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v3.15
   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
  42static char *rds_ib_wc_status_strings[] = {
  43#define RDS_IB_WC_STATUS_STR(foo) \
  44		[IB_WC_##foo] = __stringify(IB_WC_##foo)
  45	RDS_IB_WC_STATUS_STR(SUCCESS),
  46	RDS_IB_WC_STATUS_STR(LOC_LEN_ERR),
  47	RDS_IB_WC_STATUS_STR(LOC_QP_OP_ERR),
  48	RDS_IB_WC_STATUS_STR(LOC_EEC_OP_ERR),
  49	RDS_IB_WC_STATUS_STR(LOC_PROT_ERR),
  50	RDS_IB_WC_STATUS_STR(WR_FLUSH_ERR),
  51	RDS_IB_WC_STATUS_STR(MW_BIND_ERR),
  52	RDS_IB_WC_STATUS_STR(BAD_RESP_ERR),
  53	RDS_IB_WC_STATUS_STR(LOC_ACCESS_ERR),
  54	RDS_IB_WC_STATUS_STR(REM_INV_REQ_ERR),
  55	RDS_IB_WC_STATUS_STR(REM_ACCESS_ERR),
  56	RDS_IB_WC_STATUS_STR(REM_OP_ERR),
  57	RDS_IB_WC_STATUS_STR(RETRY_EXC_ERR),
  58	RDS_IB_WC_STATUS_STR(RNR_RETRY_EXC_ERR),
  59	RDS_IB_WC_STATUS_STR(LOC_RDD_VIOL_ERR),
  60	RDS_IB_WC_STATUS_STR(REM_INV_RD_REQ_ERR),
  61	RDS_IB_WC_STATUS_STR(REM_ABORT_ERR),
  62	RDS_IB_WC_STATUS_STR(INV_EECN_ERR),
  63	RDS_IB_WC_STATUS_STR(INV_EEC_STATE_ERR),
  64	RDS_IB_WC_STATUS_STR(FATAL_ERR),
  65	RDS_IB_WC_STATUS_STR(RESP_TIMEOUT_ERR),
  66	RDS_IB_WC_STATUS_STR(GENERAL_ERR),
  67#undef RDS_IB_WC_STATUS_STR
  68};
  69
  70char *rds_ib_wc_status_str(enum ib_wc_status status)
  71{
  72	return rds_str_array(rds_ib_wc_status_strings,
  73			     ARRAY_SIZE(rds_ib_wc_status_strings), status);
  74}
  75
  76/*
  77 * Convert IB-specific error message to RDS error message and call core
  78 * completion handler.
  79 */
  80static void rds_ib_send_complete(struct rds_message *rm,
  81				 int wc_status,
  82				 void (*complete)(struct rds_message *rm, int status))
  83{
  84	int notify_status;
  85
  86	switch (wc_status) {
  87	case IB_WC_WR_FLUSH_ERR:
  88		return;
  89
  90	case IB_WC_SUCCESS:
  91		notify_status = RDS_RDMA_SUCCESS;
  92		break;
  93
  94	case IB_WC_REM_ACCESS_ERR:
  95		notify_status = RDS_RDMA_REMOTE_ERROR;
  96		break;
  97
  98	default:
  99		notify_status = RDS_RDMA_OTHER_ERROR;
 100		break;
 101	}
 102	complete(rm, notify_status);
 103}
 104
 105static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
 106				   struct rm_data_op *op,
 107				   int wc_status)
 108{
 109	if (op->op_nents)
 110		ib_dma_unmap_sg(ic->i_cm_id->device,
 111				op->op_sg, op->op_nents,
 112				DMA_TO_DEVICE);
 113}
 114
 115static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
 116				   struct rm_rdma_op *op,
 117				   int wc_status)
 118{
 119	if (op->op_mapped) {
 120		ib_dma_unmap_sg(ic->i_cm_id->device,
 121				op->op_sg, op->op_nents,
 122				op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 123		op->op_mapped = 0;
 124	}
 125
 126	/* If the user asked for a completion notification on this
 127	 * message, we can implement three different semantics:
 128	 *  1.	Notify when we received the ACK on the RDS message
 129	 *	that was queued with the RDMA. This provides reliable
 130	 *	notification of RDMA status at the expense of a one-way
 131	 *	packet delay.
 132	 *  2.	Notify when the IB stack gives us the completion event for
 133	 *	the RDMA operation.
 134	 *  3.	Notify when the IB stack gives us the completion event for
 135	 *	the accompanying RDS messages.
 136	 * Here, we implement approach #3. To implement approach #2,
 137	 * we would need to take an event for the rdma WR. To implement #1,
 138	 * don't call rds_rdma_send_complete at all, and fall back to the notify
 139	 * handling in the ACK processing code.
 140	 *
 141	 * Note: There's no need to explicitly sync any RDMA buffers using
 142	 * ib_dma_sync_sg_for_cpu - the completion for the RDMA
 143	 * operation itself unmapped the RDMA buffers, which takes care
 144	 * of synching.
 145	 */
 146	rds_ib_send_complete(container_of(op, struct rds_message, rdma),
 147			     wc_status, rds_rdma_send_complete);
 148
 149	if (op->op_write)
 150		rds_stats_add(s_send_rdma_bytes, op->op_bytes);
 151	else
 152		rds_stats_add(s_recv_rdma_bytes, op->op_bytes);
 153}
 154
 155static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
 156				     struct rm_atomic_op *op,
 157				     int wc_status)
 158{
 159	/* unmap atomic recvbuf */
 160	if (op->op_mapped) {
 161		ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1,
 162				DMA_FROM_DEVICE);
 163		op->op_mapped = 0;
 164	}
 165
 166	rds_ib_send_complete(container_of(op, struct rds_message, atomic),
 167			     wc_status, rds_atomic_send_complete);
 168
 169	if (op->op_type == RDS_ATOMIC_TYPE_CSWP)
 170		rds_ib_stats_inc(s_ib_atomic_cswp);
 171	else
 172		rds_ib_stats_inc(s_ib_atomic_fadd);
 173}
 174
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 175/*
 176 * Unmap the resources associated with a struct send_work.
 177 *
 178 * Returns the rm for no good reason other than it is unobtainable
 179 * other than by switching on wr.opcode, currently, and the caller,
 180 * the event handler, needs it.
 181 */
 182static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic,
 183						struct rds_ib_send_work *send,
 184						int wc_status)
 185{
 186	struct rds_message *rm = NULL;
 187
 188	/* In the error case, wc.opcode sometimes contains garbage */
 189	switch (send->s_wr.opcode) {
 190	case IB_WR_SEND:
 191		if (send->s_op) {
 192			rm = container_of(send->s_op, struct rds_message, data);
 193			rds_ib_send_unmap_data(ic, send->s_op, wc_status);
 194		}
 195		break;
 196	case IB_WR_RDMA_WRITE:
 197	case IB_WR_RDMA_READ:
 198		if (send->s_op) {
 199			rm = container_of(send->s_op, struct rds_message, rdma);
 200			rds_ib_send_unmap_rdma(ic, send->s_op, wc_status);
 201		}
 202		break;
 203	case IB_WR_ATOMIC_FETCH_AND_ADD:
 204	case IB_WR_ATOMIC_CMP_AND_SWP:
 205		if (send->s_op) {
 206			rm = container_of(send->s_op, struct rds_message, atomic);
 207			rds_ib_send_unmap_atomic(ic, send->s_op, wc_status);
 208		}
 209		break;
 210	default:
 211		printk_ratelimited(KERN_NOTICE
 212			       "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
 213			       __func__, send->s_wr.opcode);
 214		break;
 215	}
 216
 217	send->s_wr.opcode = 0xdead;
 218
 219	return rm;
 220}
 221
 222void rds_ib_send_init_ring(struct rds_ib_connection *ic)
 223{
 224	struct rds_ib_send_work *send;
 225	u32 i;
 226
 227	for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
 228		struct ib_sge *sge;
 229
 230		send->s_op = NULL;
 231
 232		send->s_wr.wr_id = i;
 233		send->s_wr.sg_list = send->s_sge;
 234		send->s_wr.ex.imm_data = 0;
 235
 236		sge = &send->s_sge[0];
 237		sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
 238		sge->length = sizeof(struct rds_header);
 239		sge->lkey = ic->i_mr->lkey;
 240
 241		send->s_sge[1].lkey = ic->i_mr->lkey;
 242	}
 243}
 244
 245void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
 246{
 247	struct rds_ib_send_work *send;
 248	u32 i;
 249
 250	for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
 251		if (send->s_op && send->s_wr.opcode != 0xdead)
 252			rds_ib_send_unmap_op(ic, send, IB_WC_WR_FLUSH_ERR);
 253	}
 254}
 255
 256/*
 257 * The only fast path caller always has a non-zero nr, so we don't
 258 * bother testing nr before performing the atomic sub.
 259 */
 260static void rds_ib_sub_signaled(struct rds_ib_connection *ic, int nr)
 261{
 262	if ((atomic_sub_return(nr, &ic->i_signaled_sends) == 0) &&
 263	    waitqueue_active(&rds_ib_ring_empty_wait))
 264		wake_up(&rds_ib_ring_empty_wait);
 265	BUG_ON(atomic_read(&ic->i_signaled_sends) < 0);
 266}
 267
 268/*
 269 * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
 270 * operations performed in the send path.  As the sender allocs and potentially
 271 * unallocs the next free entry in the ring it doesn't alter which is
 272 * the next to be freed, which is what this is concerned with.
 273 */
 274void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context)
 275{
 276	struct rds_connection *conn = context;
 277	struct rds_ib_connection *ic = conn->c_transport_data;
 278	struct rds_message *rm = NULL;
 279	struct ib_wc wc;
 280	struct rds_ib_send_work *send;
 281	u32 completed;
 282	u32 oldest;
 283	u32 i = 0;
 284	int ret;
 285	int nr_sig = 0;
 286
 287	rdsdebug("cq %p conn %p\n", cq, conn);
 288	rds_ib_stats_inc(s_ib_tx_cq_call);
 289	ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
 290	if (ret)
 291		rdsdebug("ib_req_notify_cq send failed: %d\n", ret);
 292
 293	while (ib_poll_cq(cq, 1, &wc) > 0) {
 294		rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
 295			 (unsigned long long)wc.wr_id, wc.status,
 296			 rds_ib_wc_status_str(wc.status), wc.byte_len,
 297			 be32_to_cpu(wc.ex.imm_data));
 298		rds_ib_stats_inc(s_ib_tx_cq_event);
 299
 300		if (wc.wr_id == RDS_IB_ACK_WR_ID) {
 301			if (ic->i_ack_queued + HZ/2 < jiffies)
 302				rds_ib_stats_inc(s_ib_tx_stalled);
 303			rds_ib_ack_send_complete(ic);
 304			continue;
 305		}
 306
 307		oldest = rds_ib_ring_oldest(&ic->i_send_ring);
 308
 309		completed = rds_ib_ring_completed(&ic->i_send_ring, wc.wr_id, oldest);
 310
 311		for (i = 0; i < completed; i++) {
 312			send = &ic->i_sends[oldest];
 313			if (send->s_wr.send_flags & IB_SEND_SIGNALED)
 314				nr_sig++;
 315
 316			rm = rds_ib_send_unmap_op(ic, send, wc.status);
 317
 318			if (send->s_queued + HZ/2 < jiffies)
 319				rds_ib_stats_inc(s_ib_tx_stalled);
 320
 321			if (send->s_op) {
 322				if (send->s_op == rm->m_final_op) {
 323					/* If anyone waited for this message to get flushed out, wake
 324					 * them up now */
 325					rds_message_unmapped(rm);
 326				}
 327				rds_message_put(rm);
 328				send->s_op = NULL;
 329			}
 330
 331			oldest = (oldest + 1) % ic->i_send_ring.w_nr;
 332		}
 
 
 
 
 
 
 
 
 
 
 333
 334		rds_ib_ring_free(&ic->i_send_ring, completed);
 335		rds_ib_sub_signaled(ic, nr_sig);
 336		nr_sig = 0;
 
 
 
 
 
 
 
 
 
 
 337
 338		if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
 339		    test_bit(0, &conn->c_map_queued))
 340			queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 341
 342		/* We expect errors as the qp is drained during shutdown */
 343		if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) {
 344			rds_ib_conn_error(conn, "send completion on %pI4 had status "
 345					  "%u (%s), disconnecting and reconnecting\n",
 346					  &conn->c_faddr, wc.status,
 347					  rds_ib_wc_status_str(wc.status));
 348		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 349	}
 350}
 351
 352/*
 353 * This is the main function for allocating credits when sending
 354 * messages.
 355 *
 356 * Conceptually, we have two counters:
 357 *  -	send credits: this tells us how many WRs we're allowed
 358 *	to submit without overruning the receiver's queue. For
 359 *	each SEND WR we post, we decrement this by one.
 360 *
 361 *  -	posted credits: this tells us how many WRs we recently
 362 *	posted to the receive queue. This value is transferred
 363 *	to the peer as a "credit update" in a RDS header field.
 364 *	Every time we transmit credits to the peer, we subtract
 365 *	the amount of transferred credits from this counter.
 366 *
 367 * It is essential that we avoid situations where both sides have
 368 * exhausted their send credits, and are unable to send new credits
 369 * to the peer. We achieve this by requiring that we send at least
 370 * one credit update to the peer before exhausting our credits.
 371 * When new credits arrive, we subtract one credit that is withheld
 372 * until we've posted new buffers and are ready to transmit these
 373 * credits (see rds_ib_send_add_credits below).
 374 *
 375 * The RDS send code is essentially single-threaded; rds_send_xmit
 376 * sets RDS_IN_XMIT to ensure exclusive access to the send ring.
 377 * However, the ACK sending code is independent and can race with
 378 * message SENDs.
 379 *
 380 * In the send path, we need to update the counters for send credits
 381 * and the counter of posted buffers atomically - when we use the
 382 * last available credit, we cannot allow another thread to race us
 383 * and grab the posted credits counter.  Hence, we have to use a
 384 * spinlock to protect the credit counter, or use atomics.
 385 *
 386 * Spinlocks shared between the send and the receive path are bad,
 387 * because they create unnecessary delays. An early implementation
 388 * using a spinlock showed a 5% degradation in throughput at some
 389 * loads.
 390 *
 391 * This implementation avoids spinlocks completely, putting both
 392 * counters into a single atomic, and updating that atomic using
 393 * atomic_add (in the receive path, when receiving fresh credits),
 394 * and using atomic_cmpxchg when updating the two counters.
 395 */
 396int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
 397			     u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
 398{
 399	unsigned int avail, posted, got = 0, advertise;
 400	long oldval, newval;
 401
 402	*adv_credits = 0;
 403	if (!ic->i_flowctl)
 404		return wanted;
 405
 406try_again:
 407	advertise = 0;
 408	oldval = newval = atomic_read(&ic->i_credits);
 409	posted = IB_GET_POST_CREDITS(oldval);
 410	avail = IB_GET_SEND_CREDITS(oldval);
 411
 412	rdsdebug("rds_ib_send_grab_credits(%u): credits=%u posted=%u\n",
 413			wanted, avail, posted);
 414
 415	/* The last credit must be used to send a credit update. */
 416	if (avail && !posted)
 417		avail--;
 418
 419	if (avail < wanted) {
 420		struct rds_connection *conn = ic->i_cm_id->context;
 421
 422		/* Oops, there aren't that many credits left! */
 423		set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
 424		got = avail;
 425	} else {
 426		/* Sometimes you get what you want, lalala. */
 427		got = wanted;
 428	}
 429	newval -= IB_SET_SEND_CREDITS(got);
 430
 431	/*
 432	 * If need_posted is non-zero, then the caller wants
 433	 * the posted regardless of whether any send credits are
 434	 * available.
 435	 */
 436	if (posted && (got || need_posted)) {
 437		advertise = min_t(unsigned int, posted, max_posted);
 438		newval -= IB_SET_POST_CREDITS(advertise);
 439	}
 440
 441	/* Finally bill everything */
 442	if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
 443		goto try_again;
 444
 445	*adv_credits = advertise;
 446	return got;
 447}
 448
 449void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
 450{
 451	struct rds_ib_connection *ic = conn->c_transport_data;
 452
 453	if (credits == 0)
 454		return;
 455
 456	rdsdebug("rds_ib_send_add_credits(%u): current=%u%s\n",
 457			credits,
 458			IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
 459			test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
 460
 461	atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
 462	if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
 463		queue_delayed_work(rds_wq, &conn->c_send_w, 0);
 464
 465	WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
 466
 467	rds_ib_stats_inc(s_ib_rx_credit_updates);
 468}
 469
 470void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
 471{
 472	struct rds_ib_connection *ic = conn->c_transport_data;
 473
 474	if (posted == 0)
 475		return;
 476
 477	atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
 478
 479	/* Decide whether to send an update to the peer now.
 480	 * If we would send a credit update for every single buffer we
 481	 * post, we would end up with an ACK storm (ACK arrives,
 482	 * consumes buffer, we refill the ring, send ACK to remote
 483	 * advertising the newly posted buffer... ad inf)
 484	 *
 485	 * Performance pretty much depends on how often we send
 486	 * credit updates - too frequent updates mean lots of ACKs.
 487	 * Too infrequent updates, and the peer will run out of
 488	 * credits and has to throttle.
 489	 * For the time being, 16 seems to be a good compromise.
 490	 */
 491	if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
 492		set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 493}
 494
 495static inline int rds_ib_set_wr_signal_state(struct rds_ib_connection *ic,
 496					     struct rds_ib_send_work *send,
 497					     bool notify)
 498{
 499	/*
 500	 * We want to delay signaling completions just enough to get
 501	 * the batching benefits but not so much that we create dead time
 502	 * on the wire.
 503	 */
 504	if (ic->i_unsignaled_wrs-- == 0 || notify) {
 505		ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
 506		send->s_wr.send_flags |= IB_SEND_SIGNALED;
 507		return 1;
 508	}
 509	return 0;
 510}
 511
 512/*
 513 * This can be called multiple times for a given message.  The first time
 514 * we see a message we map its scatterlist into the IB device so that
 515 * we can provide that mapped address to the IB scatter gather entries
 516 * in the IB work requests.  We translate the scatterlist into a series
 517 * of work requests that fragment the message.  These work requests complete
 518 * in order so we pass ownership of the message to the completion handler
 519 * once we send the final fragment.
 520 *
 521 * The RDS core uses the c_send_lock to only enter this function once
 522 * per connection.  This makes sure that the tx ring alloc/unalloc pairs
 523 * don't get out of sync and confuse the ring.
 524 */
 525int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
 526		unsigned int hdr_off, unsigned int sg, unsigned int off)
 527{
 528	struct rds_ib_connection *ic = conn->c_transport_data;
 529	struct ib_device *dev = ic->i_cm_id->device;
 530	struct rds_ib_send_work *send = NULL;
 531	struct rds_ib_send_work *first;
 532	struct rds_ib_send_work *prev;
 533	struct ib_send_wr *failed_wr;
 534	struct scatterlist *scat;
 535	u32 pos;
 536	u32 i;
 537	u32 work_alloc;
 538	u32 credit_alloc = 0;
 539	u32 posted;
 540	u32 adv_credits = 0;
 541	int send_flags = 0;
 542	int bytes_sent = 0;
 543	int ret;
 544	int flow_controlled = 0;
 545	int nr_sig = 0;
 546
 547	BUG_ON(off % RDS_FRAG_SIZE);
 548	BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
 549
 550	/* Do not send cong updates to IB loopback */
 551	if (conn->c_loopback
 552	    && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
 553		rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
 554		scat = &rm->data.op_sg[sg];
 555		ret = max_t(int, RDS_CONG_MAP_BYTES, scat->length);
 556		return sizeof(struct rds_header) + ret;
 557	}
 558
 559	/* FIXME we may overallocate here */
 560	if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
 561		i = 1;
 562	else
 563		i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
 564
 565	work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
 566	if (work_alloc == 0) {
 567		set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
 568		rds_ib_stats_inc(s_ib_tx_ring_full);
 569		ret = -ENOMEM;
 570		goto out;
 571	}
 572
 573	if (ic->i_flowctl) {
 574		credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
 575		adv_credits += posted;
 576		if (credit_alloc < work_alloc) {
 577			rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
 578			work_alloc = credit_alloc;
 579			flow_controlled = 1;
 580		}
 581		if (work_alloc == 0) {
 582			set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
 583			rds_ib_stats_inc(s_ib_tx_throttle);
 584			ret = -ENOMEM;
 585			goto out;
 586		}
 587	}
 588
 589	/* map the message the first time we see it */
 590	if (!ic->i_data_op) {
 591		if (rm->data.op_nents) {
 592			rm->data.op_count = ib_dma_map_sg(dev,
 593							  rm->data.op_sg,
 594							  rm->data.op_nents,
 595							  DMA_TO_DEVICE);
 596			rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
 597			if (rm->data.op_count == 0) {
 598				rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
 599				rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
 600				ret = -ENOMEM; /* XXX ? */
 601				goto out;
 602			}
 603		} else {
 604			rm->data.op_count = 0;
 605		}
 606
 607		rds_message_addref(rm);
 
 
 608		ic->i_data_op = &rm->data;
 609
 610		/* Finalize the header */
 611		if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
 612			rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
 613		if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
 614			rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
 615
 616		/* If it has a RDMA op, tell the peer we did it. This is
 617		 * used by the peer to release use-once RDMA MRs. */
 618		if (rm->rdma.op_active) {
 619			struct rds_ext_header_rdma ext_hdr;
 620
 621			ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
 622			rds_message_add_extension(&rm->m_inc.i_hdr,
 623					RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
 624		}
 625		if (rm->m_rdma_cookie) {
 626			rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
 627					rds_rdma_cookie_key(rm->m_rdma_cookie),
 628					rds_rdma_cookie_offset(rm->m_rdma_cookie));
 629		}
 630
 631		/* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
 632		 * we should not do this unless we have a chance of at least
 633		 * sticking the header into the send ring. Which is why we
 634		 * should call rds_ib_ring_alloc first. */
 635		rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
 636		rds_message_make_checksum(&rm->m_inc.i_hdr);
 637
 638		/*
 639		 * Update adv_credits since we reset the ACK_REQUIRED bit.
 640		 */
 641		if (ic->i_flowctl) {
 642			rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
 643			adv_credits += posted;
 644			BUG_ON(adv_credits > 255);
 645		}
 646	}
 647
 648	/* Sometimes you want to put a fence between an RDMA
 649	 * READ and the following SEND.
 650	 * We could either do this all the time
 651	 * or when requested by the user. Right now, we let
 652	 * the application choose.
 653	 */
 654	if (rm->rdma.op_active && rm->rdma.op_fence)
 655		send_flags = IB_SEND_FENCE;
 656
 657	/* Each frag gets a header. Msgs may be 0 bytes */
 658	send = &ic->i_sends[pos];
 659	first = send;
 660	prev = NULL;
 661	scat = &ic->i_data_op->op_sg[sg];
 662	i = 0;
 663	do {
 664		unsigned int len = 0;
 665
 666		/* Set up the header */
 667		send->s_wr.send_flags = send_flags;
 668		send->s_wr.opcode = IB_WR_SEND;
 669		send->s_wr.num_sge = 1;
 670		send->s_wr.next = NULL;
 671		send->s_queued = jiffies;
 672		send->s_op = NULL;
 673
 674		send->s_sge[0].addr = ic->i_send_hdrs_dma
 675			+ (pos * sizeof(struct rds_header));
 676		send->s_sge[0].length = sizeof(struct rds_header);
 677
 678		memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
 679
 680		/* Set up the data, if present */
 681		if (i < work_alloc
 682		    && scat != &rm->data.op_sg[rm->data.op_count]) {
 683			len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off);
 
 684			send->s_wr.num_sge = 2;
 685
 686			send->s_sge[1].addr = ib_sg_dma_address(dev, scat) + off;
 
 687			send->s_sge[1].length = len;
 688
 689			bytes_sent += len;
 690			off += len;
 691			if (off == ib_sg_dma_len(dev, scat)) {
 692				scat++;
 693				off = 0;
 
 694			}
 695		}
 696
 697		rds_ib_set_wr_signal_state(ic, send, 0);
 698
 699		/*
 700		 * Always signal the last one if we're stopping due to flow control.
 701		 */
 702		if (ic->i_flowctl && flow_controlled && i == (work_alloc-1))
 703			send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED;
 
 
 704
 705		if (send->s_wr.send_flags & IB_SEND_SIGNALED)
 706			nr_sig++;
 707
 708		rdsdebug("send %p wr %p num_sge %u next %p\n", send,
 709			 &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
 710
 711		if (ic->i_flowctl && adv_credits) {
 712			struct rds_header *hdr = &ic->i_send_hdrs[pos];
 713
 714			/* add credit and redo the header checksum */
 715			hdr->h_credit = adv_credits;
 716			rds_message_make_checksum(hdr);
 717			adv_credits = 0;
 718			rds_ib_stats_inc(s_ib_tx_credit_updates);
 719		}
 720
 721		if (prev)
 722			prev->s_wr.next = &send->s_wr;
 723		prev = send;
 724
 725		pos = (pos + 1) % ic->i_send_ring.w_nr;
 726		send = &ic->i_sends[pos];
 727		i++;
 728
 729	} while (i < work_alloc
 730		 && scat != &rm->data.op_sg[rm->data.op_count]);
 731
 732	/* Account the RDS header in the number of bytes we sent, but just once.
 733	 * The caller has no concept of fragmentation. */
 734	if (hdr_off == 0)
 735		bytes_sent += sizeof(struct rds_header);
 736
 737	/* if we finished the message then send completion owns it */
 738	if (scat == &rm->data.op_sg[rm->data.op_count]) {
 739		prev->s_op = ic->i_data_op;
 740		prev->s_wr.send_flags |= IB_SEND_SOLICITED;
 
 
 741		ic->i_data_op = NULL;
 742	}
 743
 744	/* Put back wrs & credits we didn't use */
 745	if (i < work_alloc) {
 746		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
 747		work_alloc = i;
 748	}
 749	if (ic->i_flowctl && i < credit_alloc)
 750		rds_ib_send_add_credits(conn, credit_alloc - i);
 751
 752	if (nr_sig)
 753		atomic_add(nr_sig, &ic->i_signaled_sends);
 754
 755	/* XXX need to worry about failed_wr and partial sends. */
 756	failed_wr = &first->s_wr;
 757	ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
 758	rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
 759		 first, &first->s_wr, ret, failed_wr);
 760	BUG_ON(failed_wr != &first->s_wr);
 761	if (ret) {
 762		printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 "
 763		       "returned %d\n", &conn->c_faddr, ret);
 764		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
 765		rds_ib_sub_signaled(ic, nr_sig);
 766		if (prev->s_op) {
 767			ic->i_data_op = prev->s_op;
 768			prev->s_op = NULL;
 769		}
 770
 771		rds_ib_conn_error(ic->conn, "ib_post_send failed\n");
 772		goto out;
 773	}
 774
 775	ret = bytes_sent;
 776out:
 777	BUG_ON(adv_credits);
 778	return ret;
 779}
 780
 781/*
 782 * Issue atomic operation.
 783 * A simplified version of the rdma case, we always map 1 SG, and
 784 * only 8 bytes, for the return value from the atomic operation.
 785 */
 786int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
 787{
 788	struct rds_ib_connection *ic = conn->c_transport_data;
 789	struct rds_ib_send_work *send = NULL;
 790	struct ib_send_wr *failed_wr;
 791	struct rds_ib_device *rds_ibdev;
 792	u32 pos;
 793	u32 work_alloc;
 794	int ret;
 795	int nr_sig = 0;
 796
 797	rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
 798
 799	work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
 800	if (work_alloc != 1) {
 801		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
 802		rds_ib_stats_inc(s_ib_tx_ring_full);
 803		ret = -ENOMEM;
 804		goto out;
 805	}
 806
 807	/* address of send request in ring */
 808	send = &ic->i_sends[pos];
 809	send->s_queued = jiffies;
 810
 811	if (op->op_type == RDS_ATOMIC_TYPE_CSWP) {
 812		send->s_wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP;
 813		send->s_wr.wr.atomic.compare_add = op->op_m_cswp.compare;
 814		send->s_wr.wr.atomic.swap = op->op_m_cswp.swap;
 815		send->s_wr.wr.atomic.compare_add_mask = op->op_m_cswp.compare_mask;
 816		send->s_wr.wr.atomic.swap_mask = op->op_m_cswp.swap_mask;
 817	} else { /* FADD */
 818		send->s_wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD;
 819		send->s_wr.wr.atomic.compare_add = op->op_m_fadd.add;
 820		send->s_wr.wr.atomic.swap = 0;
 821		send->s_wr.wr.atomic.compare_add_mask = op->op_m_fadd.nocarry_mask;
 822		send->s_wr.wr.atomic.swap_mask = 0;
 823	}
 
 824	nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify);
 825	send->s_wr.num_sge = 1;
 826	send->s_wr.next = NULL;
 827	send->s_wr.wr.atomic.remote_addr = op->op_remote_addr;
 828	send->s_wr.wr.atomic.rkey = op->op_rkey;
 829	send->s_op = op;
 830	rds_message_addref(container_of(send->s_op, struct rds_message, atomic));
 831
 832	/* map 8 byte retval buffer to the device */
 833	ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE);
 834	rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret);
 835	if (ret != 1) {
 836		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
 837		rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
 838		ret = -ENOMEM; /* XXX ? */
 839		goto out;
 840	}
 841
 842	/* Convert our struct scatterlist to struct ib_sge */
 843	send->s_sge[0].addr = ib_sg_dma_address(ic->i_cm_id->device, op->op_sg);
 844	send->s_sge[0].length = ib_sg_dma_len(ic->i_cm_id->device, op->op_sg);
 845	send->s_sge[0].lkey = ic->i_mr->lkey;
 846
 847	rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
 848		 send->s_sge[0].addr, send->s_sge[0].length);
 849
 850	if (nr_sig)
 851		atomic_add(nr_sig, &ic->i_signaled_sends);
 852
 853	failed_wr = &send->s_wr;
 854	ret = ib_post_send(ic->i_cm_id->qp, &send->s_wr, &failed_wr);
 855	rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
 856		 send, &send->s_wr, ret, failed_wr);
 857	BUG_ON(failed_wr != &send->s_wr);
 858	if (ret) {
 859		printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI4 "
 860		       "returned %d\n", &conn->c_faddr, ret);
 861		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
 862		rds_ib_sub_signaled(ic, nr_sig);
 863		goto out;
 864	}
 865
 866	if (unlikely(failed_wr != &send->s_wr)) {
 867		printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
 868		BUG_ON(failed_wr != &send->s_wr);
 869	}
 870
 871out:
 872	return ret;
 873}
 874
 875int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
 876{
 877	struct rds_ib_connection *ic = conn->c_transport_data;
 878	struct rds_ib_send_work *send = NULL;
 879	struct rds_ib_send_work *first;
 880	struct rds_ib_send_work *prev;
 881	struct ib_send_wr *failed_wr;
 882	struct scatterlist *scat;
 883	unsigned long len;
 884	u64 remote_addr = op->op_remote_addr;
 885	u32 max_sge = ic->rds_ibdev->max_sge;
 886	u32 pos;
 887	u32 work_alloc;
 888	u32 i;
 889	u32 j;
 890	int sent;
 891	int ret;
 892	int num_sge;
 893	int nr_sig = 0;
 894
 895	/* map the op the first time we see it */
 896	if (!op->op_mapped) {
 897		op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
 898					     op->op_sg, op->op_nents, (op->op_write) ?
 899					     DMA_TO_DEVICE : DMA_FROM_DEVICE);
 900		rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
 901		if (op->op_count == 0) {
 902			rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
 903			ret = -ENOMEM; /* XXX ? */
 904			goto out;
 905		}
 906
 907		op->op_mapped = 1;
 908	}
 909
 910	/*
 911	 * Instead of knowing how to return a partial rdma read/write we insist that there
 912	 * be enough work requests to send the entire message.
 913	 */
 914	i = ceil(op->op_count, max_sge);
 915
 916	work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
 917	if (work_alloc != i) {
 918		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
 919		rds_ib_stats_inc(s_ib_tx_ring_full);
 920		ret = -ENOMEM;
 921		goto out;
 922	}
 923
 924	send = &ic->i_sends[pos];
 925	first = send;
 926	prev = NULL;
 927	scat = &op->op_sg[0];
 928	sent = 0;
 929	num_sge = op->op_count;
 930
 931	for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
 932		send->s_wr.send_flags = 0;
 933		send->s_queued = jiffies;
 934		send->s_op = NULL;
 935
 936		nr_sig += rds_ib_set_wr_signal_state(ic, send, op->op_notify);
 937
 938		send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
 939		send->s_wr.wr.rdma.remote_addr = remote_addr;
 940		send->s_wr.wr.rdma.rkey = op->op_rkey;
 941
 942		if (num_sge > max_sge) {
 943			send->s_wr.num_sge = max_sge;
 944			num_sge -= max_sge;
 945		} else {
 946			send->s_wr.num_sge = num_sge;
 947		}
 948
 949		send->s_wr.next = NULL;
 950
 951		if (prev)
 952			prev->s_wr.next = &send->s_wr;
 953
 954		for (j = 0; j < send->s_wr.num_sge && scat != &op->op_sg[op->op_count]; j++) {
 
 955			len = ib_sg_dma_len(ic->i_cm_id->device, scat);
 956			send->s_sge[j].addr =
 957				 ib_sg_dma_address(ic->i_cm_id->device, scat);
 958			send->s_sge[j].length = len;
 959			send->s_sge[j].lkey = ic->i_mr->lkey;
 960
 961			sent += len;
 962			rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
 963
 964			remote_addr += len;
 965			scat++;
 966		}
 967
 968		rdsdebug("send %p wr %p num_sge %u next %p\n", send,
 969			&send->s_wr, send->s_wr.num_sge, send->s_wr.next);
 
 
 970
 971		prev = send;
 972		if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
 973			send = ic->i_sends;
 974	}
 975
 976	/* give a reference to the last op */
 977	if (scat == &op->op_sg[op->op_count]) {
 978		prev->s_op = op;
 979		rds_message_addref(container_of(op, struct rds_message, rdma));
 980	}
 981
 982	if (i < work_alloc) {
 983		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
 984		work_alloc = i;
 985	}
 986
 987	if (nr_sig)
 988		atomic_add(nr_sig, &ic->i_signaled_sends);
 989
 990	failed_wr = &first->s_wr;
 991	ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
 992	rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
 993		 first, &first->s_wr, ret, failed_wr);
 994	BUG_ON(failed_wr != &first->s_wr);
 995	if (ret) {
 996		printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 "
 997		       "returned %d\n", &conn->c_faddr, ret);
 998		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
 999		rds_ib_sub_signaled(ic, nr_sig);
1000		goto out;
1001	}
1002
1003	if (unlikely(failed_wr != &first->s_wr)) {
1004		printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
1005		BUG_ON(failed_wr != &first->s_wr);
1006	}
1007
1008
1009out:
1010	return ret;
1011}
1012
1013void rds_ib_xmit_complete(struct rds_connection *conn)
1014{
 
1015	struct rds_ib_connection *ic = conn->c_transport_data;
1016
1017	/* We may have a pending ACK or window update we were unable
1018	 * to send previously (due to flow control). Try again. */
1019	rds_ib_attempt_ack(ic);
1020}
v4.17
  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_single_path.h"
 40#include "rds.h"
 41#include "ib.h"
 42
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 43/*
 44 * Convert IB-specific error message to RDS error message and call core
 45 * completion handler.
 46 */
 47static void rds_ib_send_complete(struct rds_message *rm,
 48				 int wc_status,
 49				 void (*complete)(struct rds_message *rm, int status))
 50{
 51	int notify_status;
 52
 53	switch (wc_status) {
 54	case IB_WC_WR_FLUSH_ERR:
 55		return;
 56
 57	case IB_WC_SUCCESS:
 58		notify_status = RDS_RDMA_SUCCESS;
 59		break;
 60
 61	case IB_WC_REM_ACCESS_ERR:
 62		notify_status = RDS_RDMA_REMOTE_ERROR;
 63		break;
 64
 65	default:
 66		notify_status = RDS_RDMA_OTHER_ERROR;
 67		break;
 68	}
 69	complete(rm, notify_status);
 70}
 71
 
 
 
 
 
 
 
 
 
 
 72static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic,
 73				   struct rm_rdma_op *op,
 74				   int wc_status)
 75{
 76	if (op->op_mapped) {
 77		ib_dma_unmap_sg(ic->i_cm_id->device,
 78				op->op_sg, op->op_nents,
 79				op->op_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 80		op->op_mapped = 0;
 81	}
 82
 83	/* If the user asked for a completion notification on this
 84	 * message, we can implement three different semantics:
 85	 *  1.	Notify when we received the ACK on the RDS message
 86	 *	that was queued with the RDMA. This provides reliable
 87	 *	notification of RDMA status at the expense of a one-way
 88	 *	packet delay.
 89	 *  2.	Notify when the IB stack gives us the completion event for
 90	 *	the RDMA operation.
 91	 *  3.	Notify when the IB stack gives us the completion event for
 92	 *	the accompanying RDS messages.
 93	 * Here, we implement approach #3. To implement approach #2,
 94	 * we would need to take an event for the rdma WR. To implement #1,
 95	 * don't call rds_rdma_send_complete at all, and fall back to the notify
 96	 * handling in the ACK processing code.
 97	 *
 98	 * Note: There's no need to explicitly sync any RDMA buffers using
 99	 * ib_dma_sync_sg_for_cpu - the completion for the RDMA
100	 * operation itself unmapped the RDMA buffers, which takes care
101	 * of synching.
102	 */
103	rds_ib_send_complete(container_of(op, struct rds_message, rdma),
104			     wc_status, rds_rdma_send_complete);
105
106	if (op->op_write)
107		rds_stats_add(s_send_rdma_bytes, op->op_bytes);
108	else
109		rds_stats_add(s_recv_rdma_bytes, op->op_bytes);
110}
111
112static void rds_ib_send_unmap_atomic(struct rds_ib_connection *ic,
113				     struct rm_atomic_op *op,
114				     int wc_status)
115{
116	/* unmap atomic recvbuf */
117	if (op->op_mapped) {
118		ib_dma_unmap_sg(ic->i_cm_id->device, op->op_sg, 1,
119				DMA_FROM_DEVICE);
120		op->op_mapped = 0;
121	}
122
123	rds_ib_send_complete(container_of(op, struct rds_message, atomic),
124			     wc_status, rds_atomic_send_complete);
125
126	if (op->op_type == RDS_ATOMIC_TYPE_CSWP)
127		rds_ib_stats_inc(s_ib_atomic_cswp);
128	else
129		rds_ib_stats_inc(s_ib_atomic_fadd);
130}
131
132static void rds_ib_send_unmap_data(struct rds_ib_connection *ic,
133				   struct rm_data_op *op,
134				   int wc_status)
135{
136	struct rds_message *rm = container_of(op, struct rds_message, data);
137
138	if (op->op_nents)
139		ib_dma_unmap_sg(ic->i_cm_id->device,
140				op->op_sg, op->op_nents,
141				DMA_TO_DEVICE);
142
143	if (rm->rdma.op_active && rm->data.op_notify)
144		rds_ib_send_unmap_rdma(ic, &rm->rdma, wc_status);
145}
146
147/*
148 * Unmap the resources associated with a struct send_work.
149 *
150 * Returns the rm for no good reason other than it is unobtainable
151 * other than by switching on wr.opcode, currently, and the caller,
152 * the event handler, needs it.
153 */
154static struct rds_message *rds_ib_send_unmap_op(struct rds_ib_connection *ic,
155						struct rds_ib_send_work *send,
156						int wc_status)
157{
158	struct rds_message *rm = NULL;
159
160	/* In the error case, wc.opcode sometimes contains garbage */
161	switch (send->s_wr.opcode) {
162	case IB_WR_SEND:
163		if (send->s_op) {
164			rm = container_of(send->s_op, struct rds_message, data);
165			rds_ib_send_unmap_data(ic, send->s_op, wc_status);
166		}
167		break;
168	case IB_WR_RDMA_WRITE:
169	case IB_WR_RDMA_READ:
170		if (send->s_op) {
171			rm = container_of(send->s_op, struct rds_message, rdma);
172			rds_ib_send_unmap_rdma(ic, send->s_op, wc_status);
173		}
174		break;
175	case IB_WR_ATOMIC_FETCH_AND_ADD:
176	case IB_WR_ATOMIC_CMP_AND_SWP:
177		if (send->s_op) {
178			rm = container_of(send->s_op, struct rds_message, atomic);
179			rds_ib_send_unmap_atomic(ic, send->s_op, wc_status);
180		}
181		break;
182	default:
183		printk_ratelimited(KERN_NOTICE
184			       "RDS/IB: %s: unexpected opcode 0x%x in WR!\n",
185			       __func__, send->s_wr.opcode);
186		break;
187	}
188
189	send->s_wr.opcode = 0xdead;
190
191	return rm;
192}
193
194void rds_ib_send_init_ring(struct rds_ib_connection *ic)
195{
196	struct rds_ib_send_work *send;
197	u32 i;
198
199	for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
200		struct ib_sge *sge;
201
202		send->s_op = NULL;
203
204		send->s_wr.wr_id = i;
205		send->s_wr.sg_list = send->s_sge;
206		send->s_wr.ex.imm_data = 0;
207
208		sge = &send->s_sge[0];
209		sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header));
210		sge->length = sizeof(struct rds_header);
211		sge->lkey = ic->i_pd->local_dma_lkey;
212
213		send->s_sge[1].lkey = ic->i_pd->local_dma_lkey;
214	}
215}
216
217void rds_ib_send_clear_ring(struct rds_ib_connection *ic)
218{
219	struct rds_ib_send_work *send;
220	u32 i;
221
222	for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) {
223		if (send->s_op && send->s_wr.opcode != 0xdead)
224			rds_ib_send_unmap_op(ic, send, IB_WC_WR_FLUSH_ERR);
225	}
226}
227
228/*
229 * The only fast path caller always has a non-zero nr, so we don't
230 * bother testing nr before performing the atomic sub.
231 */
232static void rds_ib_sub_signaled(struct rds_ib_connection *ic, int nr)
233{
234	if ((atomic_sub_return(nr, &ic->i_signaled_sends) == 0) &&
235	    waitqueue_active(&rds_ib_ring_empty_wait))
236		wake_up(&rds_ib_ring_empty_wait);
237	BUG_ON(atomic_read(&ic->i_signaled_sends) < 0);
238}
239
240/*
241 * The _oldest/_free ring operations here race cleanly with the alloc/unalloc
242 * operations performed in the send path.  As the sender allocs and potentially
243 * unallocs the next free entry in the ring it doesn't alter which is
244 * the next to be freed, which is what this is concerned with.
245 */
246void rds_ib_send_cqe_handler(struct rds_ib_connection *ic, struct ib_wc *wc)
247{
 
 
248	struct rds_message *rm = NULL;
249	struct rds_connection *conn = ic->conn;
250	struct rds_ib_send_work *send;
251	u32 completed;
252	u32 oldest;
253	u32 i = 0;
 
254	int nr_sig = 0;
255
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
256
257	rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
258		 (unsigned long long)wc->wr_id, wc->status,
259		 ib_wc_status_msg(wc->status), wc->byte_len,
260		 be32_to_cpu(wc->ex.imm_data));
261	rds_ib_stats_inc(s_ib_tx_cq_event);
262
263	if (wc->wr_id == RDS_IB_ACK_WR_ID) {
264		if (time_after(jiffies, ic->i_ack_queued + HZ / 2))
265			rds_ib_stats_inc(s_ib_tx_stalled);
266		rds_ib_ack_send_complete(ic);
267		return;
268	}
269
270	oldest = rds_ib_ring_oldest(&ic->i_send_ring);
271
272	completed = rds_ib_ring_completed(&ic->i_send_ring, wc->wr_id, oldest);
273
274	for (i = 0; i < completed; i++) {
275		send = &ic->i_sends[oldest];
276		if (send->s_wr.send_flags & IB_SEND_SIGNALED)
277			nr_sig++;
278
279		rm = rds_ib_send_unmap_op(ic, send, wc->status);
280
281		if (time_after(jiffies, send->s_queued + HZ / 2))
282			rds_ib_stats_inc(s_ib_tx_stalled);
283
284		if (send->s_op) {
285			if (send->s_op == rm->m_final_op) {
286				/* If anyone waited for this message to get
287				 * flushed out, wake them up now
288				 */
289				rds_message_unmapped(rm);
290			}
291			rds_message_put(rm);
292			send->s_op = NULL;
 
293		}
294
295		oldest = (oldest + 1) % ic->i_send_ring.w_nr;
296	}
297
298	rds_ib_ring_free(&ic->i_send_ring, completed);
299	rds_ib_sub_signaled(ic, nr_sig);
300	nr_sig = 0;
301
302	if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) ||
303	    test_bit(0, &conn->c_map_queued))
304		queue_delayed_work(rds_wq, &conn->c_send_w, 0);
305
306	/* We expect errors as the qp is drained during shutdown */
307	if (wc->status != IB_WC_SUCCESS && rds_conn_up(conn)) {
308		rds_ib_conn_error(conn, "send completion on <%pI4,%pI4> had status %u (%s), disconnecting and reconnecting\n",
309				  &conn->c_laddr, &conn->c_faddr, wc->status,
310				  ib_wc_status_msg(wc->status));
311	}
312}
313
314/*
315 * This is the main function for allocating credits when sending
316 * messages.
317 *
318 * Conceptually, we have two counters:
319 *  -	send credits: this tells us how many WRs we're allowed
320 *	to submit without overruning the receiver's queue. For
321 *	each SEND WR we post, we decrement this by one.
322 *
323 *  -	posted credits: this tells us how many WRs we recently
324 *	posted to the receive queue. This value is transferred
325 *	to the peer as a "credit update" in a RDS header field.
326 *	Every time we transmit credits to the peer, we subtract
327 *	the amount of transferred credits from this counter.
328 *
329 * It is essential that we avoid situations where both sides have
330 * exhausted their send credits, and are unable to send new credits
331 * to the peer. We achieve this by requiring that we send at least
332 * one credit update to the peer before exhausting our credits.
333 * When new credits arrive, we subtract one credit that is withheld
334 * until we've posted new buffers and are ready to transmit these
335 * credits (see rds_ib_send_add_credits below).
336 *
337 * The RDS send code is essentially single-threaded; rds_send_xmit
338 * sets RDS_IN_XMIT to ensure exclusive access to the send ring.
339 * However, the ACK sending code is independent and can race with
340 * message SENDs.
341 *
342 * In the send path, we need to update the counters for send credits
343 * and the counter of posted buffers atomically - when we use the
344 * last available credit, we cannot allow another thread to race us
345 * and grab the posted credits counter.  Hence, we have to use a
346 * spinlock to protect the credit counter, or use atomics.
347 *
348 * Spinlocks shared between the send and the receive path are bad,
349 * because they create unnecessary delays. An early implementation
350 * using a spinlock showed a 5% degradation in throughput at some
351 * loads.
352 *
353 * This implementation avoids spinlocks completely, putting both
354 * counters into a single atomic, and updating that atomic using
355 * atomic_add (in the receive path, when receiving fresh credits),
356 * and using atomic_cmpxchg when updating the two counters.
357 */
358int rds_ib_send_grab_credits(struct rds_ib_connection *ic,
359			     u32 wanted, u32 *adv_credits, int need_posted, int max_posted)
360{
361	unsigned int avail, posted, got = 0, advertise;
362	long oldval, newval;
363
364	*adv_credits = 0;
365	if (!ic->i_flowctl)
366		return wanted;
367
368try_again:
369	advertise = 0;
370	oldval = newval = atomic_read(&ic->i_credits);
371	posted = IB_GET_POST_CREDITS(oldval);
372	avail = IB_GET_SEND_CREDITS(oldval);
373
374	rdsdebug("wanted=%u credits=%u posted=%u\n",
375			wanted, avail, posted);
376
377	/* The last credit must be used to send a credit update. */
378	if (avail && !posted)
379		avail--;
380
381	if (avail < wanted) {
382		struct rds_connection *conn = ic->i_cm_id->context;
383
384		/* Oops, there aren't that many credits left! */
385		set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
386		got = avail;
387	} else {
388		/* Sometimes you get what you want, lalala. */
389		got = wanted;
390	}
391	newval -= IB_SET_SEND_CREDITS(got);
392
393	/*
394	 * If need_posted is non-zero, then the caller wants
395	 * the posted regardless of whether any send credits are
396	 * available.
397	 */
398	if (posted && (got || need_posted)) {
399		advertise = min_t(unsigned int, posted, max_posted);
400		newval -= IB_SET_POST_CREDITS(advertise);
401	}
402
403	/* Finally bill everything */
404	if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval)
405		goto try_again;
406
407	*adv_credits = advertise;
408	return got;
409}
410
411void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits)
412{
413	struct rds_ib_connection *ic = conn->c_transport_data;
414
415	if (credits == 0)
416		return;
417
418	rdsdebug("credits=%u current=%u%s\n",
419			credits,
420			IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)),
421			test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : "");
422
423	atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits);
424	if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags))
425		queue_delayed_work(rds_wq, &conn->c_send_w, 0);
426
427	WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384);
428
429	rds_ib_stats_inc(s_ib_rx_credit_updates);
430}
431
432void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted)
433{
434	struct rds_ib_connection *ic = conn->c_transport_data;
435
436	if (posted == 0)
437		return;
438
439	atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits);
440
441	/* Decide whether to send an update to the peer now.
442	 * If we would send a credit update for every single buffer we
443	 * post, we would end up with an ACK storm (ACK arrives,
444	 * consumes buffer, we refill the ring, send ACK to remote
445	 * advertising the newly posted buffer... ad inf)
446	 *
447	 * Performance pretty much depends on how often we send
448	 * credit updates - too frequent updates mean lots of ACKs.
449	 * Too infrequent updates, and the peer will run out of
450	 * credits and has to throttle.
451	 * For the time being, 16 seems to be a good compromise.
452	 */
453	if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16)
454		set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
455}
456
457static inline int rds_ib_set_wr_signal_state(struct rds_ib_connection *ic,
458					     struct rds_ib_send_work *send,
459					     bool notify)
460{
461	/*
462	 * We want to delay signaling completions just enough to get
463	 * the batching benefits but not so much that we create dead time
464	 * on the wire.
465	 */
466	if (ic->i_unsignaled_wrs-- == 0 || notify) {
467		ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs;
468		send->s_wr.send_flags |= IB_SEND_SIGNALED;
469		return 1;
470	}
471	return 0;
472}
473
474/*
475 * This can be called multiple times for a given message.  The first time
476 * we see a message we map its scatterlist into the IB device so that
477 * we can provide that mapped address to the IB scatter gather entries
478 * in the IB work requests.  We translate the scatterlist into a series
479 * of work requests that fragment the message.  These work requests complete
480 * in order so we pass ownership of the message to the completion handler
481 * once we send the final fragment.
482 *
483 * The RDS core uses the c_send_lock to only enter this function once
484 * per connection.  This makes sure that the tx ring alloc/unalloc pairs
485 * don't get out of sync and confuse the ring.
486 */
487int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm,
488		unsigned int hdr_off, unsigned int sg, unsigned int off)
489{
490	struct rds_ib_connection *ic = conn->c_transport_data;
491	struct ib_device *dev = ic->i_cm_id->device;
492	struct rds_ib_send_work *send = NULL;
493	struct rds_ib_send_work *first;
494	struct rds_ib_send_work *prev;
495	struct ib_send_wr *failed_wr;
496	struct scatterlist *scat;
497	u32 pos;
498	u32 i;
499	u32 work_alloc;
500	u32 credit_alloc = 0;
501	u32 posted;
502	u32 adv_credits = 0;
503	int send_flags = 0;
504	int bytes_sent = 0;
505	int ret;
506	int flow_controlled = 0;
507	int nr_sig = 0;
508
509	BUG_ON(off % RDS_FRAG_SIZE);
510	BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header));
511
512	/* Do not send cong updates to IB loopback */
513	if (conn->c_loopback
514	    && rm->m_inc.i_hdr.h_flags & RDS_FLAG_CONG_BITMAP) {
515		rds_cong_map_updated(conn->c_fcong, ~(u64) 0);
516		scat = &rm->data.op_sg[sg];
517		ret = max_t(int, RDS_CONG_MAP_BYTES, scat->length);
518		return sizeof(struct rds_header) + ret;
519	}
520
521	/* FIXME we may overallocate here */
522	if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0)
523		i = 1;
524	else
525		i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE);
526
527	work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
528	if (work_alloc == 0) {
529		set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
530		rds_ib_stats_inc(s_ib_tx_ring_full);
531		ret = -ENOMEM;
532		goto out;
533	}
534
535	if (ic->i_flowctl) {
536		credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0, RDS_MAX_ADV_CREDIT);
537		adv_credits += posted;
538		if (credit_alloc < work_alloc) {
539			rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc);
540			work_alloc = credit_alloc;
541			flow_controlled = 1;
542		}
543		if (work_alloc == 0) {
544			set_bit(RDS_LL_SEND_FULL, &conn->c_flags);
545			rds_ib_stats_inc(s_ib_tx_throttle);
546			ret = -ENOMEM;
547			goto out;
548		}
549	}
550
551	/* map the message the first time we see it */
552	if (!ic->i_data_op) {
553		if (rm->data.op_nents) {
554			rm->data.op_count = ib_dma_map_sg(dev,
555							  rm->data.op_sg,
556							  rm->data.op_nents,
557							  DMA_TO_DEVICE);
558			rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->data.op_count);
559			if (rm->data.op_count == 0) {
560				rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
561				rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
562				ret = -ENOMEM; /* XXX ? */
563				goto out;
564			}
565		} else {
566			rm->data.op_count = 0;
567		}
568
569		rds_message_addref(rm);
570		rm->data.op_dmasg = 0;
571		rm->data.op_dmaoff = 0;
572		ic->i_data_op = &rm->data;
573
574		/* Finalize the header */
575		if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags))
576			rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED;
577		if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags))
578			rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED;
579
580		/* If it has a RDMA op, tell the peer we did it. This is
581		 * used by the peer to release use-once RDMA MRs. */
582		if (rm->rdma.op_active) {
583			struct rds_ext_header_rdma ext_hdr;
584
585			ext_hdr.h_rdma_rkey = cpu_to_be32(rm->rdma.op_rkey);
586			rds_message_add_extension(&rm->m_inc.i_hdr,
587					RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr));
588		}
589		if (rm->m_rdma_cookie) {
590			rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr,
591					rds_rdma_cookie_key(rm->m_rdma_cookie),
592					rds_rdma_cookie_offset(rm->m_rdma_cookie));
593		}
594
595		/* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so
596		 * we should not do this unless we have a chance of at least
597		 * sticking the header into the send ring. Which is why we
598		 * should call rds_ib_ring_alloc first. */
599		rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic));
600		rds_message_make_checksum(&rm->m_inc.i_hdr);
601
602		/*
603		 * Update adv_credits since we reset the ACK_REQUIRED bit.
604		 */
605		if (ic->i_flowctl) {
606			rds_ib_send_grab_credits(ic, 0, &posted, 1, RDS_MAX_ADV_CREDIT - adv_credits);
607			adv_credits += posted;
608			BUG_ON(adv_credits > 255);
609		}
610	}
611
612	/* Sometimes you want to put a fence between an RDMA
613	 * READ and the following SEND.
614	 * We could either do this all the time
615	 * or when requested by the user. Right now, we let
616	 * the application choose.
617	 */
618	if (rm->rdma.op_active && rm->rdma.op_fence)
619		send_flags = IB_SEND_FENCE;
620
621	/* Each frag gets a header. Msgs may be 0 bytes */
622	send = &ic->i_sends[pos];
623	first = send;
624	prev = NULL;
625	scat = &ic->i_data_op->op_sg[rm->data.op_dmasg];
626	i = 0;
627	do {
628		unsigned int len = 0;
629
630		/* Set up the header */
631		send->s_wr.send_flags = send_flags;
632		send->s_wr.opcode = IB_WR_SEND;
633		send->s_wr.num_sge = 1;
634		send->s_wr.next = NULL;
635		send->s_queued = jiffies;
636		send->s_op = NULL;
637
638		send->s_sge[0].addr = ic->i_send_hdrs_dma
639			+ (pos * sizeof(struct rds_header));
640		send->s_sge[0].length = sizeof(struct rds_header);
641
642		memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header));
643
644		/* Set up the data, if present */
645		if (i < work_alloc
646		    && scat != &rm->data.op_sg[rm->data.op_count]) {
647			len = min(RDS_FRAG_SIZE,
648				ib_sg_dma_len(dev, scat) - rm->data.op_dmaoff);
649			send->s_wr.num_sge = 2;
650
651			send->s_sge[1].addr = ib_sg_dma_address(dev, scat);
652			send->s_sge[1].addr += rm->data.op_dmaoff;
653			send->s_sge[1].length = len;
654
655			bytes_sent += len;
656			rm->data.op_dmaoff += len;
657			if (rm->data.op_dmaoff == ib_sg_dma_len(dev, scat)) {
658				scat++;
659				rm->data.op_dmasg++;
660				rm->data.op_dmaoff = 0;
661			}
662		}
663
664		rds_ib_set_wr_signal_state(ic, send, false);
665
666		/*
667		 * Always signal the last one if we're stopping due to flow control.
668		 */
669		if (ic->i_flowctl && flow_controlled && i == (work_alloc - 1)) {
670			rds_ib_set_wr_signal_state(ic, send, true);
671			send->s_wr.send_flags |= IB_SEND_SOLICITED;
672		}
673
674		if (send->s_wr.send_flags & IB_SEND_SIGNALED)
675			nr_sig++;
676
677		rdsdebug("send %p wr %p num_sge %u next %p\n", send,
678			 &send->s_wr, send->s_wr.num_sge, send->s_wr.next);
679
680		if (ic->i_flowctl && adv_credits) {
681			struct rds_header *hdr = &ic->i_send_hdrs[pos];
682
683			/* add credit and redo the header checksum */
684			hdr->h_credit = adv_credits;
685			rds_message_make_checksum(hdr);
686			adv_credits = 0;
687			rds_ib_stats_inc(s_ib_tx_credit_updates);
688		}
689
690		if (prev)
691			prev->s_wr.next = &send->s_wr;
692		prev = send;
693
694		pos = (pos + 1) % ic->i_send_ring.w_nr;
695		send = &ic->i_sends[pos];
696		i++;
697
698	} while (i < work_alloc
699		 && scat != &rm->data.op_sg[rm->data.op_count]);
700
701	/* Account the RDS header in the number of bytes we sent, but just once.
702	 * The caller has no concept of fragmentation. */
703	if (hdr_off == 0)
704		bytes_sent += sizeof(struct rds_header);
705
706	/* if we finished the message then send completion owns it */
707	if (scat == &rm->data.op_sg[rm->data.op_count]) {
708		prev->s_op = ic->i_data_op;
709		prev->s_wr.send_flags |= IB_SEND_SOLICITED;
710		if (!(prev->s_wr.send_flags & IB_SEND_SIGNALED))
711			nr_sig += rds_ib_set_wr_signal_state(ic, prev, true);
712		ic->i_data_op = NULL;
713	}
714
715	/* Put back wrs & credits we didn't use */
716	if (i < work_alloc) {
717		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
718		work_alloc = i;
719	}
720	if (ic->i_flowctl && i < credit_alloc)
721		rds_ib_send_add_credits(conn, credit_alloc - i);
722
723	if (nr_sig)
724		atomic_add(nr_sig, &ic->i_signaled_sends);
725
726	/* XXX need to worry about failed_wr and partial sends. */
727	failed_wr = &first->s_wr;
728	ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr);
729	rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
730		 first, &first->s_wr, ret, failed_wr);
731	BUG_ON(failed_wr != &first->s_wr);
732	if (ret) {
733		printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 "
734		       "returned %d\n", &conn->c_faddr, ret);
735		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
736		rds_ib_sub_signaled(ic, nr_sig);
737		if (prev->s_op) {
738			ic->i_data_op = prev->s_op;
739			prev->s_op = NULL;
740		}
741
742		rds_ib_conn_error(ic->conn, "ib_post_send failed\n");
743		goto out;
744	}
745
746	ret = bytes_sent;
747out:
748	BUG_ON(adv_credits);
749	return ret;
750}
751
752/*
753 * Issue atomic operation.
754 * A simplified version of the rdma case, we always map 1 SG, and
755 * only 8 bytes, for the return value from the atomic operation.
756 */
757int rds_ib_xmit_atomic(struct rds_connection *conn, struct rm_atomic_op *op)
758{
759	struct rds_ib_connection *ic = conn->c_transport_data;
760	struct rds_ib_send_work *send = NULL;
761	struct ib_send_wr *failed_wr;
762	struct rds_ib_device *rds_ibdev;
763	u32 pos;
764	u32 work_alloc;
765	int ret;
766	int nr_sig = 0;
767
768	rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client);
769
770	work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, 1, &pos);
771	if (work_alloc != 1) {
 
772		rds_ib_stats_inc(s_ib_tx_ring_full);
773		ret = -ENOMEM;
774		goto out;
775	}
776
777	/* address of send request in ring */
778	send = &ic->i_sends[pos];
779	send->s_queued = jiffies;
780
781	if (op->op_type == RDS_ATOMIC_TYPE_CSWP) {
782		send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_CMP_AND_SWP;
783		send->s_atomic_wr.compare_add = op->op_m_cswp.compare;
784		send->s_atomic_wr.swap = op->op_m_cswp.swap;
785		send->s_atomic_wr.compare_add_mask = op->op_m_cswp.compare_mask;
786		send->s_atomic_wr.swap_mask = op->op_m_cswp.swap_mask;
787	} else { /* FADD */
788		send->s_atomic_wr.wr.opcode = IB_WR_MASKED_ATOMIC_FETCH_AND_ADD;
789		send->s_atomic_wr.compare_add = op->op_m_fadd.add;
790		send->s_atomic_wr.swap = 0;
791		send->s_atomic_wr.compare_add_mask = op->op_m_fadd.nocarry_mask;
792		send->s_atomic_wr.swap_mask = 0;
793	}
794	send->s_wr.send_flags = 0;
795	nr_sig = rds_ib_set_wr_signal_state(ic, send, op->op_notify);
796	send->s_atomic_wr.wr.num_sge = 1;
797	send->s_atomic_wr.wr.next = NULL;
798	send->s_atomic_wr.remote_addr = op->op_remote_addr;
799	send->s_atomic_wr.rkey = op->op_rkey;
800	send->s_op = op;
801	rds_message_addref(container_of(send->s_op, struct rds_message, atomic));
802
803	/* map 8 byte retval buffer to the device */
804	ret = ib_dma_map_sg(ic->i_cm_id->device, op->op_sg, 1, DMA_FROM_DEVICE);
805	rdsdebug("ic %p mapping atomic op %p. mapped %d pg\n", ic, op, ret);
806	if (ret != 1) {
807		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
808		rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
809		ret = -ENOMEM; /* XXX ? */
810		goto out;
811	}
812
813	/* Convert our struct scatterlist to struct ib_sge */
814	send->s_sge[0].addr = ib_sg_dma_address(ic->i_cm_id->device, op->op_sg);
815	send->s_sge[0].length = ib_sg_dma_len(ic->i_cm_id->device, op->op_sg);
816	send->s_sge[0].lkey = ic->i_pd->local_dma_lkey;
817
818	rdsdebug("rva %Lx rpa %Lx len %u\n", op->op_remote_addr,
819		 send->s_sge[0].addr, send->s_sge[0].length);
820
821	if (nr_sig)
822		atomic_add(nr_sig, &ic->i_signaled_sends);
823
824	failed_wr = &send->s_atomic_wr.wr;
825	ret = ib_post_send(ic->i_cm_id->qp, &send->s_atomic_wr.wr, &failed_wr);
826	rdsdebug("ic %p send %p (wr %p) ret %d wr %p\n", ic,
827		 send, &send->s_atomic_wr, ret, failed_wr);
828	BUG_ON(failed_wr != &send->s_atomic_wr.wr);
829	if (ret) {
830		printk(KERN_WARNING "RDS/IB: atomic ib_post_send to %pI4 "
831		       "returned %d\n", &conn->c_faddr, ret);
832		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
833		rds_ib_sub_signaled(ic, nr_sig);
834		goto out;
835	}
836
837	if (unlikely(failed_wr != &send->s_atomic_wr.wr)) {
838		printk(KERN_WARNING "RDS/IB: atomic ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
839		BUG_ON(failed_wr != &send->s_atomic_wr.wr);
840	}
841
842out:
843	return ret;
844}
845
846int rds_ib_xmit_rdma(struct rds_connection *conn, struct rm_rdma_op *op)
847{
848	struct rds_ib_connection *ic = conn->c_transport_data;
849	struct rds_ib_send_work *send = NULL;
850	struct rds_ib_send_work *first;
851	struct rds_ib_send_work *prev;
852	struct ib_send_wr *failed_wr;
853	struct scatterlist *scat;
854	unsigned long len;
855	u64 remote_addr = op->op_remote_addr;
856	u32 max_sge = ic->rds_ibdev->max_sge;
857	u32 pos;
858	u32 work_alloc;
859	u32 i;
860	u32 j;
861	int sent;
862	int ret;
863	int num_sge;
864	int nr_sig = 0;
865
866	/* map the op the first time we see it */
867	if (!op->op_mapped) {
868		op->op_count = ib_dma_map_sg(ic->i_cm_id->device,
869					     op->op_sg, op->op_nents, (op->op_write) ?
870					     DMA_TO_DEVICE : DMA_FROM_DEVICE);
871		rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->op_count);
872		if (op->op_count == 0) {
873			rds_ib_stats_inc(s_ib_tx_sg_mapping_failure);
874			ret = -ENOMEM; /* XXX ? */
875			goto out;
876		}
877
878		op->op_mapped = 1;
879	}
880
881	/*
882	 * Instead of knowing how to return a partial rdma read/write we insist that there
883	 * be enough work requests to send the entire message.
884	 */
885	i = ceil(op->op_count, max_sge);
886
887	work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos);
888	if (work_alloc != i) {
889		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
890		rds_ib_stats_inc(s_ib_tx_ring_full);
891		ret = -ENOMEM;
892		goto out;
893	}
894
895	send = &ic->i_sends[pos];
896	first = send;
897	prev = NULL;
898	scat = &op->op_sg[0];
899	sent = 0;
900	num_sge = op->op_count;
901
902	for (i = 0; i < work_alloc && scat != &op->op_sg[op->op_count]; i++) {
903		send->s_wr.send_flags = 0;
904		send->s_queued = jiffies;
905		send->s_op = NULL;
906
907		nr_sig += rds_ib_set_wr_signal_state(ic, send, op->op_notify);
908
909		send->s_wr.opcode = op->op_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ;
910		send->s_rdma_wr.remote_addr = remote_addr;
911		send->s_rdma_wr.rkey = op->op_rkey;
912
913		if (num_sge > max_sge) {
914			send->s_rdma_wr.wr.num_sge = max_sge;
915			num_sge -= max_sge;
916		} else {
917			send->s_rdma_wr.wr.num_sge = num_sge;
918		}
919
920		send->s_rdma_wr.wr.next = NULL;
921
922		if (prev)
923			prev->s_rdma_wr.wr.next = &send->s_rdma_wr.wr;
924
925		for (j = 0; j < send->s_rdma_wr.wr.num_sge &&
926		     scat != &op->op_sg[op->op_count]; j++) {
927			len = ib_sg_dma_len(ic->i_cm_id->device, scat);
928			send->s_sge[j].addr =
929				 ib_sg_dma_address(ic->i_cm_id->device, scat);
930			send->s_sge[j].length = len;
931			send->s_sge[j].lkey = ic->i_pd->local_dma_lkey;
932
933			sent += len;
934			rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr);
935
936			remote_addr += len;
937			scat++;
938		}
939
940		rdsdebug("send %p wr %p num_sge %u next %p\n", send,
941			&send->s_rdma_wr.wr,
942			send->s_rdma_wr.wr.num_sge,
943			send->s_rdma_wr.wr.next);
944
945		prev = send;
946		if (++send == &ic->i_sends[ic->i_send_ring.w_nr])
947			send = ic->i_sends;
948	}
949
950	/* give a reference to the last op */
951	if (scat == &op->op_sg[op->op_count]) {
952		prev->s_op = op;
953		rds_message_addref(container_of(op, struct rds_message, rdma));
954	}
955
956	if (i < work_alloc) {
957		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i);
958		work_alloc = i;
959	}
960
961	if (nr_sig)
962		atomic_add(nr_sig, &ic->i_signaled_sends);
963
964	failed_wr = &first->s_rdma_wr.wr;
965	ret = ib_post_send(ic->i_cm_id->qp, &first->s_rdma_wr.wr, &failed_wr);
966	rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic,
967		 first, &first->s_rdma_wr.wr, ret, failed_wr);
968	BUG_ON(failed_wr != &first->s_rdma_wr.wr);
969	if (ret) {
970		printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 "
971		       "returned %d\n", &conn->c_faddr, ret);
972		rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc);
973		rds_ib_sub_signaled(ic, nr_sig);
974		goto out;
975	}
976
977	if (unlikely(failed_wr != &first->s_rdma_wr.wr)) {
978		printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret);
979		BUG_ON(failed_wr != &first->s_rdma_wr.wr);
980	}
981
982
983out:
984	return ret;
985}
986
987void rds_ib_xmit_path_complete(struct rds_conn_path *cp)
988{
989	struct rds_connection *conn = cp->cp_conn;
990	struct rds_ib_connection *ic = conn->c_transport_data;
991
992	/* We may have a pending ACK or window update we were unable
993	 * to send previously (due to flow control). Try again. */
994	rds_ib_attempt_ack(ic);
995}