Initial import

1 files changed, 283 insertions, 0 deletions

diff --git a/net/rxrpc/ar-transport.c b/net/rxrpc/ar-transport.c
new file mode 100644
index 000000000..1976dec84
--- /dev/null
+++ b/net/rxrpc/ar-transport.c
@@ -0,0 +1,283 @@
+/* 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 = 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_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("");
+}