1 /* 2 * Copyright (c) 2006 Oracle. All rights reserved. 3 * 4 * This software is available to you under a choice of one of two 5 * licenses. You may choose to be licensed under the terms of the GNU 6 * General Public License (GPL) Version 2, available from the file 7 * COPYING in the main directory of this source tree, or the 8 * OpenIB.org BSD license below: 9 * 10 * Redistribution and use in source and binary forms, with or 11 * without modification, are permitted provided that the following 12 * conditions are met: 13 * 14 * - Redistributions of source code must retain the above 15 * copyright notice, this list of conditions and the following 16 * disclaimer. 17 * 18 * - Redistributions in binary form must reproduce the above 19 * copyright notice, this list of conditions and the following 20 * disclaimer in the documentation and/or other materials 21 * provided with the distribution. 22 * 23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 30 * SOFTWARE. 31 * 32 */ 33 #include <linux/kernel.h> 34 #include <linux/in.h> 35 #include <linux/device.h> 36 #include <linux/dmapool.h> 37 #include <linux/ratelimit.h> 38 39 #include "rds.h" 40 #include "ib.h" 41 42 /* 43 * Convert IB-specific error message to RDS error message and call core 44 * completion handler. 45 */ 46 static void rds_ib_send_complete(struct rds_message *rm, 47 int wc_status, 48 void (*complete)(struct rds_message *rm, int status)) 49 { 50 int notify_status; 51 52 switch (wc_status) { 53 case IB_WC_WR_FLUSH_ERR: 54 return; 55 56 case IB_WC_SUCCESS: 57 notify_status = RDS_RDMA_SUCCESS; 58 break; 59 60 case IB_WC_REM_ACCESS_ERR: 61 notify_status = RDS_RDMA_REMOTE_ERROR; 62 break; 63 64 default: 65 notify_status = RDS_RDMA_OTHER_ERROR; 66 break; 67 } 68 complete(rm, notify_status); 69 } 70 71 static void rds_ib_send_unmap_data(struct rds_ib_connection *ic, 72 struct rm_data_op *op, 73 int wc_status) 74 { 75 if (op->op_nents) 76 ib_dma_unmap_sg(ic->i_cm_id->device, 77 op->op_sg, op->op_nents, 78 DMA_TO_DEVICE); 79 } 80 81 static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic, 82 struct rm_rdma_op *op, 83 int wc_status) 84 { 85 if (op->op_mapped) { 86 ib_dma_unmap_sg(ic->i_cm_id->device, 87 op->op_sg, op->op_nents, 88 op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE); 89 op->op_mapped = 0; 90 } 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 * we would need to take an event for the rdma WR. 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_complete(container_of(op, struct rds_message, rdma), 113 wc_status, rds_rdma_send_complete); 114 115 if (op->op_write) 116 rds_stats_add(s_send_rdma_bytes, op->op_bytes); 117 else 118 rds_stats_add(s_recv_rdma_bytes, op->op_bytes); 119 } 120 121 static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic, 122 struct rm_atomic_op *op, 123 int wc_status) 124 { 125 /* unmap atomic recvbuf */ 126 if (op->op_mapped) { 127 ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1, 128 DMA_FROM_DEVICE); 129 op->op_mapped = 0; 130 } 131 132 rds_ib_send_complete(container_of(op, struct rds_message, atomic), 133 wc_status, rds_atomic_send_complete); 134 135 if (op->op_type == RDS_ATOMIC_TYPE_CSWP) 136 rds_ib_stats_inc(s_ib_atomic_cswp); 137 else 138 rds_ib_stats_inc(s_ib_atomic_fadd); 139 } 140 141 /* 142 * Unmap the resources associated with a struct send_work. 143 * 144 * Returns the rm for no good reason other than it is unobtainable 145 * other than by switching on wr.opcode, currently, and the caller, 146 * the event handler, needs it. 147 */ 148 static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic, 149 struct rds_ib_send_work *send, 150 int wc_status) 151 { 152 struct rds_message *rm = NULL; 153 154 /* In the error case, wc.opcode sometimes contains garbage */ 155 switch (send->s_wr.opcode) { 156 case IB_WR_SEND: 157 if (send->s_op) { 158 rm = container_of(send->s_op, struct rds_message, data); 159 rds_ib_send_unmap_data(ic, send->s_op, wc_status); 160 } 161 break; 162 case IB_WR_RDMA_WRITE: 163 case IB_WR_RDMA_READ: 164 if (send->s_op) { 165 rm = container_of(send->s_op, struct rds_message, rdma); 166 rds_ib_send_unmap_rdma(ic, send->s_op, wc_status); 167 } 168 break; 169 case IB_WR_ATOMIC_FETCH_AND_ADD: 170 case IB_WR_ATOMIC_CMP_AND_SWP: 171 if (send->s_op) { 172 rm = container_of(send->s_op, struct rds_message, atomic); 173 rds_ib_send_unmap_atomic(ic, send->s_op, wc_status); 174 } 175 break; 176 default: 177 printk_ratelimited(KERN_NOTICE 178 "RDS/IB: %s: unexpected opcode 0x%x in WR!\n", 179 __func__, send->s_wr.opcode); 180 break; 181 } 182 183 send->s_wr.opcode = 0xdead; 184 185 return rm; 186 } 187 188 void rds_ib_send_init_ring(struct rds_ib_connection *ic) 189 { 190 struct rds_ib_send_work *send; 191 u32 i; 192 193 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) { 194 struct ib_sge *sge; 195 196 send->s_op = NULL; 197 198 send->s_wr.wr_id = i; 199 send->s_wr.sg_list = send->s_sge; 200 send->s_wr.ex.imm_data = 0; 201 202 sge = &send->s_sge[0]; 203 sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header)); 204 sge->length = sizeof(struct rds_header); 205 sge->lkey = ic->i_pd->local_dma_lkey; 206 207 send->s_sge[1].lkey = ic->i_pd->local_dma_lkey; 208 } 209 } 210 211 void rds_ib_send_clear_ring(struct rds_ib_connection *ic) 212 { 213 struct rds_ib_send_work *send; 214 u32 i; 215 216 for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) { 217 if (send->s_op && send->s_wr.opcode != 0xdead) 218 rds_ib_send_unmap_op(ic, send, IB_WC_WR_FLUSH_ERR); 219 } 220 } 221 222 /* 223 * The only fast path caller always has a non-zero nr, so we don't 224 * bother testing nr before performing the atomic sub. 225 */ 226 static void rds_ib_sub_signaled(struct rds_ib_connection *ic, int nr) 227 { 228 if ((atomic_sub_return(nr, &ic->i_signaled_sends) == 0) && 229 waitqueue_active(&rds_ib_ring_empty_wait)) 230 wake_up(&rds_ib_ring_empty_wait); 231 BUG_ON(atomic_read(&ic->i_signaled_sends) < 0); 232 } 233 234 /* 235 * The _oldest/_free ring operations here race cleanly with the alloc/unalloc 236 * operations performed in the send path. As the sender allocs and potentially 237 * unallocs the next free entry in the ring it doesn't alter which is 238 * the next to be freed, which is what this is concerned with. 239 */ 240 void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context) 241 { 242 struct rds_connection *conn = context; 243 struct rds_ib_connection *ic = conn->c_transport_data; 244 struct rds_message *rm = NULL; 245 struct ib_wc wc; 246 struct rds_ib_send_work *send; 247 u32 completed; 248 u32 oldest; 249 u32 i = 0; 250 int ret; 251 int nr_sig = 0; 252 253 rdsdebug("cq %p conn %p\n", cq, conn); 254 rds_ib_stats_inc(s_ib_tx_cq_call); 255 ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP); 256 if (ret) 257 rdsdebug("ib_req_notify_cq send failed: %d\n", ret); 258 259 while (ib_poll_cq(cq, 1, &wc) > 0) { 260 rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n", 261 (unsigned long long)wc.wr_id, wc.status, 262 ib_wc_status_msg(wc.status), wc.byte_len, 263 be32_to_cpu(wc.ex.imm_data)); 264 rds_ib_stats_inc(s_ib_tx_cq_event); 265 266 if (wc.wr_id == RDS_IB_ACK_WR_ID) { 267 if (time_after(jiffies, ic->i_ack_queued + HZ/2)) 268 rds_ib_stats_inc(s_ib_tx_stalled); 269 rds_ib_ack_send_complete(ic); 270 continue; 271 } 272 273 oldest = rds_ib_ring_oldest(&ic->i_send_ring); 274 275 completed = rds_ib_ring_completed(&ic->i_send_ring, wc.wr_id, oldest); 276 277 for (i = 0; i < completed; i++) { 278 send = &ic->i_sends[oldest]; 279 if (send->s_wr.send_flags & IB_SEND_SIGNALED) 280 nr_sig++; 281 282 rm = rds_ib_send_unmap_op(ic, send, wc.status); 283 284 if (time_after(jiffies, send->s_queued + HZ/2)) 285 rds_ib_stats_inc(s_ib_tx_stalled); 286 287 if (send->s_op) { 288 if (send->s_op == rm->m_final_op) { 289 /* If anyone waited for this message to get flushed out, wake 290 * them up now */ 291 rds_message_unmapped(rm); 292 } 293 rds_message_put(rm); 294 send->s_op = NULL; 295 } 296 297 oldest = (oldest + 1) % ic->i_send_ring.w_nr; 298 } 299 300 rds_ib_ring_free(&ic->i_send_ring, completed); 301 rds_ib_sub_signaled(ic, nr_sig); 302 nr_sig = 0; 303 304 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) || 305 test_bit(0, &conn->c_map_queued)) 306 queue_delayed_work(rds_wq, &conn->c_send_w, 0); 307 308 /* We expect errors as the qp is drained during shutdown */ 309 if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) { 310 rds_ib_conn_error(conn, "send completion on %pI4 had status " 311 "%u (%s), disconnecting and reconnecting\n", 312 &conn->c_faddr, wc.status, 313 ib_wc_status_msg(wc.status)); 314 } 315 } 316 } 317 318 /* 319 * This is the main function for allocating credits when sending 320 * messages. 321 * 322 * Conceptually, we have two counters: 323 * - send credits: this tells us how many WRs we're allowed 324 * to submit without overruning the receiver's queue. For 325 * each SEND WR we post, we decrement this by one. 326 * 327 * - posted credits: this tells us how many WRs we recently 328 * posted to the receive queue. This value is transferred 329 * to the peer as a "credit update" in a RDS header field. 330 * Every time we transmit credits to the peer, we subtract 331 * the amount of transferred credits from this counter. 332 * 333 * It is essential that we avoid situations where both sides have 334 * exhausted their send credits, and are unable to send new credits 335 * to the peer. We achieve this by requiring that we send at least 336 * one credit update to the peer before exhausting our credits. 337 * When new credits arrive, we subtract one credit that is withheld 338 * until we've posted new buffers and are ready to transmit these 339 * credits (see rds_ib_send_add_credits below). 340 * 341 * The RDS send code is essentially single-threaded; rds_send_xmit 342 * sets RDS_IN_XMIT to ensure exclusive access to the send ring. 343 * However, the ACK sending code is independent and can race with 344 * message SENDs. 345 * 346 * In the send path, we need to update the counters for send credits 347 * and the counter of posted buffers atomically - when we use the 348 * last available credit, we cannot allow another thread to race us 349 * and grab the posted credits counter. Hence, we have to use a 350 * spinlock to protect the credit counter, or use atomics. 351 * 352 * Spinlocks shared between the send and the receive path are bad, 353 * because they create unnecessary delays. An early implementation 354 * using a spinlock showed a 5% degradation in throughput at some 355 * loads. 356 * 357 * This implementation avoids spinlocks completely, putting both 358 * counters into a single atomic, and updating that atomic using 359 * atomic_add (in the receive path, when receiving fresh credits), 360 * and using atomic_cmpxchg when updating the two counters. 361 */ 362 int rds_ib_send_grab_credits(struct rds_ib_connection *ic, 363 u32 wanted, u32 *adv_credits, int need_posted, int max_posted) 364 { 365 unsigned int avail, posted, got = 0, advertise; 366 long oldval, newval; 367 368 *adv_credits = 0; 369 if (!ic->i_flowctl) 370 return wanted; 371 372 try_again: 373 advertise = 0; 374 oldval = newval = atomic_read(&ic->i_credits); 375 posted = IB_GET_POST_CREDITS(oldval); 376 avail = IB_GET_SEND_CREDITS(oldval); 377 378 rdsdebug("wanted=%u credits=%u posted=%u\n", 379 wanted, avail, posted); 380 381 /* The last credit must be used to send a credit update. */ 382 if (avail && !posted) 383 avail--; 384 385 if (avail < wanted) { 386 struct rds_connection *conn = ic->i_cm_id->context; 387 388 /* Oops, there aren't that many credits left! */ 389 set_bit(RDS_LL_SEND_FULL, &conn->c_flags); 390 got = avail; 391 } else { 392 /* Sometimes you get what you want, lalala. */ 393 got = wanted; 394 } 395 newval -= IB_SET_SEND_CREDITS(got); 396 397 /* 398 * If need_posted is non-zero, then the caller wants 399 * the posted regardless of whether any send credits are 400 * available. 401 */ 402 if (posted && (got || need_posted)) { 403 advertise = min_t(unsigned int, posted, max_posted); 404 newval -= IB_SET_POST_CREDITS(advertise); 405 } 406 407 /* Finally bill everything */ 408 if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval) 409 goto try_again; 410 411 *adv_credits = advertise; 412 return got; 413 } 414 415 void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits) 416 { 417 struct rds_ib_connection *ic = conn->c_transport_data; 418 419 if (credits == 0) 420 return; 421 422 rdsdebug("credits=%u current=%u%s\n", 423 credits, 424 IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)), 425 test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : ""); 426 427 atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits); 428 if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags)) 429 queue_delayed_work(rds_wq, &conn->c_send_w, 0); 430 431 WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384); 432 433 rds_ib_stats_inc(s_ib_rx_credit_updates); 434 } 435 436 void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted) 437 { 438 struct rds_ib_connection *ic = conn->c_transport_data; 439 440 if (posted == 0) 441 return; 442 443 atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits); 444 445 /* Decide whether to send an update to the peer now. 446 * If we would send a credit update for every single buffer we 447 * post, we would end up with an ACK storm (ACK arrives, 448 * consumes buffer, we refill the ring, send ACK to remote 449 * advertising the newly posted buffer... ad inf) 450 * 451 * Performance pretty much depends on how often we send 452 * credit updates - too frequent updates mean lots of ACKs. 453 * Too infrequent updates, and the peer will run out of 454 * credits and has to throttle. 455 * For the time being, 16 seems to be a good compromise. 456 */ 457 if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16) 458 set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); 459 } 460 461 static inline int rds_ib_set_wr_signal_state(struct rds_ib_connection *ic, 462 struct rds_ib_send_work *send, 463 bool notify) 464 { 465 /* 466 * We want to delay signaling completions just enough to get 467 * the batching benefits but not so much that we create dead time 468 * on the wire. 469 */ 470 if (ic->i_unsignaled_wrs-- == 0 || notify) { 471 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs; 472 send->s_wr.send_flags |= IB_SEND_SIGNALED; 473 return 1; 474 } 475 return 0; 476 } 477 478 /* 479 * This can be called multiple times for a given message. The first time 480 * we see a message we map its scatterlist into the IB device so that 481 * we can provide that mapped address to the IB scatter gather entries 482 * in the IB work requests. We translate the scatterlist into a series 483 * of work requests that fragment the message. These work requests complete 484 * in order so we pass ownership of the message to the completion handler 485 * once we send the final fragment. 486 * 487 * The RDS core uses the c_send_lock to only enter this function once 488 * per connection. This makes sure that the tx ring alloc/unalloc pairs 489 * don't get out of sync and confuse the ring. 490 */ 491 int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm, 492 unsigned int hdr_off, unsigned int sg, unsigned int off) 493 { 494 struct rds_ib_connection *ic = conn->c_transport_data; 495 struct ib_device *dev = ic->i_cm_id->device; 496 struct rds_ib_send_work *send = NULL; 497 struct rds_ib_send_work *first; 498 struct rds_ib_send_work *prev; 499 struct ib_send_wr *failed_wr; 500 struct scatterlist *scat; 501 u32 pos; 502 u32 i; 503 u32 work_alloc; 504 u32 credit_alloc = 0; 505 u32 posted; 506 u32 adv_credits = 0; 507 int send_flags = 0; 508 int bytes_sent = 0; 509 int ret; 510 int flow_controlled = 0; 511 int nr_sig = 0; 512 513 BUG_ON(off % RDS_FRAG_SIZE); 514 BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header)); 515 516 /* Do not send cong updates to IB loopback */ 517 if (conn->c_loopback 518 && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) { 519 rds_cong_map_updated(conn->c_fcong, ~(u64) 0); 520 scat = &rm->data.op_sg[sg]; 521 ret = max_t(int, RDS_CONG_MAP_BYTES, scat->length); 522 return sizeof(struct rds_header) + ret; 523 } 524 525 /* FIXME we may overallocate here */ 526 if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) 527 i = 1; 528 else 529 i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE); 530 531 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos); 532 if (work_alloc == 0) { 533 set_bit(RDS_LL_SEND_FULL, &conn->c_flags); 534 rds_ib_stats_inc(s_ib_tx_ring_full); 535 ret = -ENOMEM; 536 goto out; 537 } 538 539 if (ic->i_flowctl) { 540 credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT); 541 adv_credits += posted; 542 if (credit_alloc < work_alloc) { 543 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc); 544 work_alloc = credit_alloc; 545 flow_controlled = 1; 546 } 547 if (work_alloc == 0) { 548 set_bit(RDS_LL_SEND_FULL, &conn->c_flags); 549 rds_ib_stats_inc(s_ib_tx_throttle); 550 ret = -ENOMEM; 551 goto out; 552 } 553 } 554 555 /* map the message the first time we see it */ 556 if (!ic->i_data_op) { 557 if (rm->data.op_nents) { 558 rm->data.op_count = ib_dma_map_sg(dev, 559 rm->data.op_sg, 560 rm->data.op_nents, 561 DMA_TO_DEVICE); 562 rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count); 563 if (rm->data.op_count == 0) { 564 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure); 565 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 566 ret = -ENOMEM; /* XXX ? */ 567 goto out; 568 } 569 } else { 570 rm->data.op_count = 0; 571 } 572 573 rds_message_addref(rm); 574 rm->data.op_dmasg = 0; 575 rm->data.op_dmaoff = 0; 576 ic->i_data_op = &rm->data; 577 578 /* Finalize the header */ 579 if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags)) 580 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED; 581 if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) 582 rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED; 583 584 /* If it has a RDMA op, tell the peer we did it. This is 585 * used by the peer to release use-once RDMA MRs. */ 586 if (rm->rdma.op_active) { 587 struct rds_ext_header_rdma ext_hdr; 588 589 ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey); 590 rds_message_add_extension(&rm->m_inc.i_hdr, 591 RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr)); 592 } 593 if (rm->m_rdma_cookie) { 594 rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr, 595 rds_rdma_cookie_key(rm->m_rdma_cookie), 596 rds_rdma_cookie_offset(rm->m_rdma_cookie)); 597 } 598 599 /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so 600 * we should not do this unless we have a chance of at least 601 * sticking the header into the send ring. Which is why we 602 * should call rds_ib_ring_alloc first. */ 603 rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic)); 604 rds_message_make_checksum(&rm->m_inc.i_hdr); 605 606 /* 607 * Update adv_credits since we reset the ACK_REQUIRED bit. 608 */ 609 if (ic->i_flowctl) { 610 rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits); 611 adv_credits += posted; 612 BUG_ON(adv_credits > 255); 613 } 614 } 615 616 /* Sometimes you want to put a fence between an RDMA 617 * READ and the following SEND. 618 * We could either do this all the time 619 * or when requested by the user. Right now, we let 620 * the application choose. 621 */ 622 if (rm->rdma.op_active && rm->rdma.op_fence) 623 send_flags = IB_SEND_FENCE; 624 625 /* Each frag gets a header. Msgs may be 0 bytes */ 626 send = &ic->i_sends[pos]; 627 first = send; 628 prev = NULL; 629 scat = &ic->i_data_op->op_sg[rm->data.op_dmasg]; 630 i = 0; 631 do { 632 unsigned int len = 0; 633 634 /* Set up the header */ 635 send->s_wr.send_flags = send_flags; 636 send->s_wr.opcode = IB_WR_SEND; 637 send->s_wr.num_sge = 1; 638 send->s_wr.next = NULL; 639 send->s_queued = jiffies; 640 send->s_op = NULL; 641 642 send->s_sge[0].addr = ic->i_send_hdrs_dma 643 + (pos * sizeof(struct rds_header)); 644 send->s_sge[0].length = sizeof(struct rds_header); 645 646 memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header)); 647 648 /* Set up the data, if present */ 649 if (i < work_alloc 650 && scat != &rm->data.op_sg[rm->data.op_count]) { 651 len = min(RDS_FRAG_SIZE, 652 ib_sg_dma_len(dev, scat) - rm->data.op_dmaoff); 653 send->s_wr.num_sge = 2; 654 655 send->s_sge[1].addr = ib_sg_dma_address(dev, scat); 656 send->s_sge[1].addr += rm->data.op_dmaoff; 657 send->s_sge[1].length = len; 658 659 bytes_sent += len; 660 rm->data.op_dmaoff += len; 661 if (rm->data.op_dmaoff == ib_sg_dma_len(dev, scat)) { 662 scat++; 663 rm->data.op_dmasg++; 664 rm->data.op_dmaoff = 0; 665 } 666 } 667 668 rds_ib_set_wr_signal_state(ic, send, 0); 669 670 /* 671 * Always signal the last one if we're stopping due to flow control. 672 */ 673 if (ic->i_flowctl && flow_controlled && i == (work_alloc-1)) 674 send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; 675 676 if (send->s_wr.send_flags & IB_SEND_SIGNALED) 677 nr_sig++; 678 679 rdsdebug("send %p wr %p num_sge %u next %p\n", send, 680 &send->s_wr, send->s_wr.num_sge, send->s_wr.next); 681 682 if (ic->i_flowctl && adv_credits) { 683 struct rds_header *hdr = &ic->i_send_hdrs[pos]; 684 685 /* add credit and redo the header checksum */ 686 hdr->h_credit = adv_credits; 687 rds_message_make_checksum(hdr); 688 adv_credits = 0; 689 rds_ib_stats_inc(s_ib_tx_credit_updates); 690 } 691 692 if (prev) 693 prev->s_wr.next = &send->s_wr; 694 prev = send; 695 696 pos = (pos + 1) % ic->i_send_ring.w_nr; 697 send = &ic->i_sends[pos]; 698 i++; 699 700 } while (i < work_alloc 701 && scat != &rm->data.op_sg[rm->data.op_count]); 702 703 /* Account the RDS header in the number of bytes we sent, but just once. 704 * The caller has no concept of fragmentation. */ 705 if (hdr_off == 0) 706 bytes_sent += sizeof(struct rds_header); 707 708 /* if we finished the message then send completion owns it */ 709 if (scat == &rm->data.op_sg[rm->data.op_count]) { 710 prev->s_op = ic->i_data_op; 711 prev->s_wr.send_flags |= IB_SEND_SOLICITED; 712 if (!(prev->s_wr.send_flags & IB_SEND_SIGNALED)) { 713 ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs; 714 prev->s_wr.send_flags |= IB_SEND_SIGNALED; 715 nr_sig++; 716 } 717 ic->i_data_op = NULL; 718 } 719 720 /* Put back wrs & credits we didn't use */ 721 if (i < work_alloc) { 722 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i); 723 work_alloc = i; 724 } 725 if (ic->i_flowctl && i < credit_alloc) 726 rds_ib_send_add_credits(conn, credit_alloc - i); 727 728 if (nr_sig) 729 atomic_add(nr_sig, &ic->i_signaled_sends); 730 731 /* XXX need to worry about failed_wr and partial sends. */ 732 failed_wr = &first->s_wr; 733 ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr); 734 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic, 735 first, &first->s_wr, ret, failed_wr); 736 BUG_ON(failed_wr != &first->s_wr); 737 if (ret) { 738 printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 " 739 "returned %d\n", &conn->c_faddr, ret); 740 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 741 rds_ib_sub_signaled(ic, nr_sig); 742 if (prev->s_op) { 743 ic->i_data_op = prev->s_op; 744 prev->s_op = NULL; 745 } 746 747 rds_ib_conn_error(ic->conn, "ib_post_send failed\n"); 748 goto out; 749 } 750 751 ret = bytes_sent; 752 out: 753 BUG_ON(adv_credits); 754 return ret; 755 } 756 757 /* 758 * Issue atomic operation. 759 * A simplified version of the rdma case, we always map 1 SG, and 760 * only 8 bytes, for the return value from the atomic operation. 761 */ 762 int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op) 763 { 764 struct rds_ib_connection *ic = conn->c_transport_data; 765 struct rds_ib_send_work *send = NULL; 766 struct ib_send_wr *failed_wr; 767 struct rds_ib_device *rds_ibdev; 768 u32 pos; 769 u32 work_alloc; 770 int ret; 771 int nr_sig = 0; 772 773 rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client); 774 775 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos); 776 if (work_alloc != 1) { 777 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 778 rds_ib_stats_inc(s_ib_tx_ring_full); 779 ret = -ENOMEM; 780 goto out; 781 } 782 783 /* address of send request in ring */ 784 send = &ic->i_sends[pos]; 785 send->s_queued = jiffies; 786 787 if (op->op_type == RDS_ATOMIC_TYPE_CSWP) { 788 send->s_wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP; 789 send->s_wr.wr.atomic.compare_add = op->op_m_cswp.compare; 790 send->s_wr.wr.atomic.swap = op->op_m_cswp.swap; 791 send->s_wr.wr.atomic.compare_add_mask = op->op_m_cswp.compare_mask; 792 send->s_wr.wr.atomic.swap_mask = op->op_m_cswp.swap_mask; 793 } else { /* FADD */ 794 send->s_wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD; 795 send->s_wr.wr.atomic.compare_add = op->op_m_fadd.add; 796 send->s_wr.wr.atomic.swap = 0; 797 send->s_wr.wr.atomic.compare_add_mask = op->op_m_fadd.nocarry_mask; 798 send->s_wr.wr.atomic.swap_mask = 0; 799 } 800 nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify); 801 send->s_wr.num_sge = 1; 802 send->s_wr.next = NULL; 803 send->s_wr.wr.atomic.remote_addr = op->op_remote_addr; 804 send->s_wr.wr.atomic.rkey = op->op_rkey; 805 send->s_op = op; 806 rds_message_addref(container_of(send->s_op, struct rds_message, atomic)); 807 808 /* map 8 byte retval buffer to the device */ 809 ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE); 810 rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret); 811 if (ret != 1) { 812 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 813 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure); 814 ret = -ENOMEM; /* XXX ? */ 815 goto out; 816 } 817 818 /* Convert our struct scatterlist to struct ib_sge */ 819 send->s_sge[0].addr = ib_sg_dma_address(ic->i_cm_id->device, op->op_sg); 820 send->s_sge[0].length = ib_sg_dma_len(ic->i_cm_id->device, op->op_sg); 821 send->s_sge[0].lkey = ic->i_pd->local_dma_lkey; 822 823 rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr, 824 send->s_sge[0].addr, send->s_sge[0].length); 825 826 if (nr_sig) 827 atomic_add(nr_sig, &ic->i_signaled_sends); 828 829 failed_wr = &send->s_wr; 830 ret = ib_post_send(ic->i_cm_id->qp, &send->s_wr, &failed_wr); 831 rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic, 832 send, &send->s_wr, ret, failed_wr); 833 BUG_ON(failed_wr != &send->s_wr); 834 if (ret) { 835 printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI4 " 836 "returned %d\n", &conn->c_faddr, ret); 837 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 838 rds_ib_sub_signaled(ic, nr_sig); 839 goto out; 840 } 841 842 if (unlikely(failed_wr != &send->s_wr)) { 843 printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret); 844 BUG_ON(failed_wr != &send->s_wr); 845 } 846 847 out: 848 return ret; 849 } 850 851 int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op) 852 { 853 struct rds_ib_connection *ic = conn->c_transport_data; 854 struct rds_ib_send_work *send = NULL; 855 struct rds_ib_send_work *first; 856 struct rds_ib_send_work *prev; 857 struct ib_send_wr *failed_wr; 858 struct scatterlist *scat; 859 unsigned long len; 860 u64 remote_addr = op->op_remote_addr; 861 u32 max_sge = ic->rds_ibdev->max_sge; 862 u32 pos; 863 u32 work_alloc; 864 u32 i; 865 u32 j; 866 int sent; 867 int ret; 868 int num_sge; 869 int nr_sig = 0; 870 871 /* map the op the first time we see it */ 872 if (!op->op_mapped) { 873 op->op_count = ib_dma_map_sg(ic->i_cm_id->device, 874 op->op_sg, op->op_nents, (op->op_write) ? 875 DMA_TO_DEVICE : DMA_FROM_DEVICE); 876 rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count); 877 if (op->op_count == 0) { 878 rds_ib_stats_inc(s_ib_tx_sg_mapping_failure); 879 ret = -ENOMEM; /* XXX ? */ 880 goto out; 881 } 882 883 op->op_mapped = 1; 884 } 885 886 /* 887 * Instead of knowing how to return a partial rdma read/write we insist that there 888 * be enough work requests to send the entire message. 889 */ 890 i = ceil(op->op_count, max_sge); 891 892 work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos); 893 if (work_alloc != i) { 894 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 895 rds_ib_stats_inc(s_ib_tx_ring_full); 896 ret = -ENOMEM; 897 goto out; 898 } 899 900 send = &ic->i_sends[pos]; 901 first = send; 902 prev = NULL; 903 scat = &op->op_sg[0]; 904 sent = 0; 905 num_sge = op->op_count; 906 907 for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) { 908 send->s_wr.send_flags = 0; 909 send->s_queued = jiffies; 910 send->s_op = NULL; 911 912 nr_sig += rds_ib_set_wr_signal_state(ic, send, op->op_notify); 913 914 send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ; 915 send->s_wr.wr.rdma.remote_addr = remote_addr; 916 send->s_wr.wr.rdma.rkey = op->op_rkey; 917 918 if (num_sge > max_sge) { 919 send->s_wr.num_sge = max_sge; 920 num_sge -= max_sge; 921 } else { 922 send->s_wr.num_sge = num_sge; 923 } 924 925 send->s_wr.next = NULL; 926 927 if (prev) 928 prev->s_wr.next = &send->s_wr; 929 930 for (j = 0; j < send->s_wr.num_sge && scat != &op->op_sg[op->op_count]; j++) { 931 len = ib_sg_dma_len(ic->i_cm_id->device, scat); 932 send->s_sge[j].addr = 933 ib_sg_dma_address(ic->i_cm_id->device, scat); 934 send->s_sge[j].length = len; 935 send->s_sge[j].lkey = ic->i_pd->local_dma_lkey; 936 937 sent += len; 938 rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr); 939 940 remote_addr += len; 941 scat++; 942 } 943 944 rdsdebug("send %p wr %p num_sge %u next %p\n", send, 945 &send->s_wr, send->s_wr.num_sge, send->s_wr.next); 946 947 prev = send; 948 if (++send == &ic->i_sends[ic->i_send_ring.w_nr]) 949 send = ic->i_sends; 950 } 951 952 /* give a reference to the last op */ 953 if (scat == &op->op_sg[op->op_count]) { 954 prev->s_op = op; 955 rds_message_addref(container_of(op, struct rds_message, rdma)); 956 } 957 958 if (i < work_alloc) { 959 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i); 960 work_alloc = i; 961 } 962 963 if (nr_sig) 964 atomic_add(nr_sig, &ic->i_signaled_sends); 965 966 failed_wr = &first->s_wr; 967 ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr); 968 rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic, 969 first, &first->s_wr, ret, failed_wr); 970 BUG_ON(failed_wr != &first->s_wr); 971 if (ret) { 972 printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 " 973 "returned %d\n", &conn->c_faddr, ret); 974 rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); 975 rds_ib_sub_signaled(ic, nr_sig); 976 goto out; 977 } 978 979 if (unlikely(failed_wr != &first->s_wr)) { 980 printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret); 981 BUG_ON(failed_wr != &first->s_wr); 982 } 983 984 985 out: 986 return ret; 987 } 988 989 void rds_ib_xmit_complete(struct rds_connection *conn) 990 { 991 struct rds_ib_connection *ic = conn->c_transport_data; 992 993 /* We may have a pending ACK or window update we were unable 994 * to send previously (due to flow control). Try again. */ 995 rds_ib_attempt_ack(ic); 996 } 997