[linux-2.6-block.git] / net / rxrpc / ar-transport.c

/* RxRPC point-to-point transport session management
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <net/af_rxrpc.h>
#include "ar-internal.h"

/*
 * Time after last use at which transport record is cleaned up.
 */
unsigned int rxrpc_transport_expiry = 3600 * 24;

static void rxrpc_transport_reaper(struct work_struct *work);

static LIST_HEAD(rxrpc_transports);
static DEFINE_RWLOCK(rxrpc_transport_lock);
static DECLARE_DELAYED_WORK(rxrpc_transport_reap, rxrpc_transport_reaper);

/*
 * allocate a new transport session manager
 */
static struct rxrpc_transport *rxrpc_alloc_transport(struct rxrpc_local *local,
						     struct rxrpc_peer *peer,
						     gfp_t gfp)
{
	struct rxrpc_transport *trans;

	_enter("");

	trans = kzalloc(sizeof(struct rxrpc_transport), gfp);
	if (trans) {
		trans->local = local;
		trans->peer = peer;
		INIT_LIST_HEAD(&trans->link);
		trans->bundles = RB_ROOT;
		trans->client_conns = RB_ROOT;
		trans->server_conns = RB_ROOT;
		skb_queue_head_init(&trans->error_queue);
		spin_lock_init(&trans->client_lock);
		rwlock_init(&trans->conn_lock);
		atomic_set(&trans->usage, 1);
		trans->conn_idcounter = peer->srx.srx_service << 16;
		trans->debug_id = atomic_inc_return(&rxrpc_debug_id);

		if (peer->srx.transport.family == AF_INET) {
			switch (peer->srx.transport_type) {
			case SOCK_DGRAM:
				INIT_WORK(&trans->error_handler,
					  rxrpc_UDP_error_handler);
				break;
			default:
				BUG();
				break;
			}
		} else {
			BUG();
		}
	}

	_leave(" = %p", trans);
	return trans;
}

/*
 * obtain a transport session for the nominated endpoints
 */
struct rxrpc_transport *rxrpc_get_transport(struct rxrpc_local *local,
					    struct rxrpc_peer *peer,
					    gfp_t gfp)
{
	struct rxrpc_transport *trans, *candidate;
	const char *new = "old";
	int usage;

	_enter("{%pI4+%hu},{%pI4+%hu},",
	       &local->srx.transport.sin.sin_addr,
	       ntohs(local->srx.transport.sin.sin_port),
	       &peer->srx.transport.sin.sin_addr,
	       ntohs(peer->srx.transport.sin.sin_port));

	/* search the transport list first */
	read_lock_bh(&rxrpc_transport_lock);
	list_for_each_entry(trans, &rxrpc_transports, link) {
		if (trans->local == local && trans->peer == peer)
			goto found_extant_transport;
	}
	read_unlock_bh(&rxrpc_transport_lock);

	/* not yet present - create a candidate for a new record and then
	 * redo the search */
	candidate = rxrpc_alloc_transport(local, peer, gfp);
	if (!candidate) {
		_leave(" = -ENOMEM");
		return ERR_PTR(-ENOMEM);
	}

	write_lock_bh(&rxrpc_transport_lock);

	list_for_each_entry(trans, &rxrpc_transports, link) {
		if (trans->local == local && trans->peer == peer)
			goto found_extant_second;
	}

	/* we can now add the new candidate to the list */
	trans = candidate;
	candidate = NULL;
	usage = atomic_read(&trans->usage);

	rxrpc_get_local(trans->local);
	atomic_inc(&trans->peer->usage);
	list_add_tail(&trans->link, &rxrpc_transports);
	write_unlock_bh(&rxrpc_transport_lock);
	new = "new";

success:
	_net("TRANSPORT %s %d local %d -> peer %d",
	     new,
	     trans->debug_id,
	     trans->local->debug_id,
	     trans->peer->debug_id);

	_leave(" = %p {u=%d}", trans, usage);
	return trans;

	/* we found the transport in the list immediately */
found_extant_transport:
	usage = atomic_inc_return(&trans->usage);
	read_unlock_bh(&rxrpc_transport_lock);
	goto success;

	/* we found the transport on the second time through the list */
found_extant_second:
	usage = atomic_inc_return(&trans->usage);
	write_unlock_bh(&rxrpc_transport_lock);
	kfree(candidate);
	goto success;
}

/*
 * find the transport connecting two endpoints
 */
struct rxrpc_transport *rxrpc_find_transport(struct rxrpc_local *local,
					     struct rxrpc_peer *peer)
{
	struct rxrpc_transport *trans;

	_enter("{%pI4+%hu},{%pI4+%hu},",
	       &local->srx.transport.sin.sin_addr,
	       ntohs(local->srx.transport.sin.sin_port),
	       &peer->srx.transport.sin.sin_addr,
	       ntohs(peer->srx.transport.sin.sin_port));

	/* search the transport list */
	read_lock_bh(&rxrpc_transport_lock);

	list_for_each_entry(trans, &rxrpc_transports, link) {
		if (trans->local == local && trans->peer == peer)
			goto found_extant_transport;
	}

	read_unlock_bh(&rxrpc_transport_lock);
	_leave(" = NULL");
	return NULL;

found_extant_transport:
	atomic_inc(&trans->usage);
	read_unlock_bh(&rxrpc_transport_lock);
	_leave(" = %p", trans);
	return trans;
}

/*
 * release a transport session
 */
void rxrpc_put_transport(struct rxrpc_transport *trans)
{
	_enter("%p{u=%d}", trans, atomic_read(&trans->usage));

	ASSERTCMP(atomic_read(&trans->usage), >, 0);

	trans->put_time = ktime_get_seconds();
	if (unlikely(atomic_dec_and_test(&trans->usage))) {
		_debug("zombie");
		/* let the reaper determine the timeout to avoid a race with
		 * overextending the timeout if the reaper is running at the
		 * same time */
		rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
	}
	_leave("");
}

/*
 * clean up a transport session
 */
static void rxrpc_cleanup_transport(struct rxrpc_transport *trans)
{
	_net("DESTROY TRANS %d", trans->debug_id);

	rxrpc_purge_queue(&trans->error_queue);

	rxrpc_put_local(trans->local);
	rxrpc_put_peer(trans->peer);
	kfree(trans);
}

/*
 * reap dead transports that have passed their expiry date
 */
static void rxrpc_transport_reaper(struct work_struct *work)
{
	struct rxrpc_transport *trans, *_p;
	unsigned long now, earliest, reap_time;

	LIST_HEAD(graveyard);

	_enter("");

	now = ktime_get_seconds();
	earliest = ULONG_MAX;

	/* extract all the transports that have been dead too long */
	write_lock_bh(&rxrpc_transport_lock);
	list_for_each_entry_safe(trans, _p, &rxrpc_transports, link) {
		_debug("reap TRANS %d { u=%d t=%ld }",
		       trans->debug_id, atomic_read(&trans->usage),
		       (long) now - (long) trans->put_time);

		if (likely(atomic_read(&trans->usage) > 0))
			continue;

		reap_time = trans->put_time + rxrpc_transport_expiry;
		if (reap_time <= now)
			list_move_tail(&trans->link, &graveyard);
		else if (reap_time < earliest)
			earliest = reap_time;
	}
	write_unlock_bh(&rxrpc_transport_lock);

	if (earliest != ULONG_MAX) {
		_debug("reschedule reaper %ld", (long) earliest - now);
		ASSERTCMP(earliest, >, now);
		rxrpc_queue_delayed_work(&rxrpc_transport_reap,
					 (earliest - now) * HZ);
	}

	/* then destroy all those pulled out */
	while (!list_empty(&graveyard)) {
		trans = list_entry(graveyard.next, struct rxrpc_transport,
				   link);
		list_del_init(&trans->link);

		ASSERTCMP(atomic_read(&trans->usage), ==, 0);
		rxrpc_cleanup_transport(trans);
	}

	_leave("");
}

/*
 * preemptively destroy all the transport session records rather than waiting
 * for them to time out
 */
void __exit rxrpc_destroy_all_transports(void)
{
	_enter("");

	rxrpc_transport_expiry = 0;
	cancel_delayed_work(&rxrpc_transport_reap);
	rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);

	_leave("");
}
Commit	Line	Data
17926a79 DH	1	/* RxRPC point-to-point transport session management
	2	*
	3	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public License
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the License, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/net.h>
	14	#include <linux/skbuff.h>
5a0e3ad6	15	#include <linux/slab.h>
17926a79 DH	16	#include <net/sock.h>
	17	#include <net/af_rxrpc.h>
	18	#include "ar-internal.h"
	19
5873c083 DH	20	/*
	21	* Time after last use at which transport record is cleaned up.
	22	*/
dad8aff7	23	unsigned int rxrpc_transport_expiry = 3600 * 24;
5873c083	24
17926a79 DH	25	static void rxrpc_transport_reaper(struct work_struct *work);
	26
	27	static LIST_HEAD(rxrpc_transports);
	28	static DEFINE_RWLOCK(rxrpc_transport_lock);
17926a79 DH	29	static DECLARE_DELAYED_WORK(rxrpc_transport_reap, rxrpc_transport_reaper);
	30
	31	/*
	32	* allocate a new transport session manager
	33	*/
	34	static struct rxrpc_transport rxrpc_alloc_transport(struct rxrpc_local local,
	35	struct rxrpc_peer *peer,
	36	gfp_t gfp)
	37	{
	38	struct rxrpc_transport *trans;
	39
	40	_enter("");
	41
	42	trans = kzalloc(sizeof(struct rxrpc_transport), gfp);
	43	if (trans) {
	44	trans->local = local;
	45	trans->peer = peer;
	46	INIT_LIST_HEAD(&trans->link);
	47	trans->bundles = RB_ROOT;
	48	trans->client_conns = RB_ROOT;
	49	trans->server_conns = RB_ROOT;
	50	skb_queue_head_init(&trans->error_queue);
	51	spin_lock_init(&trans->client_lock);
	52	rwlock_init(&trans->conn_lock);
	53	atomic_set(&trans->usage, 1);
0d12f8a4	54	trans->conn_idcounter = peer->srx.srx_service << 16;
17926a79 DH	55	trans->debug_id = atomic_inc_return(&rxrpc_debug_id);
	56
	57	if (peer->srx.transport.family == AF_INET) {
	58	switch (peer->srx.transport_type) {
	59	case SOCK_DGRAM:
	60	INIT_WORK(&trans->error_handler,
	61	rxrpc_UDP_error_handler);
	62	break;
	63	default:
	64	BUG();
	65	break;
	66	}
	67	} else {
	68	BUG();
	69	}
	70	}
	71
	72	_leave(" = %p", trans);
	73	return trans;
	74	}
	75
	76	/*
	77	* obtain a transport session for the nominated endpoints
	78	*/
	79	struct rxrpc_transport rxrpc_get_transport(struct rxrpc_local local,
	80	struct rxrpc_peer *peer,
	81	gfp_t gfp)
	82	{
	83	struct rxrpc_transport trans, candidate;
	84	const char *new = "old";
	85	int usage;
	86
21454aaa HH	87	_enter("{%pI4+%hu},{%pI4+%hu},",
21454aaa HH	88	&local->srx.transport.sin.sin_addr,
17926a79	89	ntohs(local->srx.transport.sin.sin_port),
21454aaa	90	&peer->srx.transport.sin.sin_addr,
17926a79 DH	91	ntohs(peer->srx.transport.sin.sin_port));
	92
	93	/* search the transport list first */
	94	read_lock_bh(&rxrpc_transport_lock);
	95	list_for_each_entry(trans, &rxrpc_transports, link) {
	96	if (trans->local == local && trans->peer == peer)
	97	goto found_extant_transport;
	98	}
	99	read_unlock_bh(&rxrpc_transport_lock);
	100
	101	/* not yet present - create a candidate for a new record and then
	102	* redo the search */
	103	candidate = rxrpc_alloc_transport(local, peer, gfp);
	104	if (!candidate) {
	105	_leave(" = -ENOMEM");
	106	return ERR_PTR(-ENOMEM);
	107	}
	108
	109	write_lock_bh(&rxrpc_transport_lock);
	110
	111	list_for_each_entry(trans, &rxrpc_transports, link) {
	112	if (trans->local == local && trans->peer == peer)
	113	goto found_extant_second;
	114	}
	115
	116	/* we can now add the new candidate to the list */
	117	trans = candidate;
	118	candidate = NULL;
ed84cadb	119	usage = atomic_read(&trans->usage);
17926a79 DH	120
	121	rxrpc_get_local(trans->local);
	122	atomic_inc(&trans->peer->usage);
	123	list_add_tail(&trans->link, &rxrpc_transports);
	124	write_unlock_bh(&rxrpc_transport_lock);
	125	new = "new";
	126
	127	success:
	128	_net("TRANSPORT %s %d local %d -> peer %d",
	129	new,
	130	trans->debug_id,
	131	trans->local->debug_id,
	132	trans->peer->debug_id);
	133
ed84cadb	134	_leave(" = %p {u=%d}", trans, usage);
17926a79 DH	135	return trans;
	136
	137	/* we found the transport in the list immediately */
	138	found_extant_transport:
	139	usage = atomic_inc_return(&trans->usage);
	140	read_unlock_bh(&rxrpc_transport_lock);
	141	goto success;
	142
	143	/* we found the transport on the second time through the list */
	144	found_extant_second:
	145	usage = atomic_inc_return(&trans->usage);
	146	write_unlock_bh(&rxrpc_transport_lock);
	147	kfree(candidate);
	148	goto success;
	149	}
	150
	151	/*
	152	* find the transport connecting two endpoints
	153	*/
	154	struct rxrpc_transport rxrpc_find_transport(struct rxrpc_local local,
	155	struct rxrpc_peer *peer)
	156	{
	157	struct rxrpc_transport *trans;
	158
21454aaa HH	159	_enter("{%pI4+%hu},{%pI4+%hu},",
21454aaa HH	160	&local->srx.transport.sin.sin_addr,
17926a79	161	ntohs(local->srx.transport.sin.sin_port),
21454aaa	162	&peer->srx.transport.sin.sin_addr,
17926a79 DH	163	ntohs(peer->srx.transport.sin.sin_port));
	164
	165	/* search the transport list */
	166	read_lock_bh(&rxrpc_transport_lock);
	167
	168	list_for_each_entry(trans, &rxrpc_transports, link) {
	169	if (trans->local == local && trans->peer == peer)
	170	goto found_extant_transport;
	171	}
	172
	173	read_unlock_bh(&rxrpc_transport_lock);
	174	_leave(" = NULL");
	175	return NULL;
	176
	177	found_extant_transport:
	178	atomic_inc(&trans->usage);
	179	read_unlock_bh(&rxrpc_transport_lock);
	180	_leave(" = %p", trans);
	181	return trans;
	182	}
	183
	184	/*
	185	* release a transport session
	186	*/
	187	void rxrpc_put_transport(struct rxrpc_transport *trans)
	188	{
	189	_enter("%p{u=%d}", trans, atomic_read(&trans->usage));
	190
	191	ASSERTCMP(atomic_read(&trans->usage), >, 0);
	192
22a3f9a2	193	trans->put_time = ktime_get_seconds();
50aab54f	194	if (unlikely(atomic_dec_and_test(&trans->usage))) {
17926a79 DH	195	_debug("zombie");
	196	/* let the reaper determine the timeout to avoid a race with
	197	* overextending the timeout if the reaper is running at the
	198	* same time */
651350d1	199	rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
50aab54f	200	}
17926a79 DH	201	_leave("");
	202	}
	203
	204	/*
	205	* clean up a transport session
	206	*/
	207	static void rxrpc_cleanup_transport(struct rxrpc_transport *trans)
	208	{
	209	_net("DESTROY TRANS %d", trans->debug_id);
	210
	211	rxrpc_purge_queue(&trans->error_queue);
	212
	213	rxrpc_put_local(trans->local);
	214	rxrpc_put_peer(trans->peer);
	215	kfree(trans);
	216	}
	217
	218	/*
	219	* reap dead transports that have passed their expiry date
	220	*/
	221	static void rxrpc_transport_reaper(struct work_struct *work)
	222	{
	223	struct rxrpc_transport trans, _p;
	224	unsigned long now, earliest, reap_time;
	225
	226	LIST_HEAD(graveyard);
	227
	228	_enter("");
	229
22a3f9a2	230	now = ktime_get_seconds();
17926a79 DH	231	earliest = ULONG_MAX;
	232
	233	/* extract all the transports that have been dead too long */
	234	write_lock_bh(&rxrpc_transport_lock);
	235	list_for_each_entry_safe(trans, _p, &rxrpc_transports, link) {
	236	_debug("reap TRANS %d { u=%d t=%ld }",
	237	trans->debug_id, atomic_read(&trans->usage),
	238	(long) now - (long) trans->put_time);
	239
	240	if (likely(atomic_read(&trans->usage) > 0))
	241	continue;
	242
5873c083	243	reap_time = trans->put_time + rxrpc_transport_expiry;
17926a79 DH	244	if (reap_time <= now)
	245	list_move_tail(&trans->link, &graveyard);
	246	else if (reap_time < earliest)
	247	earliest = reap_time;
	248	}
	249	write_unlock_bh(&rxrpc_transport_lock);
	250
	251	if (earliest != ULONG_MAX) {
	252	_debug("reschedule reaper %ld", (long) earliest - now);
	253	ASSERTCMP(earliest, >, now);
651350d1 DH	254	rxrpc_queue_delayed_work(&rxrpc_transport_reap,
651350d1 DH	255	(earliest - now) * HZ);
17926a79 DH	256	}
	257
	258	/* then destroy all those pulled out */
	259	while (!list_empty(&graveyard)) {
	260	trans = list_entry(graveyard.next, struct rxrpc_transport,
	261	link);
	262	list_del_init(&trans->link);
	263
	264	ASSERTCMP(atomic_read(&trans->usage), ==, 0);
	265	rxrpc_cleanup_transport(trans);
	266	}
	267
	268	_leave("");
	269	}
	270
	271	/*
	272	* preemptively destroy all the transport session records rather than waiting
	273	* for them to time out
	274	*/
	275	void __exit rxrpc_destroy_all_transports(void)
	276	{
	277	_enter("");
	278
5873c083	279	rxrpc_transport_expiry = 0;
17926a79	280	cancel_delayed_work(&rxrpc_transport_reap);
651350d1	281	rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
17926a79 DH	282
	283	_leave("");
	284	}