Merge git://git.kernel.org/pub/scm/linux/kernel/git/hirofumi/fatfs-2.6
[linux-2.6] / net / rds / iw_recv.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/pci.h>
35 #include <linux/dma-mapping.h>
36 #include <rdma/rdma_cm.h>
37
38 #include "rds.h"
39 #include "iw.h"
40
41 static struct kmem_cache *rds_iw_incoming_slab;
42 static struct kmem_cache *rds_iw_frag_slab;
43 static atomic_t rds_iw_allocation = ATOMIC_INIT(0);
44
45 static void rds_iw_frag_drop_page(struct rds_page_frag *frag)
46 {
47         rdsdebug("frag %p page %p\n", frag, frag->f_page);
48         __free_page(frag->f_page);
49         frag->f_page = NULL;
50 }
51
52 static void rds_iw_frag_free(struct rds_page_frag *frag)
53 {
54         rdsdebug("frag %p page %p\n", frag, frag->f_page);
55         BUG_ON(frag->f_page != NULL);
56         kmem_cache_free(rds_iw_frag_slab, frag);
57 }
58
59 /*
60  * We map a page at a time.  Its fragments are posted in order.  This
61  * is called in fragment order as the fragments get send completion events.
62  * Only the last frag in the page performs the unmapping.
63  *
64  * It's OK for ring cleanup to call this in whatever order it likes because
65  * DMA is not in flight and so we can unmap while other ring entries still
66  * hold page references in their frags.
67  */
68 static void rds_iw_recv_unmap_page(struct rds_iw_connection *ic,
69                                    struct rds_iw_recv_work *recv)
70 {
71         struct rds_page_frag *frag = recv->r_frag;
72
73         rdsdebug("recv %p frag %p page %p\n", recv, frag, frag->f_page);
74         if (frag->f_mapped)
75                 ib_dma_unmap_page(ic->i_cm_id->device,
76                                frag->f_mapped,
77                                RDS_FRAG_SIZE, DMA_FROM_DEVICE);
78         frag->f_mapped = 0;
79 }
80
81 void rds_iw_recv_init_ring(struct rds_iw_connection *ic)
82 {
83         struct rds_iw_recv_work *recv;
84         u32 i;
85
86         for (i = 0, recv = ic->i_recvs; i < ic->i_recv_ring.w_nr; i++, recv++) {
87                 struct ib_sge *sge;
88
89                 recv->r_iwinc = NULL;
90                 recv->r_frag = NULL;
91
92                 recv->r_wr.next = NULL;
93                 recv->r_wr.wr_id = i;
94                 recv->r_wr.sg_list = recv->r_sge;
95                 recv->r_wr.num_sge = RDS_IW_RECV_SGE;
96
97                 sge = rds_iw_data_sge(ic, recv->r_sge);
98                 sge->addr = 0;
99                 sge->length = RDS_FRAG_SIZE;
100                 sge->lkey = 0;
101
102                 sge = rds_iw_header_sge(ic, recv->r_sge);
103                 sge->addr = ic->i_recv_hdrs_dma + (i * sizeof(struct rds_header));
104                 sge->length = sizeof(struct rds_header);
105                 sge->lkey = 0;
106         }
107 }
108
109 static void rds_iw_recv_clear_one(struct rds_iw_connection *ic,
110                                   struct rds_iw_recv_work *recv)
111 {
112         if (recv->r_iwinc) {
113                 rds_inc_put(&recv->r_iwinc->ii_inc);
114                 recv->r_iwinc = NULL;
115         }
116         if (recv->r_frag) {
117                 rds_iw_recv_unmap_page(ic, recv);
118                 if (recv->r_frag->f_page)
119                         rds_iw_frag_drop_page(recv->r_frag);
120                 rds_iw_frag_free(recv->r_frag);
121                 recv->r_frag = NULL;
122         }
123 }
124
125 void rds_iw_recv_clear_ring(struct rds_iw_connection *ic)
126 {
127         u32 i;
128
129         for (i = 0; i < ic->i_recv_ring.w_nr; i++)
130                 rds_iw_recv_clear_one(ic, &ic->i_recvs[i]);
131
132         if (ic->i_frag.f_page)
133                 rds_iw_frag_drop_page(&ic->i_frag);
134 }
135
136 static int rds_iw_recv_refill_one(struct rds_connection *conn,
137                                   struct rds_iw_recv_work *recv,
138                                   gfp_t kptr_gfp, gfp_t page_gfp)
139 {
140         struct rds_iw_connection *ic = conn->c_transport_data;
141         dma_addr_t dma_addr;
142         struct ib_sge *sge;
143         int ret = -ENOMEM;
144
145         if (recv->r_iwinc == NULL) {
146                 if (atomic_read(&rds_iw_allocation) >= rds_iw_sysctl_max_recv_allocation) {
147                         rds_iw_stats_inc(s_iw_rx_alloc_limit);
148                         goto out;
149                 }
150                 recv->r_iwinc = kmem_cache_alloc(rds_iw_incoming_slab,
151                                                  kptr_gfp);
152                 if (recv->r_iwinc == NULL)
153                         goto out;
154                 atomic_inc(&rds_iw_allocation);
155                 INIT_LIST_HEAD(&recv->r_iwinc->ii_frags);
156                 rds_inc_init(&recv->r_iwinc->ii_inc, conn, conn->c_faddr);
157         }
158
159         if (recv->r_frag == NULL) {
160                 recv->r_frag = kmem_cache_alloc(rds_iw_frag_slab, kptr_gfp);
161                 if (recv->r_frag == NULL)
162                         goto out;
163                 INIT_LIST_HEAD(&recv->r_frag->f_item);
164                 recv->r_frag->f_page = NULL;
165         }
166
167         if (ic->i_frag.f_page == NULL) {
168                 ic->i_frag.f_page = alloc_page(page_gfp);
169                 if (ic->i_frag.f_page == NULL)
170                         goto out;
171                 ic->i_frag.f_offset = 0;
172         }
173
174         dma_addr = ib_dma_map_page(ic->i_cm_id->device,
175                                   ic->i_frag.f_page,
176                                   ic->i_frag.f_offset,
177                                   RDS_FRAG_SIZE,
178                                   DMA_FROM_DEVICE);
179         if (ib_dma_mapping_error(ic->i_cm_id->device, dma_addr))
180                 goto out;
181
182         /*
183          * Once we get the RDS_PAGE_LAST_OFF frag then rds_iw_frag_unmap()
184          * must be called on this recv.  This happens as completions hit
185          * in order or on connection shutdown.
186          */
187         recv->r_frag->f_page = ic->i_frag.f_page;
188         recv->r_frag->f_offset = ic->i_frag.f_offset;
189         recv->r_frag->f_mapped = dma_addr;
190
191         sge = rds_iw_data_sge(ic, recv->r_sge);
192         sge->addr = dma_addr;
193         sge->length = RDS_FRAG_SIZE;
194
195         sge = rds_iw_header_sge(ic, recv->r_sge);
196         sge->addr = ic->i_recv_hdrs_dma + (recv - ic->i_recvs) * sizeof(struct rds_header);
197         sge->length = sizeof(struct rds_header);
198
199         get_page(recv->r_frag->f_page);
200
201         if (ic->i_frag.f_offset < RDS_PAGE_LAST_OFF) {
202                 ic->i_frag.f_offset += RDS_FRAG_SIZE;
203         } else {
204                 put_page(ic->i_frag.f_page);
205                 ic->i_frag.f_page = NULL;
206                 ic->i_frag.f_offset = 0;
207         }
208
209         ret = 0;
210 out:
211         return ret;
212 }
213
214 /*
215  * This tries to allocate and post unused work requests after making sure that
216  * they have all the allocations they need to queue received fragments into
217  * sockets.  The i_recv_mutex is held here so that ring_alloc and _unalloc
218  * pairs don't go unmatched.
219  *
220  * -1 is returned if posting fails due to temporary resource exhaustion.
221  */
222 int rds_iw_recv_refill(struct rds_connection *conn, gfp_t kptr_gfp,
223                        gfp_t page_gfp, int prefill)
224 {
225         struct rds_iw_connection *ic = conn->c_transport_data;
226         struct rds_iw_recv_work *recv;
227         struct ib_recv_wr *failed_wr;
228         unsigned int posted = 0;
229         int ret = 0;
230         u32 pos;
231
232         while ((prefill || rds_conn_up(conn))
233                         && rds_iw_ring_alloc(&ic->i_recv_ring, 1, &pos)) {
234                 if (pos >= ic->i_recv_ring.w_nr) {
235                         printk(KERN_NOTICE "Argh - ring alloc returned pos=%u\n",
236                                         pos);
237                         ret = -EINVAL;
238                         break;
239                 }
240
241                 recv = &ic->i_recvs[pos];
242                 ret = rds_iw_recv_refill_one(conn, recv, kptr_gfp, page_gfp);
243                 if (ret) {
244                         ret = -1;
245                         break;
246                 }
247
248                 /* XXX when can this fail? */
249                 ret = ib_post_recv(ic->i_cm_id->qp, &recv->r_wr, &failed_wr);
250                 rdsdebug("recv %p iwinc %p page %p addr %lu ret %d\n", recv,
251                          recv->r_iwinc, recv->r_frag->f_page,
252                          (long) recv->r_frag->f_mapped, ret);
253                 if (ret) {
254                         rds_iw_conn_error(conn, "recv post on "
255                                "%pI4 returned %d, disconnecting and "
256                                "reconnecting\n", &conn->c_faddr,
257                                ret);
258                         ret = -1;
259                         break;
260                 }
261
262                 posted++;
263         }
264
265         /* We're doing flow control - update the window. */
266         if (ic->i_flowctl && posted)
267                 rds_iw_advertise_credits(conn, posted);
268
269         if (ret)
270                 rds_iw_ring_unalloc(&ic->i_recv_ring, 1);
271         return ret;
272 }
273
274 void rds_iw_inc_purge(struct rds_incoming *inc)
275 {
276         struct rds_iw_incoming *iwinc;
277         struct rds_page_frag *frag;
278         struct rds_page_frag *pos;
279
280         iwinc = container_of(inc, struct rds_iw_incoming, ii_inc);
281         rdsdebug("purging iwinc %p inc %p\n", iwinc, inc);
282
283         list_for_each_entry_safe(frag, pos, &iwinc->ii_frags, f_item) {
284                 list_del_init(&frag->f_item);
285                 rds_iw_frag_drop_page(frag);
286                 rds_iw_frag_free(frag);
287         }
288 }
289
290 void rds_iw_inc_free(struct rds_incoming *inc)
291 {
292         struct rds_iw_incoming *iwinc;
293
294         iwinc = container_of(inc, struct rds_iw_incoming, ii_inc);
295
296         rds_iw_inc_purge(inc);
297         rdsdebug("freeing iwinc %p inc %p\n", iwinc, inc);
298         BUG_ON(!list_empty(&iwinc->ii_frags));
299         kmem_cache_free(rds_iw_incoming_slab, iwinc);
300         atomic_dec(&rds_iw_allocation);
301         BUG_ON(atomic_read(&rds_iw_allocation) < 0);
302 }
303
304 int rds_iw_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
305                             size_t size)
306 {
307         struct rds_iw_incoming *iwinc;
308         struct rds_page_frag *frag;
309         struct iovec *iov = first_iov;
310         unsigned long to_copy;
311         unsigned long frag_off = 0;
312         unsigned long iov_off = 0;
313         int copied = 0;
314         int ret;
315         u32 len;
316
317         iwinc = container_of(inc, struct rds_iw_incoming, ii_inc);
318         frag = list_entry(iwinc->ii_frags.next, struct rds_page_frag, f_item);
319         len = be32_to_cpu(inc->i_hdr.h_len);
320
321         while (copied < size && copied < len) {
322                 if (frag_off == RDS_FRAG_SIZE) {
323                         frag = list_entry(frag->f_item.next,
324                                           struct rds_page_frag, f_item);
325                         frag_off = 0;
326                 }
327                 while (iov_off == iov->iov_len) {
328                         iov_off = 0;
329                         iov++;
330                 }
331
332                 to_copy = min(iov->iov_len - iov_off, RDS_FRAG_SIZE - frag_off);
333                 to_copy = min_t(size_t, to_copy, size - copied);
334                 to_copy = min_t(unsigned long, to_copy, len - copied);
335
336                 rdsdebug("%lu bytes to user [%p, %zu] + %lu from frag "
337                          "[%p, %lu] + %lu\n",
338                          to_copy, iov->iov_base, iov->iov_len, iov_off,
339                          frag->f_page, frag->f_offset, frag_off);
340
341                 /* XXX needs + offset for multiple recvs per page */
342                 ret = rds_page_copy_to_user(frag->f_page,
343                                             frag->f_offset + frag_off,
344                                             iov->iov_base + iov_off,
345                                             to_copy);
346                 if (ret) {
347                         copied = ret;
348                         break;
349                 }
350
351                 iov_off += to_copy;
352                 frag_off += to_copy;
353                 copied += to_copy;
354         }
355
356         return copied;
357 }
358
359 /* ic starts out kzalloc()ed */
360 void rds_iw_recv_init_ack(struct rds_iw_connection *ic)
361 {
362         struct ib_send_wr *wr = &ic->i_ack_wr;
363         struct ib_sge *sge = &ic->i_ack_sge;
364
365         sge->addr = ic->i_ack_dma;
366         sge->length = sizeof(struct rds_header);
367         sge->lkey = rds_iw_local_dma_lkey(ic);
368
369         wr->sg_list = sge;
370         wr->num_sge = 1;
371         wr->opcode = IB_WR_SEND;
372         wr->wr_id = RDS_IW_ACK_WR_ID;
373         wr->send_flags = IB_SEND_SIGNALED | IB_SEND_SOLICITED;
374 }
375
376 /*
377  * You'd think that with reliable IB connections you wouldn't need to ack
378  * messages that have been received.  The problem is that IB hardware generates
379  * an ack message before it has DMAed the message into memory.  This creates a
380  * potential message loss if the HCA is disabled for any reason between when it
381  * sends the ack and before the message is DMAed and processed.  This is only a
382  * potential issue if another HCA is available for fail-over.
383  *
384  * When the remote host receives our ack they'll free the sent message from
385  * their send queue.  To decrease the latency of this we always send an ack
386  * immediately after we've received messages.
387  *
388  * For simplicity, we only have one ack in flight at a time.  This puts
389  * pressure on senders to have deep enough send queues to absorb the latency of
390  * a single ack frame being in flight.  This might not be good enough.
391  *
392  * This is implemented by have a long-lived send_wr and sge which point to a
393  * statically allocated ack frame.  This ack wr does not fall under the ring
394  * accounting that the tx and rx wrs do.  The QP attribute specifically makes
395  * room for it beyond the ring size.  Send completion notices its special
396  * wr_id and avoids working with the ring in that case.
397  */
398 #ifndef KERNEL_HAS_ATOMIC64
399 static void rds_iw_set_ack(struct rds_iw_connection *ic, u64 seq,
400                                 int ack_required)
401 {
402         unsigned long flags;
403
404         spin_lock_irqsave(&ic->i_ack_lock, flags);
405         ic->i_ack_next = seq;
406         if (ack_required)
407                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
408         spin_unlock_irqrestore(&ic->i_ack_lock, flags);
409 }
410
411 static u64 rds_iw_get_ack(struct rds_iw_connection *ic)
412 {
413         unsigned long flags;
414         u64 seq;
415
416         clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
417
418         spin_lock_irqsave(&ic->i_ack_lock, flags);
419         seq = ic->i_ack_next;
420         spin_unlock_irqrestore(&ic->i_ack_lock, flags);
421
422         return seq;
423 }
424 #else
425 static void rds_iw_set_ack(struct rds_iw_connection *ic, u64 seq,
426                                 int ack_required)
427 {
428         atomic64_set(&ic->i_ack_next, seq);
429         if (ack_required) {
430                 smp_mb__before_clear_bit();
431                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
432         }
433 }
434
435 static u64 rds_iw_get_ack(struct rds_iw_connection *ic)
436 {
437         clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
438         smp_mb__after_clear_bit();
439
440         return atomic64_read(&ic->i_ack_next);
441 }
442 #endif
443
444
445 static void rds_iw_send_ack(struct rds_iw_connection *ic, unsigned int adv_credits)
446 {
447         struct rds_header *hdr = ic->i_ack;
448         struct ib_send_wr *failed_wr;
449         u64 seq;
450         int ret;
451
452         seq = rds_iw_get_ack(ic);
453
454         rdsdebug("send_ack: ic %p ack %llu\n", ic, (unsigned long long) seq);
455         rds_message_populate_header(hdr, 0, 0, 0);
456         hdr->h_ack = cpu_to_be64(seq);
457         hdr->h_credit = adv_credits;
458         rds_message_make_checksum(hdr);
459         ic->i_ack_queued = jiffies;
460
461         ret = ib_post_send(ic->i_cm_id->qp, &ic->i_ack_wr, &failed_wr);
462         if (unlikely(ret)) {
463                 /* Failed to send. Release the WR, and
464                  * force another ACK.
465                  */
466                 clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
467                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
468
469                 rds_iw_stats_inc(s_iw_ack_send_failure);
470                 /* Need to finesse this later. */
471                 BUG();
472         } else
473                 rds_iw_stats_inc(s_iw_ack_sent);
474 }
475
476 /*
477  * There are 3 ways of getting acknowledgements to the peer:
478  *  1.  We call rds_iw_attempt_ack from the recv completion handler
479  *      to send an ACK-only frame.
480  *      However, there can be only one such frame in the send queue
481  *      at any time, so we may have to postpone it.
482  *  2.  When another (data) packet is transmitted while there's
483  *      an ACK in the queue, we piggyback the ACK sequence number
484  *      on the data packet.
485  *  3.  If the ACK WR is done sending, we get called from the
486  *      send queue completion handler, and check whether there's
487  *      another ACK pending (postponed because the WR was on the
488  *      queue). If so, we transmit it.
489  *
490  * We maintain 2 variables:
491  *  -   i_ack_flags, which keeps track of whether the ACK WR
492  *      is currently in the send queue or not (IB_ACK_IN_FLIGHT)
493  *  -   i_ack_next, which is the last sequence number we received
494  *
495  * Potentially, send queue and receive queue handlers can run concurrently.
496  * It would be nice to not have to use a spinlock to synchronize things,
497  * but the one problem that rules this out is that 64bit updates are
498  * not atomic on all platforms. Things would be a lot simpler if
499  * we had atomic64 or maybe cmpxchg64 everywhere.
500  *
501  * Reconnecting complicates this picture just slightly. When we
502  * reconnect, we may be seeing duplicate packets. The peer
503  * is retransmitting them, because it hasn't seen an ACK for
504  * them. It is important that we ACK these.
505  *
506  * ACK mitigation adds a header flag "ACK_REQUIRED"; any packet with
507  * this flag set *MUST* be acknowledged immediately.
508  */
509
510 /*
511  * When we get here, we're called from the recv queue handler.
512  * Check whether we ought to transmit an ACK.
513  */
514 void rds_iw_attempt_ack(struct rds_iw_connection *ic)
515 {
516         unsigned int adv_credits;
517
518         if (!test_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
519                 return;
520
521         if (test_and_set_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags)) {
522                 rds_iw_stats_inc(s_iw_ack_send_delayed);
523                 return;
524         }
525
526         /* Can we get a send credit? */
527         if (!rds_iw_send_grab_credits(ic, 1, &adv_credits, 0, RDS_MAX_ADV_CREDIT)) {
528                 rds_iw_stats_inc(s_iw_tx_throttle);
529                 clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
530                 return;
531         }
532
533         clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
534         rds_iw_send_ack(ic, adv_credits);
535 }
536
537 /*
538  * We get here from the send completion handler, when the
539  * adapter tells us the ACK frame was sent.
540  */
541 void rds_iw_ack_send_complete(struct rds_iw_connection *ic)
542 {
543         clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
544         rds_iw_attempt_ack(ic);
545 }
546
547 /*
548  * This is called by the regular xmit code when it wants to piggyback
549  * an ACK on an outgoing frame.
550  */
551 u64 rds_iw_piggyb_ack(struct rds_iw_connection *ic)
552 {
553         if (test_and_clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
554                 rds_iw_stats_inc(s_iw_ack_send_piggybacked);
555         return rds_iw_get_ack(ic);
556 }
557
558 /*
559  * It's kind of lame that we're copying from the posted receive pages into
560  * long-lived bitmaps.  We could have posted the bitmaps and rdma written into
561  * them.  But receiving new congestion bitmaps should be a *rare* event, so
562  * hopefully we won't need to invest that complexity in making it more
563  * efficient.  By copying we can share a simpler core with TCP which has to
564  * copy.
565  */
566 static void rds_iw_cong_recv(struct rds_connection *conn,
567                               struct rds_iw_incoming *iwinc)
568 {
569         struct rds_cong_map *map;
570         unsigned int map_off;
571         unsigned int map_page;
572         struct rds_page_frag *frag;
573         unsigned long frag_off;
574         unsigned long to_copy;
575         unsigned long copied;
576         uint64_t uncongested = 0;
577         void *addr;
578
579         /* catch completely corrupt packets */
580         if (be32_to_cpu(iwinc->ii_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
581                 return;
582
583         map = conn->c_fcong;
584         map_page = 0;
585         map_off = 0;
586
587         frag = list_entry(iwinc->ii_frags.next, struct rds_page_frag, f_item);
588         frag_off = 0;
589
590         copied = 0;
591
592         while (copied < RDS_CONG_MAP_BYTES) {
593                 uint64_t *src, *dst;
594                 unsigned int k;
595
596                 to_copy = min(RDS_FRAG_SIZE - frag_off, PAGE_SIZE - map_off);
597                 BUG_ON(to_copy & 7); /* Must be 64bit aligned. */
598
599                 addr = kmap_atomic(frag->f_page, KM_SOFTIRQ0);
600
601                 src = addr + frag_off;
602                 dst = (void *)map->m_page_addrs[map_page] + map_off;
603                 for (k = 0; k < to_copy; k += 8) {
604                         /* Record ports that became uncongested, ie
605                          * bits that changed from 0 to 1. */
606                         uncongested |= ~(*src) & *dst;
607                         *dst++ = *src++;
608                 }
609                 kunmap_atomic(addr, KM_SOFTIRQ0);
610
611                 copied += to_copy;
612
613                 map_off += to_copy;
614                 if (map_off == PAGE_SIZE) {
615                         map_off = 0;
616                         map_page++;
617                 }
618
619                 frag_off += to_copy;
620                 if (frag_off == RDS_FRAG_SIZE) {
621                         frag = list_entry(frag->f_item.next,
622                                           struct rds_page_frag, f_item);
623                         frag_off = 0;
624                 }
625         }
626
627         /* the congestion map is in little endian order */
628         uncongested = le64_to_cpu(uncongested);
629
630         rds_cong_map_updated(map, uncongested);
631 }
632
633 /*
634  * Rings are posted with all the allocations they'll need to queue the
635  * incoming message to the receiving socket so this can't fail.
636  * All fragments start with a header, so we can make sure we're not receiving
637  * garbage, and we can tell a small 8 byte fragment from an ACK frame.
638  */
639 struct rds_iw_ack_state {
640         u64             ack_next;
641         u64             ack_recv;
642         unsigned int    ack_required:1;
643         unsigned int    ack_next_valid:1;
644         unsigned int    ack_recv_valid:1;
645 };
646
647 static void rds_iw_process_recv(struct rds_connection *conn,
648                                 struct rds_iw_recv_work *recv, u32 byte_len,
649                                 struct rds_iw_ack_state *state)
650 {
651         struct rds_iw_connection *ic = conn->c_transport_data;
652         struct rds_iw_incoming *iwinc = ic->i_iwinc;
653         struct rds_header *ihdr, *hdr;
654
655         /* XXX shut down the connection if port 0,0 are seen? */
656
657         rdsdebug("ic %p iwinc %p recv %p byte len %u\n", ic, iwinc, recv,
658                  byte_len);
659
660         if (byte_len < sizeof(struct rds_header)) {
661                 rds_iw_conn_error(conn, "incoming message "
662                        "from %pI4 didn't inclue a "
663                        "header, disconnecting and "
664                        "reconnecting\n",
665                        &conn->c_faddr);
666                 return;
667         }
668         byte_len -= sizeof(struct rds_header);
669
670         ihdr = &ic->i_recv_hdrs[recv - ic->i_recvs];
671
672         /* Validate the checksum. */
673         if (!rds_message_verify_checksum(ihdr)) {
674                 rds_iw_conn_error(conn, "incoming message "
675                        "from %pI4 has corrupted header - "
676                        "forcing a reconnect\n",
677                        &conn->c_faddr);
678                 rds_stats_inc(s_recv_drop_bad_checksum);
679                 return;
680         }
681
682         /* Process the ACK sequence which comes with every packet */
683         state->ack_recv = be64_to_cpu(ihdr->h_ack);
684         state->ack_recv_valid = 1;
685
686         /* Process the credits update if there was one */
687         if (ihdr->h_credit)
688                 rds_iw_send_add_credits(conn, ihdr->h_credit);
689
690         if (ihdr->h_sport == 0 && ihdr->h_dport == 0 && byte_len == 0) {
691                 /* This is an ACK-only packet. The fact that it gets
692                  * special treatment here is that historically, ACKs
693                  * were rather special beasts.
694                  */
695                 rds_iw_stats_inc(s_iw_ack_received);
696
697                 /*
698                  * Usually the frags make their way on to incs and are then freed as
699                  * the inc is freed.  We don't go that route, so we have to drop the
700                  * page ref ourselves.  We can't just leave the page on the recv
701                  * because that confuses the dma mapping of pages and each recv's use
702                  * of a partial page.  We can leave the frag, though, it will be
703                  * reused.
704                  *
705                  * FIXME: Fold this into the code path below.
706                  */
707                 rds_iw_frag_drop_page(recv->r_frag);
708                 return;
709         }
710
711         /*
712          * If we don't already have an inc on the connection then this
713          * fragment has a header and starts a message.. copy its header
714          * into the inc and save the inc so we can hang upcoming fragments
715          * off its list.
716          */
717         if (iwinc == NULL) {
718                 iwinc = recv->r_iwinc;
719                 recv->r_iwinc = NULL;
720                 ic->i_iwinc = iwinc;
721
722                 hdr = &iwinc->ii_inc.i_hdr;
723                 memcpy(hdr, ihdr, sizeof(*hdr));
724                 ic->i_recv_data_rem = be32_to_cpu(hdr->h_len);
725
726                 rdsdebug("ic %p iwinc %p rem %u flag 0x%x\n", ic, iwinc,
727                          ic->i_recv_data_rem, hdr->h_flags);
728         } else {
729                 hdr = &iwinc->ii_inc.i_hdr;
730                 /* We can't just use memcmp here; fragments of a
731                  * single message may carry different ACKs */
732                 if (hdr->h_sequence != ihdr->h_sequence
733                  || hdr->h_len != ihdr->h_len
734                  || hdr->h_sport != ihdr->h_sport
735                  || hdr->h_dport != ihdr->h_dport) {
736                         rds_iw_conn_error(conn,
737                                 "fragment header mismatch; forcing reconnect\n");
738                         return;
739                 }
740         }
741
742         list_add_tail(&recv->r_frag->f_item, &iwinc->ii_frags);
743         recv->r_frag = NULL;
744
745         if (ic->i_recv_data_rem > RDS_FRAG_SIZE)
746                 ic->i_recv_data_rem -= RDS_FRAG_SIZE;
747         else {
748                 ic->i_recv_data_rem = 0;
749                 ic->i_iwinc = NULL;
750
751                 if (iwinc->ii_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
752                         rds_iw_cong_recv(conn, iwinc);
753                 else {
754                         rds_recv_incoming(conn, conn->c_faddr, conn->c_laddr,
755                                           &iwinc->ii_inc, GFP_ATOMIC,
756                                           KM_SOFTIRQ0);
757                         state->ack_next = be64_to_cpu(hdr->h_sequence);
758                         state->ack_next_valid = 1;
759                 }
760
761                 /* Evaluate the ACK_REQUIRED flag *after* we received
762                  * the complete frame, and after bumping the next_rx
763                  * sequence. */
764                 if (hdr->h_flags & RDS_FLAG_ACK_REQUIRED) {
765                         rds_stats_inc(s_recv_ack_required);
766                         state->ack_required = 1;
767                 }
768
769                 rds_inc_put(&iwinc->ii_inc);
770         }
771 }
772
773 /*
774  * Plucking the oldest entry from the ring can be done concurrently with
775  * the thread refilling the ring.  Each ring operation is protected by
776  * spinlocks and the transient state of refilling doesn't change the
777  * recording of which entry is oldest.
778  *
779  * This relies on IB only calling one cq comp_handler for each cq so that
780  * there will only be one caller of rds_recv_incoming() per RDS connection.
781  */
782 void rds_iw_recv_cq_comp_handler(struct ib_cq *cq, void *context)
783 {
784         struct rds_connection *conn = context;
785         struct rds_iw_connection *ic = conn->c_transport_data;
786         struct ib_wc wc;
787         struct rds_iw_ack_state state = { 0, };
788         struct rds_iw_recv_work *recv;
789
790         rdsdebug("conn %p cq %p\n", conn, cq);
791
792         rds_iw_stats_inc(s_iw_rx_cq_call);
793
794         ib_req_notify_cq(cq, IB_CQ_SOLICITED);
795
796         while (ib_poll_cq(cq, 1, &wc) > 0) {
797                 rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
798                          (unsigned long long)wc.wr_id, wc.status, wc.byte_len,
799                          be32_to_cpu(wc.ex.imm_data));
800                 rds_iw_stats_inc(s_iw_rx_cq_event);
801
802                 recv = &ic->i_recvs[rds_iw_ring_oldest(&ic->i_recv_ring)];
803
804                 rds_iw_recv_unmap_page(ic, recv);
805
806                 /*
807                  * Also process recvs in connecting state because it is possible
808                  * to get a recv completion _before_ the rdmacm ESTABLISHED
809                  * event is processed.
810                  */
811                 if (rds_conn_up(conn) || rds_conn_connecting(conn)) {
812                         /* We expect errors as the qp is drained during shutdown */
813                         if (wc.status == IB_WC_SUCCESS) {
814                                 rds_iw_process_recv(conn, recv, wc.byte_len, &state);
815                         } else {
816                                 rds_iw_conn_error(conn, "recv completion on "
817                                        "%pI4 had status %u, disconnecting and "
818                                        "reconnecting\n", &conn->c_faddr,
819                                        wc.status);
820                         }
821                 }
822
823                 rds_iw_ring_free(&ic->i_recv_ring, 1);
824         }
825
826         if (state.ack_next_valid)
827                 rds_iw_set_ack(ic, state.ack_next, state.ack_required);
828         if (state.ack_recv_valid && state.ack_recv > ic->i_ack_recv) {
829                 rds_send_drop_acked(conn, state.ack_recv, NULL);
830                 ic->i_ack_recv = state.ack_recv;
831         }
832         if (rds_conn_up(conn))
833                 rds_iw_attempt_ack(ic);
834
835         /* If we ever end up with a really empty receive ring, we're
836          * in deep trouble, as the sender will definitely see RNR
837          * timeouts. */
838         if (rds_iw_ring_empty(&ic->i_recv_ring))
839                 rds_iw_stats_inc(s_iw_rx_ring_empty);
840
841         /*
842          * If the ring is running low, then schedule the thread to refill.
843          */
844         if (rds_iw_ring_low(&ic->i_recv_ring))
845                 queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
846 }
847
848 int rds_iw_recv(struct rds_connection *conn)
849 {
850         struct rds_iw_connection *ic = conn->c_transport_data;
851         int ret = 0;
852
853         rdsdebug("conn %p\n", conn);
854
855         /*
856          * If we get a temporary posting failure in this context then
857          * we're really low and we want the caller to back off for a bit.
858          */
859         mutex_lock(&ic->i_recv_mutex);
860         if (rds_iw_recv_refill(conn, GFP_KERNEL, GFP_HIGHUSER, 0))
861                 ret = -ENOMEM;
862         else
863                 rds_iw_stats_inc(s_iw_rx_refill_from_thread);
864         mutex_unlock(&ic->i_recv_mutex);
865
866         if (rds_conn_up(conn))
867                 rds_iw_attempt_ack(ic);
868
869         return ret;
870 }
871
872 int __init rds_iw_recv_init(void)
873 {
874         struct sysinfo si;
875         int ret = -ENOMEM;
876
877         /* Default to 30% of all available RAM for recv memory */
878         si_meminfo(&si);
879         rds_iw_sysctl_max_recv_allocation = si.totalram / 3 * PAGE_SIZE / RDS_FRAG_SIZE;
880
881         rds_iw_incoming_slab = kmem_cache_create("rds_iw_incoming",
882                                         sizeof(struct rds_iw_incoming),
883                                         0, 0, NULL);
884         if (rds_iw_incoming_slab == NULL)
885                 goto out;
886
887         rds_iw_frag_slab = kmem_cache_create("rds_iw_frag",
888                                         sizeof(struct rds_page_frag),
889                                         0, 0, NULL);
890         if (rds_iw_frag_slab == NULL)
891                 kmem_cache_destroy(rds_iw_incoming_slab);
892         else
893                 ret = 0;
894 out:
895         return ret;
896 }
897
898 void rds_iw_recv_exit(void)
899 {
900         kmem_cache_destroy(rds_iw_incoming_slab);
901         kmem_cache_destroy(rds_iw_frag_slab);
902 }