1/*
   2 * Copyright (c) 2006, 2019 Oracle and/or its affiliates. All rights reserved.
   3 *
   4 * This software is available to you under a choice of one of two
   5 * licenses.  You may choose to be licensed under the terms of the GNU
   6 * General Public License (GPL) Version 2, available from the file
   7 * COPYING in the main directory of this source tree, or the
   8 * OpenIB.org BSD license below:
   9 *
  10 *     Redistribution and use in source and binary forms, with or
  11 *     without modification, are permitted provided that the following
  12 *     conditions are met:
  13 *
  14 *      - Redistributions of source code must retain the above
  15 *        copyright notice, this list of conditions and the following
  16 *        disclaimer.
  17 *
  18 *      - Redistributions in binary form must reproduce the above
  19 *        copyright notice, this list of conditions and the following
  20 *        disclaimer in the documentation and/or other materials
  21 *        provided with the distribution.
  22 *
  23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30 * SOFTWARE.
  31 *
  32 */
  33#include <linux/kernel.h>
  34#include <linux/slab.h>
  35#include <linux/pci.h>
  36#include <linux/dma-mapping.h>
  37#include <rdma/rdma_cm.h>
  38
  39#include "rds_single_path.h"
  40#include "rds.h"
  41#include "ib.h"
  42
  43static struct kmem_cache *rds_ib_incoming_slab;
  44static struct kmem_cache *rds_ib_frag_slab;
  45static atomic_t	rds_ib_allocation = ATOMIC_INIT(0);
  46
  47void rds_ib_recv_init_ring(struct rds_ib_connection *ic)
  48{
  49	struct rds_ib_recv_work *recv;
  50	u32 i;
  51
  52	for (i = 0, recv = ic->i_recvs; i < ic->i_recv_ring.w_nr; i++, recv++) {
  53		struct ib_sge *sge;
  54
  55		recv->r_ibinc = NULL;
  56		recv->r_frag = NULL;
  57
  58		recv->r_wr.next = NULL;
  59		recv->r_wr.wr_id = i;
  60		recv->r_wr.sg_list = recv->r_sge;
  61		recv->r_wr.num_sge = RDS_IB_RECV_SGE;
  62
  63		sge = &recv->r_sge[0];
  64		sge->addr = ic->i_recv_hdrs_dma[i];
  65		sge->length = sizeof(struct rds_header);
  66		sge->lkey = ic->i_pd->local_dma_lkey;
  67
  68		sge = &recv->r_sge[1];
  69		sge->addr = 0;
  70		sge->length = RDS_FRAG_SIZE;
  71		sge->lkey = ic->i_pd->local_dma_lkey;
  72	}
  73}
  74
  75/*
  76 * The entire 'from' list, including the from element itself, is put on
  77 * to the tail of the 'to' list.
  78 */
  79static void list_splice_entire_tail(struct list_head *from,
  80				    struct list_head *to)
  81{
  82	struct list_head *from_last = from->prev;
  83
  84	list_splice_tail(from_last, to);
  85	list_add_tail(from_last, to);
  86}
  87
  88static void rds_ib_cache_xfer_to_ready(struct rds_ib_refill_cache *cache)
  89{
  90	struct list_head *tmp;
  91
  92	tmp = xchg(&cache->xfer, NULL);
  93	if (tmp) {
  94		if (cache->ready)
  95			list_splice_entire_tail(tmp, cache->ready);
  96		else
  97			cache->ready = tmp;
  98	}
  99}
 100
 101static int rds_ib_recv_alloc_cache(struct rds_ib_refill_cache *cache, gfp_t gfp)
 102{
 103	struct rds_ib_cache_head *head;
 104	int cpu;
 105
 106	cache->percpu = alloc_percpu_gfp(struct rds_ib_cache_head, gfp);
 107	if (!cache->percpu)
 108	       return -ENOMEM;
 109
 110	for_each_possible_cpu(cpu) {
 111		head = per_cpu_ptr(cache->percpu, cpu);
 112		head->first = NULL;
 113		head->count = 0;
 114	}
 115	cache->xfer = NULL;
 116	cache->ready = NULL;
 117
 118	return 0;
 119}
 120
 121int rds_ib_recv_alloc_caches(struct rds_ib_connection *ic, gfp_t gfp)
 122{
 123	int ret;
 124
 125	ret = rds_ib_recv_alloc_cache(&ic->i_cache_incs, gfp);
 126	if (!ret) {
 127		ret = rds_ib_recv_alloc_cache(&ic->i_cache_frags, gfp);
 128		if (ret)
 129			free_percpu(ic->i_cache_incs.percpu);
 130	}
 131
 132	return ret;
 133}
 134
 135static void rds_ib_cache_splice_all_lists(struct rds_ib_refill_cache *cache,
 136					  struct list_head *caller_list)
 137{
 138	struct rds_ib_cache_head *head;
 139	int cpu;
 140
 141	for_each_possible_cpu(cpu) {
 142		head = per_cpu_ptr(cache->percpu, cpu);
 143		if (head->first) {
 144			list_splice_entire_tail(head->first, caller_list);
 145			head->first = NULL;
 146		}
 147	}
 148
 149	if (cache->ready) {
 150		list_splice_entire_tail(cache->ready, caller_list);
 151		cache->ready = NULL;
 152	}
 153}
 154
 155void rds_ib_recv_free_caches(struct rds_ib_connection *ic)
 156{
 157	struct rds_ib_incoming *inc;
 158	struct rds_ib_incoming *inc_tmp;
 159	struct rds_page_frag *frag;
 160	struct rds_page_frag *frag_tmp;
 161	LIST_HEAD(list);
 162
 163	rds_ib_cache_xfer_to_ready(&ic->i_cache_incs);
 164	rds_ib_cache_splice_all_lists(&ic->i_cache_incs, &list);
 165	free_percpu(ic->i_cache_incs.percpu);
 166
 167	list_for_each_entry_safe(inc, inc_tmp, &list, ii_cache_entry) {
 168		list_del(&inc->ii_cache_entry);
 169		WARN_ON(!list_empty(&inc->ii_frags));
 170		kmem_cache_free(rds_ib_incoming_slab, inc);
 171		atomic_dec(&rds_ib_allocation);
 172	}
 173
 174	rds_ib_cache_xfer_to_ready(&ic->i_cache_frags);
 175	rds_ib_cache_splice_all_lists(&ic->i_cache_frags, &list);
 176	free_percpu(ic->i_cache_frags.percpu);
 177
 178	list_for_each_entry_safe(frag, frag_tmp, &list, f_cache_entry) {
 179		list_del(&frag->f_cache_entry);
 180		WARN_ON(!list_empty(&frag->f_item));
 181		kmem_cache_free(rds_ib_frag_slab, frag);
 182	}
 183}
 184
 185/* fwd decl */
 186static void rds_ib_recv_cache_put(struct list_head *new_item,
 187				  struct rds_ib_refill_cache *cache);
 188static struct list_head *rds_ib_recv_cache_get(struct rds_ib_refill_cache *cache);
 189
 190
 191/* Recycle frag and attached recv buffer f_sg */
 192static void rds_ib_frag_free(struct rds_ib_connection *ic,
 193			     struct rds_page_frag *frag)
 194{
 195	rdsdebug("frag %p page %p\n", frag, sg_page(&frag->f_sg));
 196
 197	rds_ib_recv_cache_put(&frag->f_cache_entry, &ic->i_cache_frags);
 198	atomic_add(RDS_FRAG_SIZE / SZ_1K, &ic->i_cache_allocs);
 199	rds_ib_stats_add(s_ib_recv_added_to_cache, RDS_FRAG_SIZE);
 200}
 201
 202/* Recycle inc after freeing attached frags */
 203void rds_ib_inc_free(struct rds_incoming *inc)
 204{
 205	struct rds_ib_incoming *ibinc;
 206	struct rds_page_frag *frag;
 207	struct rds_page_frag *pos;
 208	struct rds_ib_connection *ic = inc->i_conn->c_transport_data;
 209
 210	ibinc = container_of(inc, struct rds_ib_incoming, ii_inc);
 211
 212	/* Free attached frags */
 213	list_for_each_entry_safe(frag, pos, &ibinc->ii_frags, f_item) {
 214		list_del_init(&frag->f_item);
 215		rds_ib_frag_free(ic, frag);
 216	}
 217	BUG_ON(!list_empty(&ibinc->ii_frags));
 218
 219	rdsdebug("freeing ibinc %p inc %p\n", ibinc, inc);
 220	rds_ib_recv_cache_put(&ibinc->ii_cache_entry, &ic->i_cache_incs);
 221}
 222
 223static void rds_ib_recv_clear_one(struct rds_ib_connection *ic,
 224				  struct rds_ib_recv_work *recv)
 225{
 226	if (recv->r_ibinc) {
 227		rds_inc_put(&recv->r_ibinc->ii_inc);
 228		recv->r_ibinc = NULL;
 229	}
 230	if (recv->r_frag) {
 231		ib_dma_unmap_sg(ic->i_cm_id->device, &recv->r_frag->f_sg, 1, DMA_FROM_DEVICE);
 232		rds_ib_frag_free(ic, recv->r_frag);
 233		recv->r_frag = NULL;
 234	}
 235}
 236
 237void rds_ib_recv_clear_ring(struct rds_ib_connection *ic)
 238{
 239	u32 i;
 240
 241	for (i = 0; i < ic->i_recv_ring.w_nr; i++)
 242		rds_ib_recv_clear_one(ic, &ic->i_recvs[i]);
 243}
 244
 245static struct rds_ib_incoming *rds_ib_refill_one_inc(struct rds_ib_connection *ic,
 246						     gfp_t slab_mask)
 247{
 248	struct rds_ib_incoming *ibinc;
 249	struct list_head *cache_item;
 250	int avail_allocs;
 251
 252	cache_item = rds_ib_recv_cache_get(&ic->i_cache_incs);
 253	if (cache_item) {
 254		ibinc = container_of(cache_item, struct rds_ib_incoming, ii_cache_entry);
 255	} else {
 256		avail_allocs = atomic_add_unless(&rds_ib_allocation,
 257						 1, rds_ib_sysctl_max_recv_allocation);
 258		if (!avail_allocs) {
 259			rds_ib_stats_inc(s_ib_rx_alloc_limit);
 260			return NULL;
 261		}
 262		ibinc = kmem_cache_alloc(rds_ib_incoming_slab, slab_mask);
 263		if (!ibinc) {
 264			atomic_dec(&rds_ib_allocation);
 265			return NULL;
 266		}
 267		rds_ib_stats_inc(s_ib_rx_total_incs);
 268	}
 269	INIT_LIST_HEAD(&ibinc->ii_frags);
 270	rds_inc_init(&ibinc->ii_inc, ic->conn, &ic->conn->c_faddr);
 271
 272	return ibinc;
 273}
 274
 275static struct rds_page_frag *rds_ib_refill_one_frag(struct rds_ib_connection *ic,
 276						    gfp_t slab_mask, gfp_t page_mask)
 277{
 278	struct rds_page_frag *frag;
 279	struct list_head *cache_item;
 280	int ret;
 281
 282	cache_item = rds_ib_recv_cache_get(&ic->i_cache_frags);
 283	if (cache_item) {
 284		frag = container_of(cache_item, struct rds_page_frag, f_cache_entry);
 285		atomic_sub(RDS_FRAG_SIZE / SZ_1K, &ic->i_cache_allocs);
 286		rds_ib_stats_add(s_ib_recv_added_to_cache, RDS_FRAG_SIZE);
 287	} else {
 288		frag = kmem_cache_alloc(rds_ib_frag_slab, slab_mask);
 289		if (!frag)
 290			return NULL;
 291
 292		sg_init_table(&frag->f_sg, 1);
 293		ret = rds_page_remainder_alloc(&frag->f_sg,
 294					       RDS_FRAG_SIZE, page_mask);
 295		if (ret) {
 296			kmem_cache_free(rds_ib_frag_slab, frag);
 297			return NULL;
 298		}
 299		rds_ib_stats_inc(s_ib_rx_total_frags);
 300	}
 301
 302	INIT_LIST_HEAD(&frag->f_item);
 303
 304	return frag;
 305}
 306
 307static int rds_ib_recv_refill_one(struct rds_connection *conn,
 308				  struct rds_ib_recv_work *recv, gfp_t gfp)
 309{
 310	struct rds_ib_connection *ic = conn->c_transport_data;
 311	struct ib_sge *sge;
 312	int ret = -ENOMEM;
 313	gfp_t slab_mask = GFP_NOWAIT;
 314	gfp_t page_mask = GFP_NOWAIT;
 315
 316	if (gfp & __GFP_DIRECT_RECLAIM) {
 317		slab_mask = GFP_KERNEL;
 318		page_mask = GFP_HIGHUSER;
 319	}
 320
 321	if (!ic->i_cache_incs.ready)
 322		rds_ib_cache_xfer_to_ready(&ic->i_cache_incs);
 323	if (!ic->i_cache_frags.ready)
 324		rds_ib_cache_xfer_to_ready(&ic->i_cache_frags);
 325
 326	/*
 327	 * ibinc was taken from recv if recv contained the start of a message.
 328	 * recvs that were continuations will still have this allocated.
 329	 */
 330	if (!recv->r_ibinc) {
 331		recv->r_ibinc = rds_ib_refill_one_inc(ic, slab_mask);
 332		if (!recv->r_ibinc)
 333			goto out;
 334	}
 335
 336	WARN_ON(recv->r_frag); /* leak! */
 337	recv->r_frag = rds_ib_refill_one_frag(ic, slab_mask, page_mask);
 338	if (!recv->r_frag)
 339		goto out;
 340
 341	ret = ib_dma_map_sg(ic->i_cm_id->device, &recv->r_frag->f_sg,
 342			    1, DMA_FROM_DEVICE);
 343	WARN_ON(ret != 1);
 344
 345	sge = &recv->r_sge[0];
 346	sge->addr = ic->i_recv_hdrs_dma[recv - ic->i_recvs];
 347	sge->length = sizeof(struct rds_header);
 348
 349	sge = &recv->r_sge[1];
 350	sge->addr = sg_dma_address(&recv->r_frag->f_sg);
 351	sge->length = sg_dma_len(&recv->r_frag->f_sg);
 352
 353	ret = 0;
 354out:
 355	return ret;
 356}
 357
 358static int acquire_refill(struct rds_connection *conn)
 359{
 360	return test_and_set_bit(RDS_RECV_REFILL, &conn->c_flags) == 0;
 361}
 362
 363static void release_refill(struct rds_connection *conn)
 364{
 365	clear_bit(RDS_RECV_REFILL, &conn->c_flags);
 
 366
 367	/* We don't use wait_on_bit()/wake_up_bit() because our waking is in a
 368	 * hot path and finding waiters is very rare.  We don't want to walk
 369	 * the system-wide hashed waitqueue buckets in the fast path only to
 370	 * almost never find waiters.
 371	 */
 372	if (waitqueue_active(&conn->c_waitq))
 373		wake_up_all(&conn->c_waitq);
 374}
 375
 376/*
 377 * This tries to allocate and post unused work requests after making sure that
 378 * they have all the allocations they need to queue received fragments into
 379 * sockets.
 380 */
 381void rds_ib_recv_refill(struct rds_connection *conn, int prefill, gfp_t gfp)
 382{
 383	struct rds_ib_connection *ic = conn->c_transport_data;
 384	struct rds_ib_recv_work *recv;
 385	unsigned int posted = 0;
 386	int ret = 0;
 387	bool can_wait = !!(gfp & __GFP_DIRECT_RECLAIM);
 388	bool must_wake = false;
 389	u32 pos;
 390
 391	/* the goal here is to just make sure that someone, somewhere
 392	 * is posting buffers.  If we can't get the refill lock,
 393	 * let them do their thing
 394	 */
 395	if (!acquire_refill(conn))
 396		return;
 397
 398	while ((prefill || rds_conn_up(conn)) &&
 399	       rds_ib_ring_alloc(&ic->i_recv_ring, 1, &pos)) {
 400		if (pos >= ic->i_recv_ring.w_nr) {
 401			printk(KERN_NOTICE "Argh - ring alloc returned pos=%u\n",
 402					pos);
 403			break;
 404		}
 405
 406		recv = &ic->i_recvs[pos];
 407		ret = rds_ib_recv_refill_one(conn, recv, gfp);
 408		if (ret) {
 409			must_wake = true;
 410			break;
 411		}
 412
 413		rdsdebug("recv %p ibinc %p page %p addr %lu\n", recv,
 414			 recv->r_ibinc, sg_page(&recv->r_frag->f_sg),
 415			 (long)sg_dma_address(&recv->r_frag->f_sg));
 416
 417		/* XXX when can this fail? */
 418		ret = ib_post_recv(ic->i_cm_id->qp, &recv->r_wr, NULL);
 419		if (ret) {
 420			rds_ib_conn_error(conn, "recv post on "
 421			       "%pI6c returned %d, disconnecting and "
 422			       "reconnecting\n", &conn->c_faddr,
 423			       ret);
 424			break;
 425		}
 426
 427		posted++;
 428
 429		if ((posted > 128 && need_resched()) || posted > 8192) {
 430			must_wake = true;
 431			break;
 432		}
 433	}
 434
 435	/* We're doing flow control - update the window. */
 436	if (ic->i_flowctl && posted)
 437		rds_ib_advertise_credits(conn, posted);
 438
 439	if (ret)
 440		rds_ib_ring_unalloc(&ic->i_recv_ring, 1);
 441
 442	release_refill(conn);
 443
 444	/* if we're called from the softirq handler, we'll be GFP_NOWAIT.
 445	 * in this case the ring being low is going to lead to more interrupts
 446	 * and we can safely let the softirq code take care of it unless the
 447	 * ring is completely empty.
 448	 *
 449	 * if we're called from krdsd, we'll be GFP_KERNEL.  In this case
 450	 * we might have raced with the softirq code while we had the refill
 451	 * lock held.  Use rds_ib_ring_low() instead of ring_empty to decide
 452	 * if we should requeue.
 453	 */
 454	if (rds_conn_up(conn) &&
 455	    (must_wake ||
 456	    (can_wait && rds_ib_ring_low(&ic->i_recv_ring)) ||
 457	    rds_ib_ring_empty(&ic->i_recv_ring))) {
 458		queue_delayed_work(rds_wq, &conn->c_recv_w, 1);
 459	}
 460	if (can_wait)
 461		cond_resched();
 462}
 463
 464/*
 465 * We want to recycle several types of recv allocations, like incs and frags.
 466 * To use this, the *_free() function passes in the ptr to a list_head within
 467 * the recyclee, as well as the cache to put it on.
 468 *
 469 * First, we put the memory on a percpu list. When this reaches a certain size,
 470 * We move it to an intermediate non-percpu list in a lockless manner, with some
 471 * xchg/compxchg wizardry.
 472 *
 473 * N.B. Instead of a list_head as the anchor, we use a single pointer, which can
 474 * be NULL and xchg'd. The list is actually empty when the pointer is NULL, and
 475 * list_empty() will return true with one element is actually present.
 476 */
 477static void rds_ib_recv_cache_put(struct list_head *new_item,
 478				 struct rds_ib_refill_cache *cache)
 479{
 480	unsigned long flags;
 481	struct list_head *old, *chpfirst;
 482
 483	local_irq_save(flags);
 484
 485	chpfirst = __this_cpu_read(cache->percpu->first);
 486	if (!chpfirst)
 487		INIT_LIST_HEAD(new_item);
 488	else /* put on front */
 489		list_add_tail(new_item, chpfirst);
 490
 491	__this_cpu_write(cache->percpu->first, new_item);
 492	__this_cpu_inc(cache->percpu->count);
 493
 494	if (__this_cpu_read(cache->percpu->count) < RDS_IB_RECYCLE_BATCH_COUNT)
 495		goto end;
 496
 497	/*
 498	 * Return our per-cpu first list to the cache's xfer by atomically
 499	 * grabbing the current xfer list, appending it to our per-cpu list,
 500	 * and then atomically returning that entire list back to the
 501	 * cache's xfer list as long as it's still empty.
 502	 */
 503	do {
 504		old = xchg(&cache->xfer, NULL);
 505		if (old)
 506			list_splice_entire_tail(old, chpfirst);
 507		old = cmpxchg(&cache->xfer, NULL, chpfirst);
 508	} while (old);
 509
 510
 511	__this_cpu_write(cache->percpu->first, NULL);
 512	__this_cpu_write(cache->percpu->count, 0);
 513end:
 514	local_irq_restore(flags);
 515}
 516
 517static struct list_head *rds_ib_recv_cache_get(struct rds_ib_refill_cache *cache)
 518{
 519	struct list_head *head = cache->ready;
 520
 521	if (head) {
 522		if (!list_empty(head)) {
 523			cache->ready = head->next;
 524			list_del_init(head);
 525		} else
 526			cache->ready = NULL;
 527	}
 528
 529	return head;
 530}
 531
 532int rds_ib_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to)
 533{
 534	struct rds_ib_incoming *ibinc;
 535	struct rds_page_frag *frag;
 536	unsigned long to_copy;
 537	unsigned long frag_off = 0;
 538	int copied = 0;
 539	int ret;
 540	u32 len;
 541
 542	ibinc = container_of(inc, struct rds_ib_incoming, ii_inc);
 543	frag = list_entry(ibinc->ii_frags.next, struct rds_page_frag, f_item);
 544	len = be32_to_cpu(inc->i_hdr.h_len);
 545
 546	while (iov_iter_count(to) && copied < len) {
 547		if (frag_off == RDS_FRAG_SIZE) {
 548			frag = list_entry(frag->f_item.next,
 549					  struct rds_page_frag, f_item);
 550			frag_off = 0;
 551		}
 552		to_copy = min_t(unsigned long, iov_iter_count(to),
 553				RDS_FRAG_SIZE - frag_off);
 554		to_copy = min_t(unsigned long, to_copy, len - copied);
 555
 556		/* XXX needs + offset for multiple recvs per page */
 557		rds_stats_add(s_copy_to_user, to_copy);
 558		ret = copy_page_to_iter(sg_page(&frag->f_sg),
 559					frag->f_sg.offset + frag_off,
 560					to_copy,
 561					to);
 562		if (ret != to_copy)
 563			return -EFAULT;
 564
 565		frag_off += to_copy;
 566		copied += to_copy;
 567	}
 568
 569	return copied;
 570}
 571
 572/* ic starts out kzalloc()ed */
 573void rds_ib_recv_init_ack(struct rds_ib_connection *ic)
 574{
 575	struct ib_send_wr *wr = &ic->i_ack_wr;
 576	struct ib_sge *sge = &ic->i_ack_sge;
 577
 578	sge->addr = ic->i_ack_dma;
 579	sge->length = sizeof(struct rds_header);
 580	sge->lkey = ic->i_pd->local_dma_lkey;
 581
 582	wr->sg_list = sge;
 583	wr->num_sge = 1;
 584	wr->opcode = IB_WR_SEND;
 585	wr->wr_id = RDS_IB_ACK_WR_ID;
 586	wr->send_flags = IB_SEND_SIGNALED | IB_SEND_SOLICITED;
 587}
 588
 589/*
 590 * You'd think that with reliable IB connections you wouldn't need to ack
 591 * messages that have been received.  The problem is that IB hardware generates
 592 * an ack message before it has DMAed the message into memory.  This creates a
 593 * potential message loss if the HCA is disabled for any reason between when it
 594 * sends the ack and before the message is DMAed and processed.  This is only a
 595 * potential issue if another HCA is available for fail-over.
 596 *
 597 * When the remote host receives our ack they'll free the sent message from
 598 * their send queue.  To decrease the latency of this we always send an ack
 599 * immediately after we've received messages.
 600 *
 601 * For simplicity, we only have one ack in flight at a time.  This puts
 602 * pressure on senders to have deep enough send queues to absorb the latency of
 603 * a single ack frame being in flight.  This might not be good enough.
 604 *
 605 * This is implemented by have a long-lived send_wr and sge which point to a
 606 * statically allocated ack frame.  This ack wr does not fall under the ring
 607 * accounting that the tx and rx wrs do.  The QP attribute specifically makes
 608 * room for it beyond the ring size.  Send completion notices its special
 609 * wr_id and avoids working with the ring in that case.
 610 */
 611#ifndef KERNEL_HAS_ATOMIC64
 612void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq, int ack_required)
 613{
 614	unsigned long flags;
 615
 616	spin_lock_irqsave(&ic->i_ack_lock, flags);
 617	ic->i_ack_next = seq;
 618	if (ack_required)
 619		set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 620	spin_unlock_irqrestore(&ic->i_ack_lock, flags);
 621}
 622
 623static u64 rds_ib_get_ack(struct rds_ib_connection *ic)
 624{
 625	unsigned long flags;
 626	u64 seq;
 627
 628	clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 629
 630	spin_lock_irqsave(&ic->i_ack_lock, flags);
 631	seq = ic->i_ack_next;
 632	spin_unlock_irqrestore(&ic->i_ack_lock, flags);
 633
 634	return seq;
 635}
 636#else
 637void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq, int ack_required)
 638{
 639	atomic64_set(&ic->i_ack_next, seq);
 640	if (ack_required) {
 641		smp_mb__before_atomic();
 642		set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 643	}
 644}
 645
 646static u64 rds_ib_get_ack(struct rds_ib_connection *ic)
 647{
 648	clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 649	smp_mb__after_atomic();
 650
 651	return atomic64_read(&ic->i_ack_next);
 652}
 653#endif
 654
 655
 656static void rds_ib_send_ack(struct rds_ib_connection *ic, unsigned int adv_credits)
 657{
 658	struct rds_header *hdr = ic->i_ack;
 659	u64 seq;
 660	int ret;
 661
 662	seq = rds_ib_get_ack(ic);
 663
 664	rdsdebug("send_ack: ic %p ack %llu\n", ic, (unsigned long long) seq);
 
 
 
 665	rds_message_populate_header(hdr, 0, 0, 0);
 666	hdr->h_ack = cpu_to_be64(seq);
 667	hdr->h_credit = adv_credits;
 668	rds_message_make_checksum(hdr);
 
 
 
 669	ic->i_ack_queued = jiffies;
 670
 671	ret = ib_post_send(ic->i_cm_id->qp, &ic->i_ack_wr, NULL);
 672	if (unlikely(ret)) {
 673		/* Failed to send. Release the WR, and
 674		 * force another ACK.
 675		 */
 676		clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
 677		set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 678
 679		rds_ib_stats_inc(s_ib_ack_send_failure);
 680
 681		rds_ib_conn_error(ic->conn, "sending ack failed\n");
 682	} else
 683		rds_ib_stats_inc(s_ib_ack_sent);
 684}
 685
 686/*
 687 * There are 3 ways of getting acknowledgements to the peer:
 688 *  1.	We call rds_ib_attempt_ack from the recv completion handler
 689 *	to send an ACK-only frame.
 690 *	However, there can be only one such frame in the send queue
 691 *	at any time, so we may have to postpone it.
 692 *  2.	When another (data) packet is transmitted while there's
 693 *	an ACK in the queue, we piggyback the ACK sequence number
 694 *	on the data packet.
 695 *  3.	If the ACK WR is done sending, we get called from the
 696 *	send queue completion handler, and check whether there's
 697 *	another ACK pending (postponed because the WR was on the
 698 *	queue). If so, we transmit it.
 699 *
 700 * We maintain 2 variables:
 701 *  -	i_ack_flags, which keeps track of whether the ACK WR
 702 *	is currently in the send queue or not (IB_ACK_IN_FLIGHT)
 703 *  -	i_ack_next, which is the last sequence number we received
 704 *
 705 * Potentially, send queue and receive queue handlers can run concurrently.
 706 * It would be nice to not have to use a spinlock to synchronize things,
 707 * but the one problem that rules this out is that 64bit updates are
 708 * not atomic on all platforms. Things would be a lot simpler if
 709 * we had atomic64 or maybe cmpxchg64 everywhere.
 710 *
 711 * Reconnecting complicates this picture just slightly. When we
 712 * reconnect, we may be seeing duplicate packets. The peer
 713 * is retransmitting them, because it hasn't seen an ACK for
 714 * them. It is important that we ACK these.
 715 *
 716 * ACK mitigation adds a header flag "ACK_REQUIRED"; any packet with
 717 * this flag set *MUST* be acknowledged immediately.
 718 */
 719
 720/*
 721 * When we get here, we're called from the recv queue handler.
 722 * Check whether we ought to transmit an ACK.
 723 */
 724void rds_ib_attempt_ack(struct rds_ib_connection *ic)
 725{
 726	unsigned int adv_credits;
 727
 728	if (!test_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
 729		return;
 730
 731	if (test_and_set_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags)) {
 732		rds_ib_stats_inc(s_ib_ack_send_delayed);
 733		return;
 734	}
 735
 736	/* Can we get a send credit? */
 737	if (!rds_ib_send_grab_credits(ic, 1, &adv_credits, 0, RDS_MAX_ADV_CREDIT)) {
 738		rds_ib_stats_inc(s_ib_tx_throttle);
 739		clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
 740		return;
 741	}
 742
 743	clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
 744	rds_ib_send_ack(ic, adv_credits);
 745}
 746
 747/*
 748 * We get here from the send completion handler, when the
 749 * adapter tells us the ACK frame was sent.
 750 */
 751void rds_ib_ack_send_complete(struct rds_ib_connection *ic)
 752{
 753	clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
 754	rds_ib_attempt_ack(ic);
 755}
 756
 757/*
 758 * This is called by the regular xmit code when it wants to piggyback
 759 * an ACK on an outgoing frame.
 760 */
 761u64 rds_ib_piggyb_ack(struct rds_ib_connection *ic)
 762{
 763	if (test_and_clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
 764		rds_ib_stats_inc(s_ib_ack_send_piggybacked);
 765	return rds_ib_get_ack(ic);
 766}
 767
 768/*
 769 * It's kind of lame that we're copying from the posted receive pages into
 770 * long-lived bitmaps.  We could have posted the bitmaps and rdma written into
 771 * them.  But receiving new congestion bitmaps should be a *rare* event, so
 772 * hopefully we won't need to invest that complexity in making it more
 773 * efficient.  By copying we can share a simpler core with TCP which has to
 774 * copy.
 775 */
 776static void rds_ib_cong_recv(struct rds_connection *conn,
 777			      struct rds_ib_incoming *ibinc)
 778{
 779	struct rds_cong_map *map;
 780	unsigned int map_off;
 781	unsigned int map_page;
 782	struct rds_page_frag *frag;
 783	unsigned long frag_off;
 784	unsigned long to_copy;
 785	unsigned long copied;
 786	__le64 uncongested = 0;
 787	void *addr;
 788
 789	/* catch completely corrupt packets */
 790	if (be32_to_cpu(ibinc->ii_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
 791		return;
 792
 793	map = conn->c_fcong;
 794	map_page = 0;
 795	map_off = 0;
 796
 797	frag = list_entry(ibinc->ii_frags.next, struct rds_page_frag, f_item);
 798	frag_off = 0;
 799
 800	copied = 0;
 801
 802	while (copied < RDS_CONG_MAP_BYTES) {
 803		__le64 *src, *dst;
 804		unsigned int k;
 805
 806		to_copy = min(RDS_FRAG_SIZE - frag_off, PAGE_SIZE - map_off);
 807		BUG_ON(to_copy & 7); /* Must be 64bit aligned. */
 808
 809		addr = kmap_atomic(sg_page(&frag->f_sg));
 810
 811		src = addr + frag->f_sg.offset + frag_off;
 812		dst = (void *)map->m_page_addrs[map_page] + map_off;
 813		for (k = 0; k < to_copy; k += 8) {
 814			/* Record ports that became uncongested, ie
 815			 * bits that changed from 0 to 1. */
 816			uncongested |= ~(*src) & *dst;
 817			*dst++ = *src++;
 818		}
 819		kunmap_atomic(addr);
 820
 821		copied += to_copy;
 822
 823		map_off += to_copy;
 824		if (map_off == PAGE_SIZE) {
 825			map_off = 0;
 826			map_page++;
 827		}
 828
 829		frag_off += to_copy;
 830		if (frag_off == RDS_FRAG_SIZE) {
 831			frag = list_entry(frag->f_item.next,
 832					  struct rds_page_frag, f_item);
 833			frag_off = 0;
 834		}
 835	}
 836
 837	/* the congestion map is in little endian order */
 838	rds_cong_map_updated(map, le64_to_cpu(uncongested));
 839}
 840
 841static void rds_ib_process_recv(struct rds_connection *conn,
 842				struct rds_ib_recv_work *recv, u32 data_len,
 843				struct rds_ib_ack_state *state)
 844{
 845	struct rds_ib_connection *ic = conn->c_transport_data;
 846	struct rds_ib_incoming *ibinc = ic->i_ibinc;
 847	struct rds_header *ihdr, *hdr;
 
 848
 849	/* XXX shut down the connection if port 0,0 are seen? */
 850
 851	rdsdebug("ic %p ibinc %p recv %p byte len %u\n", ic, ibinc, recv,
 852		 data_len);
 853
 854	if (data_len < sizeof(struct rds_header)) {
 855		rds_ib_conn_error(conn, "incoming message "
 856		       "from %pI6c didn't include a "
 857		       "header, disconnecting and "
 858		       "reconnecting\n",
 859		       &conn->c_faddr);
 860		return;
 861	}
 862	data_len -= sizeof(struct rds_header);
 863
 864	ihdr = ic->i_recv_hdrs[recv - ic->i_recvs];
 865
 
 
 866	/* Validate the checksum. */
 867	if (!rds_message_verify_checksum(ihdr)) {
 868		rds_ib_conn_error(conn, "incoming message "
 869		       "from %pI6c has corrupted header - "
 870		       "forcing a reconnect\n",
 871		       &conn->c_faddr);
 872		rds_stats_inc(s_recv_drop_bad_checksum);
 873		return;
 874	}
 875
 876	/* Process the ACK sequence which comes with every packet */
 877	state->ack_recv = be64_to_cpu(ihdr->h_ack);
 878	state->ack_recv_valid = 1;
 879
 880	/* Process the credits update if there was one */
 881	if (ihdr->h_credit)
 882		rds_ib_send_add_credits(conn, ihdr->h_credit);
 883
 884	if (ihdr->h_sport == 0 && ihdr->h_dport == 0 && data_len == 0) {
 885		/* This is an ACK-only packet. The fact that it gets
 886		 * special treatment here is that historically, ACKs
 887		 * were rather special beasts.
 888		 */
 889		rds_ib_stats_inc(s_ib_ack_received);
 890
 891		/*
 892		 * Usually the frags make their way on to incs and are then freed as
 893		 * the inc is freed.  We don't go that route, so we have to drop the
 894		 * page ref ourselves.  We can't just leave the page on the recv
 895		 * because that confuses the dma mapping of pages and each recv's use
 896		 * of a partial page.
 897		 *
 898		 * FIXME: Fold this into the code path below.
 899		 */
 900		rds_ib_frag_free(ic, recv->r_frag);
 901		recv->r_frag = NULL;
 902		return;
 903	}
 904
 905	/*
 906	 * If we don't already have an inc on the connection then this
 907	 * fragment has a header and starts a message.. copy its header
 908	 * into the inc and save the inc so we can hang upcoming fragments
 909	 * off its list.
 910	 */
 911	if (!ibinc) {
 912		ibinc = recv->r_ibinc;
 913		recv->r_ibinc = NULL;
 914		ic->i_ibinc = ibinc;
 915
 916		hdr = &ibinc->ii_inc.i_hdr;
 917		ibinc->ii_inc.i_rx_lat_trace[RDS_MSG_RX_HDR] =
 918				local_clock();
 919		memcpy(hdr, ihdr, sizeof(*hdr));
 920		ic->i_recv_data_rem = be32_to_cpu(hdr->h_len);
 921		ibinc->ii_inc.i_rx_lat_trace[RDS_MSG_RX_START] =
 922				local_clock();
 923
 924		rdsdebug("ic %p ibinc %p rem %u flag 0x%x\n", ic, ibinc,
 925			 ic->i_recv_data_rem, hdr->h_flags);
 926	} else {
 927		hdr = &ibinc->ii_inc.i_hdr;
 928		/* We can't just use memcmp here; fragments of a
 929		 * single message may carry different ACKs */
 930		if (hdr->h_sequence != ihdr->h_sequence ||
 931		    hdr->h_len != ihdr->h_len ||
 932		    hdr->h_sport != ihdr->h_sport ||
 933		    hdr->h_dport != ihdr->h_dport) {
 934			rds_ib_conn_error(conn,
 935				"fragment header mismatch; forcing reconnect\n");
 936			return;
 937		}
 938	}
 939
 940	list_add_tail(&recv->r_frag->f_item, &ibinc->ii_frags);
 941	recv->r_frag = NULL;
 942
 943	if (ic->i_recv_data_rem > RDS_FRAG_SIZE)
 944		ic->i_recv_data_rem -= RDS_FRAG_SIZE;
 945	else {
 946		ic->i_recv_data_rem = 0;
 947		ic->i_ibinc = NULL;
 948
 949		if (ibinc->ii_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP) {
 950			rds_ib_cong_recv(conn, ibinc);
 951		} else {
 952			rds_recv_incoming(conn, &conn->c_faddr, &conn->c_laddr,
 953					  &ibinc->ii_inc, GFP_ATOMIC);
 954			state->ack_next = be64_to_cpu(hdr->h_sequence);
 955			state->ack_next_valid = 1;
 956		}
 957
 958		/* Evaluate the ACK_REQUIRED flag *after* we received
 959		 * the complete frame, and after bumping the next_rx
 960		 * sequence. */
 961		if (hdr->h_flags & RDS_FLAG_ACK_REQUIRED) {
 962			rds_stats_inc(s_recv_ack_required);
 963			state->ack_required = 1;
 964		}
 965
 966		rds_inc_put(&ibinc->ii_inc);
 967	}
 
 
 
 968}
 969
 970void rds_ib_recv_cqe_handler(struct rds_ib_connection *ic,
 971			     struct ib_wc *wc,
 972			     struct rds_ib_ack_state *state)
 973{
 974	struct rds_connection *conn = ic->conn;
 975	struct rds_ib_recv_work *recv;
 976
 977	rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n",
 978		 (unsigned long long)wc->wr_id, wc->status,
 979		 ib_wc_status_msg(wc->status), wc->byte_len,
 980		 be32_to_cpu(wc->ex.imm_data));
 981
 982	rds_ib_stats_inc(s_ib_rx_cq_event);
 983	recv = &ic->i_recvs[rds_ib_ring_oldest(&ic->i_recv_ring)];
 984	ib_dma_unmap_sg(ic->i_cm_id->device, &recv->r_frag->f_sg, 1,
 985			DMA_FROM_DEVICE);
 986
 987	/* Also process recvs in connecting state because it is possible
 988	 * to get a recv completion _before_ the rdmacm ESTABLISHED
 989	 * event is processed.
 990	 */
 991	if (wc->status == IB_WC_SUCCESS) {
 992		rds_ib_process_recv(conn, recv, wc->byte_len, state);
 993	} else {
 994		/* We expect errors as the qp is drained during shutdown */
 995		if (rds_conn_up(conn) || rds_conn_connecting(conn))
 996			rds_ib_conn_error(conn, "recv completion on <%pI6c,%pI6c, %d> had status %u (%s), vendor err 0x%x, disconnecting and reconnecting\n",
 997					  &conn->c_laddr, &conn->c_faddr,
 998					  conn->c_tos, wc->status,
 999					  ib_wc_status_msg(wc->status),
1000					  wc->vendor_err);
1001	}
1002
1003	/* rds_ib_process_recv() doesn't always consume the frag, and
1004	 * we might not have called it at all if the wc didn't indicate
1005	 * success. We already unmapped the frag's pages, though, and
1006	 * the following rds_ib_ring_free() call tells the refill path
1007	 * that it will not find an allocated frag here. Make sure we
1008	 * keep that promise by freeing a frag that's still on the ring.
1009	 */
1010	if (recv->r_frag) {
1011		rds_ib_frag_free(ic, recv->r_frag);
1012		recv->r_frag = NULL;
1013	}
1014	rds_ib_ring_free(&ic->i_recv_ring, 1);
1015
1016	/* If we ever end up with a really empty receive ring, we're
1017	 * in deep trouble, as the sender will definitely see RNR
1018	 * timeouts. */
1019	if (rds_ib_ring_empty(&ic->i_recv_ring))
1020		rds_ib_stats_inc(s_ib_rx_ring_empty);
1021
1022	if (rds_ib_ring_low(&ic->i_recv_ring)) {
1023		rds_ib_recv_refill(conn, 0, GFP_NOWAIT);
1024		rds_ib_stats_inc(s_ib_rx_refill_from_cq);
1025	}
1026}
1027
1028int rds_ib_recv_path(struct rds_conn_path *cp)
1029{
1030	struct rds_connection *conn = cp->cp_conn;
1031	struct rds_ib_connection *ic = conn->c_transport_data;
1032
1033	rdsdebug("conn %p\n", conn);
1034	if (rds_conn_up(conn)) {
1035		rds_ib_attempt_ack(ic);
1036		rds_ib_recv_refill(conn, 0, GFP_KERNEL);
1037		rds_ib_stats_inc(s_ib_rx_refill_from_thread);
1038	}
1039
1040	return 0;
1041}
1042
1043int rds_ib_recv_init(void)
1044{
1045	struct sysinfo si;
1046	int ret = -ENOMEM;
1047
1048	/* Default to 30% of all available RAM for recv memory */
1049	si_meminfo(&si);
1050	rds_ib_sysctl_max_recv_allocation = si.totalram / 3 * PAGE_SIZE / RDS_FRAG_SIZE;
1051
1052	rds_ib_incoming_slab =
1053		kmem_cache_create_usercopy("rds_ib_incoming",
1054					   sizeof(struct rds_ib_incoming),
1055					   0, SLAB_HWCACHE_ALIGN,
1056					   offsetof(struct rds_ib_incoming,
1057						    ii_inc.i_usercopy),
1058					   sizeof(struct rds_inc_usercopy),
1059					   NULL);
1060	if (!rds_ib_incoming_slab)
1061		goto out;
1062
1063	rds_ib_frag_slab = kmem_cache_create("rds_ib_frag",
1064					sizeof(struct rds_page_frag),
1065					0, SLAB_HWCACHE_ALIGN, NULL);
1066	if (!rds_ib_frag_slab) {
1067		kmem_cache_destroy(rds_ib_incoming_slab);
1068		rds_ib_incoming_slab = NULL;
1069	} else
1070		ret = 0;
1071out:
1072	return ret;
1073}
1074
1075void rds_ib_recv_exit(void)
1076{
1077	WARN_ON(atomic_read(&rds_ib_allocation));
1078
1079	kmem_cache_destroy(rds_ib_incoming_slab);
1080	kmem_cache_destroy(rds_ib_frag_slab);
1081}