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