aboutsummaryrefslogtreecommitdiffstats
path: root/net/rds/connection.c
blob: 9e07c756d1f95252c66726fe6157e7dea9c8fe8f (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
/*
 * Copyright (c) 2006 Oracle.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <linux/export.h>
#include <net/inet_hashtables.h>

#include "rds.h"
#include "loop.h"

#define RDS_CONNECTION_HASH_BITS 12
#define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
#define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)

/* converting this to RCU is a chore for another day.. */
static DEFINE_SPINLOCK(rds_conn_lock);
static unsigned long rds_conn_count;
static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
static struct kmem_cache *rds_conn_slab;

static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
{
	/* Pass NULL, don't need struct net for hash */
	unsigned long hash = inet_ehashfn(NULL,
					  be32_to_cpu(laddr), 0,
					  be32_to_cpu(faddr), 0);
	return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
}

#define rds_conn_info_set(var, test, suffix) do {		\
	if (test)						\
		var |= RDS_INFO_CONNECTION_FLAG_##suffix;	\
} while (0)

/* rcu read lock must be held or the connection spinlock */
static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
					      __be32 laddr, __be32 faddr,
					      struct rds_transport *trans)
{
	struct rds_connection *conn, *ret = NULL;
	struct hlist_node *pos;

	hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {
		if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
				conn->c_trans == trans) {
			ret = conn;
			break;
		}
	}
	rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
		 &laddr, &faddr);
	return ret;
}

/*
 * This is called by transports as they're bringing down a connection.
 * It clears partial message state so that the transport can start sending
 * and receiving over this connection again in the future.  It is up to
 * the transport to have serialized this call with its send and recv.
 */
static void rds_conn_reset(struct rds_connection *conn)
{
	rdsdebug("connection %pI4 to %pI4 reset\n",
	  &conn->c_laddr, &conn->c_faddr);

	rds_stats_inc(s_conn_reset);
	rds_send_reset(conn);
	conn->c_flags = 0;

	/* Do not clear next_rx_seq here, else we cannot distinguish
	 * retransmitted packets from new packets, and will hand all
	 * of them to the application. That is not consistent with the
	 * reliability guarantees of RDS. */
}

/*
 * There is only every one 'conn' for a given pair of addresses in the
 * system at a time.  They contain messages to be retransmitted and so
 * span the lifetime of the actual underlying transport connections.
 *
 * For now they are not garbage collected once they're created.  They
 * are torn down as the module is removed, if ever.
 */
static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
				       struct rds_transport *trans, gfp_t gfp,
				       int is_outgoing)
{
	struct rds_connection *conn, *parent = NULL;
	struct hlist_head *head = rds_conn_bucket(laddr, faddr);
	struct rds_transport *loop_trans;
	unsigned long flags;
	int ret;

	rcu_read_lock();
	conn = rds_conn_lookup(head, laddr, faddr, trans);
	if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
	    !is_outgoing) {
		/* This is a looped back IB connection, and we're
		 * called by the code handling the incoming connect.
		 * We need a second connection object into which we
		 * can stick the other QP. */
		parent = conn;
		conn = parent->c_passive;
	}
	rcu_read_unlock();
	if (conn)
		goto out;

	conn = kmem_cache_zalloc(rds_conn_slab, gfp);
	if (!conn) {
		conn = ERR_PTR(-ENOMEM);
		goto out;
	}

	INIT_HLIST_NODE(&conn->c_hash_node);
	conn->c_laddr = laddr;
	conn->c_faddr = faddr;
	spin_lock_init(&conn->c_lock);
	conn->c_next_tx_seq = 1;

	init_waitqueue_head(&conn->c_waitq);
	INIT_LIST_HEAD(&conn->c_send_queue);
	INIT_LIST_HEAD(&conn->c_retrans);

	ret = rds_cong_get_maps(conn);
	if (ret) {
		kmem_cache_free(rds_conn_slab, conn);
		conn = ERR_PTR(ret);
		goto out;
	}

	/*
	 * This is where a connection becomes loopback.  If *any* RDS sockets
	 * can bind to the destination address then we'd rather the messages
	 * flow through loopback rather than either transport.
	 */
	loop_trans = rds_trans_get_preferred(faddr);
	if (loop_trans) {
		rds_trans_put(loop_trans);
		conn->c_loopback = 1;
		if (is_outgoing && trans->t_prefer_loopback) {
			/* "outgoing" connection - and the transport
			 * says it wants the connection handled by the
			 * loopback transport. This is what TCP does.
			 */
			trans = &rds_loop_transport;
		}
	}

	conn->c_trans = trans;

	ret = trans->conn_alloc(conn, gfp);
	if (ret) {
		kmem_cache_free(rds_conn_slab, conn);
		conn = ERR_PTR(ret);
		goto out;
	}

	atomic_set(&conn->c_state, RDS_CONN_DOWN);
	conn->c_reconnect_jiffies = 0;
	INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
	INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
	INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
	INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
	mutex_init(&conn->c_cm_lock);
	conn->c_flags = 0;

	rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
	  conn, &laddr, &faddr,
	  trans->t_name ? trans->t_name : "[unknown]",
	  is_outgoing ? "(outgoing)" : "");

	/*
	 * Since we ran without holding the conn lock, someone could
	 * have created the same conn (either normal or passive) in the
	 * interim. We check while holding the lock. If we won, we complete
	 * init and return our conn. If we lost, we rollback and return the
	 * other one.
	 */
	spin_lock_irqsave(&rds_conn_lock, flags);
	if (parent) {
		/* Creating passive conn */
		if (parent->c_passive) {
			trans->conn_free(conn->c_transport_data);
			kmem_cache_free(rds_conn_slab, conn);
			conn = parent->c_passive;
		} else {
			parent->c_passive = conn;
			rds_cong_add_conn(conn);
			rds_conn_count++;
		}
	} else {
		/* Creating normal conn */
		struct rds_connection *found;

		found = rds_conn_lookup(head, laddr, faddr, trans);
		if (found) {
			trans->conn_free(conn->c_transport_data);
			kmem_cache_free(rds_conn_slab, conn);
			conn = found;
		} else {
			hlist_add_head_rcu(&conn->c_hash_node, head);
			rds_cong_add_conn(conn);
			rds_conn_count++;
		}
	}
	spin_unlock_irqrestore(&rds_conn_lock, flags);

out:
	return conn;
}

struct rds_connection *rds_conn_create(__be32 laddr, __be32 faddr,
				       struct rds_transport *trans, gfp_t gfp)
{
	return __rds_conn_create(laddr, faddr, trans, gfp, 0);
}
EXPORT_SYMBOL_GPL(rds_conn_create);

struct rds_connection *rds_conn_create_outgoing(__be32 laddr, __be32 faddr,
				       struct rds_transport *trans, gfp_t gfp)
{
	return __rds_conn_create(laddr, faddr, trans, gfp, 1);
}
EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);

void rds_conn_shutdown(struct rds_connection *conn)
{
	/* shut it down unless it's down already */
	if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
		/*
		 * Quiesce the connection mgmt handlers before we start tearing
		 * things down. We don't hold the mutex for the entire
		 * duration of the shutdown operation, else we may be
		 * deadlocking with the CM handler. Instead, the CM event
		 * handler is supposed to check for state DISCONNECTING
		 */
		mutex_lock(&conn->c_cm_lock);
		if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
		 && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
			rds_conn_error(conn, "shutdown called in state %d\n",
					atomic_read(&conn->c_state));
			mutex_unlock(&conn->c_cm_lock);
			return;
		}
		mutex_unlock(&conn->c_cm_lock);

		wait_event(conn->c_waitq,
			   !test_bit(RDS_IN_XMIT, &conn->c_flags));

		conn->c_trans->conn_shutdown(conn);
		rds_conn_reset(conn);

		if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
			/* This can happen - eg when we're in the middle of tearing
			 * down the connection, and someone unloads the rds module.
			 * Quite reproduceable with loopback connections.
			 * Mostly harmless.
			 */
			rds_conn_error(conn,
				"%s: failed to transition to state DOWN, "
				"current state is %d\n",
				__func__,
				atomic_read(&conn->c_state));
			return;
		}
	}

	/* Then reconnect if it's still live.
	 * The passive side of an IB loopback connection is never added
	 * to the conn hash, so we never trigger a reconnect on this
	 * conn - the reconnect is always triggered by the active peer. */
	cancel_delayed_work_sync(&conn->c_conn_w);
	rcu_read_lock();
	if (!hlist_unhashed(&conn->c_hash_node)) {
		rcu_read_unlock();
		rds_queue_reconnect(conn);
	} else {
		rcu_read_unlock();
	}
}

/*
 * Stop and free a connection.
 *
 * This can only be used in very limited circumstances.  It assumes that once
 * the conn has been shutdown that no one else is referencing the connection.
 * We can only ensure this in the rmmod path in the current code.
 */
void rds_conn_destroy(struct rds_connection *conn)
{
	struct rds_message *rm, *rtmp;
	unsigned long flags;

	rdsdebug("freeing conn %p for %pI4 -> "
		 "%pI4\n", conn, &conn->c_laddr,
		 &conn->c_faddr);

	/* Ensure conn will not be scheduled for reconnect */
	spin_lock_irq(&rds_conn_lock);
	hlist_del_init_rcu(&conn->c_hash_node);
	spin_unlock_irq(&rds_conn_lock);
	synchronize_rcu();

	/* shut the connection down */
	rds_conn_drop(conn);
	flush_work(&conn->c_down_w);

	/* make sure lingering queued work won't try to ref the conn */
	cancel_delayed_work_sync(&conn->c_send_w);
	cancel_delayed_work_sync(&conn->c_recv_w);

	/* tear down queued messages */
	list_for_each_entry_safe(rm, rtmp,
				 &conn->c_send_queue,
				 m_conn_item) {
		list_del_init(&rm->m_conn_item);
		BUG_ON(!list_empty(&rm->m_sock_item));
		rds_message_put(rm);
	}
	if (conn->c_xmit_rm)
		rds_message_put(conn->c_xmit_rm);

	conn->c_trans->conn_free(conn->c_transport_data);

	/*
	 * The congestion maps aren't freed up here.  They're
	 * freed by rds_cong_exit() after all the connections
	 * have been freed.
	 */
	rds_cong_remove_conn(conn);

	BUG_ON(!list_empty(&conn->c_retrans));
	kmem_cache_free(rds_conn_slab, conn);

	spin_lock_irqsave(&rds_conn_lock, flags);
	rds_conn_count--;
	spin_unlock_irqrestore(&rds_conn_lock, flags);
}
EXPORT_SYMBOL_GPL(rds_conn_destroy);

static void rds_conn_message_info(struct socket *sock, unsigned int len,
				  struct rds_info_iterator *iter,
				  struct rds_info_lengths *lens,
				  int want_send)
{
	struct hlist_head *head;
	struct hlist_node *pos;
	struct list_head *list;
	struct rds_connection *conn;
	struct rds_message *rm;
	unsigned int total = 0;
	unsigned long flags;
	size_t i;

	len /= sizeof(struct rds_info_message);

	rcu_read_lock();

	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
	     i++, head++) {
		hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {
			if (want_send)
				list = &conn->c_send_queue;
			else
				list = &conn->c_retrans;

			spin_lock_irqsave(&conn->c_lock, flags);

			/* XXX too lazy to maintain counts.. */
			list_for_each_entry(rm, list, m_conn_item) {
				total++;
				if (total <= len)
					rds_inc_info_copy(&rm->m_inc, iter,
							  conn->c_laddr,
							  conn->c_faddr, 0);
			}

			spin_unlock_irqrestore(&conn->c_lock, flags);
		}
	}
	rcu_read_unlock();

	lens->nr = total;
	lens->each = sizeof(struct rds_info_message);
}

static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
				       struct rds_info_iterator *iter,
				       struct rds_info_lengths *lens)
{
	rds_conn_message_info(sock, len, iter, lens, 1);
}

static void rds_conn_message_info_retrans(struct socket *sock,
					  unsigned int len,
					  struct rds_info_iterator *iter,
					  struct rds_info_lengths *lens)
{
	rds_conn_message_info(sock, len, iter, lens, 0);
}

void rds_for_each_conn_info(struct socket *sock, unsigned int len,
			  struct rds_info_iterator *iter,
			  struct rds_info_lengths *lens,
			  int (*visitor)(struct rds_connection *, void *),
			  size_t item_len)
{
	uint64_t buffer[(item_len + 7) / 8];
	struct hlist_head *head;
	struct hlist_node *pos;
	struct rds_connection *conn;
	size_t i;

	rcu_read_lock();

	lens->nr = 0;
	lens->each = item_len;

	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
	     i++, head++) {
		hlist_for_each_entry_rcu(conn, pos, head, c_hash_node) {

			/* XXX no c_lock usage.. */
			if (!visitor(conn, buffer))
				continue;

			/* We copy as much as we can fit in the buffer,
			 * but we count all items so that the caller
			 * can resize the buffer. */
			if (len >= item_len) {
				rds_info_copy(iter, buffer, item_len);
				len -= item_len;
			}
			lens->nr++;
		}
	}
	rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(rds_for_each_conn_info);

static int rds_conn_info_visitor(struct rds_connection *conn,
				  void *buffer)
{
	struct rds_info_connection *cinfo = buffer;

	cinfo->next_tx_seq = conn->c_next_tx_seq;
	cinfo->next_rx_seq = conn->c_next_rx_seq;
	cinfo->laddr = conn->c_laddr;
	cinfo->faddr = conn->c_faddr;
	strncpy(cinfo->transport, conn->c_trans->t_name,
		sizeof(cinfo->transport));
	cinfo->flags = 0;

	rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &conn->c_flags),
			  SENDING);
	/* XXX Future: return the state rather than these funky bits */
	rds_conn_info_set(cinfo->flags,
			  atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
			  CONNECTING);
	rds_conn_info_set(cinfo->flags,
			  atomic_read(&conn->c_state) == RDS_CONN_UP,
			  CONNECTED);
	return 1;
}

static void rds_conn_info(struct socket *sock, unsigned int len,
			  struct rds_info_iterator *iter,
			  struct rds_info_lengths *lens)
{
	rds_for_each_conn_info(sock, len, iter, lens,
				rds_conn_info_visitor,
				sizeof(struct rds_info_connection));
}

int rds_conn_init(void)
{
	rds_conn_slab = kmem_cache_create("rds_connection",
					  sizeof(struct rds_connection),
					  0, 0, NULL);
	if (!rds_conn_slab)
		return -ENOMEM;

	rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
	rds_info_register_func(RDS_INFO_SEND_MESSAGES,
			       rds_conn_message_info_send);
	rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
			       rds_conn_message_info_retrans);

	return 0;
}

void rds_conn_exit(void)
{
	rds_loop_exit();

	WARN_ON(!hlist_empty(rds_conn_hash));

	kmem_cache_destroy(rds_conn_slab);

	rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
	rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
				 rds_conn_message_info_send);
	rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
				 rds_conn_message_info_retrans);
}

/*
 * Force a disconnect
 */
void rds_conn_drop(struct rds_connection *conn)
{
	atomic_set(&conn->c_state, RDS_CONN_ERROR);
	queue_work(rds_wq, &conn->c_down_w);
}
EXPORT_SYMBOL_GPL(rds_conn_drop);

/*
 * If the connection is down, trigger a connect. We may have scheduled a
 * delayed reconnect however - in this case we should not interfere.
 */
void rds_conn_connect_if_down(struct rds_connection *conn)
{
	if (rds_conn_state(conn) == RDS_CONN_DOWN &&
	    !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
		queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
}
EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);

/*
 * An error occurred on the connection
 */
void
__rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	vprintk(fmt, ap);
	va_end(ap);

	rds_conn_drop(conn);
}