[people/ms/linux.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 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->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	*/
	23	unsigned rxrpc_transport_expiry = 3600 * 24;
	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);
	54	trans->debug_id = atomic_inc_return(&rxrpc_debug_id);
	55
	56	if (peer->srx.transport.family == AF_INET) {
	57	switch (peer->srx.transport_type) {
	58	case SOCK_DGRAM:
	59	INIT_WORK(&trans->error_handler,
	60	rxrpc_UDP_error_handler);
	61	break;
	62	default:
	63	BUG();
	64	break;
	65	}
	66	} else {
	67	BUG();
	68	}
	69	}
	70
	71	_leave(" = %p", trans);
	72	return trans;
	73	}
	74
	75	/*
	76	* obtain a transport session for the nominated endpoints
	77	*/
	78	struct rxrpc_transport rxrpc_get_transport(struct rxrpc_local local,
	79	struct rxrpc_peer *peer,
	80	gfp_t gfp)
	81	{
	82	struct rxrpc_transport trans, candidate;
	83	const char *new = "old";
	84	int usage;
	85
21454aaa HH	86	_enter("{%pI4+%hu},{%pI4+%hu},",
21454aaa HH	87	&local->srx.transport.sin.sin_addr,
17926a79	88	ntohs(local->srx.transport.sin.sin_port),
21454aaa	89	&peer->srx.transport.sin.sin_addr,
17926a79 DH	90	ntohs(peer->srx.transport.sin.sin_port));
	91
	92	/* search the transport list first */
	93	read_lock_bh(&rxrpc_transport_lock);
	94	list_for_each_entry(trans, &rxrpc_transports, link) {
	95	if (trans->local == local && trans->peer == peer)
	96	goto found_extant_transport;
	97	}
	98	read_unlock_bh(&rxrpc_transport_lock);
	99
	100	/* not yet present - create a candidate for a new record and then
	101	* redo the search */
	102	candidate = rxrpc_alloc_transport(local, peer, gfp);
	103	if (!candidate) {
	104	_leave(" = -ENOMEM");
	105	return ERR_PTR(-ENOMEM);
	106	}
	107
	108	write_lock_bh(&rxrpc_transport_lock);
	109
	110	list_for_each_entry(trans, &rxrpc_transports, link) {
	111	if (trans->local == local && trans->peer == peer)
	112	goto found_extant_second;
	113	}
	114
	115	/* we can now add the new candidate to the list */
	116	trans = candidate;
	117	candidate = NULL;
ed84cadb	118	usage = atomic_read(&trans->usage);
17926a79 DH	119
	120	rxrpc_get_local(trans->local);
	121	atomic_inc(&trans->peer->usage);
	122	list_add_tail(&trans->link, &rxrpc_transports);
	123	write_unlock_bh(&rxrpc_transport_lock);
	124	new = "new";
	125
	126	success:
	127	_net("TRANSPORT %s %d local %d -> peer %d",
	128	new,
	129	trans->debug_id,
	130	trans->local->debug_id,
	131	trans->peer->debug_id);
	132
ed84cadb	133	_leave(" = %p {u=%d}", trans, usage);
17926a79 DH	134	return trans;
	135
	136	/* we found the transport in the list immediately */
	137	found_extant_transport:
	138	usage = atomic_inc_return(&trans->usage);
	139	read_unlock_bh(&rxrpc_transport_lock);
	140	goto success;
	141
	142	/* we found the transport on the second time through the list */
	143	found_extant_second:
	144	usage = atomic_inc_return(&trans->usage);
	145	write_unlock_bh(&rxrpc_transport_lock);
	146	kfree(candidate);
	147	goto success;
	148	}
	149
	150	/*
	151	* find the transport connecting two endpoints
	152	*/
	153	struct rxrpc_transport rxrpc_find_transport(struct rxrpc_local local,
	154	struct rxrpc_peer *peer)
	155	{
	156	struct rxrpc_transport *trans;
	157
21454aaa HH	158	_enter("{%pI4+%hu},{%pI4+%hu},",
21454aaa HH	159	&local->srx.transport.sin.sin_addr,
17926a79	160	ntohs(local->srx.transport.sin.sin_port),
21454aaa	161	&peer->srx.transport.sin.sin_addr,
17926a79 DH	162	ntohs(peer->srx.transport.sin.sin_port));
	163
	164	/* search the transport list */
	165	read_lock_bh(&rxrpc_transport_lock);
	166
	167	list_for_each_entry(trans, &rxrpc_transports, link) {
	168	if (trans->local == local && trans->peer == peer)
	169	goto found_extant_transport;
	170	}
	171
	172	read_unlock_bh(&rxrpc_transport_lock);
	173	_leave(" = NULL");
	174	return NULL;
	175
	176	found_extant_transport:
	177	atomic_inc(&trans->usage);
	178	read_unlock_bh(&rxrpc_transport_lock);
	179	_leave(" = %p", trans);
	180	return trans;
	181	}
	182
	183	/*
	184	* release a transport session
	185	*/
	186	void rxrpc_put_transport(struct rxrpc_transport *trans)
	187	{
	188	_enter("%p{u=%d}", trans, atomic_read(&trans->usage));
	189
	190	ASSERTCMP(atomic_read(&trans->usage), >, 0);
	191
22a3f9a2	192	trans->put_time = ktime_get_seconds();
50aab54f	193	if (unlikely(atomic_dec_and_test(&trans->usage))) {
17926a79 DH	194	_debug("zombie");
	195	/* let the reaper determine the timeout to avoid a race with
	196	* overextending the timeout if the reaper is running at the
	197	* same time */
651350d1	198	rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
50aab54f	199	}
17926a79 DH	200	_leave("");
	201	}
	202
	203	/*
	204	* clean up a transport session
	205	*/
	206	static void rxrpc_cleanup_transport(struct rxrpc_transport *trans)
	207	{
	208	_net("DESTROY TRANS %d", trans->debug_id);
	209
	210	rxrpc_purge_queue(&trans->error_queue);
	211
	212	rxrpc_put_local(trans->local);
	213	rxrpc_put_peer(trans->peer);
	214	kfree(trans);
	215	}
	216
	217	/*
	218	* reap dead transports that have passed their expiry date
	219	*/
	220	static void rxrpc_transport_reaper(struct work_struct *work)
	221	{
	222	struct rxrpc_transport trans, _p;
	223	unsigned long now, earliest, reap_time;
	224
	225	LIST_HEAD(graveyard);
	226
	227	_enter("");
	228
22a3f9a2	229	now = ktime_get_seconds();
17926a79 DH	230	earliest = ULONG_MAX;
	231
	232	/* extract all the transports that have been dead too long */
	233	write_lock_bh(&rxrpc_transport_lock);
	234	list_for_each_entry_safe(trans, _p, &rxrpc_transports, link) {
	235	_debug("reap TRANS %d { u=%d t=%ld }",
	236	trans->debug_id, atomic_read(&trans->usage),
	237	(long) now - (long) trans->put_time);
	238
	239	if (likely(atomic_read(&trans->usage) > 0))
	240	continue;
	241
5873c083	242	reap_time = trans->put_time + rxrpc_transport_expiry;
17926a79 DH	243	if (reap_time <= now)
	244	list_move_tail(&trans->link, &graveyard);
	245	else if (reap_time < earliest)
	246	earliest = reap_time;
	247	}
	248	write_unlock_bh(&rxrpc_transport_lock);
	249
	250	if (earliest != ULONG_MAX) {
	251	_debug("reschedule reaper %ld", (long) earliest - now);
	252	ASSERTCMP(earliest, >, now);
651350d1 DH	253	rxrpc_queue_delayed_work(&rxrpc_transport_reap,
651350d1 DH	254	(earliest - now) * HZ);
17926a79 DH	255	}
	256
	257	/* then destroy all those pulled out */
	258	while (!list_empty(&graveyard)) {
	259	trans = list_entry(graveyard.next, struct rxrpc_transport,
	260	link);
	261	list_del_init(&trans->link);
	262
	263	ASSERTCMP(atomic_read(&trans->usage), ==, 0);
	264	rxrpc_cleanup_transport(trans);
	265	}
	266
	267	_leave("");
	268	}
	269
	270	/*
	271	* preemptively destroy all the transport session records rather than waiting
	272	* for them to time out
	273	*/
	274	void __exit rxrpc_destroy_all_transports(void)
	275	{
	276	_enter("");
	277
5873c083	278	rxrpc_transport_expiry = 0;
17926a79	279	cancel_delayed_work(&rxrpc_transport_reap);
651350d1	280	rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
17926a79 DH	281
	282	_leave("");
	283	}