sctp: Do not account for sizeof(struct sk_buff) in estimated rwnd
[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 #include <linux/ratelimit.h>
38
39 #include "rds.h"
40 #include "ib.h"
41
42 static char *rds_ib_wc_status_strings[] = {
43 #define RDS_IB_WC_STATUS_STR(foo) \
44                 [IB_WC_##foo] = __stringify(IB_WC_##foo)
45         RDS_IB_WC_STATUS_STR(SUCCESS),
46         RDS_IB_WC_STATUS_STR(LOC_LEN_ERR),
47         RDS_IB_WC_STATUS_STR(LOC_QP_OP_ERR),
48         RDS_IB_WC_STATUS_STR(LOC_EEC_OP_ERR),
49         RDS_IB_WC_STATUS_STR(LOC_PROT_ERR),
50         RDS_IB_WC_STATUS_STR(WR_FLUSH_ERR),
51         RDS_IB_WC_STATUS_STR(MW_BIND_ERR),
52         RDS_IB_WC_STATUS_STR(BAD_RESP_ERR),
53         RDS_IB_WC_STATUS_STR(LOC_ACCESS_ERR),
54         RDS_IB_WC_STATUS_STR(REM_INV_REQ_ERR),
55         RDS_IB_WC_STATUS_STR(REM_ACCESS_ERR),
56         RDS_IB_WC_STATUS_STR(REM_OP_ERR),
57         RDS_IB_WC_STATUS_STR(RETRY_EXC_ERR),
58         RDS_IB_WC_STATUS_STR(RNR_RETRY_EXC_ERR),
59         RDS_IB_WC_STATUS_STR(LOC_RDD_VIOL_ERR),
60         RDS_IB_WC_STATUS_STR(REM_INV_RD_REQ_ERR),
61         RDS_IB_WC_STATUS_STR(REM_ABORT_ERR),
62         RDS_IB_WC_STATUS_STR(INV_EECN_ERR),
63         RDS_IB_WC_STATUS_STR(INV_EEC_STATE_ERR),
64         RDS_IB_WC_STATUS_STR(FATAL_ERR),
65         RDS_IB_WC_STATUS_STR(RESP_TIMEOUT_ERR),
66         RDS_IB_WC_STATUS_STR(GENERAL_ERR),
67 #undef RDS_IB_WC_STATUS_STR
68 };
69
70 char *rds_ib_wc_status_str(enum ib_wc_status status)
71 {
72         return rds_str_array(rds_ib_wc_status_strings,
73                              ARRAY_SIZE(rds_ib_wc_status_strings), status);
74 }
75
76 /*
77  * Convert IB-specific error message to RDS error message and call core
78  * completion handler.
79  */
80 static void rds_ib_send_complete(struct rds_message *rm,
81                                  int wc_status,
82                                  void (*complete)(struct rds_message *rm, int status))
83 {
84         int notify_status;
85
86         switch (wc_status) {
87         case IB_WC_WR_FLUSH_ERR:
88                 return;
89
90         case IB_WC_SUCCESS:
91                 notify_status = RDS_RDMA_SUCCESS;
92                 break;
93
94         case IB_WC_REM_ACCESS_ERR:
95                 notify_status = RDS_RDMA_REMOTE_ERROR;
96                 break;
97
98         default:
99                 notify_status = RDS_RDMA_OTHER_ERROR;
100                 break;
101         }
102         complete(rm, notify_status);
103 }
104
105 static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
106                                    struct rm_data_op *op,
107                                    int wc_status)
108 {
109         if (op->op_nents)
110                 ib_dma_unmap_sg(ic->i_cm_id->device,
111                                 op->op_sg, op->op_nents,
112                                 DMA_TO_DEVICE);
113 }
114
115 static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
116                                    struct rm_rdma_op *op,
117                                    int wc_status)
118 {
119         if (op->op_mapped) {
120                 ib_dma_unmap_sg(ic->i_cm_id->device,
121                                 op->op_sg, op->op_nents,
122                                 op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
123                 op->op_mapped = 0;
124         }
125
126         /* If the user asked for a completion notification on this
127          * message, we can implement three different semantics:
128          *  1.  Notify when we received the ACK on the RDS message
129          *      that was queued with the RDMA. This provides reliable
130          *      notification of RDMA status at the expense of a one-way
131          *      packet delay.
132          *  2.  Notify when the IB stack gives us the completion event for
133          *      the RDMA operation.
134          *  3.  Notify when the IB stack gives us the completion event for
135          *      the accompanying RDS messages.
136          * Here, we implement approach #3. To implement approach #2,
137          * we would need to take an event for the rdma WR. To implement #1,
138          * don't call rds_rdma_send_complete at all, and fall back to the notify
139          * handling in the ACK processing code.
140          *
141          * Note: There's no need to explicitly sync any RDMA buffers using
142          * ib_dma_sync_sg_for_cpu - the completion for the RDMA
143          * operation itself unmapped the RDMA buffers, which takes care
144          * of synching.
145          */
146         rds_ib_send_complete(container_of(op, struct rds_message, rdma),
147                              wc_status, rds_rdma_send_complete);
148
149         if (op->op_write)
150                 rds_stats_add(s_send_rdma_bytes, op->op_bytes);
151         else
152                 rds_stats_add(s_recv_rdma_bytes, op->op_bytes);
153 }
154
155 static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
156                                      struct rm_atomic_op *op,
157                                      int wc_status)
158 {
159         /* unmap atomic recvbuf */
160         if (op->op_mapped) {
161                 ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1,
162                                 DMA_FROM_DEVICE);
163                 op->op_mapped = 0;
164         }
165
166         rds_ib_send_complete(container_of(op, struct rds_message, atomic),
167                              wc_status, rds_atomic_send_complete);
168
169         if (op->op_type == RDS_ATOMIC_TYPE_CSWP)
170                 rds_ib_stats_inc(s_ib_atomic_cswp);
171         else
172                 rds_ib_stats_inc(s_ib_atomic_fadd);
173 }
174
175 /*
176  * Unmap the resources associated with a struct send_work.
177  *
178  * Returns the rm for no good reason other than it is unobtainable
179  * other than by switching on wr.opcode, currently, and the caller,
180  * the event handler, needs it.
181  */
182 static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic,
183                                                 struct rds_ib_send_work *send,
184                                                 int wc_status)
185 {
186         struct rds_message *rm = NULL;
187
188         /* In the error case, wc.opcode sometimes contains garbage */
189         switch (send->s_wr.opcode) {
190         case IB_WR_SEND:
191                 if (send->s_op) {
192                         rm = container_of(send->s_op, struct rds_message, data);
193                         rds_ib_send_unmap_data(ic, send->s_op, wc_status);
194                 }
195                 break;
196         case IB_WR_RDMA_WRITE:
197         case IB_WR_RDMA_READ:
198                 if (send->s_op) {
199                         rm = container_of(send->s_op, struct rds_message, rdma);
200                         rds_ib_send_unmap_rdma(ic, send->s_op, wc_status);
201                 }
202                 break;
203         case IB_WR_ATOMIC_FETCH_AND_ADD:
204         case IB_WR_ATOMIC_CMP_AND_SWP:
205                 if (send->s_op) {
206                         rm = container_of(send->s_op, struct rds_message, atomic);
207                         rds_ib_send_unmap_atomic(ic, send->s_op, wc_status);
208                 }
209                 break;
210         default:
211                 printk_ratelimited(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 receiver'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                 scat = &rm->data.op_sg[sg];
555                 ret = sizeof(struct rds_header) + RDS_CONG_MAP_BYTES;
556                 ret = min_t(int, ret, scat->length - conn->c_xmit_data_off);
557                 return ret;
558         }
559
560         /* FIXME we may overallocate here */
561         if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
562                 i = 1;
563         else
564                 i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
565
566         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
567         if (work_alloc == 0) {
568                 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
569                 rds_ib_stats_inc(s_ib_tx_ring_full);
570                 ret = -ENOMEM;
571                 goto out;
572         }
573
574         if (ic->i_flowctl) {
575                 credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
576                 adv_credits += posted;
577                 if (credit_alloc < work_alloc) {
578                         rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
579                         work_alloc = credit_alloc;
580                         flow_controlled = 1;
581                 }
582                 if (work_alloc == 0) {
583                         set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
584                         rds_ib_stats_inc(s_ib_tx_throttle);
585                         ret = -ENOMEM;
586                         goto out;
587                 }
588         }
589
590         /* map the message the first time we see it */
591         if (!ic->i_data_op) {
592                 if (rm->data.op_nents) {
593                         rm->data.op_count = ib_dma_map_sg(dev,
594                                                           rm->data.op_sg,
595                                                           rm->data.op_nents,
596                                                           DMA_TO_DEVICE);
597                         rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
598                         if (rm->data.op_count == 0) {
599                                 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
600                                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
601                                 ret = -ENOMEM; /* XXX ? */
602                                 goto out;
603                         }
604                 } else {
605                         rm->data.op_count = 0;
606                 }
607
608                 rds_message_addref(rm);
609                 ic->i_data_op = &rm->data;
610
611                 /* Finalize the header */
612                 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
613                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
614                 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
615                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
616
617                 /* If it has a RDMA op, tell the peer we did it. This is
618                  * used by the peer to release use-once RDMA MRs. */
619                 if (rm->rdma.op_active) {
620                         struct rds_ext_header_rdma ext_hdr;
621
622                         ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
623                         rds_message_add_extension(&rm->m_inc.i_hdr,
624                                         RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
625                 }
626                 if (rm->m_rdma_cookie) {
627                         rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
628                                         rds_rdma_cookie_key(rm->m_rdma_cookie),
629                                         rds_rdma_cookie_offset(rm->m_rdma_cookie));
630                 }
631
632                 /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
633                  * we should not do this unless we have a chance of at least
634                  * sticking the header into the send ring. Which is why we
635                  * should call rds_ib_ring_alloc first. */
636                 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
637                 rds_message_make_checksum(&rm->m_inc.i_hdr);
638
639                 /*
640                  * Update adv_credits since we reset the ACK_REQUIRED bit.
641                  */
642                 if (ic->i_flowctl) {
643                         rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
644                         adv_credits += posted;
645                         BUG_ON(adv_credits > 255);
646                 }
647         }
648
649         /* Sometimes you want to put a fence between an RDMA
650          * READ and the following SEND.
651          * We could either do this all the time
652          * or when requested by the user. Right now, we let
653          * the application choose.
654          */
655         if (rm->rdma.op_active && rm->rdma.op_fence)
656                 send_flags = IB_SEND_FENCE;
657
658         /* Each frag gets a header. Msgs may be 0 bytes */
659         send = &ic->i_sends[pos];
660         first = send;
661         prev = NULL;
662         scat = &ic->i_data_op->op_sg[sg];
663         i = 0;
664         do {
665                 unsigned int len = 0;
666
667                 /* Set up the header */
668                 send->s_wr.send_flags = send_flags;
669                 send->s_wr.opcode = IB_WR_SEND;
670                 send->s_wr.num_sge = 1;
671                 send->s_wr.next = NULL;
672                 send->s_queued = jiffies;
673                 send->s_op = NULL;
674
675                 send->s_sge[0].addr = ic->i_send_hdrs_dma
676                         + (pos * sizeof(struct rds_header));
677                 send->s_sge[0].length = sizeof(struct rds_header);
678
679                 memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
680
681                 /* Set up the data, if present */
682                 if (i < work_alloc
683                     && scat != &rm->data.op_sg[rm->data.op_count]) {
684                         len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
685                         send->s_wr.num_sge = 2;
686
687                         send->s_sge[1].addr = ib_sg_dma_address(dev, scat) + off;
688                         send->s_sge[1].length = len;
689
690                         bytes_sent += len;
691                         off += len;
692                         if (off == ib_sg_dma_len(dev, scat)) {
693                                 scat++;
694                                 off = 0;
695                         }
696                 }
697
698                 rds_ib_set_wr_signal_state(ic, send, 0);
699
700                 /*
701                  * Always signal the last one if we're stopping due to flow control.
702                  */
703                 if (ic->i_flowctl && flow_controlled && i == (work_alloc-1))
704                         send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
705
706                 if (send->s_wr.send_flags & IB_SEND_SIGNALED)
707                         nr_sig++;
708
709                 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
710                          &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
711
712                 if (ic->i_flowctl && adv_credits) {
713                         struct rds_header *hdr = &ic->i_send_hdrs[pos];
714
715                         /* add credit and redo the header checksum */
716                         hdr->h_credit = adv_credits;
717                         rds_message_make_checksum(hdr);
718                         adv_credits = 0;
719                         rds_ib_stats_inc(s_ib_tx_credit_updates);
720                 }
721
722                 if (prev)
723                         prev->s_wr.next = &send->s_wr;
724                 prev = send;
725
726                 pos = (pos + 1) % ic->i_send_ring.w_nr;
727                 send = &ic->i_sends[pos];
728                 i++;
729
730         } while (i < work_alloc
731                  && scat != &rm->data.op_sg[rm->data.op_count]);
732
733         /* Account the RDS header in the number of bytes we sent, but just once.
734          * The caller has no concept of fragmentation. */
735         if (hdr_off == 0)
736                 bytes_sent += sizeof(struct rds_header);
737
738         /* if we finished the message then send completion owns it */
739         if (scat == &rm->data.op_sg[rm->data.op_count]) {
740                 prev->s_op = ic->i_data_op;
741                 prev->s_wr.send_flags |= IB_SEND_SOLICITED;
742                 ic->i_data_op = NULL;
743         }
744
745         /* Put back wrs & credits we didn't use */
746         if (i < work_alloc) {
747                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
748                 work_alloc = i;
749         }
750         if (ic->i_flowctl && i < credit_alloc)
751                 rds_ib_send_add_credits(conn, credit_alloc - i);
752
753         if (nr_sig)
754                 atomic_add(nr_sig, &ic->i_signaled_sends);
755
756         /* XXX need to worry about failed_wr and partial sends. */
757         failed_wr = &first->s_wr;
758         ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
759         rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
760                  first, &first->s_wr, ret, failed_wr);
761         BUG_ON(failed_wr != &first->s_wr);
762         if (ret) {
763                 printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 "
764                        "returned %d\n", &conn->c_faddr, ret);
765                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
766                 rds_ib_sub_signaled(ic, nr_sig);
767                 if (prev->s_op) {
768                         ic->i_data_op = prev->s_op;
769                         prev->s_op = NULL;
770                 }
771
772                 rds_ib_conn_error(ic->conn, "ib_post_send failed\n");
773                 goto out;
774         }
775
776         ret = bytes_sent;
777 out:
778         BUG_ON(adv_credits);
779         return ret;
780 }
781
782 /*
783  * Issue atomic operation.
784  * A simplified version of the rdma case, we always map 1 SG, and
785  * only 8 bytes, for the return value from the atomic operation.
786  */
787 int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
788 {
789         struct rds_ib_connection *ic = conn->c_transport_data;
790         struct rds_ib_send_work *send = NULL;
791         struct ib_send_wr *failed_wr;
792         struct rds_ib_device *rds_ibdev;
793         u32 pos;
794         u32 work_alloc;
795         int ret;
796         int nr_sig = 0;
797
798         rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
799
800         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
801         if (work_alloc != 1) {
802                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
803                 rds_ib_stats_inc(s_ib_tx_ring_full);
804                 ret = -ENOMEM;
805                 goto out;
806         }
807
808         /* address of send request in ring */
809         send = &ic->i_sends[pos];
810         send->s_queued = jiffies;
811
812         if (op->op_type == RDS_ATOMIC_TYPE_CSWP) {
813                 send->s_wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP;
814                 send->s_wr.wr.atomic.compare_add = op->op_m_cswp.compare;
815                 send->s_wr.wr.atomic.swap = op->op_m_cswp.swap;
816                 send->s_wr.wr.atomic.compare_add_mask = op->op_m_cswp.compare_mask;
817                 send->s_wr.wr.atomic.swap_mask = op->op_m_cswp.swap_mask;
818         } else { /* FADD */
819                 send->s_wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD;
820                 send->s_wr.wr.atomic.compare_add = op->op_m_fadd.add;
821                 send->s_wr.wr.atomic.swap = 0;
822                 send->s_wr.wr.atomic.compare_add_mask = op->op_m_fadd.nocarry_mask;
823                 send->s_wr.wr.atomic.swap_mask = 0;
824         }
825         nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify);
826         send->s_wr.num_sge = 1;
827         send->s_wr.next = NULL;
828         send->s_wr.wr.atomic.remote_addr = op->op_remote_addr;
829         send->s_wr.wr.atomic.rkey = op->op_rkey;
830         send->s_op = op;
831         rds_message_addref(container_of(send->s_op, struct rds_message, atomic));
832
833         /* map 8 byte retval buffer to the device */
834         ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE);
835         rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret);
836         if (ret != 1) {
837                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
838                 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
839                 ret = -ENOMEM; /* XXX ? */
840                 goto out;
841         }
842
843         /* Convert our struct scatterlist to struct ib_sge */
844         send->s_sge[0].addr = ib_sg_dma_address(ic->i_cm_id->device, op->op_sg);
845         send->s_sge[0].length = ib_sg_dma_len(ic->i_cm_id->device, op->op_sg);
846         send->s_sge[0].lkey = ic->i_mr->lkey;
847
848         rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
849                  send->s_sge[0].addr, send->s_sge[0].length);
850
851         if (nr_sig)
852                 atomic_add(nr_sig, &ic->i_signaled_sends);
853
854         failed_wr = &send->s_wr;
855         ret = ib_post_send(ic->i_cm_id->qp, &send->s_wr, &failed_wr);
856         rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
857                  send, &send->s_wr, ret, failed_wr);
858         BUG_ON(failed_wr != &send->s_wr);
859         if (ret) {
860                 printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI4 "
861                        "returned %d\n", &conn->c_faddr, ret);
862                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
863                 rds_ib_sub_signaled(ic, nr_sig);
864                 goto out;
865         }
866
867         if (unlikely(failed_wr != &send->s_wr)) {
868                 printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
869                 BUG_ON(failed_wr != &send->s_wr);
870         }
871
872 out:
873         return ret;
874 }
875
876 int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
877 {
878         struct rds_ib_connection *ic = conn->c_transport_data;
879         struct rds_ib_send_work *send = NULL;
880         struct rds_ib_send_work *first;
881         struct rds_ib_send_work *prev;
882         struct ib_send_wr *failed_wr;
883         struct scatterlist *scat;
884         unsigned long len;
885         u64 remote_addr = op->op_remote_addr;
886         u32 max_sge = ic->rds_ibdev->max_sge;
887         u32 pos;
888         u32 work_alloc;
889         u32 i;
890         u32 j;
891         int sent;
892         int ret;
893         int num_sge;
894         int nr_sig = 0;
895
896         /* map the op the first time we see it */
897         if (!op->op_mapped) {
898                 op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
899                                              op->op_sg, op->op_nents, (op->op_write) ?
900                                              DMA_TO_DEVICE : DMA_FROM_DEVICE);
901                 rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
902                 if (op->op_count == 0) {
903                         rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
904                         ret = -ENOMEM; /* XXX ? */
905                         goto out;
906                 }
907
908                 op->op_mapped = 1;
909         }
910
911         /*
912          * Instead of knowing how to return a partial rdma read/write we insist that there
913          * be enough work requests to send the entire message.
914          */
915         i = ceil(op->op_count, max_sge);
916
917         work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
918         if (work_alloc != i) {
919                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
920                 rds_ib_stats_inc(s_ib_tx_ring_full);
921                 ret = -ENOMEM;
922                 goto out;
923         }
924
925         send = &ic->i_sends[pos];
926         first = send;
927         prev = NULL;
928         scat = &op->op_sg[0];
929         sent = 0;
930         num_sge = op->op_count;
931
932         for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
933                 send->s_wr.send_flags = 0;
934                 send->s_queued = jiffies;
935                 send->s_op = NULL;
936
937                 nr_sig += rds_ib_set_wr_signal_state(ic, send, op->op_notify);
938
939                 send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
940                 send->s_wr.wr.rdma.remote_addr = remote_addr;
941                 send->s_wr.wr.rdma.rkey = op->op_rkey;
942
943                 if (num_sge > max_sge) {
944                         send->s_wr.num_sge = max_sge;
945                         num_sge -= max_sge;
946                 } else {
947                         send->s_wr.num_sge = num_sge;
948                 }
949
950                 send->s_wr.next = NULL;
951
952                 if (prev)
953                         prev->s_wr.next = &send->s_wr;
954
955                 for (j = 0; j < send->s_wr.num_sge && scat != &op->op_sg[op->op_count]; j++) {
956                         len = ib_sg_dma_len(ic->i_cm_id->device, scat);
957                         send->s_sge[j].addr =
958                                  ib_sg_dma_address(ic->i_cm_id->device, scat);
959                         send->s_sge[j].length = len;
960                         send->s_sge[j].lkey = ic->i_mr->lkey;
961
962                         sent += len;
963                         rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
964
965                         remote_addr += len;
966                         scat++;
967                 }
968
969                 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
970                         &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
971
972                 prev = send;
973                 if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
974                         send = ic->i_sends;
975         }
976
977         /* give a reference to the last op */
978         if (scat == &op->op_sg[op->op_count]) {
979                 prev->s_op = op;
980                 rds_message_addref(container_of(op, struct rds_message, rdma));
981         }
982
983         if (i < work_alloc) {
984                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
985                 work_alloc = i;
986         }
987
988         if (nr_sig)
989                 atomic_add(nr_sig, &ic->i_signaled_sends);
990
991         failed_wr = &first->s_wr;
992         ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
993         rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
994                  first, &first->s_wr, ret, failed_wr);
995         BUG_ON(failed_wr != &first->s_wr);
996         if (ret) {
997                 printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 "
998                        "returned %d\n", &conn->c_faddr, ret);
999                 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
1000                 rds_ib_sub_signaled(ic, nr_sig);
1001                 goto out;
1002         }
1003
1004         if (unlikely(failed_wr != &first->s_wr)) {
1005                 printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
1006                 BUG_ON(failed_wr != &first->s_wr);
1007         }
1008
1009
1010 out:
1011         return ret;
1012 }
1013
1014 void rds_ib_xmit_complete(struct rds_connection *conn)
1015 {
1016         struct rds_ib_connection *ic = conn->c_transport_data;
1017
1018         /* We may have a pending ACK or window update we were unable
1019          * to send previously (due to flow control). Try again. */
1020         rds_ib_attempt_ack(ic);
1021 }