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 38 #include "rds.h" 39 #include "rdma.h" 40 #include "ib.h" 41 42 static void rds_ib_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_ib_send_unmap_rdma(struct rds_ib_connection *ic, 67 struct rds_rdma_op *op) 68 { 69 if (op->r_mapped) { 70 ib_dma_unmap_sg(ic->i_cm_id->device, 71 op->r_sg, op->r_nents, 72 op->r_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE); 73 op->r_mapped = 0; 74 } 75 } 76 77 static void rds_ib_send_unmap_rm(struct rds_ib_connection *ic, 78 struct rds_ib_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->m_sg, rm->m_nents, 87 DMA_TO_DEVICE); 88 89 if (rm->m_rdma_op != NULL) { 90 rds_ib_send_unmap_rdma(ic, rm->m_rdma_op); 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_ib_send_rdma_complete(rm, wc_status); 113 114 if (rm->m_rdma_op->r_write) 115 rds_stats_add(s_send_rdma_bytes, rm->m_rdma_op->r_bytes); 116 else 117 rds_stats_add(s_recv_rdma_bytes, rm->m_rdma_op->r_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_ib_send_init_ring(struct rds_ib_connection *ic) 129 { 130 struct rds_ib_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; 138 139 send->s_wr.wr_id = i; 140 send->s_wr.sg_list = send->s_sge; 141 send->s_wr.num_sge = 1; 142 send->s_wr.opcode = IB_WR_SEND; 143 send->s_wr.send_flags = 0; 144 send->s_wr.ex.imm_data = 0; 145 146 sge = rds_ib_data_sge(ic, send->s_sge); 147 sge->lkey = ic->i_mr->lkey; 148 149 sge = rds_ib_header_sge(ic, send->s_sge); 150 sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header)); 151 sge->length = sizeof(struct rds_header); 152 sge->lkey = ic->i_mr->lkey; 153 } 154 } 155 156 void rds_ib_send_clear_ring(struct rds_ib_connection *ic) 157 { 158 struct rds_ib_send_work *send; 159 u32 i; 160 161 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) { 162 if (send->s_wr.opcode == 0xdead) 163 continue; 164 if (send->s_rm) 165 rds_ib_send_unmap_rm(ic, send, IB_WC_WR_FLUSH_ERR); 166 if (send->s_op) 167 rds_ib_send_unmap_rdma(ic, send->s_op); 168 } 169 } 170 171 /* 172 * The _oldest/_free ring operations here race cleanly with the alloc/unalloc 173 * operations performed in the send path. As the sender allocs and potentially 174 * unallocs the next free entry in the ring it doesn't alter which is 175 * the next to be freed, which is what this is concerned with. 176 */ 177 void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context) 178 { 179 struct rds_connection *conn = context; 180 struct rds_ib_connection *ic = conn->c_transport_data; 181 struct ib_wc wc; 182 struct rds_ib_send_work *send; 183 u32 completed; 184 u32 oldest; 185 u32 i = 0; 186 int ret; 187 188 rdsdebug("cq %p conn %p\n", cq, conn); 189 rds_ib_stats_inc(s_ib_tx_cq_call); 190 ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP); 191 if (ret) 192 rdsdebug("ib_req_notify_cq send failed: %d\n", ret); 193 194 while (ib_poll_cq(cq, 1, &wc) > 0) { 195 rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n", 196 (unsigned long long)wc.wr_id, wc.status, wc.byte_len, 197 be32_to_cpu(wc.ex.imm_data)); 198 rds_ib_stats_inc(s_ib_tx_cq_event); 199 200 if (wc.wr_id == RDS_IB_ACK_WR_ID) { 201 if (ic->i_ack_queued + HZ/2 < jiffies) 202 rds_ib_stats_inc(s_ib_tx_stalled); 203 rds_ib_ack_send_complete(ic); 204 continue; 205 } 206 207 oldest = rds_ib_ring_oldest(&ic->i_send_ring); 208 209 completed = rds_ib_ring_completed(&ic->i_send_ring, wc.wr_id, oldest); 210 211 for (i = 0; i < completed; i++) { 212 send = &ic->i_sends[oldest]; 213 214 /* In the error case, wc.opcode sometimes contains garbage */ 215 switch (send->s_wr.opcode) { 216 case IB_WR_SEND: 217 if (send->s_rm) 218 rds_ib_send_unmap_rm(ic, send, wc.status); 219 break; 220 case IB_WR_RDMA_WRITE: 221 case IB_WR_RDMA_READ: 222 /* Nothing to be done - the SG list will be unmapped 223 * when the SEND completes. */ 224 break; 225 default: 226 if (printk_ratelimit()) 227 printk(KERN_NOTICE 228 "RDS/IB: %s: unexpected opcode 0x%x in WR!\n", 229 __func__, send->s_wr.opcode); 230 break; 231 } 232 233 send->s_wr.opcode = 0xdead; 234 send->s_wr.num_sge = 1; 235 if (send->s_queued + HZ/2 < jiffies) 236 rds_ib_stats_inc(s_ib_tx_stalled); 237 238 /* If a RDMA operation produced an error, signal this right 239 * away. If we don't, the subsequent SEND that goes with this 240 * RDMA will be canceled with ERR_WFLUSH, and the application 241 * never learn that the RDMA failed. */ 242 if (unlikely(wc.status == IB_WC_REM_ACCESS_ERR && send->s_op)) { 243 struct rds_message *rm; 244 245 rm = rds_send_get_message(conn, send->s_op); 246 if (rm) { 247 if (rm->m_rdma_op) 248 rds_ib_send_unmap_rdma(ic, rm->m_rdma_op); 249 rds_ib_send_rdma_complete(rm, wc.status); 250 rds_message_put(rm); 251 } 252 } 253 254 oldest = (oldest + 1) % ic->i_send_ring.w_nr; 255 } 256 257 rds_ib_ring_free(&ic->i_send_ring, completed); 258 259 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) || 260 test_bit(0, &conn->c_map_queued)) 261 queue_delayed_work(rds_wq, &conn->c_send_w, 0); 262 263 /* We expect errors as the qp is drained during shutdown */ 264 if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) { 265 rds_ib_conn_error(conn, 266 "send completion on %pI4 " 267 "had status %u, disconnecting and reconnecting\n", 268 &conn->c_faddr, wc.status); 269 } 270 } 271 } 272 273 /* 274 * This is the main function for allocating credits when sending 275 * messages. 276 * 277 * Conceptually, we have two counters: 278 * - send credits: this tells us how many WRs we're allowed 279 * to submit without overruning the reciever's queue. For 280 * each SEND WR we post, we decrement this by one. 281 * 282 * - posted credits: this tells us how many WRs we recently 283 * posted to the receive queue. This value is transferred 284 * to the peer as a "credit update" in a RDS header field. 285 * Every time we transmit credits to the peer, we subtract 286 * the amount of transferred credits from this counter. 287 * 288 * It is essential that we avoid situations where both sides have 289 * exhausted their send credits, and are unable to send new credits 290 * to the peer. We achieve this by requiring that we send at least 291 * one credit update to the peer before exhausting our credits. 292 * When new credits arrive, we subtract one credit that is withheld 293 * until we've posted new buffers and are ready to transmit these 294 * credits (see rds_ib_send_add_credits below). 295 * 296 * The RDS send code is essentially single-threaded; rds_send_xmit 297 * grabs c_send_lock to ensure exclusive access to the send ring. 298 * However, the ACK sending code is independent and can race with 299 * message SENDs. 300 * 301 * In the send path, we need to update the counters for send credits 302 * and the counter of posted buffers atomically - when we use the 303 * last available credit, we cannot allow another thread to race us 304 * and grab the posted credits counter. Hence, we have to use a 305 * spinlock to protect the credit counter, or use atomics. 306 * 307 * Spinlocks shared between the send and the receive path are bad, 308 * because they create unnecessary delays. An early implementation 309 * using a spinlock showed a 5% degradation in throughput at some 310 * loads. 311 * 312 * This implementation avoids spinlocks completely, putting both 313 * counters into a single atomic, and updating that atomic using 314 * atomic_add (in the receive path, when receiving fresh credits), 315 * and using atomic_cmpxchg when updating the two counters. 316 */ 317 int rds_ib_send_grab_credits(struct rds_ib_connection *ic, 318 u32 wanted, u32 *adv_credits, int need_posted, int max_posted) 319 { 320 unsigned int avail, posted, got = 0, advertise; 321 long oldval, newval; 322 323 *adv_credits = 0; 324 if (!ic->i_flowctl) 325 return wanted; 326 327 try_again: 328 advertise = 0; 329 oldval = newval = atomic_read(&ic->i_credits); 330 posted = IB_GET_POST_CREDITS(oldval); 331 avail = IB_GET_SEND_CREDITS(oldval); 332 333 rdsdebug("rds_ib_send_grab_credits(%u): credits=%u posted=%u\n", 334 wanted, avail, posted); 335 336 /* The last credit must be used to send a credit update. */ 337 if (avail && !posted) 338 avail--; 339 340 if (avail < wanted) { 341 struct rds_connection *conn = ic->i_cm_id->context; 342 343 /* Oops, there aren't that many credits left! */ 344 set_bit(RDS_LL_SEND_FULL, &conn->c_flags); 345 got = avail; 346 } else { 347 /* Sometimes you get what you want, lalala. */ 348 got = wanted; 349 } 350 newval -= IB_SET_SEND_CREDITS(got); 351 352 /* 353 * If need_posted is non-zero, then the caller wants 354 * the posted regardless of whether any send credits are 355 * available. 356 */ 357 if (posted && (got || need_posted)) { 358 advertise = min_t(unsigned int, posted, max_posted); 359 newval -= IB_SET_POST_CREDITS(advertise); 360 } 361 362 /* Finally bill everything */ 363 if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval) 364 goto try_again; 365 366 *adv_credits = advertise; 367 return got; 368 } 369 370 void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits) 371 { 372 struct rds_ib_connection *ic = conn->c_transport_data; 373 374 if (credits == 0) 375 return; 376 377 rdsdebug("rds_ib_send_add_credits(%u): current=%u%s\n", 378 credits, 379 IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)), 380 test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : ""); 381 382 atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits); 383 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags)) 384 queue_delayed_work(rds_wq, &conn->c_send_w, 0); 385 386 WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384); 387 388 rds_ib_stats_inc(s_ib_rx_credit_updates); 389 } 390 391 void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted) 392 { 393 struct rds_ib_connection *ic = conn->c_transport_data; 394 395 if (posted == 0) 396 return; 397 398 atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits); 399 400 /* Decide whether to send an update to the peer now. 401 * If we would send a credit update for every single buffer we 402 * post, we would end up with an ACK storm (ACK arrives, 403 * consumes buffer, we refill the ring, send ACK to remote 404 * advertising the newly posted buffer... ad inf) 405 * 406 * Performance pretty much depends on how often we send 407 * credit updates - too frequent updates mean lots of ACKs. 408 * Too infrequent updates, and the peer will run out of 409 * credits and has to throttle. 410 * For the time being, 16 seems to be a good compromise. 411 */ 412 if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16) 413 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); 414 } 415 416 static inline void 417 rds_ib_xmit_populate_wr(struct rds_ib_connection *ic, 418 struct rds_ib_send_work *send, unsigned int pos, 419 unsigned long buffer, unsigned int length, 420 int send_flags) 421 { 422 struct ib_sge *sge; 423 424 WARN_ON(pos != send - ic->i_sends); 425 426 send->s_wr.send_flags = send_flags; 427 send->s_wr.opcode = IB_WR_SEND; 428 send->s_wr.num_sge = 2; 429 send->s_wr.next = NULL; 430 send->s_queued = jiffies; 431 send->s_op = NULL; 432 433 if (length != 0) { 434 sge = rds_ib_data_sge(ic, send->s_sge); 435 sge->addr = buffer; 436 sge->length = length; 437 sge->lkey = ic->i_mr->lkey; 438 439 sge = rds_ib_header_sge(ic, send->s_sge); 440 } else { 441 /* We're sending a packet with no payload. There is only 442 * one SGE */ 443 send->s_wr.num_sge = 1; 444 sge = &send->s_sge[0]; 445 } 446 447 sge->addr = ic->i_send_hdrs_dma + (pos * sizeof(struct rds_header)); 448 sge->length = sizeof(struct rds_header); 449 sge->lkey = ic->i_mr->lkey; 450 } 451 452 /* 453 * This can be called multiple times for a given message. The first time 454 * we see a message we map its scatterlist into the IB device so that 455 * we can provide that mapped address to the IB scatter gather entries 456 * in the IB work requests. We translate the scatterlist into a series 457 * of work requests that fragment the message. These work requests complete 458 * in order so we pass ownership of the message to the completion handler 459 * once we send the final fragment. 460 * 461 * The RDS core uses the c_send_lock to only enter this function once 462 * per connection. This makes sure that the tx ring alloc/unalloc pairs 463 * don't get out of sync and confuse the ring. 464 */ 465 int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm, 466 unsigned int hdr_off, unsigned int sg, unsigned int off) 467 { 468 struct rds_ib_connection *ic = conn->c_transport_data; 469 struct ib_device *dev = ic->i_cm_id->device; 470 struct rds_ib_send_work *send = NULL; 471 struct rds_ib_send_work *first; 472 struct rds_ib_send_work *prev; 473 struct ib_send_wr *failed_wr; 474 struct scatterlist *scat; 475 u32 pos; 476 u32 i; 477 u32 work_alloc; 478 u32 credit_alloc; 479 u32 posted; 480 u32 adv_credits = 0; 481 int send_flags = 0; 482 int sent; 483 int ret; 484 int flow_controlled = 0; 485 486 BUG_ON(off % RDS_FRAG_SIZE); 487 BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header)); 488 489 /* Do not send cong updates to IB loopback */ 490 if (conn->c_loopback 491 && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) { 492 rds_cong_map_updated(conn->c_fcong, ~(u64) 0); 493 return sizeof(struct rds_header) + RDS_CONG_MAP_BYTES; 494 } 495 496 /* FIXME we may overallocate here */ 497 if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) 498 i = 1; 499 else 500 i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE); 501 502 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos); 503 if (work_alloc == 0) { 504 set_bit(RDS_LL_SEND_FULL, &conn->c_flags); 505 rds_ib_stats_inc(s_ib_tx_ring_full); 506 ret = -ENOMEM; 507 goto out; 508 } 509 510 credit_alloc = work_alloc; 511 if (ic->i_flowctl) { 512 credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT); 513 adv_credits += posted; 514 if (credit_alloc < work_alloc) { 515 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc); 516 work_alloc = credit_alloc; 517 flow_controlled++; 518 } 519 if (work_alloc == 0) { 520 set_bit(RDS_LL_SEND_FULL, &conn->c_flags); 521 rds_ib_stats_inc(s_ib_tx_throttle); 522 ret = -ENOMEM; 523 goto out; 524 } 525 } 526 527 /* map the message the first time we see it */ 528 if (ic->i_rm == NULL) { 529 /* 530 printk(KERN_NOTICE "rds_ib_xmit prep msg dport=%u flags=0x%x len=%d\n", 531 be16_to_cpu(rm->m_inc.i_hdr.h_dport), 532 rm->m_inc.i_hdr.h_flags, 533 be32_to_cpu(rm->m_inc.i_hdr.h_len)); 534 */ 535 if (rm->m_nents) { 536 rm->m_count = ib_dma_map_sg(dev, 537 rm->m_sg, rm->m_nents, DMA_TO_DEVICE); 538 rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->m_count); 539 if (rm->m_count == 0) { 540 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure); 541 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 542 ret = -ENOMEM; /* XXX ? */ 543 goto out; 544 } 545 } else { 546 rm->m_count = 0; 547 } 548 549 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs; 550 ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes; 551 rds_message_addref(rm); 552 ic->i_rm = rm; 553 554 /* Finalize the header */ 555 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags)) 556 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED; 557 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) 558 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED; 559 560 /* If it has a RDMA op, tell the peer we did it. This is 561 * used by the peer to release use-once RDMA MRs. */ 562 if (rm->m_rdma_op) { 563 struct rds_ext_header_rdma ext_hdr; 564 565 ext_hdr.h_rdma_rkey = cpu_to_be32(rm->m_rdma_op->r_key); 566 rds_message_add_extension(&rm->m_inc.i_hdr, 567 RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr)); 568 } 569 if (rm->m_rdma_cookie) { 570 rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr, 571 rds_rdma_cookie_key(rm->m_rdma_cookie), 572 rds_rdma_cookie_offset(rm->m_rdma_cookie)); 573 } 574 575 /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so 576 * we should not do this unless we have a chance of at least 577 * sticking the header into the send ring. Which is why we 578 * should call rds_ib_ring_alloc first. */ 579 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic)); 580 rds_message_make_checksum(&rm->m_inc.i_hdr); 581 582 /* 583 * Update adv_credits since we reset the ACK_REQUIRED bit. 584 */ 585 rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits); 586 adv_credits += posted; 587 BUG_ON(adv_credits > 255); 588 } 589 590 send = &ic->i_sends[pos]; 591 first = send; 592 prev = NULL; 593 scat = &rm->m_sg[sg]; 594 sent = 0; 595 i = 0; 596 597 /* Sometimes you want to put a fence between an RDMA 598 * READ and the following SEND. 599 * We could either do this all the time 600 * or when requested by the user. Right now, we let 601 * the application choose. 602 */ 603 if (rm->m_rdma_op && rm->m_rdma_op->r_fence) 604 send_flags = IB_SEND_FENCE; 605 606 /* 607 * We could be copying the header into the unused tail of the page. 608 * That would need to be changed in the future when those pages might 609 * be mapped userspace pages or page cache pages. So instead we always 610 * use a second sge and our long-lived ring of mapped headers. We send 611 * the header after the data so that the data payload can be aligned on 612 * the receiver. 613 */ 614 615 /* handle a 0-len message */ 616 if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) { 617 rds_ib_xmit_populate_wr(ic, send, pos, 0, 0, send_flags); 618 goto add_header; 619 } 620 621 /* if there's data reference it with a chain of work reqs */ 622 for (; i < work_alloc && scat != &rm->m_sg[rm->m_count]; i++) { 623 unsigned int len; 624 625 send = &ic->i_sends[pos]; 626 627 len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off); 628 rds_ib_xmit_populate_wr(ic, send, pos, 629 ib_sg_dma_address(dev, scat) + off, len, 630 send_flags); 631 632 /* 633 * We want to delay signaling completions just enough to get 634 * the batching benefits but not so much that we create dead time 635 * on the wire. 636 */ 637 if (ic->i_unsignaled_wrs-- == 0) { 638 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs; 639 send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; 640 } 641 642 ic->i_unsignaled_bytes -= len; 643 if (ic->i_unsignaled_bytes <= 0) { 644 ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes; 645 send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; 646 } 647 648 /* 649 * Always signal the last one if we're stopping due to flow control. 650 */ 651 if (flow_controlled && i == (work_alloc-1)) 652 send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; 653 654 rdsdebug("send %p wr %p num_sge %u next %p\n", send, 655 &send->s_wr, send->s_wr.num_sge, send->s_wr.next); 656 657 sent += len; 658 off += len; 659 if (off == ib_sg_dma_len(dev, scat)) { 660 scat++; 661 off = 0; 662 } 663 664 add_header: 665 /* Tack on the header after the data. The header SGE should already 666 * have been set up to point to the right header buffer. */ 667 memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header)); 668 669 if (0) { 670 struct rds_header *hdr = &ic->i_send_hdrs[pos]; 671 672 printk(KERN_NOTICE "send WR dport=%u flags=0x%x len=%d\n", 673 be16_to_cpu(hdr->h_dport), 674 hdr->h_flags, 675 be32_to_cpu(hdr->h_len)); 676 } 677 if (adv_credits) { 678 struct rds_header *hdr = &ic->i_send_hdrs[pos]; 679 680 /* add credit and redo the header checksum */ 681 hdr->h_credit = adv_credits; 682 rds_message_make_checksum(hdr); 683 adv_credits = 0; 684 rds_ib_stats_inc(s_ib_tx_credit_updates); 685 } 686 687 if (prev) 688 prev->s_wr.next = &send->s_wr; 689 prev = send; 690 691 pos = (pos + 1) % ic->i_send_ring.w_nr; 692 } 693 694 /* Account the RDS header in the number of bytes we sent, but just once. 695 * The caller has no concept of fragmentation. */ 696 if (hdr_off == 0) 697 sent += sizeof(struct rds_header); 698 699 /* if we finished the message then send completion owns it */ 700 if (scat == &rm->m_sg[rm->m_count]) { 701 prev->s_rm = ic->i_rm; 702 prev->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; 703 ic->i_rm = NULL; 704 } 705 706 if (i < work_alloc) { 707 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i); 708 work_alloc = i; 709 } 710 if (ic->i_flowctl && i < credit_alloc) 711 rds_ib_send_add_credits(conn, credit_alloc - i); 712 713 /* XXX need to worry about failed_wr and partial sends. */ 714 failed_wr = &first->s_wr; 715 ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr); 716 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic, 717 first, &first->s_wr, ret, failed_wr); 718 BUG_ON(failed_wr != &first->s_wr); 719 if (ret) { 720 printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 " 721 "returned %d\n", &conn->c_faddr, ret); 722 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 723 if (prev->s_rm) { 724 ic->i_rm = prev->s_rm; 725 prev->s_rm = NULL; 726 } 727 728 rds_ib_conn_error(ic->conn, "ib_post_send failed\n"); 729 goto out; 730 } 731 732 ret = sent; 733 out: 734 BUG_ON(adv_credits); 735 return ret; 736 } 737 738 int rds_ib_xmit_rdma(struct rds_connection *conn, struct rds_rdma_op *op) 739 { 740 struct rds_ib_connection *ic = conn->c_transport_data; 741 struct rds_ib_send_work *send = NULL; 742 struct rds_ib_send_work *first; 743 struct rds_ib_send_work *prev; 744 struct ib_send_wr *failed_wr; 745 struct rds_ib_device *rds_ibdev; 746 struct scatterlist *scat; 747 unsigned long len; 748 u64 remote_addr = op->r_remote_addr; 749 u32 pos; 750 u32 work_alloc; 751 u32 i; 752 u32 j; 753 int sent; 754 int ret; 755 int num_sge; 756 757 rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client); 758 759 /* map the message the first time we see it */ 760 if (!op->r_mapped) { 761 op->r_count = ib_dma_map_sg(ic->i_cm_id->device, 762 op->r_sg, op->r_nents, (op->r_write) ? 763 DMA_TO_DEVICE : DMA_FROM_DEVICE); 764 rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->r_count); 765 if (op->r_count == 0) { 766 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure); 767 ret = -ENOMEM; /* XXX ? */ 768 goto out; 769 } 770 771 op->r_mapped = 1; 772 } 773 774 /* 775 * Instead of knowing how to return a partial rdma read/write we insist that there 776 * be enough work requests to send the entire message. 777 */ 778 i = ceil(op->r_count, rds_ibdev->max_sge); 779 780 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos); 781 if (work_alloc != i) { 782 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 783 rds_ib_stats_inc(s_ib_tx_ring_full); 784 ret = -ENOMEM; 785 goto out; 786 } 787 788 send = &ic->i_sends[pos]; 789 first = send; 790 prev = NULL; 791 scat = &op->r_sg[0]; 792 sent = 0; 793 num_sge = op->r_count; 794 795 for (i = 0; i < work_alloc && scat != &op->r_sg[op->r_count]; i++) { 796 send->s_wr.send_flags = 0; 797 send->s_queued = jiffies; 798 /* 799 * We want to delay signaling completions just enough to get 800 * the batching benefits but not so much that we create dead time on the wire. 801 */ 802 if (ic->i_unsignaled_wrs-- == 0) { 803 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs; 804 send->s_wr.send_flags = IB_SEND_SIGNALED; 805 } 806 807 send->s_wr.opcode = op->r_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ; 808 send->s_wr.wr.rdma.remote_addr = remote_addr; 809 send->s_wr.wr.rdma.rkey = op->r_key; 810 send->s_op = op; 811 812 if (num_sge > rds_ibdev->max_sge) { 813 send->s_wr.num_sge = rds_ibdev->max_sge; 814 num_sge -= rds_ibdev->max_sge; 815 } else { 816 send->s_wr.num_sge = num_sge; 817 } 818 819 send->s_wr.next = NULL; 820 821 if (prev) 822 prev->s_wr.next = &send->s_wr; 823 824 for (j = 0; j < send->s_wr.num_sge && scat != &op->r_sg[op->r_count]; j++) { 825 len = ib_sg_dma_len(ic->i_cm_id->device, scat); 826 send->s_sge[j].addr = 827 ib_sg_dma_address(ic->i_cm_id->device, scat); 828 send->s_sge[j].length = len; 829 send->s_sge[j].lkey = ic->i_mr->lkey; 830 831 sent += len; 832 rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr); 833 834 remote_addr += len; 835 scat++; 836 } 837 838 rdsdebug("send %p wr %p num_sge %u next %p\n", send, 839 &send->s_wr, send->s_wr.num_sge, send->s_wr.next); 840 841 prev = send; 842 if (++send == &ic->i_sends[ic->i_send_ring.w_nr]) 843 send = ic->i_sends; 844 } 845 846 /* if we finished the message then send completion owns it */ 847 if (scat == &op->r_sg[op->r_count]) 848 prev->s_wr.send_flags = IB_SEND_SIGNALED; 849 850 if (i < work_alloc) { 851 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i); 852 work_alloc = i; 853 } 854 855 failed_wr = &first->s_wr; 856 ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr); 857 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic, 858 first, &first->s_wr, ret, failed_wr); 859 BUG_ON(failed_wr != &first->s_wr); 860 if (ret) { 861 printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 " 862 "returned %d\n", &conn->c_faddr, ret); 863 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 864 goto out; 865 } 866 867 if (unlikely(failed_wr != &first->s_wr)) { 868 printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret); 869 BUG_ON(failed_wr != &first->s_wr); 870 } 871 872 873 out: 874 return ret; 875 } 876 877 void rds_ib_xmit_complete(struct rds_connection *conn) 878 { 879 struct rds_ib_connection *ic = conn->c_transport_data; 880 881 /* We may have a pending ACK or window update we were unable 882 * to send previously (due to flow control). Try again. */ 883 rds_ib_attempt_ack(ic); 884 } 885