~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/net/rds/iw_recv.c

Version: ~ [ linux-5.4 ] ~ [ linux-5.3.13 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.86 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.156 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.203 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.202 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.78 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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/slab.h>
 35 #include <linux/pci.h>
 36 #include <linux/dma-mapping.h>
 37 #include <rdma/rdma_cm.h>
 38 
 39 #include "rds.h"
 40 #include "iw.h"
 41 
 42 static struct kmem_cache *rds_iw_incoming_slab;
 43 static struct kmem_cache *rds_iw_frag_slab;
 44 static atomic_t rds_iw_allocation = ATOMIC_INIT(0);
 45 
 46 static void rds_iw_frag_drop_page(struct rds_page_frag *frag)
 47 {
 48         rdsdebug("frag %p page %p\n", frag, frag->f_page);
 49         __free_page(frag->f_page);
 50         frag->f_page = NULL;
 51 }
 52 
 53 static void rds_iw_frag_free(struct rds_page_frag *frag)
 54 {
 55         rdsdebug("frag %p page %p\n", frag, frag->f_page);
 56         BUG_ON(frag->f_page);
 57         kmem_cache_free(rds_iw_frag_slab, frag);
 58 }
 59 
 60 /*
 61  * We map a page at a time.  Its fragments are posted in order.  This
 62  * is called in fragment order as the fragments get send completion events.
 63  * Only the last frag in the page performs the unmapping.
 64  *
 65  * It's OK for ring cleanup to call this in whatever order it likes because
 66  * DMA is not in flight and so we can unmap while other ring entries still
 67  * hold page references in their frags.
 68  */
 69 static void rds_iw_recv_unmap_page(struct rds_iw_connection *ic,
 70                                    struct rds_iw_recv_work *recv)
 71 {
 72         struct rds_page_frag *frag = recv->r_frag;
 73 
 74         rdsdebug("recv %p frag %p page %p\n", recv, frag, frag->f_page);
 75         if (frag->f_mapped)
 76                 ib_dma_unmap_page(ic->i_cm_id->device,
 77                                frag->f_mapped,
 78                                RDS_FRAG_SIZE, DMA_FROM_DEVICE);
 79         frag->f_mapped = 0;
 80 }
 81 
 82 void rds_iw_recv_init_ring(struct rds_iw_connection *ic)
 83 {
 84         struct rds_iw_recv_work *recv;
 85         u32 i;
 86 
 87         for (i = 0, recv = ic->i_recvs; i < ic->i_recv_ring.w_nr; i++, recv++) {
 88                 struct ib_sge *sge;
 89 
 90                 recv->r_iwinc = NULL;
 91                 recv->r_frag = NULL;
 92 
 93                 recv->r_wr.next = NULL;
 94                 recv->r_wr.wr_id = i;
 95                 recv->r_wr.sg_list = recv->r_sge;
 96                 recv->r_wr.num_sge = RDS_IW_RECV_SGE;
 97 
 98                 sge = rds_iw_data_sge(ic, recv->r_sge);
 99                 sge->addr = 0;
100                 sge->length = RDS_FRAG_SIZE;
101                 sge->lkey = 0;
102 
103                 sge = rds_iw_header_sge(ic, recv->r_sge);
104                 sge->addr = ic->i_recv_hdrs_dma + (i * sizeof(struct rds_header));
105                 sge->length = sizeof(struct rds_header);
106                 sge->lkey = 0;
107         }
108 }
109 
110 static void rds_iw_recv_clear_one(struct rds_iw_connection *ic,
111                                   struct rds_iw_recv_work *recv)
112 {
113         if (recv->r_iwinc) {
114                 rds_inc_put(&recv->r_iwinc->ii_inc);
115                 recv->r_iwinc = NULL;
116         }
117         if (recv->r_frag) {
118                 rds_iw_recv_unmap_page(ic, recv);
119                 if (recv->r_frag->f_page)
120                         rds_iw_frag_drop_page(recv->r_frag);
121                 rds_iw_frag_free(recv->r_frag);
122                 recv->r_frag = NULL;
123         }
124 }
125 
126 void rds_iw_recv_clear_ring(struct rds_iw_connection *ic)
127 {
128         u32 i;
129 
130         for (i = 0; i < ic->i_recv_ring.w_nr; i++)
131                 rds_iw_recv_clear_one(ic, &ic->i_recvs[i]);
132 
133         if (ic->i_frag.f_page)
134                 rds_iw_frag_drop_page(&ic->i_frag);
135 }
136 
137 static int rds_iw_recv_refill_one(struct rds_connection *conn,
138                                   struct rds_iw_recv_work *recv,
139                                   gfp_t kptr_gfp, gfp_t page_gfp)
140 {
141         struct rds_iw_connection *ic = conn->c_transport_data;
142         dma_addr_t dma_addr;
143         struct ib_sge *sge;
144         int ret = -ENOMEM;
145 
146         if (!recv->r_iwinc) {
147                 if (!atomic_add_unless(&rds_iw_allocation, 1, rds_iw_sysctl_max_recv_allocation)) {
148                         rds_iw_stats_inc(s_iw_rx_alloc_limit);
149                         goto out;
150                 }
151                 recv->r_iwinc = kmem_cache_alloc(rds_iw_incoming_slab,
152                                                  kptr_gfp);
153                 if (!recv->r_iwinc) {
154                         atomic_dec(&rds_iw_allocation);
155                         goto out;
156                 }
157                 INIT_LIST_HEAD(&recv->r_iwinc->ii_frags);
158                 rds_inc_init(&recv->r_iwinc->ii_inc, conn, conn->c_faddr);
159         }
160 
161         if (!recv->r_frag) {
162                 recv->r_frag = kmem_cache_alloc(rds_iw_frag_slab, kptr_gfp);
163                 if (!recv->r_frag)
164                         goto out;
165                 INIT_LIST_HEAD(&recv->r_frag->f_item);
166                 recv->r_frag->f_page = NULL;
167         }
168 
169         if (!ic->i_frag.f_page) {
170                 ic->i_frag.f_page = alloc_page(page_gfp);
171                 if (!ic->i_frag.f_page)
172                         goto out;
173                 ic->i_frag.f_offset = 0;
174         }
175 
176         dma_addr = ib_dma_map_page(ic->i_cm_id->device,
177                                   ic->i_frag.f_page,
178                                   ic->i_frag.f_offset,
179                                   RDS_FRAG_SIZE,
180                                   DMA_FROM_DEVICE);
181         if (ib_dma_mapping_error(ic->i_cm_id->device, dma_addr))
182                 goto out;
183 
184         /*
185          * Once we get the RDS_PAGE_LAST_OFF frag then rds_iw_frag_unmap()
186          * must be called on this recv.  This happens as completions hit
187          * in order or on connection shutdown.
188          */
189         recv->r_frag->f_page = ic->i_frag.f_page;
190         recv->r_frag->f_offset = ic->i_frag.f_offset;
191         recv->r_frag->f_mapped = dma_addr;
192 
193         sge = rds_iw_data_sge(ic, recv->r_sge);
194         sge->addr = dma_addr;
195         sge->length = RDS_FRAG_SIZE;
196 
197         sge = rds_iw_header_sge(ic, recv->r_sge);
198         sge->addr = ic->i_recv_hdrs_dma + (recv - ic->i_recvs) * sizeof(struct rds_header);
199         sge->length = sizeof(struct rds_header);
200 
201         get_page(recv->r_frag->f_page);
202 
203         if (ic->i_frag.f_offset < RDS_PAGE_LAST_OFF) {
204                 ic->i_frag.f_offset += RDS_FRAG_SIZE;
205         } else {
206                 put_page(ic->i_frag.f_page);
207                 ic->i_frag.f_page = NULL;
208                 ic->i_frag.f_offset = 0;
209         }
210 
211         ret = 0;
212 out:
213         return ret;
214 }
215 
216 /*
217  * This tries to allocate and post unused work requests after making sure that
218  * they have all the allocations they need to queue received fragments into
219  * sockets.  The i_recv_mutex is held here so that ring_alloc and _unalloc
220  * pairs don't go unmatched.
221  *
222  * -1 is returned if posting fails due to temporary resource exhaustion.
223  */
224 int rds_iw_recv_refill(struct rds_connection *conn, gfp_t kptr_gfp,
225                        gfp_t page_gfp, int prefill)
226 {
227         struct rds_iw_connection *ic = conn->c_transport_data;
228         struct rds_iw_recv_work *recv;
229         struct ib_recv_wr *failed_wr;
230         unsigned int posted = 0;
231         int ret = 0;
232         u32 pos;
233 
234         while ((prefill || rds_conn_up(conn)) &&
235                rds_iw_ring_alloc(&ic->i_recv_ring, 1, &pos)) {
236                 if (pos >= ic->i_recv_ring.w_nr) {
237                         printk(KERN_NOTICE "Argh - ring alloc returned pos=%u\n",
238                                         pos);
239                         ret = -EINVAL;
240                         break;
241                 }
242 
243                 recv = &ic->i_recvs[pos];
244                 ret = rds_iw_recv_refill_one(conn, recv, kptr_gfp, page_gfp);
245                 if (ret) {
246                         ret = -1;
247                         break;
248                 }
249 
250                 /* XXX when can this fail? */
251                 ret = ib_post_recv(ic->i_cm_id->qp, &recv->r_wr, &failed_wr);
252                 rdsdebug("recv %p iwinc %p page %p addr %lu ret %d\n", recv,
253                          recv->r_iwinc, recv->r_frag->f_page,
254                          (long) recv->r_frag->f_mapped, ret);
255                 if (ret) {
256                         rds_iw_conn_error(conn, "recv post on "
257                                "%pI4 returned %d, disconnecting and "
258                                "reconnecting\n", &conn->c_faddr,
259                                ret);
260                         ret = -1;
261                         break;
262                 }
263 
264                 posted++;
265         }
266 
267         /* We're doing flow control - update the window. */
268         if (ic->i_flowctl && posted)
269                 rds_iw_advertise_credits(conn, posted);
270 
271         if (ret)
272                 rds_iw_ring_unalloc(&ic->i_recv_ring, 1);
273         return ret;
274 }
275 
276 static void rds_iw_inc_purge(struct rds_incoming *inc)
277 {
278         struct rds_iw_incoming *iwinc;
279         struct rds_page_frag *frag;
280         struct rds_page_frag *pos;
281 
282         iwinc = container_of(inc, struct rds_iw_incoming, ii_inc);
283         rdsdebug("purging iwinc %p inc %p\n", iwinc, inc);
284 
285         list_for_each_entry_safe(frag, pos, &iwinc->ii_frags, f_item) {
286                 list_del_init(&frag->f_item);
287                 rds_iw_frag_drop_page(frag);
288                 rds_iw_frag_free(frag);
289         }
290 }
291 
292 void rds_iw_inc_free(struct rds_incoming *inc)
293 {
294         struct rds_iw_incoming *iwinc;
295 
296         iwinc = container_of(inc, struct rds_iw_incoming, ii_inc);
297 
298         rds_iw_inc_purge(inc);
299         rdsdebug("freeing iwinc %p inc %p\n", iwinc, inc);
300         BUG_ON(!list_empty(&iwinc->ii_frags));
301         kmem_cache_free(rds_iw_incoming_slab, iwinc);
302         atomic_dec(&rds_iw_allocation);
303         BUG_ON(atomic_read(&rds_iw_allocation) < 0);
304 }
305 
306 int rds_iw_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to)
307 {
308         struct rds_iw_incoming *iwinc;
309         struct rds_page_frag *frag;
310         unsigned long to_copy;
311         unsigned long frag_off = 0;
312         int copied = 0;
313         int ret;
314         u32 len;
315 
316         iwinc = container_of(inc, struct rds_iw_incoming, ii_inc);
317         frag = list_entry(iwinc->ii_frags.next, struct rds_page_frag, f_item);
318         len = be32_to_cpu(inc->i_hdr.h_len);
319 
320         while (iov_iter_count(to) && copied < len) {
321                 if (frag_off == RDS_FRAG_SIZE) {
322                         frag = list_entry(frag->f_item.next,
323                                           struct rds_page_frag, f_item);
324                         frag_off = 0;
325                 }
326                 to_copy = min_t(unsigned long, iov_iter_count(to),
327                                 RDS_FRAG_SIZE - frag_off);
328                 to_copy = min_t(unsigned long, to_copy, len - copied);
329 
330                 /* XXX needs + offset for multiple recvs per page */
331                 rds_stats_add(s_copy_to_user, to_copy);
332                 ret = copy_page_to_iter(frag->f_page,
333                                         frag->f_offset + frag_off,
334                                         to_copy,
335                                         to);
336                 if (ret != to_copy)
337                         return -EFAULT;
338 
339                 frag_off += to_copy;
340                 copied += to_copy;
341         }
342 
343         return copied;
344 }
345 
346 /* ic starts out kzalloc()ed */
347 void rds_iw_recv_init_ack(struct rds_iw_connection *ic)
348 {
349         struct ib_send_wr *wr = &ic->i_ack_wr;
350         struct ib_sge *sge = &ic->i_ack_sge;
351 
352         sge->addr = ic->i_ack_dma;
353         sge->length = sizeof(struct rds_header);
354         sge->lkey = rds_iw_local_dma_lkey(ic);
355 
356         wr->sg_list = sge;
357         wr->num_sge = 1;
358         wr->opcode = IB_WR_SEND;
359         wr->wr_id = RDS_IW_ACK_WR_ID;
360         wr->send_flags = IB_SEND_SIGNALED | IB_SEND_SOLICITED;
361 }
362 
363 /*
364  * You'd think that with reliable IB connections you wouldn't need to ack
365  * messages that have been received.  The problem is that IB hardware generates
366  * an ack message before it has DMAed the message into memory.  This creates a
367  * potential message loss if the HCA is disabled for any reason between when it
368  * sends the ack and before the message is DMAed and processed.  This is only a
369  * potential issue if another HCA is available for fail-over.
370  *
371  * When the remote host receives our ack they'll free the sent message from
372  * their send queue.  To decrease the latency of this we always send an ack
373  * immediately after we've received messages.
374  *
375  * For simplicity, we only have one ack in flight at a time.  This puts
376  * pressure on senders to have deep enough send queues to absorb the latency of
377  * a single ack frame being in flight.  This might not be good enough.
378  *
379  * This is implemented by have a long-lived send_wr and sge which point to a
380  * statically allocated ack frame.  This ack wr does not fall under the ring
381  * accounting that the tx and rx wrs do.  The QP attribute specifically makes
382  * room for it beyond the ring size.  Send completion notices its special
383  * wr_id and avoids working with the ring in that case.
384  */
385 #ifndef KERNEL_HAS_ATOMIC64
386 static void rds_iw_set_ack(struct rds_iw_connection *ic, u64 seq,
387                                 int ack_required)
388 {
389         unsigned long flags;
390 
391         spin_lock_irqsave(&ic->i_ack_lock, flags);
392         ic->i_ack_next = seq;
393         if (ack_required)
394                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
395         spin_unlock_irqrestore(&ic->i_ack_lock, flags);
396 }
397 
398 static u64 rds_iw_get_ack(struct rds_iw_connection *ic)
399 {
400         unsigned long flags;
401         u64 seq;
402 
403         clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
404 
405         spin_lock_irqsave(&ic->i_ack_lock, flags);
406         seq = ic->i_ack_next;
407         spin_unlock_irqrestore(&ic->i_ack_lock, flags);
408 
409         return seq;
410 }
411 #else
412 static void rds_iw_set_ack(struct rds_iw_connection *ic, u64 seq,
413                                 int ack_required)
414 {
415         atomic64_set(&ic->i_ack_next, seq);
416         if (ack_required) {
417                 smp_mb__before_atomic();
418                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
419         }
420 }
421 
422 static u64 rds_iw_get_ack(struct rds_iw_connection *ic)
423 {
424         clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
425         smp_mb__after_atomic();
426 
427         return atomic64_read(&ic->i_ack_next);
428 }
429 #endif
430 
431 
432 static void rds_iw_send_ack(struct rds_iw_connection *ic, unsigned int adv_credits)
433 {
434         struct rds_header *hdr = ic->i_ack;
435         struct ib_send_wr *failed_wr;
436         u64 seq;
437         int ret;
438 
439         seq = rds_iw_get_ack(ic);
440 
441         rdsdebug("send_ack: ic %p ack %llu\n", ic, (unsigned long long) seq);
442         rds_message_populate_header(hdr, 0, 0, 0);
443         hdr->h_ack = cpu_to_be64(seq);
444         hdr->h_credit = adv_credits;
445         rds_message_make_checksum(hdr);
446         ic->i_ack_queued = jiffies;
447 
448         ret = ib_post_send(ic->i_cm_id->qp, &ic->i_ack_wr, &failed_wr);
449         if (unlikely(ret)) {
450                 /* Failed to send. Release the WR, and
451                  * force another ACK.
452                  */
453                 clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
454                 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
455 
456                 rds_iw_stats_inc(s_iw_ack_send_failure);
457 
458                 rds_iw_conn_error(ic->conn, "sending ack failed\n");
459         } else
460                 rds_iw_stats_inc(s_iw_ack_sent);
461 }
462 
463 /*
464  * There are 3 ways of getting acknowledgements to the peer:
465  *  1.  We call rds_iw_attempt_ack from the recv completion handler
466  *      to send an ACK-only frame.
467  *      However, there can be only one such frame in the send queue
468  *      at any time, so we may have to postpone it.
469  *  2.  When another (data) packet is transmitted while there's
470  *      an ACK in the queue, we piggyback the ACK sequence number
471  *      on the data packet.
472  *  3.  If the ACK WR is done sending, we get called from the
473  *      send queue completion handler, and check whether there's
474  *      another ACK pending (postponed because the WR was on the
475  *      queue). If so, we transmit it.
476  *
477  * We maintain 2 variables:
478  *  -   i_ack_flags, which keeps track of whether the ACK WR
479  *      is currently in the send queue or not (IB_ACK_IN_FLIGHT)
480  *  -   i_ack_next, which is the last sequence number we received
481  *
482  * Potentially, send queue and receive queue handlers can run concurrently.
483  * It would be nice to not have to use a spinlock to synchronize things,
484  * but the one problem that rules this out is that 64bit updates are
485  * not atomic on all platforms. Things would be a lot simpler if
486  * we had atomic64 or maybe cmpxchg64 everywhere.
487  *
488  * Reconnecting complicates this picture just slightly. When we
489  * reconnect, we may be seeing duplicate packets. The peer
490  * is retransmitting them, because it hasn't seen an ACK for
491  * them. It is important that we ACK these.
492  *
493  * ACK mitigation adds a header flag "ACK_REQUIRED"; any packet with
494  * this flag set *MUST* be acknowledged immediately.
495  */
496 
497 /*
498  * When we get here, we're called from the recv queue handler.
499  * Check whether we ought to transmit an ACK.
500  */
501 void rds_iw_attempt_ack(struct rds_iw_connection *ic)
502 {
503         unsigned int adv_credits;
504 
505         if (!test_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
506                 return;
507 
508         if (test_and_set_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags)) {
509                 rds_iw_stats_inc(s_iw_ack_send_delayed);
510                 return;
511         }
512 
513         /* Can we get a send credit? */
514         if (!rds_iw_send_grab_credits(ic, 1, &adv_credits, 0, RDS_MAX_ADV_CREDIT)) {
515                 rds_iw_stats_inc(s_iw_tx_throttle);
516                 clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
517                 return;
518         }
519 
520         clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
521         rds_iw_send_ack(ic, adv_credits);
522 }
523 
524 /*
525  * We get here from the send completion handler, when the
526  * adapter tells us the ACK frame was sent.
527  */
528 void rds_iw_ack_send_complete(struct rds_iw_connection *ic)
529 {
530         clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
531         rds_iw_attempt_ack(ic);
532 }
533 
534 /*
535  * This is called by the regular xmit code when it wants to piggyback
536  * an ACK on an outgoing frame.
537  */
538 u64 rds_iw_piggyb_ack(struct rds_iw_connection *ic)
539 {
540         if (test_and_clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
541                 rds_iw_stats_inc(s_iw_ack_send_piggybacked);
542         return rds_iw_get_ack(ic);
543 }
544 
545 /*
546  * It's kind of lame that we're copying from the posted receive pages into
547  * long-lived bitmaps.  We could have posted the bitmaps and rdma written into
548  * them.  But receiving new congestion bitmaps should be a *rare* event, so
549  * hopefully we won't need to invest that complexity in making it more
550  * efficient.  By copying we can share a simpler core with TCP which has to
551  * copy.
552  */
553 static void rds_iw_cong_recv(struct rds_connection *conn,
554                               struct rds_iw_incoming *iwinc)
555 {
556         struct rds_cong_map *map;
557         unsigned int map_off;
558         unsigned int map_page;
559         struct rds_page_frag *frag;
560         unsigned long frag_off;
561         unsigned long to_copy;
562         unsigned long copied;
563         uint64_t uncongested = 0;
564         void *addr;
565 
566         /* catch completely corrupt packets */
567         if (be32_to_cpu(iwinc->ii_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
568                 return;
569 
570         map = conn->c_fcong;
571         map_page = 0;
572         map_off = 0;
573 
574         frag = list_entry(iwinc->ii_frags.next, struct rds_page_frag, f_item);
575         frag_off = 0;
576 
577         copied = 0;
578 
579         while (copied < RDS_CONG_MAP_BYTES) {
580                 uint64_t *src, *dst;
581                 unsigned int k;
582 
583                 to_copy = min(RDS_FRAG_SIZE - frag_off, PAGE_SIZE - map_off);
584                 BUG_ON(to_copy & 7); /* Must be 64bit aligned. */
585 
586                 addr = kmap_atomic(frag->f_page);
587 
588                 src = addr + frag_off;
589                 dst = (void *)map->m_page_addrs[map_page] + map_off;
590                 for (k = 0; k < to_copy; k += 8) {
591                         /* Record ports that became uncongested, ie
592                          * bits that changed from 0 to 1. */
593                         uncongested |= ~(*src) & *dst;
594                         *dst++ = *src++;
595                 }
596                 kunmap_atomic(addr);
597 
598                 copied += to_copy;
599 
600                 map_off += to_copy;
601                 if (map_off == PAGE_SIZE) {
602                         map_off = 0;
603                         map_page++;
604                 }
605 
606                 frag_off += to_copy;
607                 if (frag_off == RDS_FRAG_SIZE) {
608                         frag = list_entry(frag->f_item.next,
609                                           struct rds_page_frag, f_item);
610                         frag_off = 0;
611                 }
612         }
613 
614         /* the congestion map is in little endian order */
615         uncongested = le64_to_cpu(uncongested);
616 
617         rds_cong_map_updated(map, uncongested);
618 }
619 
620 /*
621  * Rings are posted with all the allocations they'll need to queue the
622  * incoming message to the receiving socket so this can't fail.
623  * All fragments start with a header, so we can make sure we're not receiving
624  * garbage, and we can tell a small 8 byte fragment from an ACK frame.
625  */
626 struct rds_iw_ack_state {
627         u64             ack_next;
628         u64             ack_recv;
629         unsigned int    ack_required:1;
630         unsigned int    ack_next_valid:1;
631         unsigned int    ack_recv_valid:1;
632 };
633 
634 static void rds_iw_process_recv(struct rds_connection *conn,
635                                 struct rds_iw_recv_work *recv, u32 byte_len,
636                                 struct rds_iw_ack_state *state)
637 {
638         struct rds_iw_connection *ic = conn->c_transport_data;
639         struct rds_iw_incoming *iwinc = ic->i_iwinc;
640         struct rds_header *ihdr, *hdr;
641 
642         /* XXX shut down the connection if port 0,0 are seen? */
643 
644         rdsdebug("ic %p iwinc %p recv %p byte len %u\n", ic, iwinc, recv,
645                  byte_len);
646 
647         if (byte_len < sizeof(struct rds_header)) {
648                 rds_iw_conn_error(conn, "incoming message "
649                        "from %pI4 didn't include a "
650                        "header, disconnecting and "
651                        "reconnecting\n",
652                        &conn->c_faddr);
653                 return;
654         }
655         byte_len -= sizeof(struct rds_header);
656 
657         ihdr = &ic->i_recv_hdrs[recv - ic->i_recvs];
658 
659         /* Validate the checksum. */
660         if (!rds_message_verify_checksum(ihdr)) {
661                 rds_iw_conn_error(conn, "incoming message "
662                        "from %pI4 has corrupted header - "
663                        "forcing a reconnect\n",
664                        &conn->c_faddr);
665                 rds_stats_inc(s_recv_drop_bad_checksum);
666                 return;
667         }
668 
669         /* Process the ACK sequence which comes with every packet */
670         state->ack_recv = be64_to_cpu(ihdr->h_ack);
671         state->ack_recv_valid = 1;
672 
673         /* Process the credits update if there was one */
674         if (ihdr->h_credit)
675                 rds_iw_send_add_credits(conn, ihdr->h_credit);
676 
677         if (ihdr->h_sport == 0 && ihdr->h_dport == 0 && byte_len == 0) {
678                 /* This is an ACK-only packet. The fact that it gets
679                  * special treatment here is that historically, ACKs
680                  * were rather special beasts.
681                  */
682                 rds_iw_stats_inc(s_iw_ack_received);
683 
684                 /*
685                  * Usually the frags make their way on to incs and are then freed as
686                  * the inc is freed.  We don't go that route, so we have to drop the
687                  * page ref ourselves.  We can't just leave the page on the recv
688                  * because that confuses the dma mapping of pages and each recv's use
689                  * of a partial page.  We can leave the frag, though, it will be
690                  * reused.
691                  *
692                  * FIXME: Fold this into the code path below.
693                  */
694                 rds_iw_frag_drop_page(recv->r_frag);
695                 return;
696         }
697 
698         /*
699          * If we don't already have an inc on the connection then this
700          * fragment has a header and starts a message.. copy its header
701          * into the inc and save the inc so we can hang upcoming fragments
702          * off its list.
703          */
704         if (!iwinc) {
705                 iwinc = recv->r_iwinc;
706                 recv->r_iwinc = NULL;
707                 ic->i_iwinc = iwinc;
708 
709                 hdr = &iwinc->ii_inc.i_hdr;
710                 memcpy(hdr, ihdr, sizeof(*hdr));
711                 ic->i_recv_data_rem = be32_to_cpu(hdr->h_len);
712 
713                 rdsdebug("ic %p iwinc %p rem %u flag 0x%x\n", ic, iwinc,
714                          ic->i_recv_data_rem, hdr->h_flags);
715         } else {
716                 hdr = &iwinc->ii_inc.i_hdr;
717                 /* We can't just use memcmp here; fragments of a
718                  * single message may carry different ACKs */
719                 if (hdr->h_sequence != ihdr->h_sequence ||
720                     hdr->h_len != ihdr->h_len ||
721                     hdr->h_sport != ihdr->h_sport ||
722                     hdr->h_dport != ihdr->h_dport) {
723                         rds_iw_conn_error(conn,
724                                 "fragment header mismatch; forcing reconnect\n");
725                         return;
726                 }
727         }
728 
729         list_add_tail(&recv->r_frag->f_item, &iwinc->ii_frags);
730         recv->r_frag = NULL;
731 
732         if (ic->i_recv_data_rem > RDS_FRAG_SIZE)
733                 ic->i_recv_data_rem -= RDS_FRAG_SIZE;
734         else {
735                 ic->i_recv_data_rem = 0;
736                 ic->i_iwinc = NULL;
737 
738                 if (iwinc->ii_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
739                         rds_iw_cong_recv(conn, iwinc);
740                 else {
741                         rds_recv_incoming(conn, conn->c_faddr, conn->c_laddr,
742                                           &iwinc->ii_inc, GFP_ATOMIC);
743                         state->ack_next = be64_to_cpu(hdr->h_sequence);
744                         state->ack_next_valid = 1;
745                 }
746 
747                 /* Evaluate the ACK_REQUIRED flag *after* we received
748                  * the complete frame, and after bumping the next_rx
749                  * sequence. */
750                 if (hdr->h_flags & RDS_FLAG_ACK_REQUIRED) {
751                         rds_stats_inc(s_recv_ack_required);
752                         state->ack_required = 1;
753                 }
754 
755                 rds_inc_put(&iwinc->ii_inc);
756         }
757 }
758 
759 /*
760  * Plucking the oldest entry from the ring can be done concurrently with
761  * the thread refilling the ring.  Each ring operation is protected by
762  * spinlocks and the transient state of refilling doesn't change the
763  * recording of which entry is oldest.
764  *
765  * This relies on IB only calling one cq comp_handler for each cq so that
766  * there will only be one caller of rds_recv_incoming() per RDS connection.
767  */
768 void rds_iw_recv_cq_comp_handler(struct ib_cq *cq, void *context)
769 {
770         struct rds_connection *conn = context;
771         struct rds_iw_connection *ic = conn->c_transport_data;
772 
773         rdsdebug("conn %p cq %p\n", conn, cq);
774 
775         rds_iw_stats_inc(s_iw_rx_cq_call);
776 
777         tasklet_schedule(&ic->i_recv_tasklet);
778 }
779 
780 static inline void rds_poll_cq(struct rds_iw_connection *ic,
781                                struct rds_iw_ack_state *state)
782 {
783         struct rds_connection *conn = ic->conn;
784         struct ib_wc wc;
785         struct rds_iw_recv_work *recv;
786 
787         while (ib_poll_cq(ic->i_recv_cq, 1, &wc) > 0) {
788                 rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
789                          (unsigned long long)wc.wr_id, wc.status, wc.byte_len,
790                          be32_to_cpu(wc.ex.imm_data));
791                 rds_iw_stats_inc(s_iw_rx_cq_event);
792 
793                 recv = &ic->i_recvs[rds_iw_ring_oldest(&ic->i_recv_ring)];
794 
795                 rds_iw_recv_unmap_page(ic, recv);
796 
797                 /*
798                  * Also process recvs in connecting state because it is possible
799                  * to get a recv completion _before_ the rdmacm ESTABLISHED
800                  * event is processed.
801                  */
802                 if (rds_conn_up(conn) || rds_conn_connecting(conn)) {
803                         /* We expect errors as the qp is drained during shutdown */
804                         if (wc.status == IB_WC_SUCCESS) {
805                                 rds_iw_process_recv(conn, recv, wc.byte_len, state);
806                         } else {
807                                 rds_iw_conn_error(conn, "recv completion on "
808                                        "%pI4 had status %u, disconnecting and "
809                                        "reconnecting\n", &conn->c_faddr,
810                                        wc.status);
811                         }
812                 }
813 
814                 rds_iw_ring_free(&ic->i_recv_ring, 1);
815         }
816 }
817 
818 void rds_iw_recv_tasklet_fn(unsigned long data)
819 {
820         struct rds_iw_connection *ic = (struct rds_iw_connection *) data;
821         struct rds_connection *conn = ic->conn;
822         struct rds_iw_ack_state state = { 0, };
823 
824         rds_poll_cq(ic, &state);
825         ib_req_notify_cq(ic->i_recv_cq, IB_CQ_SOLICITED);
826         rds_poll_cq(ic, &state);
827 
828         if (state.ack_next_valid)
829                 rds_iw_set_ack(ic, state.ack_next, state.ack_required);
830         if (state.ack_recv_valid && state.ack_recv > ic->i_ack_recv) {
831                 rds_send_drop_acked(conn, state.ack_recv, NULL);
832                 ic->i_ack_recv = state.ack_recv;
833         }
834         if (rds_conn_up(conn))
835                 rds_iw_attempt_ack(ic);
836 
837         /* If we ever end up with a really empty receive ring, we're
838          * in deep trouble, as the sender will definitely see RNR
839          * timeouts. */
840         if (rds_iw_ring_empty(&ic->i_recv_ring))
841                 rds_iw_stats_inc(s_iw_rx_ring_empty);
842 
843         /*
844          * If the ring is running low, then schedule the thread to refill.
845          */
846         if (rds_iw_ring_low(&ic->i_recv_ring))
847                 queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
848 }
849 
850 int rds_iw_recv(struct rds_connection *conn)
851 {
852         struct rds_iw_connection *ic = conn->c_transport_data;
853         int ret = 0;
854 
855         rdsdebug("conn %p\n", conn);
856 
857         /*
858          * If we get a temporary posting failure in this context then
859          * we're really low and we want the caller to back off for a bit.
860          */
861         mutex_lock(&ic->i_recv_mutex);
862         if (rds_iw_recv_refill(conn, GFP_KERNEL, GFP_HIGHUSER, 0))
863                 ret = -ENOMEM;
864         else
865                 rds_iw_stats_inc(s_iw_rx_refill_from_thread);
866         mutex_unlock(&ic->i_recv_mutex);
867 
868         if (rds_conn_up(conn))
869                 rds_iw_attempt_ack(ic);
870 
871         return ret;
872 }
873 
874 int rds_iw_recv_init(void)
875 {
876         struct sysinfo si;
877         int ret = -ENOMEM;
878 
879         /* Default to 30% of all available RAM for recv memory */
880         si_meminfo(&si);
881         rds_iw_sysctl_max_recv_allocation = si.totalram / 3 * PAGE_SIZE / RDS_FRAG_SIZE;
882 
883         rds_iw_incoming_slab = kmem_cache_create("rds_iw_incoming",
884                                         sizeof(struct rds_iw_incoming),
885                                         0, 0, NULL);
886         if (!rds_iw_incoming_slab)
887                 goto out;
888 
889         rds_iw_frag_slab = kmem_cache_create("rds_iw_frag",
890                                         sizeof(struct rds_page_frag),
891                                         0, 0, NULL);
892         if (!rds_iw_frag_slab)
893                 kmem_cache_destroy(rds_iw_incoming_slab);
894         else
895                 ret = 0;
896 out:
897         return ret;
898 }
899 
900 void rds_iw_recv_exit(void)
901 {
902         kmem_cache_destroy(rds_iw_incoming_slab);
903         kmem_cache_destroy(rds_iw_frag_slab);
904 }
905 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp