sctp: Do not account for sizeof(struct sk_buff) in estimated rwnd
[linux-2.6.git] / net / rds / iw_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 "iw.h"
41
42 static void rds_iw_send_rdma_complete(struct rds_message *rm,
43                                       int wc_status)
44 {
45         int notify_status;
46
47         switch (wc_status) {
48         case IB_WC_WR_FLUSH_ERR:
49                 return;
50
51         case IB_WC_SUCCESS:
52                 notify_status = RDS_RDMA_SUCCESS;
53                 break;
54
55         case IB_WC_REM_ACCESS_ERR:
56                 notify_status = RDS_RDMA_REMOTE_ERROR;
57                 break;
58
59         default:
60                 notify_status = RDS_RDMA_OTHER_ERROR;
61                 break;
62         }
63         rds_rdma_send_complete(rm, notify_status);
64 }
65
66 static void rds_iw_send_unmap_rdma(struct rds_iw_connection *ic,
67                                    struct rm_rdma_op *op)
68 {
69         if (op->op_mapped) {
70                 ib_dma_unmap_sg(ic->i_cm_id->device,
71                         op->op_sg, op->op_nents,
72                         op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
73                 op->op_mapped = 0;
74         }
75 }
76
77 static void rds_iw_send_unmap_rm(struct rds_iw_connection *ic,
78                           struct rds_iw_send_work *send,
79                           int wc_status)
80 {
81         struct rds_message *rm = send->s_rm;
82
83         rdsdebug("ic %p send %p rm %p\n", ic, send, rm);
84
85         ib_dma_unmap_sg(ic->i_cm_id->device,
86                      rm->data.op_sg, rm->data.op_nents,
87                      DMA_TO_DEVICE);
88
89         if (rm->rdma.op_active) {
90                 rds_iw_send_unmap_rdma(ic, &rm->rdma);
91
92                 /* If the user asked for a completion notification on this
93                  * message, we can implement three different semantics:
94                  *  1.  Notify when we received the ACK on the RDS message
95                  *      that was queued with the RDMA. This provides reliable
96                  *      notification of RDMA status at the expense of a one-way
97                  *      packet delay.
98                  *  2.  Notify when the IB stack gives us the completion event for
99                  *      the RDMA operation.
100                  *  3.  Notify when the IB stack gives us the completion event for
101                  *      the accompanying RDS messages.
102                  * Here, we implement approach #3. To implement approach #2,
103                  * call rds_rdma_send_complete from the cq_handler. To implement #1,
104                  * don't call rds_rdma_send_complete at all, and fall back to the notify
105                  * handling in the ACK processing code.
106                  *
107                  * Note: There's no need to explicitly sync any RDMA buffers using
108                  * ib_dma_sync_sg_for_cpu - the completion for the RDMA
109                  * operation itself unmapped the RDMA buffers, which takes care
110                  * of synching.
111                  */
112                 rds_iw_send_rdma_complete(rm, wc_status);
113
114                 if (rm->rdma.op_write)
115                         rds_stats_add(s_send_rdma_bytes, rm->rdma.op_bytes);
116                 else
117                         rds_stats_add(s_recv_rdma_bytes, rm->rdma.op_bytes);
118         }
119
120         /* If anyone waited for this message to get flushed out, wake
121          * them up now */
122         rds_message_unmapped(rm);
123
124         rds_message_put(rm);
125         send->s_rm = NULL;
126 }
127
128 void rds_iw_send_init_ring(struct rds_iw_connection *ic)
129 {
130         struct rds_iw_send_work *send;
131         u32 i;
132
133         for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
134                 struct ib_sge *sge;
135
136                 send->s_rm = NULL;
137                 send->s_op = NULL;
138                 send->s_mapping = NULL;
139
140                 send->s_wr.next = NULL;
141                 send->s_wr.wr_id = i;
142                 send->s_wr.sg_list = send->s_sge;
143                 send->s_wr.num_sge = 1;
144                 send->s_wr.opcode = IB_WR_SEND;
145                 send->s_wr.send_flags = 0;
146                 send->s_wr.ex.imm_data = 0;
147
148                 sge = rds_iw_data_sge(ic, send->s_sge);
149                 sge->lkey = 0;
150
151                 sge = rds_iw_header_sge(ic, send->s_sge);
152                 sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
153                 sge->length = sizeof(struct rds_header);
154                 sge->lkey = 0;
155
156                 send->s_mr = ib_alloc_fast_reg_mr(ic->i_pd, fastreg_message_size);
157                 if (IS_ERR(send->s_mr)) {
158                         printk(KERN_WARNING "RDS/IW: ib_alloc_fast_reg_mr failed\n");
159                         break;
160                 }
161
162                 send->s_page_list = ib_alloc_fast_reg_page_list(
163                         ic->i_cm_id->device, fastreg_message_size);
164                 if (IS_ERR(send->s_page_list)) {
165                         printk(KERN_WARNING "RDS/IW: ib_alloc_fast_reg_page_list failed\n");
166                         break;
167                 }
168         }
169 }
170
171 void rds_iw_send_clear_ring(struct rds_iw_connection *ic)
172 {
173         struct rds_iw_send_work *send;
174         u32 i;
175
176         for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
177                 BUG_ON(!send->s_mr);
178                 ib_dereg_mr(send->s_mr);
179                 BUG_ON(!send->s_page_list);
180                 ib_free_fast_reg_page_list(send->s_page_list);
181                 if (send->s_wr.opcode == 0xdead)
182                         continue;
183                 if (send->s_rm)
184                         rds_iw_send_unmap_rm(ic, send, IB_WC_WR_FLUSH_ERR);
185                 if (send->s_op)
186                         rds_iw_send_unmap_rdma(ic, send->s_op);
187         }
188 }
189
190 /*
191  * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
192  * operations performed in the send path.  As the sender allocs and potentially
193  * unallocs the next free entry in the ring it doesn't alter which is
194  * the next to be freed, which is what this is concerned with.
195  */
196 void rds_iw_send_cq_comp_handler(struct ib_cq *cq, void *context)
197 {
198         struct rds_connection *conn = context;
199         struct rds_iw_connection *ic = conn->c_transport_data;
200         struct ib_wc wc;
201         struct rds_iw_send_work *send;
202         u32 completed;
203         u32 oldest;
204         u32 i;
205         int ret;
206
207         rdsdebug("cq %p conn %p\n", cq, conn);
208         rds_iw_stats_inc(s_iw_tx_cq_call);
209         ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
210         if (ret)
211                 rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
212
213         while (ib_poll_cq(cq, 1, &wc) > 0) {
214                 rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
215                          (unsigned long long)wc.wr_id, wc.status, wc.byte_len,
216                          be32_to_cpu(wc.ex.imm_data));
217                 rds_iw_stats_inc(s_iw_tx_cq_event);
218
219                 if (wc.status != IB_WC_SUCCESS) {
220                         printk(KERN_ERR "WC Error:  status = %d opcode = %d\n", wc.status, wc.opcode);
221                         break;
222                 }
223
224                 if (wc.opcode == IB_WC_LOCAL_INV && wc.wr_id == RDS_IW_LOCAL_INV_WR_ID) {
225                         ic->i_fastreg_posted = 0;
226                         continue;
227                 }
228
229                 if (wc.opcode == IB_WC_FAST_REG_MR && wc.wr_id == RDS_IW_FAST_REG_WR_ID) {
230                         ic->i_fastreg_posted = 1;
231                         continue;
232                 }
233
234                 if (wc.wr_id == RDS_IW_ACK_WR_ID) {
235                         if (ic->i_ack_queued + HZ/2 < jiffies)
236                                 rds_iw_stats_inc(s_iw_tx_stalled);
237                         rds_iw_ack_send_complete(ic);
238                         continue;
239                 }
240
241                 oldest = rds_iw_ring_oldest(&ic->i_send_ring);
242
243                 completed = rds_iw_ring_completed(&ic->i_send_ring, wc.wr_id, oldest);
244
245                 for (i = 0; i < completed; i++) {
246                         send = &ic->i_sends[oldest];
247
248                         /* In the error case, wc.opcode sometimes contains garbage */
249                         switch (send->s_wr.opcode) {
250                         case IB_WR_SEND:
251                                 if (send->s_rm)
252                                         rds_iw_send_unmap_rm(ic, send, wc.status);
253                                 break;
254                         case IB_WR_FAST_REG_MR:
255                         case IB_WR_RDMA_WRITE:
256                         case IB_WR_RDMA_READ:
257                         case IB_WR_RDMA_READ_WITH_INV:
258                                 /* Nothing to be done - the SG list will be unmapped
259                                  * when the SEND completes. */
260                                 break;
261                         default:
262                                 printk_ratelimited(KERN_NOTICE
263                                                 "RDS/IW: %s: unexpected opcode 0x%x in WR!\n",
264                                                 __func__, send->s_wr.opcode);
265                                 break;
266                         }
267
268                         send->s_wr.opcode = 0xdead;
269                         send->s_wr.num_sge = 1;
270                         if (send->s_queued + HZ/2 < jiffies)
271                                 rds_iw_stats_inc(s_iw_tx_stalled);
272
273                         /* If a RDMA operation produced an error, signal this right
274                          * away. If we don't, the subsequent SEND that goes with this
275                          * RDMA will be canceled with ERR_WFLUSH, and the application
276                          * never learn that the RDMA failed. */
277                         if (unlikely(wc.status == IB_WC_REM_ACCESS_ERR && send->s_op)) {
278                                 struct rds_message *rm;
279
280                                 rm = rds_send_get_message(conn, send->s_op);
281                                 if (rm)
282                                         rds_iw_send_rdma_complete(rm, wc.status);
283                         }
284
285                         oldest = (oldest + 1) % ic->i_send_ring.w_nr;
286                 }
287
288                 rds_iw_ring_free(&ic->i_send_ring, completed);
289
290                 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
291                     test_bit(0, &conn->c_map_queued))
292                         queue_delayed_work(rds_wq, &conn->c_send_w, 0);
293
294                 /* We expect errors as the qp is drained during shutdown */
295                 if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) {
296                         rds_iw_conn_error(conn,
297                                 "send completion on %pI4 "
298                                 "had status %u, disconnecting and reconnecting\n",
299                                 &conn->c_faddr, wc.status);
300                 }
301         }
302 }
303
304 /*
305  * This is the main function for allocating credits when sending
306  * messages.
307  *
308  * Conceptually, we have two counters:
309  *  -   send credits: this tells us how many WRs we're allowed
310  *      to submit without overruning the receiver's queue. For
311  *      each SEND WR we post, we decrement this by one.
312  *
313  *  -   posted credits: this tells us how many WRs we recently
314  *      posted to the receive queue. This value is transferred
315  *      to the peer as a "credit update" in a RDS header field.
316  *      Every time we transmit credits to the peer, we subtract
317  *      the amount of transferred credits from this counter.
318  *
319  * It is essential that we avoid situations where both sides have
320  * exhausted their send credits, and are unable to send new credits
321  * to the peer. We achieve this by requiring that we send at least
322  * one credit update to the peer before exhausting our credits.
323  * When new credits arrive, we subtract one credit that is withheld
324  * until we've posted new buffers and are ready to transmit these
325  * credits (see rds_iw_send_add_credits below).
326  *
327  * The RDS send code is essentially single-threaded; rds_send_xmit
328  * grabs c_send_lock to ensure exclusive access to the send ring.
329  * However, the ACK sending code is independent and can race with
330  * message SENDs.
331  *
332  * In the send path, we need to update the counters for send credits
333  * and the counter of posted buffers atomically - when we use the
334  * last available credit, we cannot allow another thread to race us
335  * and grab the posted credits counter.  Hence, we have to use a
336  * spinlock to protect the credit counter, or use atomics.
337  *
338  * Spinlocks shared between the send and the receive path are bad,
339  * because they create unnecessary delays. An early implementation
340  * using a spinlock showed a 5% degradation in throughput at some
341  * loads.
342  *
343  * This implementation avoids spinlocks completely, putting both
344  * counters into a single atomic, and updating that atomic using
345  * atomic_add (in the receive path, when receiving fresh credits),
346  * and using atomic_cmpxchg when updating the two counters.
347  */
348 int rds_iw_send_grab_credits(struct rds_iw_connection *ic,
349                              u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
350 {
351         unsigned int avail, posted, got = 0, advertise;
352         long oldval, newval;
353
354         *adv_credits = 0;
355         if (!ic->i_flowctl)
356                 return wanted;
357
358 try_again:
359         advertise = 0;
360         oldval = newval = atomic_read(&ic->i_credits);
361         posted = IB_GET_POST_CREDITS(oldval);
362         avail = IB_GET_SEND_CREDITS(oldval);
363
364         rdsdebug("rds_iw_send_grab_credits(%u): credits=%u posted=%u\n",
365                         wanted, avail, posted);
366
367         /* The last credit must be used to send a credit update. */
368         if (avail && !posted)
369                 avail--;
370
371         if (avail < wanted) {
372                 struct rds_connection *conn = ic->i_cm_id->context;
373
374                 /* Oops, there aren't that many credits left! */
375                 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
376                 got = avail;
377         } else {
378                 /* Sometimes you get what you want, lalala. */
379                 got = wanted;
380         }
381         newval -= IB_SET_SEND_CREDITS(got);
382
383         /*
384          * If need_posted is non-zero, then the caller wants
385          * the posted regardless of whether any send credits are
386          * available.
387          */
388         if (posted && (got || need_posted)) {
389                 advertise = min_t(unsigned int, posted, max_posted);
390                 newval -= IB_SET_POST_CREDITS(advertise);
391         }
392
393         /* Finally bill everything */
394         if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
395                 goto try_again;
396
397         *adv_credits = advertise;
398         return got;
399 }
400
401 void rds_iw_send_add_credits(struct rds_connection *conn, unsigned int credits)
402 {
403         struct rds_iw_connection *ic = conn->c_transport_data;
404
405         if (credits == 0)
406                 return;
407
408         rdsdebug("rds_iw_send_add_credits(%u): current=%u%s\n",
409                         credits,
410                         IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
411                         test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
412
413         atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
414         if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
415                 queue_delayed_work(rds_wq, &conn->c_send_w, 0);
416
417         WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
418
419         rds_iw_stats_inc(s_iw_rx_credit_updates);
420 }
421
422 void rds_iw_advertise_credits(struct rds_connection *conn, unsigned int posted)
423 {
424         struct rds_iw_connection *ic = conn->c_transport_data;
425
426         if (posted == 0)
427                 return;
428
429         atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
430
431         /* Decide whether to send an update to the peer now.
432          * If we would send a credit update for every single buffer we
433          * post, we would end up with an ACK storm (ACK arrives,
434          * consumes buffer, we refill the ring, send ACK to remote
435          * advertising the newly posted buffer... ad inf)
436          *
437          * Performance pretty much depends on how often we send
438          * credit updates - too frequent updates mean lots of ACKs.
439          * Too infrequent updates, and the peer will run out of
440          * credits and has to throttle.
441          * For the time being, 16 seems to be a good compromise.
442          */
443         if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
444                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
445 }
446
447 static inline void
448 rds_iw_xmit_populate_wr(struct rds_iw_connection *ic,
449                 struct rds_iw_send_work *send, unsigned int pos,
450                 unsigned long buffer, unsigned int length,
451                 int send_flags)
452 {
453         struct ib_sge *sge;
454
455         WARN_ON(pos != send - ic->i_sends);
456
457         send->s_wr.send_flags = send_flags;
458         send->s_wr.opcode = IB_WR_SEND;
459         send->s_wr.num_sge = 2;
460         send->s_wr.next = NULL;
461         send->s_queued = jiffies;
462         send->s_op = NULL;
463
464         if (length != 0) {
465                 sge = rds_iw_data_sge(ic, send->s_sge);
466                 sge->addr = buffer;
467                 sge->length = length;
468                 sge->lkey = rds_iw_local_dma_lkey(ic);
469
470                 sge = rds_iw_header_sge(ic, send->s_sge);
471         } else {
472                 /* We're sending a packet with no payload. There is only
473                  * one SGE */
474                 send->s_wr.num_sge = 1;
475                 sge = &send->s_sge[0];
476         }
477
478         sge->addr = ic->i_send_hdrs_dma + (pos * sizeof(struct rds_header));
479         sge->length = sizeof(struct rds_header);
480         sge->lkey = rds_iw_local_dma_lkey(ic);
481 }
482
483 /*
484  * This can be called multiple times for a given message.  The first time
485  * we see a message we map its scatterlist into the IB device so that
486  * we can provide that mapped address to the IB scatter gather entries
487  * in the IB work requests.  We translate the scatterlist into a series
488  * of work requests that fragment the message.  These work requests complete
489  * in order so we pass ownership of the message to the completion handler
490  * once we send the final fragment.
491  *
492  * The RDS core uses the c_send_lock to only enter this function once
493  * per connection.  This makes sure that the tx ring alloc/unalloc pairs
494  * don't get out of sync and confuse the ring.
495  */
496 int rds_iw_xmit(struct rds_connection *conn, struct rds_message *rm,
497                 unsigned int hdr_off, unsigned int sg, unsigned int off)
498 {
499         struct rds_iw_connection *ic = conn->c_transport_data;
500         struct ib_device *dev = ic->i_cm_id->device;
501         struct rds_iw_send_work *send = NULL;
502         struct rds_iw_send_work *first;
503         struct rds_iw_send_work *prev;
504         struct ib_send_wr *failed_wr;
505         struct scatterlist *scat;
506         u32 pos;
507         u32 i;
508         u32 work_alloc;
509         u32 credit_alloc;
510         u32 posted;
511         u32 adv_credits = 0;
512         int send_flags = 0;
513         int sent;
514         int ret;
515         int flow_controlled = 0;
516
517         BUG_ON(off % RDS_FRAG_SIZE);
518         BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
519
520         /* Fastreg support */
521         if (rds_rdma_cookie_key(rm->m_rdma_cookie) && !ic->i_fastreg_posted) {
522                 ret = -EAGAIN;
523                 goto out;
524         }
525
526         /* FIXME we may overallocate here */
527         if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
528                 i = 1;
529         else
530                 i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
531
532         work_alloc = rds_iw_ring_alloc(&ic->i_send_ring, i, &pos);
533         if (work_alloc == 0) {
534                 set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
535                 rds_iw_stats_inc(s_iw_tx_ring_full);
536                 ret = -ENOMEM;
537                 goto out;
538         }
539
540         credit_alloc = work_alloc;
541         if (ic->i_flowctl) {
542                 credit_alloc = rds_iw_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
543                 adv_credits += posted;
544                 if (credit_alloc < work_alloc) {
545                         rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
546                         work_alloc = credit_alloc;
547                         flow_controlled++;
548                 }
549                 if (work_alloc == 0) {
550                         set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
551                         rds_iw_stats_inc(s_iw_tx_throttle);
552                         ret = -ENOMEM;
553                         goto out;
554                 }
555         }
556
557         /* map the message the first time we see it */
558         if (!ic->i_rm) {
559                 /*
560                 printk(KERN_NOTICE "rds_iw_xmit prep msg dport=%u flags=0x%x len=%d\n",
561                                 be16_to_cpu(rm->m_inc.i_hdr.h_dport),
562                                 rm->m_inc.i_hdr.h_flags,
563                                 be32_to_cpu(rm->m_inc.i_hdr.h_len));
564                    */
565                 if (rm->data.op_nents) {
566                         rm->data.op_count = ib_dma_map_sg(dev,
567                                                           rm->data.op_sg,
568                                                           rm->data.op_nents,
569                                                           DMA_TO_DEVICE);
570                         rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
571                         if (rm->data.op_count == 0) {
572                                 rds_iw_stats_inc(s_iw_tx_sg_mapping_failure);
573                                 rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
574                                 ret = -ENOMEM; /* XXX ? */
575                                 goto out;
576                         }
577                 } else {
578                         rm->data.op_count = 0;
579                 }
580
581                 ic->i_unsignaled_wrs = rds_iw_sysctl_max_unsig_wrs;
582                 ic->i_unsignaled_bytes = rds_iw_sysctl_max_unsig_bytes;
583                 rds_message_addref(rm);
584                 ic->i_rm = rm;
585
586                 /* Finalize the header */
587                 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
588                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
589                 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
590                         rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
591
592                 /* If it has a RDMA op, tell the peer we did it. This is
593                  * used by the peer to release use-once RDMA MRs. */
594                 if (rm->rdma.op_active) {
595                         struct rds_ext_header_rdma ext_hdr;
596
597                         ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
598                         rds_message_add_extension(&rm->m_inc.i_hdr,
599                                         RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
600                 }
601                 if (rm->m_rdma_cookie) {
602                         rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
603                                         rds_rdma_cookie_key(rm->m_rdma_cookie),
604                                         rds_rdma_cookie_offset(rm->m_rdma_cookie));
605                 }
606
607                 /* Note - rds_iw_piggyb_ack clears the ACK_REQUIRED bit, so
608                  * we should not do this unless we have a chance of at least
609                  * sticking the header into the send ring. Which is why we
610                  * should call rds_iw_ring_alloc first. */
611                 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_iw_piggyb_ack(ic));
612                 rds_message_make_checksum(&rm->m_inc.i_hdr);
613
614                 /*
615                  * Update adv_credits since we reset the ACK_REQUIRED bit.
616                  */
617                 rds_iw_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
618                 adv_credits += posted;
619                 BUG_ON(adv_credits > 255);
620         }
621
622         send = &ic->i_sends[pos];
623         first = send;
624         prev = NULL;
625         scat = &rm->data.op_sg[sg];
626         sent = 0;
627         i = 0;
628
629         /* Sometimes you want to put a fence between an RDMA
630          * READ and the following SEND.
631          * We could either do this all the time
632          * or when requested by the user. Right now, we let
633          * the application choose.
634          */
635         if (rm->rdma.op_active && rm->rdma.op_fence)
636                 send_flags = IB_SEND_FENCE;
637
638         /*
639          * We could be copying the header into the unused tail of the page.
640          * That would need to be changed in the future when those pages might
641          * be mapped userspace pages or page cache pages.  So instead we always
642          * use a second sge and our long-lived ring of mapped headers.  We send
643          * the header after the data so that the data payload can be aligned on
644          * the receiver.
645          */
646
647         /* handle a 0-len message */
648         if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) {
649                 rds_iw_xmit_populate_wr(ic, send, pos, 0, 0, send_flags);
650                 goto add_header;
651         }
652
653         /* if there's data reference it with a chain of work reqs */
654         for (; i < work_alloc && scat != &rm->data.op_sg[rm->data.op_count]; i++) {
655                 unsigned int len;
656
657                 send = &ic->i_sends[pos];
658
659                 len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
660                 rds_iw_xmit_populate_wr(ic, send, pos,
661                                 ib_sg_dma_address(dev, scat) + off, len,
662                                 send_flags);
663
664                 /*
665                  * We want to delay signaling completions just enough to get
666                  * the batching benefits but not so much that we create dead time
667                  * on the wire.
668                  */
669                 if (ic->i_unsignaled_wrs-- == 0) {
670                         ic->i_unsignaled_wrs = rds_iw_sysctl_max_unsig_wrs;
671                         send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
672                 }
673
674                 ic->i_unsignaled_bytes -= len;
675                 if (ic->i_unsignaled_bytes <= 0) {
676                         ic->i_unsignaled_bytes = rds_iw_sysctl_max_unsig_bytes;
677                         send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
678                 }
679
680                 /*
681                  * Always signal the last one if we're stopping due to flow control.
682                  */
683                 if (flow_controlled && i == (work_alloc-1))
684                         send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
685
686                 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
687                          &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
688
689                 sent += len;
690                 off += len;
691                 if (off == ib_sg_dma_len(dev, scat)) {
692                         scat++;
693                         off = 0;
694                 }
695
696 add_header:
697                 /* Tack on the header after the data. The header SGE should already
698                  * have been set up to point to the right header buffer. */
699                 memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
700
701                 if (0) {
702                         struct rds_header *hdr = &ic->i_send_hdrs[pos];
703
704                         printk(KERN_NOTICE "send WR dport=%u flags=0x%x len=%d\n",
705                                 be16_to_cpu(hdr->h_dport),
706                                 hdr->h_flags,
707                                 be32_to_cpu(hdr->h_len));
708                 }
709                 if (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_iw_stats_inc(s_iw_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         }
725
726         /* Account the RDS header in the number of bytes we sent, but just once.
727          * The caller has no concept of fragmentation. */
728         if (hdr_off == 0)
729                 sent += sizeof(struct rds_header);
730
731         /* if we finished the message then send completion owns it */
732         if (scat == &rm->data.op_sg[rm->data.op_count]) {
733                 prev->s_rm = ic->i_rm;
734                 prev->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
735                 ic->i_rm = NULL;
736         }
737
738         if (i < work_alloc) {
739                 rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc - i);
740                 work_alloc = i;
741         }
742         if (ic->i_flowctl && i < credit_alloc)
743                 rds_iw_send_add_credits(conn, credit_alloc - i);
744
745         /* XXX need to worry about failed_wr and partial sends. */
746         failed_wr = &first->s_wr;
747         ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
748         rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
749                  first, &first->s_wr, ret, failed_wr);
750         BUG_ON(failed_wr != &first->s_wr);
751         if (ret) {
752                 printk(KERN_WARNING "RDS/IW: ib_post_send to %pI4 "
753                        "returned %d\n", &conn->c_faddr, ret);
754                 rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
755                 if (prev->s_rm) {
756                         ic->i_rm = prev->s_rm;
757                         prev->s_rm = NULL;
758                 }
759                 goto out;
760         }
761
762         ret = sent;
763 out:
764         BUG_ON(adv_credits);
765         return ret;
766 }
767
768 static void rds_iw_build_send_fastreg(struct rds_iw_device *rds_iwdev, struct rds_iw_connection *ic, struct rds_iw_send_work *send, int nent, int len, u64 sg_addr)
769 {
770         BUG_ON(nent > send->s_page_list->max_page_list_len);
771         /*
772          * Perform a WR for the fast_reg_mr. Each individual page
773          * in the sg list is added to the fast reg page list and placed
774          * inside the fast_reg_mr WR.
775          */
776         send->s_wr.opcode = IB_WR_FAST_REG_MR;
777         send->s_wr.wr.fast_reg.length = len;
778         send->s_wr.wr.fast_reg.rkey = send->s_mr->rkey;
779         send->s_wr.wr.fast_reg.page_list = send->s_page_list;
780         send->s_wr.wr.fast_reg.page_list_len = nent;
781         send->s_wr.wr.fast_reg.page_shift = PAGE_SHIFT;
782         send->s_wr.wr.fast_reg.access_flags = IB_ACCESS_REMOTE_WRITE;
783         send->s_wr.wr.fast_reg.iova_start = sg_addr;
784
785         ib_update_fast_reg_key(send->s_mr, send->s_remap_count++);
786 }
787
788 int rds_iw_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
789 {
790         struct rds_iw_connection *ic = conn->c_transport_data;
791         struct rds_iw_send_work *send = NULL;
792         struct rds_iw_send_work *first;
793         struct rds_iw_send_work *prev;
794         struct ib_send_wr *failed_wr;
795         struct rds_iw_device *rds_iwdev;
796         struct scatterlist *scat;
797         unsigned long len;
798         u64 remote_addr = op->op_remote_addr;
799         u32 pos, fr_pos;
800         u32 work_alloc;
801         u32 i;
802         u32 j;
803         int sent;
804         int ret;
805         int num_sge;
806
807         rds_iwdev = ib_get_client_data(ic->i_cm_id->device, &rds_iw_client);
808
809         /* map the message the first time we see it */
810         if (!op->op_mapped) {
811                 op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
812                                              op->op_sg, op->op_nents, (op->op_write) ?
813                                              DMA_TO_DEVICE : DMA_FROM_DEVICE);
814                 rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
815                 if (op->op_count == 0) {
816                         rds_iw_stats_inc(s_iw_tx_sg_mapping_failure);
817                         ret = -ENOMEM; /* XXX ? */
818                         goto out;
819                 }
820
821                 op->op_mapped = 1;
822         }
823
824         if (!op->op_write) {
825                 /* Alloc space on the send queue for the fastreg */
826                 work_alloc = rds_iw_ring_alloc(&ic->i_send_ring, 1, &fr_pos);
827                 if (work_alloc != 1) {
828                         rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
829                         rds_iw_stats_inc(s_iw_tx_ring_full);
830                         ret = -ENOMEM;
831                         goto out;
832                 }
833         }
834
835         /*
836          * Instead of knowing how to return a partial rdma read/write we insist that there
837          * be enough work requests to send the entire message.
838          */
839         i = ceil(op->op_count, rds_iwdev->max_sge);
840
841         work_alloc = rds_iw_ring_alloc(&ic->i_send_ring, i, &pos);
842         if (work_alloc != i) {
843                 rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
844                 rds_iw_stats_inc(s_iw_tx_ring_full);
845                 ret = -ENOMEM;
846                 goto out;
847         }
848
849         send = &ic->i_sends[pos];
850         if (!op->op_write) {
851                 first = prev = &ic->i_sends[fr_pos];
852         } else {
853                 first = send;
854                 prev = NULL;
855         }
856         scat = &op->op_sg[0];
857         sent = 0;
858         num_sge = op->op_count;
859
860         for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
861                 send->s_wr.send_flags = 0;
862                 send->s_queued = jiffies;
863
864                 /*
865                  * We want to delay signaling completions just enough to get
866                  * the batching benefits but not so much that we create dead time on the wire.
867                  */
868                 if (ic->i_unsignaled_wrs-- == 0) {
869                         ic->i_unsignaled_wrs = rds_iw_sysctl_max_unsig_wrs;
870                         send->s_wr.send_flags = IB_SEND_SIGNALED;
871                 }
872
873                 /* To avoid the need to have the plumbing to invalidate the fastreg_mr used
874                  * for local access after RDS is finished with it, using
875                  * IB_WR_RDMA_READ_WITH_INV will invalidate it after the read has completed.
876                  */
877                 if (op->op_write)
878                         send->s_wr.opcode = IB_WR_RDMA_WRITE;
879                 else
880                         send->s_wr.opcode = IB_WR_RDMA_READ_WITH_INV;
881
882                 send->s_wr.wr.rdma.remote_addr = remote_addr;
883                 send->s_wr.wr.rdma.rkey = op->op_rkey;
884                 send->s_op = op;
885
886                 if (num_sge > rds_iwdev->max_sge) {
887                         send->s_wr.num_sge = rds_iwdev->max_sge;
888                         num_sge -= rds_iwdev->max_sge;
889                 } else
890                         send->s_wr.num_sge = num_sge;
891
892                 send->s_wr.next = NULL;
893
894                 if (prev)
895                         prev->s_wr.next = &send->s_wr;
896
897                 for (j = 0; j < send->s_wr.num_sge && scat != &op->op_sg[op->op_count]; j++) {
898                         len = ib_sg_dma_len(ic->i_cm_id->device, scat);
899
900                         if (send->s_wr.opcode == IB_WR_RDMA_READ_WITH_INV)
901                                 send->s_page_list->page_list[j] = ib_sg_dma_address(ic->i_cm_id->device, scat);
902                         else {
903                                 send->s_sge[j].addr = ib_sg_dma_address(ic->i_cm_id->device, scat);
904                                 send->s_sge[j].length = len;
905                                 send->s_sge[j].lkey = rds_iw_local_dma_lkey(ic);
906                         }
907
908                         sent += len;
909                         rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
910                         remote_addr += len;
911
912                         scat++;
913                 }
914
915                 if (send->s_wr.opcode == IB_WR_RDMA_READ_WITH_INV) {
916                         send->s_wr.num_sge = 1;
917                         send->s_sge[0].addr = conn->c_xmit_rm->m_rs->rs_user_addr;
918                         send->s_sge[0].length = conn->c_xmit_rm->m_rs->rs_user_bytes;
919                         send->s_sge[0].lkey = ic->i_sends[fr_pos].s_mr->lkey;
920                 }
921
922                 rdsdebug("send %p wr %p num_sge %u next %p\n", send,
923                         &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
924
925                 prev = send;
926                 if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
927                         send = ic->i_sends;
928         }
929
930         /* if we finished the message then send completion owns it */
931         if (scat == &op->op_sg[op->op_count])
932                 first->s_wr.send_flags = IB_SEND_SIGNALED;
933
934         if (i < work_alloc) {
935                 rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc - i);
936                 work_alloc = i;
937         }
938
939         /* On iWARP, local memory access by a remote system (ie, RDMA Read) is not
940          * recommended.  Putting the lkey on the wire is a security hole, as it can
941          * allow for memory access to all of memory on the remote system.  Some
942          * adapters do not allow using the lkey for this at all.  To bypass this use a
943          * fastreg_mr (or possibly a dma_mr)
944          */
945         if (!op->op_write) {
946                 rds_iw_build_send_fastreg(rds_iwdev, ic, &ic->i_sends[fr_pos],
947                         op->op_count, sent, conn->c_xmit_rm->m_rs->rs_user_addr);
948                 work_alloc++;
949         }
950
951         failed_wr = &first->s_wr;
952         ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
953         rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
954                  first, &first->s_wr, ret, failed_wr);
955         BUG_ON(failed_wr != &first->s_wr);
956         if (ret) {
957                 printk(KERN_WARNING "RDS/IW: rdma ib_post_send to %pI4 "
958                        "returned %d\n", &conn->c_faddr, ret);
959                 rds_iw_ring_unalloc(&ic->i_send_ring, work_alloc);
960                 goto out;
961         }
962
963 out:
964         return ret;
965 }
966
967 void rds_iw_xmit_complete(struct rds_connection *conn)
968 {
969         struct rds_iw_connection *ic = conn->c_transport_data;
970
971         /* We may have a pending ACK or window update we were unable
972          * to send previously (due to flow control). Try again. */
973         rds_iw_attempt_ack(ic);
974 }