xref: /openbmc/linux/net/rds/connection.c (revision 8b235f2f)
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/list.h>
35 #include <linux/slab.h>
36 #include <linux/export.h>
37 #include <net/inet_hashtables.h>
38 
39 #include "rds.h"
40 #include "loop.h"
41 
42 #define RDS_CONNECTION_HASH_BITS 12
43 #define RDS_CONNECTION_HASH_ENTRIES (1 << RDS_CONNECTION_HASH_BITS)
44 #define RDS_CONNECTION_HASH_MASK (RDS_CONNECTION_HASH_ENTRIES - 1)
45 
46 /* converting this to RCU is a chore for another day.. */
47 static DEFINE_SPINLOCK(rds_conn_lock);
48 static unsigned long rds_conn_count;
49 static struct hlist_head rds_conn_hash[RDS_CONNECTION_HASH_ENTRIES];
50 static struct kmem_cache *rds_conn_slab;
51 
52 static struct hlist_head *rds_conn_bucket(__be32 laddr, __be32 faddr)
53 {
54 	static u32 rds_hash_secret __read_mostly;
55 
56 	unsigned long hash;
57 
58 	net_get_random_once(&rds_hash_secret, sizeof(rds_hash_secret));
59 
60 	/* Pass NULL, don't need struct net for hash */
61 	hash = __inet_ehashfn(be32_to_cpu(laddr), 0,
62 			      be32_to_cpu(faddr), 0,
63 			      rds_hash_secret);
64 	return &rds_conn_hash[hash & RDS_CONNECTION_HASH_MASK];
65 }
66 
67 #define rds_conn_info_set(var, test, suffix) do {		\
68 	if (test)						\
69 		var |= RDS_INFO_CONNECTION_FLAG_##suffix;	\
70 } while (0)
71 
72 /* rcu read lock must be held or the connection spinlock */
73 static struct rds_connection *rds_conn_lookup(struct hlist_head *head,
74 					      __be32 laddr, __be32 faddr,
75 					      struct rds_transport *trans)
76 {
77 	struct rds_connection *conn, *ret = NULL;
78 
79 	hlist_for_each_entry_rcu(conn, head, c_hash_node) {
80 		if (conn->c_faddr == faddr && conn->c_laddr == laddr &&
81 				conn->c_trans == trans) {
82 			ret = conn;
83 			break;
84 		}
85 	}
86 	rdsdebug("returning conn %p for %pI4 -> %pI4\n", ret,
87 		 &laddr, &faddr);
88 	return ret;
89 }
90 
91 /*
92  * This is called by transports as they're bringing down a connection.
93  * It clears partial message state so that the transport can start sending
94  * and receiving over this connection again in the future.  It is up to
95  * the transport to have serialized this call with its send and recv.
96  */
97 static void rds_conn_reset(struct rds_connection *conn)
98 {
99 	rdsdebug("connection %pI4 to %pI4 reset\n",
100 	  &conn->c_laddr, &conn->c_faddr);
101 
102 	rds_stats_inc(s_conn_reset);
103 	rds_send_reset(conn);
104 	conn->c_flags = 0;
105 
106 	/* Do not clear next_rx_seq here, else we cannot distinguish
107 	 * retransmitted packets from new packets, and will hand all
108 	 * of them to the application. That is not consistent with the
109 	 * reliability guarantees of RDS. */
110 }
111 
112 /*
113  * There is only every one 'conn' for a given pair of addresses in the
114  * system at a time.  They contain messages to be retransmitted and so
115  * span the lifetime of the actual underlying transport connections.
116  *
117  * For now they are not garbage collected once they're created.  They
118  * are torn down as the module is removed, if ever.
119  */
120 static struct rds_connection *__rds_conn_create(struct net *net,
121 						__be32 laddr, __be32 faddr,
122 				       struct rds_transport *trans, gfp_t gfp,
123 				       int is_outgoing)
124 {
125 	struct rds_connection *conn, *parent = NULL;
126 	struct hlist_head *head = rds_conn_bucket(laddr, faddr);
127 	struct rds_transport *loop_trans;
128 	unsigned long flags;
129 	int ret;
130 	struct rds_transport *otrans = trans;
131 
132 	if (!is_outgoing && otrans->t_type == RDS_TRANS_TCP)
133 		goto new_conn;
134 	rcu_read_lock();
135 	conn = rds_conn_lookup(head, laddr, faddr, trans);
136 	if (conn && conn->c_loopback && conn->c_trans != &rds_loop_transport &&
137 	    laddr == faddr && !is_outgoing) {
138 		/* This is a looped back IB connection, and we're
139 		 * called by the code handling the incoming connect.
140 		 * We need a second connection object into which we
141 		 * can stick the other QP. */
142 		parent = conn;
143 		conn = parent->c_passive;
144 	}
145 	rcu_read_unlock();
146 	if (conn)
147 		goto out;
148 
149 new_conn:
150 	conn = kmem_cache_zalloc(rds_conn_slab, gfp);
151 	if (!conn) {
152 		conn = ERR_PTR(-ENOMEM);
153 		goto out;
154 	}
155 
156 	INIT_HLIST_NODE(&conn->c_hash_node);
157 	conn->c_laddr = laddr;
158 	conn->c_faddr = faddr;
159 	spin_lock_init(&conn->c_lock);
160 	conn->c_next_tx_seq = 1;
161 	rds_conn_net_set(conn, net);
162 
163 	init_waitqueue_head(&conn->c_waitq);
164 	INIT_LIST_HEAD(&conn->c_send_queue);
165 	INIT_LIST_HEAD(&conn->c_retrans);
166 
167 	ret = rds_cong_get_maps(conn);
168 	if (ret) {
169 		kmem_cache_free(rds_conn_slab, conn);
170 		conn = ERR_PTR(ret);
171 		goto out;
172 	}
173 
174 	/*
175 	 * This is where a connection becomes loopback.  If *any* RDS sockets
176 	 * can bind to the destination address then we'd rather the messages
177 	 * flow through loopback rather than either transport.
178 	 */
179 	loop_trans = rds_trans_get_preferred(net, faddr);
180 	if (loop_trans) {
181 		rds_trans_put(loop_trans);
182 		conn->c_loopback = 1;
183 		if (is_outgoing && trans->t_prefer_loopback) {
184 			/* "outgoing" connection - and the transport
185 			 * says it wants the connection handled by the
186 			 * loopback transport. This is what TCP does.
187 			 */
188 			trans = &rds_loop_transport;
189 		}
190 	}
191 
192 	conn->c_trans = trans;
193 
194 	ret = trans->conn_alloc(conn, gfp);
195 	if (ret) {
196 		kmem_cache_free(rds_conn_slab, conn);
197 		conn = ERR_PTR(ret);
198 		goto out;
199 	}
200 
201 	atomic_set(&conn->c_state, RDS_CONN_DOWN);
202 	conn->c_send_gen = 0;
203 	conn->c_reconnect_jiffies = 0;
204 	INIT_DELAYED_WORK(&conn->c_send_w, rds_send_worker);
205 	INIT_DELAYED_WORK(&conn->c_recv_w, rds_recv_worker);
206 	INIT_DELAYED_WORK(&conn->c_conn_w, rds_connect_worker);
207 	INIT_WORK(&conn->c_down_w, rds_shutdown_worker);
208 	mutex_init(&conn->c_cm_lock);
209 	conn->c_flags = 0;
210 
211 	rdsdebug("allocated conn %p for %pI4 -> %pI4 over %s %s\n",
212 	  conn, &laddr, &faddr,
213 	  trans->t_name ? trans->t_name : "[unknown]",
214 	  is_outgoing ? "(outgoing)" : "");
215 
216 	/*
217 	 * Since we ran without holding the conn lock, someone could
218 	 * have created the same conn (either normal or passive) in the
219 	 * interim. We check while holding the lock. If we won, we complete
220 	 * init and return our conn. If we lost, we rollback and return the
221 	 * other one.
222 	 */
223 	spin_lock_irqsave(&rds_conn_lock, flags);
224 	if (parent) {
225 		/* Creating passive conn */
226 		if (parent->c_passive) {
227 			trans->conn_free(conn->c_transport_data);
228 			kmem_cache_free(rds_conn_slab, conn);
229 			conn = parent->c_passive;
230 		} else {
231 			parent->c_passive = conn;
232 			rds_cong_add_conn(conn);
233 			rds_conn_count++;
234 		}
235 	} else {
236 		/* Creating normal conn */
237 		struct rds_connection *found;
238 
239 		if (!is_outgoing && otrans->t_type == RDS_TRANS_TCP)
240 			found = NULL;
241 		else
242 			found = rds_conn_lookup(head, laddr, faddr, trans);
243 		if (found) {
244 			trans->conn_free(conn->c_transport_data);
245 			kmem_cache_free(rds_conn_slab, conn);
246 			conn = found;
247 		} else {
248 			if ((is_outgoing && otrans->t_type == RDS_TRANS_TCP) ||
249 			    (otrans->t_type != RDS_TRANS_TCP)) {
250 				/* Only the active side should be added to
251 				 * reconnect list for TCP.
252 				 */
253 				hlist_add_head_rcu(&conn->c_hash_node, head);
254 			}
255 			rds_cong_add_conn(conn);
256 			rds_conn_count++;
257 		}
258 	}
259 	spin_unlock_irqrestore(&rds_conn_lock, flags);
260 
261 out:
262 	return conn;
263 }
264 
265 struct rds_connection *rds_conn_create(struct net *net,
266 				       __be32 laddr, __be32 faddr,
267 				       struct rds_transport *trans, gfp_t gfp)
268 {
269 	return __rds_conn_create(net, laddr, faddr, trans, gfp, 0);
270 }
271 EXPORT_SYMBOL_GPL(rds_conn_create);
272 
273 struct rds_connection *rds_conn_create_outgoing(struct net *net,
274 						__be32 laddr, __be32 faddr,
275 				       struct rds_transport *trans, gfp_t gfp)
276 {
277 	return __rds_conn_create(net, laddr, faddr, trans, gfp, 1);
278 }
279 EXPORT_SYMBOL_GPL(rds_conn_create_outgoing);
280 
281 void rds_conn_shutdown(struct rds_connection *conn)
282 {
283 	/* shut it down unless it's down already */
284 	if (!rds_conn_transition(conn, RDS_CONN_DOWN, RDS_CONN_DOWN)) {
285 		/*
286 		 * Quiesce the connection mgmt handlers before we start tearing
287 		 * things down. We don't hold the mutex for the entire
288 		 * duration of the shutdown operation, else we may be
289 		 * deadlocking with the CM handler. Instead, the CM event
290 		 * handler is supposed to check for state DISCONNECTING
291 		 */
292 		mutex_lock(&conn->c_cm_lock);
293 		if (!rds_conn_transition(conn, RDS_CONN_UP, RDS_CONN_DISCONNECTING)
294 		 && !rds_conn_transition(conn, RDS_CONN_ERROR, RDS_CONN_DISCONNECTING)) {
295 			rds_conn_error(conn, "shutdown called in state %d\n",
296 					atomic_read(&conn->c_state));
297 			mutex_unlock(&conn->c_cm_lock);
298 			return;
299 		}
300 		mutex_unlock(&conn->c_cm_lock);
301 
302 		wait_event(conn->c_waitq,
303 			   !test_bit(RDS_IN_XMIT, &conn->c_flags));
304 		wait_event(conn->c_waitq,
305 			   !test_bit(RDS_RECV_REFILL, &conn->c_flags));
306 
307 		conn->c_trans->conn_shutdown(conn);
308 		rds_conn_reset(conn);
309 
310 		if (!rds_conn_transition(conn, RDS_CONN_DISCONNECTING, RDS_CONN_DOWN)) {
311 			/* This can happen - eg when we're in the middle of tearing
312 			 * down the connection, and someone unloads the rds module.
313 			 * Quite reproduceable with loopback connections.
314 			 * Mostly harmless.
315 			 */
316 			rds_conn_error(conn,
317 				"%s: failed to transition to state DOWN, "
318 				"current state is %d\n",
319 				__func__,
320 				atomic_read(&conn->c_state));
321 			return;
322 		}
323 	}
324 
325 	/* Then reconnect if it's still live.
326 	 * The passive side of an IB loopback connection is never added
327 	 * to the conn hash, so we never trigger a reconnect on this
328 	 * conn - the reconnect is always triggered by the active peer. */
329 	cancel_delayed_work_sync(&conn->c_conn_w);
330 	rcu_read_lock();
331 	if (!hlist_unhashed(&conn->c_hash_node)) {
332 		rcu_read_unlock();
333 		rds_queue_reconnect(conn);
334 	} else {
335 		rcu_read_unlock();
336 	}
337 }
338 
339 /*
340  * Stop and free a connection.
341  *
342  * This can only be used in very limited circumstances.  It assumes that once
343  * the conn has been shutdown that no one else is referencing the connection.
344  * We can only ensure this in the rmmod path in the current code.
345  */
346 void rds_conn_destroy(struct rds_connection *conn)
347 {
348 	struct rds_message *rm, *rtmp;
349 	unsigned long flags;
350 
351 	rdsdebug("freeing conn %p for %pI4 -> "
352 		 "%pI4\n", conn, &conn->c_laddr,
353 		 &conn->c_faddr);
354 
355 	/* Ensure conn will not be scheduled for reconnect */
356 	spin_lock_irq(&rds_conn_lock);
357 	hlist_del_init_rcu(&conn->c_hash_node);
358 	spin_unlock_irq(&rds_conn_lock);
359 	synchronize_rcu();
360 
361 	/* shut the connection down */
362 	rds_conn_drop(conn);
363 	flush_work(&conn->c_down_w);
364 
365 	/* make sure lingering queued work won't try to ref the conn */
366 	cancel_delayed_work_sync(&conn->c_send_w);
367 	cancel_delayed_work_sync(&conn->c_recv_w);
368 
369 	/* tear down queued messages */
370 	list_for_each_entry_safe(rm, rtmp,
371 				 &conn->c_send_queue,
372 				 m_conn_item) {
373 		list_del_init(&rm->m_conn_item);
374 		BUG_ON(!list_empty(&rm->m_sock_item));
375 		rds_message_put(rm);
376 	}
377 	if (conn->c_xmit_rm)
378 		rds_message_put(conn->c_xmit_rm);
379 
380 	conn->c_trans->conn_free(conn->c_transport_data);
381 
382 	/*
383 	 * The congestion maps aren't freed up here.  They're
384 	 * freed by rds_cong_exit() after all the connections
385 	 * have been freed.
386 	 */
387 	rds_cong_remove_conn(conn);
388 
389 	BUG_ON(!list_empty(&conn->c_retrans));
390 	kmem_cache_free(rds_conn_slab, conn);
391 
392 	spin_lock_irqsave(&rds_conn_lock, flags);
393 	rds_conn_count--;
394 	spin_unlock_irqrestore(&rds_conn_lock, flags);
395 }
396 EXPORT_SYMBOL_GPL(rds_conn_destroy);
397 
398 static void rds_conn_message_info(struct socket *sock, unsigned int len,
399 				  struct rds_info_iterator *iter,
400 				  struct rds_info_lengths *lens,
401 				  int want_send)
402 {
403 	struct hlist_head *head;
404 	struct list_head *list;
405 	struct rds_connection *conn;
406 	struct rds_message *rm;
407 	unsigned int total = 0;
408 	unsigned long flags;
409 	size_t i;
410 
411 	len /= sizeof(struct rds_info_message);
412 
413 	rcu_read_lock();
414 
415 	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
416 	     i++, head++) {
417 		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
418 			if (want_send)
419 				list = &conn->c_send_queue;
420 			else
421 				list = &conn->c_retrans;
422 
423 			spin_lock_irqsave(&conn->c_lock, flags);
424 
425 			/* XXX too lazy to maintain counts.. */
426 			list_for_each_entry(rm, list, m_conn_item) {
427 				total++;
428 				if (total <= len)
429 					rds_inc_info_copy(&rm->m_inc, iter,
430 							  conn->c_laddr,
431 							  conn->c_faddr, 0);
432 			}
433 
434 			spin_unlock_irqrestore(&conn->c_lock, flags);
435 		}
436 	}
437 	rcu_read_unlock();
438 
439 	lens->nr = total;
440 	lens->each = sizeof(struct rds_info_message);
441 }
442 
443 static void rds_conn_message_info_send(struct socket *sock, unsigned int len,
444 				       struct rds_info_iterator *iter,
445 				       struct rds_info_lengths *lens)
446 {
447 	rds_conn_message_info(sock, len, iter, lens, 1);
448 }
449 
450 static void rds_conn_message_info_retrans(struct socket *sock,
451 					  unsigned int len,
452 					  struct rds_info_iterator *iter,
453 					  struct rds_info_lengths *lens)
454 {
455 	rds_conn_message_info(sock, len, iter, lens, 0);
456 }
457 
458 void rds_for_each_conn_info(struct socket *sock, unsigned int len,
459 			  struct rds_info_iterator *iter,
460 			  struct rds_info_lengths *lens,
461 			  int (*visitor)(struct rds_connection *, void *),
462 			  size_t item_len)
463 {
464 	uint64_t buffer[(item_len + 7) / 8];
465 	struct hlist_head *head;
466 	struct rds_connection *conn;
467 	size_t i;
468 
469 	rcu_read_lock();
470 
471 	lens->nr = 0;
472 	lens->each = item_len;
473 
474 	for (i = 0, head = rds_conn_hash; i < ARRAY_SIZE(rds_conn_hash);
475 	     i++, head++) {
476 		hlist_for_each_entry_rcu(conn, head, c_hash_node) {
477 
478 			/* XXX no c_lock usage.. */
479 			if (!visitor(conn, buffer))
480 				continue;
481 
482 			/* We copy as much as we can fit in the buffer,
483 			 * but we count all items so that the caller
484 			 * can resize the buffer. */
485 			if (len >= item_len) {
486 				rds_info_copy(iter, buffer, item_len);
487 				len -= item_len;
488 			}
489 			lens->nr++;
490 		}
491 	}
492 	rcu_read_unlock();
493 }
494 EXPORT_SYMBOL_GPL(rds_for_each_conn_info);
495 
496 static int rds_conn_info_visitor(struct rds_connection *conn,
497 				  void *buffer)
498 {
499 	struct rds_info_connection *cinfo = buffer;
500 
501 	cinfo->next_tx_seq = conn->c_next_tx_seq;
502 	cinfo->next_rx_seq = conn->c_next_rx_seq;
503 	cinfo->laddr = conn->c_laddr;
504 	cinfo->faddr = conn->c_faddr;
505 	strncpy(cinfo->transport, conn->c_trans->t_name,
506 		sizeof(cinfo->transport));
507 	cinfo->flags = 0;
508 
509 	rds_conn_info_set(cinfo->flags, test_bit(RDS_IN_XMIT, &conn->c_flags),
510 			  SENDING);
511 	/* XXX Future: return the state rather than these funky bits */
512 	rds_conn_info_set(cinfo->flags,
513 			  atomic_read(&conn->c_state) == RDS_CONN_CONNECTING,
514 			  CONNECTING);
515 	rds_conn_info_set(cinfo->flags,
516 			  atomic_read(&conn->c_state) == RDS_CONN_UP,
517 			  CONNECTED);
518 	return 1;
519 }
520 
521 static void rds_conn_info(struct socket *sock, unsigned int len,
522 			  struct rds_info_iterator *iter,
523 			  struct rds_info_lengths *lens)
524 {
525 	rds_for_each_conn_info(sock, len, iter, lens,
526 				rds_conn_info_visitor,
527 				sizeof(struct rds_info_connection));
528 }
529 
530 int rds_conn_init(void)
531 {
532 	rds_conn_slab = kmem_cache_create("rds_connection",
533 					  sizeof(struct rds_connection),
534 					  0, 0, NULL);
535 	if (!rds_conn_slab)
536 		return -ENOMEM;
537 
538 	rds_info_register_func(RDS_INFO_CONNECTIONS, rds_conn_info);
539 	rds_info_register_func(RDS_INFO_SEND_MESSAGES,
540 			       rds_conn_message_info_send);
541 	rds_info_register_func(RDS_INFO_RETRANS_MESSAGES,
542 			       rds_conn_message_info_retrans);
543 
544 	return 0;
545 }
546 
547 void rds_conn_exit(void)
548 {
549 	rds_loop_exit();
550 
551 	WARN_ON(!hlist_empty(rds_conn_hash));
552 
553 	kmem_cache_destroy(rds_conn_slab);
554 
555 	rds_info_deregister_func(RDS_INFO_CONNECTIONS, rds_conn_info);
556 	rds_info_deregister_func(RDS_INFO_SEND_MESSAGES,
557 				 rds_conn_message_info_send);
558 	rds_info_deregister_func(RDS_INFO_RETRANS_MESSAGES,
559 				 rds_conn_message_info_retrans);
560 }
561 
562 /*
563  * Force a disconnect
564  */
565 void rds_conn_drop(struct rds_connection *conn)
566 {
567 	atomic_set(&conn->c_state, RDS_CONN_ERROR);
568 	queue_work(rds_wq, &conn->c_down_w);
569 }
570 EXPORT_SYMBOL_GPL(rds_conn_drop);
571 
572 /*
573  * If the connection is down, trigger a connect. We may have scheduled a
574  * delayed reconnect however - in this case we should not interfere.
575  */
576 void rds_conn_connect_if_down(struct rds_connection *conn)
577 {
578 	if (rds_conn_state(conn) == RDS_CONN_DOWN &&
579 	    !test_and_set_bit(RDS_RECONNECT_PENDING, &conn->c_flags))
580 		queue_delayed_work(rds_wq, &conn->c_conn_w, 0);
581 }
582 EXPORT_SYMBOL_GPL(rds_conn_connect_if_down);
583 
584 /*
585  * An error occurred on the connection
586  */
587 void
588 __rds_conn_error(struct rds_connection *conn, const char *fmt, ...)
589 {
590 	va_list ap;
591 
592 	va_start(ap, fmt);
593 	vprintk(fmt, ap);
594 	va_end(ap);
595 
596 	rds_conn_drop(conn);
597 }
598