % RDS_FRAG_SIZE);
548         BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
549
550         /* Do not send cong updates to IB loopback */
551         if (conn->c_loopback
552             && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
553                 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
554                 return sizeof(struct rds_header) + RDS_CONG_MAP_BYTES;
555         }
556
557         /* FIXME we may overallocate here */
558         if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
559                 i = 1;
560         else
561                 i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
562
563         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
564         if (work_alloc == 0) {
565                 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
566                 rds_ib_stats_inc(s_ib_tx_ring_full);
567                 ret = -ENOMEM;
568                 goto out;
569         }
570
571         if (ic->i_flowctl) {
572                 credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
573                 adv_credits += posted;
574                 if (credit_alloc < work_alloc) {
575                         rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
576                         work_alloc = credit_alloc;
577                         flow_controlled = 1;
578                 }
579                 if (work_alloc == 0) {
580                         set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
581                         rds_ib_stats_inc(s_ib_tx_throttle);
582                         ret = -ENOMEM;
583                         goto out;
584                 }
585         }
586
587         /* map the message the first time we see it */
588         if (!ic->i_data_op) {
589                 if (rm->data.op_nents) {
590                         rm->data.op_count = ib_dma_map_sg(dev,
591                                                           rm->data.op_sg,
592                                                           rm->data.op_nents,
593                                                           DMA_TO_DEVICE);
594                         rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
595                         if (rm->data.op_count == 0) {
596                                 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
597                                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
598                                 ret = -ENOMEM; /* XXX ? */
599                                 goto out;
600                         }
601                 } else {
602                         rm->data.op_count = 0;
603                 }
604
605                 rds_message_addref(rm);
606                 ic->i_data_op = &rm->data;
607
608                 /* Finalize the header */
609                 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
610                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
611                 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
612                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
613
614                 /* If it has a RDMA op, tell the peer we did it. This is
615                  * used by the peer to release use-once RDMA MRs. */
616                 if (rm->rdma.op_active) {
617                         struct rds_ext_header_rdma ext_hdr;
618
619                         ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
620                         rds_message_add_extension(&rm->m_inc.i_hdr,
621                                         RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
622                 }
623                 if (rm->m_rdma_cookie) {
624                         rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
625                                         rds_rdma_cookie_key(rm->m_rdma_cookie),
626                                         rds_rdma_cookie_offset(rm->m_rdma_cookie));
627                 }
628
629                 /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
630                  * we should not do this unless we have a chance of at least
631                  * sticking the header into the send ring. Which is why we
632                  * should call rds_ib_ring_alloc first. */
633                 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
634                 rds_message_make_checksum(&rm->m_inc.i_hdr);
635
636                 /*
637                  * Update adv_credits since we reset the ACK_REQUIRED bit.
638                  */
639                 if (ic->i_flowctl) {
640                         rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
641                         adv_credits += posted;
642                         BUG_ON(adv_credits > 255);
643                 }
644         }
645
646         /* Sometimes you want to put a fence between an RDMA
647          * READ and the following SEND.
648          * We could either do this all the time
649          * or when requested by the user. Right now, we let
650          * the application choose.
651          */
652         if (rm->rdma.op_active && rm->rdma.op_fence)
653                 send_flags = IB_SEND_FENCE;
654
655         /* Each frag gets a header. Msgs may be 0 bytes */
656         send = &ic->i_sends[pos];
657         first = send;
658         prev = NULL;
659         scat = &ic->i_data_op->op_sg[sg];
660         i = 0;
661         do {
662                 unsigned int len = 0;
663
664                 /* Set up the header */
665                 send->s_wr.send_flags = send_flags;
666                 send->s_wr.opcode = IB_WR_SEND;
667                 send->s_wr.num_sge = 1;
668                 send->s_wr.next = NULL;
669                 send->s_queued = jiffies;
670                 send->s_op = NULL;
671
672                 send->s_sge[0].addr = ic->i_send_hdrs_dma
673                         + (pos * sizeof(struct rds_header));
674                 send->s_sge[0].length = sizeof(struct rds_header);
675
676                 memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
677
678                 /* Set up the data, if present */
679                 if (i < work_alloc
680                     && scat != &rm->data.op_sg[rm->data.op_count]) {
681                         len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
682                         send->s_wr.num_sge = 2;
683
684                         send->s_sge[1].addr = ib_sg_dma_address(dev, scat) + off;
685                         send->s_sge[1].length = len;
686
687                         bytes_sent += len;
688                         off += len;
689                         if (off == ib_sg_dma_len(dev, scat)) {
690                                 scat++;
691                                 off = 0;
692                         }
693                 }
694
695                 rds_ib_set_wr_signal_state(ic, send, 0);
696
697                 /*
698                  * Always signal the last one if we're stopping due to flow control.
699                  */
700                 if (ic->i_flowctl && flow_controlled && i == (work_alloc-1))
701                         send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
702
703                 if (send->s_wr.send_flags & IB_SEND_SIGNALED)
704                         nr_sig++;
705
706                 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
707                          &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
708
709                 if (ic->i_flowctl && adv_credits) {
710                         struct rds_header *hdr = &ic->i_send_hdrs[pos];
711
712                         /* add credit and redo the header checksum */
713                         hdr->h_credit = adv_credits;
714                         rds_message_make_checksum(hdr);
715                         adv_credits = 0;
716                         rds_ib_stats_inc(s_ib_tx_credit_updates);
717                 }
718
719                 if (prev)
720                         prev->s_wr.next = &send->s_wr;
721                 prev = send;
722
723                 pos = (pos + 1) % ic->i_send_ring.w_nr;
724                 send = &ic->i_sends[pos];
725                 i++;
726
727         } while (i < work_alloc
728                  && scat != &rm->data.op_sg[rm->data.op_count]);
729
730         /* Account the RDS header in the number of bytes we sent, but just once.
731          * The caller has no concept of fragmentation. */
732         if (hdr_off == 0)
733                 bytes_sent += sizeof(struct rds_header);
734
735         /* if we finished the message then send completion owns it */
736         if (scat == &rm->data.op_sg[rm->data.op_count]) {
737                 prev->s_op = ic->i_data_op;
738                 prev->s_wr.send_flags |= IB_SEND_SOLICITED;
739                 ic->i_data_op = NULL;
740         }
741
742         /* Put back wrs & credits we didn't use */
743         if (i < work_alloc) {
744                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
745                 work_alloc = i;
746         }
747         if (ic->i_flowctl && i < credit_alloc)
748                 rds_ib_send_add_credits(conn, credit_alloc - i);
749
750         if (nr_sig)
751                 atomic_add(nr_sig, &ic->i_signaled_sends);
752
753         /* XXX need to worry about failed_wr and partial sends. */
754         failed_wr = &first->s_wr;
755         ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
756         rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
757                  first, &first->s_wr, ret, failed_wr);
758         BUG_ON(failed_wr != &first->s_wr);
759         if (ret) {
760                 printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 "
761                        "returned %d\n", &conn->c_faddr, ret);
762                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
763                 rds_ib_sub_signaled(ic, nr_sig);
764                 if (prev->s_op) {
765                         ic->i_data_op = prev->s_op;
766                         prev->s_op = NULL;
767                 }
768
769                 rds_ib_conn_error(ic->conn, "ib_post_send failed\n");
770                 goto out;
771         }
772
773         ret = bytes_sent;
774 out:
775         BUG_ON(adv_credits);
776         return ret;
777 }
778
779 /*
780  * Issue atomic operation.
781  * A simplified version of the rdma case, we always map 1 SG, and
782  * only 8 bytes, for the return value from the atomic operation.
783  */
784 int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
785 {
786         struct rds_ib_connection *ic = conn->c_transport_data;
787         struct rds_ib_send_work *send = NULL;
788         struct ib_send_wr *failed_wr;
789         struct rds_ib_device *rds_ibdev;
790         u32 pos;
791         u32 work_alloc;
792         int ret;
793         int nr_sig = 0;
794
795         rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
796
797         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
798         if (work_alloc != 1) {
799                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
800                 rds_ib_stats_inc(s_ib_tx_ring_full);
801                 ret = -ENOMEM;
802                 goto out;
803         }
804
805         /* address of send request in ring */
806         send = &ic->i_sends[pos];
807         send->s_queued = jiffies;
808
809         if (op->op_type == RDS_ATOMIC_TYPE_CSWP) {
810                 send->s_wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP;
811                 send->s_wr.wr.atomic.compare_add = op->op_m_cswp.compare;
812                 send->s_wr.wr.atomic.swap = op->op_m_cswp.swap;
813                 send->s_wr.wr.atomic.compare_add_mask = op->op_m_cswp.compare_mask;
814                 send->s_wr.wr.atomic.swap_mask = op->op_m_cswp.swap_mask;
815         } else { /* FADD */
816                 send->s_wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD;
817                 send->s_wr.wr.atomic.compare_add = op->op_m_fadd.add;
818                 send->s_wr.wr.atomic.swap = 0;
819                 send->s_wr.wr.atomic.compare_add_mask = op->op_m_fadd.nocarry_mask;
820                 send->s_wr.wr.atomic.swap_mask = 0;
821         }
822         nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify);
823         send->s_wr.num_sge = 1;
824         send->s_wr.next = NULL;
825         send->s_wr.wr.atomic.remote_addr = op->op_remote_addr;
826         send->s_wr.wr.atomic.rkey = op->op_rkey;
827         send->s_op = op;
828         rds_message_addref(container_of(send->s_op, struct rds_message, atomic));
829
830         /* map 8 byte retval buffer to the device */
831         ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE);
832         rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret);
833         if (ret != 1) {
834                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
835                 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
836                 ret = -ENOMEM; /* XXX ? */
837                 goto out;
838         }
839
840         /* Convert our struct scatterlist to struct ib_sge */
841         send->s_sge[0].addr = ib_sg_dma_address(ic->i_cm_id->device, op->op_sg);
842         send->s_sge[0].length = ib_sg_dma_len(ic->i_cm_id->device, op->op_sg);
843         send->s_sge[0].lkey = ic->i_mr->lkey;
844
845         rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
846                  send->s_sge[0].addr, send->s_sge[0].length);
847
848         if (nr_sig)
849                 atomic_add(nr_sig, &ic->i_signaled_sends);
850
851         failed_wr = &send->s_wr;
852         ret = ib_post_send(ic->i_cm_id->qp, &send->s_wr, &failed_wr);
853         rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
854                  send, &send->s_wr, ret, failed_wr);
855         BUG_ON(failed_wr != &send->s_wr);
856         if (ret) {
857                 printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI4 "
858                        "returned %d\n", &conn->c_faddr, ret);
859                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
860                 rds_ib_sub_signaled(ic, nr_sig);
861                 goto out;
862         }
863
864         if (unlikely(failed_wr != &send->s_wr)) {
865                 printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
866                 BUG_ON(failed_wr != &send->s_wr);
867         }
868
869 out:
870         return ret;
871 }
872
873 int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
874 {
875         struct rds_ib_connection *ic = conn->c_transport_data;
876         struct rds_ib_send_work *send = NULL;
877         struct rds_ib_send_work *first;
878         struct rds_ib_send_work *prev;
879         struct ib_send_wr *failed_wr;
880         struct scatterlist *scat;
881         unsigned long len;
882         u64 remote_addr = op->op_remote_addr;
883         u32 max_sge = ic->rds_ibdev->max_sge;
884         u32 pos;
885         u32 work_alloc;
886         u32 i;
887         u32 j;
888         int sent;
889         int ret;
890         int num_sge;
891         int nr_sig = 0;
892
893         /* map the op the first time we see it */
894         if (!op->op_mapped) {
895                 op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
896                                              op->op_sg, op->op_nents, (op->op_write) ?
897                                              DMA_TO_DEVICE : DMA_FROM_DEVICE);
898                 rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
899                 if (op->op_count == 0) {
900                         rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
901                         ret = -ENOMEM; /* XXX ? */
902                         goto out;
903                 }
904
905                 op->op_mapped = 1;
906         }
907
908         /*
909          * Instead of knowing how to return a partial rdma read/write we insist that there
910          * be enough work requests to send the entire message.
911          */
912         i = ceil(op->op_count, max_sge);
913
914         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
915         if (work_alloc != i) {
916                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
917                 rds_ib_stats_inc(s_ib_tx_ring_full);
918                 ret = -ENOMEM;
919                 goto out;
920         }
921
922         send = &ic->i_sends[pos];
923         first = send;
924         prev = NULL;
925         scat = &op->op_sg[0];
926         sent = 0;
927         num_sge = op->op_count;
928
929         for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
930                 send->s_wr.send_flags = 0;
931                 send->s_queued = jiffies;
932                 send->s_op = NULL;
933
934                 nr_sig += rds_ib_set_wr_signal_state(ic, send, op->op_notify);
935
936                 send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
937                 send->s_wr.wr.rdma.remote_addr = remote_addr;
938                 send->s_wr.wr.rdma.rkey = op->op_rkey;
939
940                 if (num_sge > max_sge) {
941                         send->s_wr.num_sge = max_sge;
942                         num_sge -= max_sge;
943                 } else {
944                         send->s_wr.num_sge = num_sge;
945                 }
946
947                 send->s_wr.next = NULL;
948
949                 if (prev)
950                         prev->s_wr.next = &send->s_wr;
951
952                 for (j = 0; j < send->s_wr.num_sge && scat != &op->op_sg[op->op_count]; j++) {
953                         len = ib_sg_dma_len(ic->i_cm_id->device, scat);
954                         send->s_sge[j].addr =
955                                  ib_sg_dma_address(ic->i_cm_id->device, scat);
956                         send->s_sge[j].length = len;
957                         send->s_sge[j].lkey = ic->i_mr->lkey;
958
959                         sent += len;
960                         rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
961
962                         remote_addr += len;
963                         scat++;
964                 }
965
966                 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
967                         &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
968
969                 prev = send;
970                 if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
971                         send = ic->i_sends;
972         }
973
974         /* give a reference to the last op */
975         if (scat == &op->op_sg[op->op_count]) {
976                 prev->s_op = op;
977                 rds_message_addref(container_of(op, struct rds_message, rdma));
978         }
979
980         if (i < work_alloc) {
981                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
982                 work_alloc = i;
983         }
984
985         if (nr_sig)
986                 atomic_add(nr_sig, &ic->i_signaled_sends);
987
988         failed_wr = &first->s_wr;
989         ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
990         rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
991                  first, &first->s_wr, ret, failed_wr);
992         BUG_ON(failed_wr != &first->s_wr);
993         if (ret) {
994                 printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 "
995                        "returned %d\n", &conn->c_faddr, ret);
996                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
997                 rds_ib_sub_signaled(ic, nr_sig);
998                 goto out;
999         }
1000
1001         if (unlikely(failed_wr != &first->s_wr)) {
1002                 printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
1003                 BUG_ON(failed_wr != &first->s_wr);
1004         }
1005
1006
1007 out:
1008         return ret;
1009 }
1010
1011 void rds_ib_xmit_complete(struct rds_connection *conn)
1012 {
1013         struct rds_ib_connection *ic = conn->c_transport_data;
1014
1015         /* We may have a pending ACK or window update we were unable
1016          * to send previously (due to flow control). Try again. */
1017         rds_ib_attempt_ack(ic);
1018 }