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