/* 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"
static void rxrpc_transport_reaper(struct work_struct *work);
static LIST_HEAD(rxrpc_transports);
static DEFINE_RWLOCK(rxrpc_transport_lock);
static unsigned long rxrpc_transport_timeout = 3600 * 24;
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 = 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 = 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_timeout;
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_timeout = 0;
cancel_delayed_work(&rxrpc_transport_reap);
rxrpc_queue_delayed_work(&rxrpc_transport_reap, 0);
_leave("");
}
