Merge branch 'linux-5.3' of git://github.com/skeggsb/linux into drm-fixes
[platform/kernel/linux-rpi.git] / net / rds / ib_send.c
1 /*
2  * Copyright (c) 2006, 2017 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
43 /*
44  * Convert IB-specific error message to RDS error message and call core
45  * completion handler.
46  */
47 static 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
72 static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
73                                    struct rm_data_op *op,
74                                    int wc_status)
75 {
76         if (op->op_nents)
77                 ib_dma_unmap_sg(ic->i_cm_id->device,
78                                 op->op_sg, op->op_nents,
79                                 DMA_TO_DEVICE);
80 }
81
82 static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
83                                    struct rm_rdma_op *op,
84                                    int wc_status)
85 {
86         if (op->op_mapped) {
87                 ib_dma_unmap_sg(ic->i_cm_id->device,
88                                 op->op_sg, op->op_nents,
89                                 op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
90                 op->op_mapped = 0;
91         }
92
93         /* If the user asked for a completion notification on this
94          * message, we can implement three different semantics:
95          *  1.  Notify when we received the ACK on the RDS message
96          *      that was queued with the RDMA. This provides reliable
97          *      notification of RDMA status at the expense of a one-way
98          *      packet delay.
99          *  2.  Notify when the IB stack gives us the completion event for
100          *      the RDMA operation.
101          *  3.  Notify when the IB stack gives us the completion event for
102          *      the accompanying RDS messages.
103          * Here, we implement approach #3. To implement approach #2,
104          * we would need to take an event for the rdma WR. To implement #1,
105          * don't call rds_rdma_send_complete at all, and fall back to the notify
106          * handling in the ACK processing code.
107          *
108          * Note: There's no need to explicitly sync any RDMA buffers using
109          * ib_dma_sync_sg_for_cpu - the completion for the RDMA
110          * operation itself unmapped the RDMA buffers, which takes care
111          * of synching.
112          */
113         rds_ib_send_complete(container_of(op, struct rds_message, rdma),
114                              wc_status, rds_rdma_send_complete);
115
116         if (op->op_write)
117                 rds_stats_add(s_send_rdma_bytes, op->op_bytes);
118         else
119                 rds_stats_add(s_recv_rdma_bytes, op->op_bytes);
120 }
121
122 static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
123                                      struct rm_atomic_op *op,
124                                      int wc_status)
125 {
126         /* unmap atomic recvbuf */
127         if (op->op_mapped) {
128                 ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1,
129                                 DMA_FROM_DEVICE);
130                 op->op_mapped = 0;
131         }
132
133         rds_ib_send_complete(container_of(op, struct rds_message, atomic),
134                              wc_status, rds_atomic_send_complete);
135
136         if (op->op_type == RDS_ATOMIC_TYPE_CSWP)
137                 rds_ib_stats_inc(s_ib_atomic_cswp);
138         else
139                 rds_ib_stats_inc(s_ib_atomic_fadd);
140 }
141
142 /*
143  * Unmap the resources associated with a struct send_work.
144  *
145  * Returns the rm for no good reason other than it is unobtainable
146  * other than by switching on wr.opcode, currently, and the caller,
147  * the event handler, needs it.
148  */
149 static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic,
150                                                 struct rds_ib_send_work *send,
151                                                 int wc_status)
152 {
153         struct rds_message *rm = NULL;
154
155         /* In the error case, wc.opcode sometimes contains garbage */
156         switch (send->s_wr.opcode) {
157         case IB_WR_SEND:
158                 if (send->s_op) {
159                         rm = container_of(send->s_op, struct rds_message, data);
160                         rds_ib_send_unmap_data(ic, send->s_op, wc_status);
161                 }
162                 break;
163         case IB_WR_RDMA_WRITE:
164         case IB_WR_RDMA_READ:
165                 if (send->s_op) {
166                         rm = container_of(send->s_op, struct rds_message, rdma);
167                         rds_ib_send_unmap_rdma(ic, send->s_op, wc_status);
168                 }
169                 break;
170         case IB_WR_ATOMIC_FETCH_AND_ADD:
171         case IB_WR_ATOMIC_CMP_AND_SWP:
172                 if (send->s_op) {
173                         rm = container_of(send->s_op, struct rds_message, atomic);
174                         rds_ib_send_unmap_atomic(ic, send->s_op, wc_status);
175                 }
176                 break;
177         default:
178                 printk_ratelimited(KERN_NOTICE
179                                "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
180                                __func__, send->s_wr.opcode);
181                 break;
182         }
183
184         send->s_wr.opcode = 0xdead;
185
186         return rm;
187 }
188
189 void rds_ib_send_init_ring(struct rds_ib_connection *ic)
190 {
191         struct rds_ib_send_work *send;
192         u32 i;
193
194         for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
195                 struct ib_sge *sge;
196
197                 send->s_op = NULL;
198
199                 send->s_wr.wr_id = i;
200                 send->s_wr.sg_list = send->s_sge;
201                 send->s_wr.ex.imm_data = 0;
202
203                 sge = &send->s_sge[0];
204                 sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
205                 sge->length = sizeof(struct rds_header);
206                 sge->lkey = ic->i_pd->local_dma_lkey;
207
208                 send->s_sge[1].lkey = ic->i_pd->local_dma_lkey;
209         }
210 }
211
212 void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
213 {
214         struct rds_ib_send_work *send;
215         u32 i;
216
217         for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
218                 if (send->s_op && send->s_wr.opcode != 0xdead)
219                         rds_ib_send_unmap_op(ic, send, IB_WC_WR_FLUSH_ERR);
220         }
221 }
222
223 /*
224  * The only fast path caller always has a non-zero nr, so we don't
225  * bother testing nr before performing the atomic sub.
226  */
227 static void rds_ib_sub_signaled(struct rds_ib_connection *ic, int nr)
228 {
229         if ((atomic_sub_return(nr, &ic->i_signaled_sends) == 0) &&
230             waitqueue_active(&rds_ib_ring_empty_wait))
231                 wake_up(&rds_ib_ring_empty_wait);
232         BUG_ON(atomic_read(&ic->i_signaled_sends) < 0);
233 }
234
235 /*
236  * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
237  * operations performed in the send path.  As the sender allocs and potentially
238  * unallocs the next free entry in the ring it doesn't alter which is
239  * the next to be freed, which is what this is concerned with.
240  */
241 void rds_ib_send_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc)
242 {
243         struct rds_message *rm = NULL;
244         struct rds_connection *conn = ic->conn;
245         struct rds_ib_send_work *send;
246         u32 completed;
247         u32 oldest;
248         u32 i = 0;
249         int nr_sig = 0;
250
251
252         rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
253                  (unsigned long long)wc->wr_id, wc->status,
254                  ib_wc_status_msg(wc->status), wc->byte_len,
255                  be32_to_cpu(wc->ex.imm_data));
256         rds_ib_stats_inc(s_ib_tx_cq_event);
257
258         if (wc->wr_id == RDS_IB_ACK_WR_ID) {
259                 if (time_after(jiffies, ic->i_ack_queued + HZ / 2))
260                         rds_ib_stats_inc(s_ib_tx_stalled);
261                 rds_ib_ack_send_complete(ic);
262                 return;
263         }
264
265         oldest = rds_ib_ring_oldest(&ic->i_send_ring);
266
267         completed = rds_ib_ring_completed(&ic->i_send_ring, wc->wr_id, oldest);
268
269         for (i = 0; i < completed; i++) {
270                 send = &ic->i_sends[oldest];
271                 if (send->s_wr.send_flags & IB_SEND_SIGNALED)
272                         nr_sig++;
273
274                 rm = rds_ib_send_unmap_op(ic, send, wc->status);
275
276                 if (time_after(jiffies, send->s_queued + HZ / 2))
277                         rds_ib_stats_inc(s_ib_tx_stalled);
278
279                 if (send->s_op) {
280                         if (send->s_op == rm->m_final_op) {
281                                 /* If anyone waited for this message to get
282                                  * flushed out, wake them up now
283                                  */
284                                 rds_message_unmapped(rm);
285                         }
286                         rds_message_put(rm);
287                         send->s_op = NULL;
288                 }
289
290                 oldest = (oldest + 1) % ic->i_send_ring.w_nr;
291         }
292
293         rds_ib_ring_free(&ic->i_send_ring, completed);
294         rds_ib_sub_signaled(ic, nr_sig);
295         nr_sig = 0;
296
297         if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
298             test_bit(0, &conn->c_map_queued))
299                 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
300
301         /* We expect errors as the qp is drained during shutdown */
302         if (wc->status != IB_WC_SUCCESS && rds_conn_up(conn)) {
303                 rds_ib_conn_error(conn, "send completion on <%pI6c,%pI6c,%d> had status %u (%s), disconnecting and reconnecting\n",
304                                   &conn->c_laddr, &conn->c_faddr,
305                                   conn->c_tos, wc->status,
306                                   ib_wc_status_msg(wc->status));
307         }
308 }
309
310 /*
311  * This is the main function for allocating credits when sending
312  * messages.
313  *
314  * Conceptually, we have two counters:
315  *  -   send credits: this tells us how many WRs we're allowed
316  *      to submit without overruning the receiver's queue. For
317  *      each SEND WR we post, we decrement this by one.
318  *
319  *  -   posted credits: this tells us how many WRs we recently
320  *      posted to the receive queue. This value is transferred
321  *      to the peer as a "credit update" in a RDS header field.
322  *      Every time we transmit credits to the peer, we subtract
323  *      the amount of transferred credits from this counter.
324  *
325  * It is essential that we avoid situations where both sides have
326  * exhausted their send credits, and are unable to send new credits
327  * to the peer. We achieve this by requiring that we send at least
328  * one credit update to the peer before exhausting our credits.
329  * When new credits arrive, we subtract one credit that is withheld
330  * until we've posted new buffers and are ready to transmit these
331  * credits (see rds_ib_send_add_credits below).
332  *
333  * The RDS send code is essentially single-threaded; rds_send_xmit
334  * sets RDS_IN_XMIT to ensure exclusive access to the send ring.
335  * However, the ACK sending code is independent and can race with
336  * message SENDs.
337  *
338  * In the send path, we need to update the counters for send credits
339  * and the counter of posted buffers atomically - when we use the
340  * last available credit, we cannot allow another thread to race us
341  * and grab the posted credits counter.  Hence, we have to use a
342  * spinlock to protect the credit counter, or use atomics.
343  *
344  * Spinlocks shared between the send and the receive path are bad,
345  * because they create unnecessary delays. An early implementation
346  * using a spinlock showed a 5% degradation in throughput at some
347  * loads.
348  *
349  * This implementation avoids spinlocks completely, putting both
350  * counters into a single atomic, and updating that atomic using
351  * atomic_add (in the receive path, when receiving fresh credits),
352  * and using atomic_cmpxchg when updating the two counters.
353  */
354 int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
355                              u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
356 {
357         unsigned int avail, posted, got = 0, advertise;
358         long oldval, newval;
359
360         *adv_credits = 0;
361         if (!ic->i_flowctl)
362                 return wanted;
363
364 try_again:
365         advertise = 0;
366         oldval = newval = atomic_read(&ic->i_credits);
367         posted = IB_GET_POST_CREDITS(oldval);
368         avail = IB_GET_SEND_CREDITS(oldval);
369
370         rdsdebug("wanted=%u credits=%u posted=%u\n",
371                         wanted, avail, posted);
372
373         /* The last credit must be used to send a credit update. */
374         if (avail && !posted)
375                 avail--;
376
377         if (avail < wanted) {
378                 struct rds_connection *conn = ic->i_cm_id->context;
379
380                 /* Oops, there aren't that many credits left! */
381                 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
382                 got = avail;
383         } else {
384                 /* Sometimes you get what you want, lalala. */
385                 got = wanted;
386         }
387         newval -= IB_SET_SEND_CREDITS(got);
388
389         /*
390          * If need_posted is non-zero, then the caller wants
391          * the posted regardless of whether any send credits are
392          * available.
393          */
394         if (posted && (got || need_posted)) {
395                 advertise = min_t(unsigned int, posted, max_posted);
396                 newval -= IB_SET_POST_CREDITS(advertise);
397         }
398
399         /* Finally bill everything */
400         if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
401                 goto try_again;
402
403         *adv_credits = advertise;
404         return got;
405 }
406
407 void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
408 {
409         struct rds_ib_connection *ic = conn->c_transport_data;
410
411         if (credits == 0)
412                 return;
413
414         rdsdebug("credits=%u current=%u%s\n",
415                         credits,
416                         IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
417                         test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
418
419         atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
420         if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
421                 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
422
423         WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
424
425         rds_ib_stats_inc(s_ib_rx_credit_updates);
426 }
427
428 void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
429 {
430         struct rds_ib_connection *ic = conn->c_transport_data;
431
432         if (posted == 0)
433                 return;
434
435         atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
436
437         /* Decide whether to send an update to the peer now.
438          * If we would send a credit update for every single buffer we
439          * post, we would end up with an ACK storm (ACK arrives,
440          * consumes buffer, we refill the ring, send ACK to remote
441          * advertising the newly posted buffer... ad inf)
442          *
443          * Performance pretty much depends on how often we send
444          * credit updates - too frequent updates mean lots of ACKs.
445          * Too infrequent updates, and the peer will run out of
446          * credits and has to throttle.
447          * For the time being, 16 seems to be a good compromise.
448          */
449         if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
450                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
451 }
452
453 static inline int rds_ib_set_wr_signal_state(struct rds_ib_connection *ic,
454                                              struct rds_ib_send_work *send,
455                                              bool notify)
456 {
457         /*
458          * We want to delay signaling completions just enough to get
459          * the batching benefits but not so much that we create dead time
460          * on the wire.
461          */
462         if (ic->i_unsignaled_wrs-- == 0 || notify) {
463                 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
464                 send->s_wr.send_flags |= IB_SEND_SIGNALED;
465                 return 1;
466         }
467         return 0;
468 }
469
470 /*
471  * This can be called multiple times for a given message.  The first time
472  * we see a message we map its scatterlist into the IB device so that
473  * we can provide that mapped address to the IB scatter gather entries
474  * in the IB work requests.  We translate the scatterlist into a series
475  * of work requests that fragment the message.  These work requests complete
476  * in order so we pass ownership of the message to the completion handler
477  * once we send the final fragment.
478  *
479  * The RDS core uses the c_send_lock to only enter this function once
480  * per connection.  This makes sure that the tx ring alloc/unalloc pairs
481  * don't get out of sync and confuse the ring.
482  */
483 int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
484                 unsigned int hdr_off, unsigned int sg, unsigned int off)
485 {
486         struct rds_ib_connection *ic = conn->c_transport_data;
487         struct ib_device *dev = ic->i_cm_id->device;
488         struct rds_ib_send_work *send = NULL;
489         struct rds_ib_send_work *first;
490         struct rds_ib_send_work *prev;
491         const struct ib_send_wr *failed_wr;
492         struct scatterlist *scat;
493         u32 pos;
494         u32 i;
495         u32 work_alloc;
496         u32 credit_alloc = 0;
497         u32 posted;
498         u32 adv_credits = 0;
499         int send_flags = 0;
500         int bytes_sent = 0;
501         int ret;
502         int flow_controlled = 0;
503         int nr_sig = 0;
504
505         BUG_ON(off % RDS_FRAG_SIZE);
506         BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
507
508         /* Do not send cong updates to IB loopback */
509         if (conn->c_loopback
510             && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
511                 rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
512                 scat = &rm->data.op_sg[sg];
513                 ret = max_t(int, RDS_CONG_MAP_BYTES, scat->length);
514                 return sizeof(struct rds_header) + ret;
515         }
516
517         /* FIXME we may overallocate here */
518         if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
519                 i = 1;
520         else
521                 i = DIV_ROUND_UP(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
522
523         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
524         if (work_alloc == 0) {
525                 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
526                 rds_ib_stats_inc(s_ib_tx_ring_full);
527                 ret = -ENOMEM;
528                 goto out;
529         }
530
531         if (ic->i_flowctl) {
532                 credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
533                 adv_credits += posted;
534                 if (credit_alloc < work_alloc) {
535                         rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
536                         work_alloc = credit_alloc;
537                         flow_controlled = 1;
538                 }
539                 if (work_alloc == 0) {
540                         set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
541                         rds_ib_stats_inc(s_ib_tx_throttle);
542                         ret = -ENOMEM;
543                         goto out;
544                 }
545         }
546
547         /* map the message the first time we see it */
548         if (!ic->i_data_op) {
549                 if (rm->data.op_nents) {
550                         rm->data.op_count = ib_dma_map_sg(dev,
551                                                           rm->data.op_sg,
552                                                           rm->data.op_nents,
553                                                           DMA_TO_DEVICE);
554                         rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
555                         if (rm->data.op_count == 0) {
556                                 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
557                                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
558                                 ret = -ENOMEM; /* XXX ? */
559                                 goto out;
560                         }
561                 } else {
562                         rm->data.op_count = 0;
563                 }
564
565                 rds_message_addref(rm);
566                 rm->data.op_dmasg = 0;
567                 rm->data.op_dmaoff = 0;
568                 ic->i_data_op = &rm->data;
569
570                 /* Finalize the header */
571                 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
572                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
573                 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
574                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
575
576                 /* If it has a RDMA op, tell the peer we did it. This is
577                  * used by the peer to release use-once RDMA MRs. */
578                 if (rm->rdma.op_active) {
579                         struct rds_ext_header_rdma ext_hdr;
580
581                         ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
582                         rds_message_add_extension(&rm->m_inc.i_hdr,
583                                         RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
584                 }
585                 if (rm->m_rdma_cookie) {
586                         rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
587                                         rds_rdma_cookie_key(rm->m_rdma_cookie),
588                                         rds_rdma_cookie_offset(rm->m_rdma_cookie));
589                 }
590
591                 /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
592                  * we should not do this unless we have a chance of at least
593                  * sticking the header into the send ring. Which is why we
594                  * should call rds_ib_ring_alloc first. */
595                 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
596                 rds_message_make_checksum(&rm->m_inc.i_hdr);
597
598                 /*
599                  * Update adv_credits since we reset the ACK_REQUIRED bit.
600                  */
601                 if (ic->i_flowctl) {
602                         rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
603                         adv_credits += posted;
604                         BUG_ON(adv_credits > 255);
605                 }
606         }
607
608         /* Sometimes you want to put a fence between an RDMA
609          * READ and the following SEND.
610          * We could either do this all the time
611          * or when requested by the user. Right now, we let
612          * the application choose.
613          */
614         if (rm->rdma.op_active && rm->rdma.op_fence)
615                 send_flags = IB_SEND_FENCE;
616
617         /* Each frag gets a header. Msgs may be 0 bytes */
618         send = &ic->i_sends[pos];
619         first = send;
620         prev = NULL;
621         scat = &ic->i_data_op->op_sg[rm->data.op_dmasg];
622         i = 0;
623         do {
624                 unsigned int len = 0;
625
626                 /* Set up the header */
627                 send->s_wr.send_flags = send_flags;
628                 send->s_wr.opcode = IB_WR_SEND;
629                 send->s_wr.num_sge = 1;
630                 send->s_wr.next = NULL;
631                 send->s_queued = jiffies;
632                 send->s_op = NULL;
633
634                 send->s_sge[0].addr = ic->i_send_hdrs_dma
635                         + (pos * sizeof(struct rds_header));
636                 send->s_sge[0].length = sizeof(struct rds_header);
637
638                 memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
639
640                 /* Set up the data, if present */
641                 if (i < work_alloc
642                     && scat != &rm->data.op_sg[rm->data.op_count]) {
643                         len = min(RDS_FRAG_SIZE,
644                                   sg_dma_len(scat) - rm->data.op_dmaoff);
645                         send->s_wr.num_sge = 2;
646
647                         send->s_sge[1].addr = sg_dma_address(scat);
648                         send->s_sge[1].addr += rm->data.op_dmaoff;
649                         send->s_sge[1].length = len;
650
651                         bytes_sent += len;
652                         rm->data.op_dmaoff += len;
653                         if (rm->data.op_dmaoff == sg_dma_len(scat)) {
654                                 scat++;
655                                 rm->data.op_dmasg++;
656                                 rm->data.op_dmaoff = 0;
657                         }
658                 }
659
660                 rds_ib_set_wr_signal_state(ic, send, false);
661
662                 /*
663                  * Always signal the last one if we're stopping due to flow control.
664                  */
665                 if (ic->i_flowctl && flow_controlled && i == (work_alloc - 1)) {
666                         rds_ib_set_wr_signal_state(ic, send, true);
667                         send->s_wr.send_flags |= IB_SEND_SOLICITED;
668                 }
669
670                 if (send->s_wr.send_flags & IB_SEND_SIGNALED)
671                         nr_sig++;
672
673                 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
674                          &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
675
676                 if (ic->i_flowctl && adv_credits) {
677                         struct rds_header *hdr = &ic->i_send_hdrs[pos];
678
679                         /* add credit and redo the header checksum */
680                         hdr->h_credit = adv_credits;
681                         rds_message_make_checksum(hdr);
682                         adv_credits = 0;
683                         rds_ib_stats_inc(s_ib_tx_credit_updates);
684                 }
685
686                 if (prev)
687                         prev->s_wr.next = &send->s_wr;
688                 prev = send;
689
690                 pos = (pos + 1) % ic->i_send_ring.w_nr;
691                 send = &ic->i_sends[pos];
692                 i++;
693
694         } while (i < work_alloc
695                  && scat != &rm->data.op_sg[rm->data.op_count]);
696
697         /* Account the RDS header in the number of bytes we sent, but just once.
698          * The caller has no concept of fragmentation. */
699         if (hdr_off == 0)
700                 bytes_sent += sizeof(struct rds_header);
701
702         /* if we finished the message then send completion owns it */
703         if (scat == &rm->data.op_sg[rm->data.op_count]) {
704                 prev->s_op = ic->i_data_op;
705                 prev->s_wr.send_flags |= IB_SEND_SOLICITED;
706                 if (!(prev->s_wr.send_flags & IB_SEND_SIGNALED))
707                         nr_sig += rds_ib_set_wr_signal_state(ic, prev, true);
708                 ic->i_data_op = NULL;
709         }
710
711         /* Put back wrs & credits we didn't use */
712         if (i < work_alloc) {
713                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
714                 work_alloc = i;
715         }
716         if (ic->i_flowctl && i < credit_alloc)
717                 rds_ib_send_add_credits(conn, credit_alloc - i);
718
719         if (nr_sig)
720                 atomic_add(nr_sig, &ic->i_signaled_sends);
721
722         /* XXX need to worry about failed_wr and partial sends. */
723         failed_wr = &first->s_wr;
724         ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
725         rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
726                  first, &first->s_wr, ret, failed_wr);
727         BUG_ON(failed_wr != &first->s_wr);
728         if (ret) {
729                 printk(KERN_WARNING "RDS/IB: ib_post_send to %pI6c "
730                        "returned %d\n", &conn->c_faddr, ret);
731                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
732                 rds_ib_sub_signaled(ic, nr_sig);
733                 if (prev->s_op) {
734                         ic->i_data_op = prev->s_op;
735                         prev->s_op = NULL;
736                 }
737
738                 rds_ib_conn_error(ic->conn, "ib_post_send failed\n");
739                 goto out;
740         }
741
742         ret = bytes_sent;
743 out:
744         BUG_ON(adv_credits);
745         return ret;
746 }
747
748 /*
749  * Issue atomic operation.
750  * A simplified version of the rdma case, we always map 1 SG, and
751  * only 8 bytes, for the return value from the atomic operation.
752  */
753 int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
754 {
755         struct rds_ib_connection *ic = conn->c_transport_data;
756         struct rds_ib_send_work *send = NULL;
757         const struct ib_send_wr *failed_wr;
758         u32 pos;
759         u32 work_alloc;
760         int ret;
761         int nr_sig = 0;
762
763         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
764         if (work_alloc != 1) {
765                 rds_ib_stats_inc(s_ib_tx_ring_full);
766                 ret = -ENOMEM;
767                 goto out;
768         }
769
770         /* address of send request in ring */
771         send = &ic->i_sends[pos];
772         send->s_queued = jiffies;
773
774         if (op->op_type == RDS_ATOMIC_TYPE_CSWP) {
775                 send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP;
776                 send->s_atomic_wr.compare_add = op->op_m_cswp.compare;
777                 send->s_atomic_wr.swap = op->op_m_cswp.swap;
778                 send->s_atomic_wr.compare_add_mask = op->op_m_cswp.compare_mask;
779                 send->s_atomic_wr.swap_mask = op->op_m_cswp.swap_mask;
780         } else { /* FADD */
781                 send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD;
782                 send->s_atomic_wr.compare_add = op->op_m_fadd.add;
783                 send->s_atomic_wr.swap = 0;
784                 send->s_atomic_wr.compare_add_mask = op->op_m_fadd.nocarry_mask;
785                 send->s_atomic_wr.swap_mask = 0;
786         }
787         send->s_wr.send_flags = 0;
788         nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify);
789         send->s_atomic_wr.wr.num_sge = 1;
790         send->s_atomic_wr.wr.next = NULL;
791         send->s_atomic_wr.remote_addr = op->op_remote_addr;
792         send->s_atomic_wr.rkey = op->op_rkey;
793         send->s_op = op;
794         rds_message_addref(container_of(send->s_op, struct rds_message, atomic));
795
796         /* map 8 byte retval buffer to the device */
797         ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE);
798         rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret);
799         if (ret != 1) {
800                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
801                 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
802                 ret = -ENOMEM; /* XXX ? */
803                 goto out;
804         }
805
806         /* Convert our struct scatterlist to struct ib_sge */
807         send->s_sge[0].addr = sg_dma_address(op->op_sg);
808         send->s_sge[0].length = sg_dma_len(op->op_sg);
809         send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
810
811         rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
812                  send->s_sge[0].addr, send->s_sge[0].length);
813
814         if (nr_sig)
815                 atomic_add(nr_sig, &ic->i_signaled_sends);
816
817         failed_wr = &send->s_atomic_wr.wr;
818         ret = ib_post_send(ic->i_cm_id->qp, &send->s_atomic_wr.wr, &failed_wr);
819         rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
820                  send, &send->s_atomic_wr, ret, failed_wr);
821         BUG_ON(failed_wr != &send->s_atomic_wr.wr);
822         if (ret) {
823                 printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI6c "
824                        "returned %d\n", &conn->c_faddr, ret);
825                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
826                 rds_ib_sub_signaled(ic, nr_sig);
827                 goto out;
828         }
829
830         if (unlikely(failed_wr != &send->s_atomic_wr.wr)) {
831                 printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
832                 BUG_ON(failed_wr != &send->s_atomic_wr.wr);
833         }
834
835 out:
836         return ret;
837 }
838
839 int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
840 {
841         struct rds_ib_connection *ic = conn->c_transport_data;
842         struct rds_ib_send_work *send = NULL;
843         struct rds_ib_send_work *first;
844         struct rds_ib_send_work *prev;
845         const struct ib_send_wr *failed_wr;
846         struct scatterlist *scat;
847         unsigned long len;
848         u64 remote_addr = op->op_remote_addr;
849         u32 max_sge = ic->rds_ibdev->max_sge;
850         u32 pos;
851         u32 work_alloc;
852         u32 i;
853         u32 j;
854         int sent;
855         int ret;
856         int num_sge;
857         int nr_sig = 0;
858
859         /* map the op the first time we see it */
860         if (!op->op_mapped) {
861                 op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
862                                              op->op_sg, op->op_nents, (op->op_write) ?
863                                              DMA_TO_DEVICE : DMA_FROM_DEVICE);
864                 rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
865                 if (op->op_count == 0) {
866                         rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
867                         ret = -ENOMEM; /* XXX ? */
868                         goto out;
869                 }
870
871                 op->op_mapped = 1;
872         }
873
874         /*
875          * Instead of knowing how to return a partial rdma read/write we insist that there
876          * be enough work requests to send the entire message.
877          */
878         i = DIV_ROUND_UP(op->op_count, max_sge);
879
880         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
881         if (work_alloc != i) {
882                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
883                 rds_ib_stats_inc(s_ib_tx_ring_full);
884                 ret = -ENOMEM;
885                 goto out;
886         }
887
888         send = &ic->i_sends[pos];
889         first = send;
890         prev = NULL;
891         scat = &op->op_sg[0];
892         sent = 0;
893         num_sge = op->op_count;
894
895         for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
896                 send->s_wr.send_flags = 0;
897                 send->s_queued = jiffies;
898                 send->s_op = NULL;
899
900                 if (!op->op_notify)
901                         nr_sig += rds_ib_set_wr_signal_state(ic, send,
902                                                              op->op_notify);
903
904                 send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
905                 send->s_rdma_wr.remote_addr = remote_addr;
906                 send->s_rdma_wr.rkey = op->op_rkey;
907
908                 if (num_sge > max_sge) {
909                         send->s_rdma_wr.wr.num_sge = max_sge;
910                         num_sge -= max_sge;
911                 } else {
912                         send->s_rdma_wr.wr.num_sge = num_sge;
913                 }
914
915                 send->s_rdma_wr.wr.next = NULL;
916
917                 if (prev)
918                         prev->s_rdma_wr.wr.next = &send->s_rdma_wr.wr;
919
920                 for (j = 0; j < send->s_rdma_wr.wr.num_sge &&
921                      scat != &op->op_sg[op->op_count]; j++) {
922                         len = sg_dma_len(scat);
923                         send->s_sge[j].addr = sg_dma_address(scat);
924                         send->s_sge[j].length = len;
925                         send->s_sge[j].lkey = ic->i_pd->local_dma_lkey;
926
927                         sent += len;
928                         rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
929
930                         remote_addr += len;
931                         scat++;
932                 }
933
934                 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
935                         &send->s_rdma_wr.wr,
936                         send->s_rdma_wr.wr.num_sge,
937                         send->s_rdma_wr.wr.next);
938
939                 prev = send;
940                 if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
941                         send = ic->i_sends;
942         }
943
944         /* give a reference to the last op */
945         if (scat == &op->op_sg[op->op_count]) {
946                 prev->s_op = op;
947                 rds_message_addref(container_of(op, struct rds_message, rdma));
948         }
949
950         if (i < work_alloc) {
951                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
952                 work_alloc = i;
953         }
954
955         if (nr_sig)
956                 atomic_add(nr_sig, &ic->i_signaled_sends);
957
958         failed_wr = &first->s_rdma_wr.wr;
959         ret = ib_post_send(ic->i_cm_id->qp, &first->s_rdma_wr.wr, &failed_wr);
960         rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
961                  first, &first->s_rdma_wr.wr, ret, failed_wr);
962         BUG_ON(failed_wr != &first->s_rdma_wr.wr);
963         if (ret) {
964                 printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI6c "
965                        "returned %d\n", &conn->c_faddr, ret);
966                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
967                 rds_ib_sub_signaled(ic, nr_sig);
968                 goto out;
969         }
970
971         if (unlikely(failed_wr != &first->s_rdma_wr.wr)) {
972                 printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
973                 BUG_ON(failed_wr != &first->s_rdma_wr.wr);
974         }
975
976
977 out:
978         return ret;
979 }
980
981 void rds_ib_xmit_path_complete(struct rds_conn_path *cp)
982 {
983         struct rds_connection *conn = cp->cp_conn;
984         struct rds_ib_connection *ic = conn->c_transport_data;
985
986         /* We may have a pending ACK or window update we were unable
987          * to send previously (due to flow control). Try again. */
988         rds_ib_attempt_ack(ic);
989 }