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/* Client connection-specific management code.
*
* Copyright (C) 2016 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 Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/slab.h>
#include <linux/idr.h>
#include <linux/timer.h>
#include "ar-internal.h"
/*
* We use machine-unique IDs for our client connections.
*/
DEFINE_IDR(rxrpc_client_conn_ids);
static DEFINE_SPINLOCK(rxrpc_conn_id_lock);
/*
* Get a connection ID and epoch for a client connection from the global pool.
* The connection struct pointer is then recorded in the idr radix tree. The
* epoch is changed if this wraps.
*
* TODO: The IDR tree gets very expensive on memory if the connection IDs are
* widely scattered throughout the number space, so we shall need to retire
* connections that have, say, an ID more than four times the maximum number of
* client conns away from the current allocation point to try and keep the IDs
* concentrated. We will also need to retire connections from an old epoch.
*/
int rxrpc_get_client_connection_id(struct rxrpc_connection *conn,
struct rxrpc_transport *trans,
gfp_t gfp)
{
u32 epoch;
int id;
_enter("");
idr_preload(gfp);
write_lock_bh(&trans->conn_lock);
spin_lock(&rxrpc_conn_id_lock);
epoch = rxrpc_epoch;
/* We could use idr_alloc_cyclic() here, but we really need to know
* when the thing wraps so that we can advance the epoch.
*/
if (rxrpc_client_conn_ids.cur == 0)
rxrpc_client_conn_ids.cur = 1;
id = idr_alloc(&rxrpc_client_conn_ids, conn,
rxrpc_client_conn_ids.cur, 0x40000000, GFP_NOWAIT);
if (id < 0) {
if (id != -ENOSPC)
goto error;
id = idr_alloc(&rxrpc_client_conn_ids, conn,
1, 0x40000000, GFP_NOWAIT);
if (id < 0)
goto error;
epoch++;
rxrpc_epoch = epoch;
}
rxrpc_client_conn_ids.cur = id + 1;
spin_unlock(&rxrpc_conn_id_lock);
write_unlock_bh(&trans->conn_lock);
idr_preload_end();
conn->proto.epoch = epoch;
conn->proto.cid = id << RXRPC_CIDSHIFT;
set_bit(RXRPC_CONN_HAS_IDR, &conn->flags);
_leave(" [CID %x:%x]", epoch, conn->proto.cid);
return 0;
error:
spin_unlock(&rxrpc_conn_id_lock);
write_unlock_bh(&trans->conn_lock);
idr_preload_end();
_leave(" = %d", id);
return id;
}
/*
* Release a connection ID for a client connection from the global pool.
*/
void rxrpc_put_client_connection_id(struct rxrpc_connection *conn)
{
if (test_bit(RXRPC_CONN_HAS_IDR, &conn->flags)) {
spin_lock(&rxrpc_conn_id_lock);
idr_remove(&rxrpc_client_conn_ids,
conn->proto.cid >> RXRPC_CIDSHIFT);
spin_unlock(&rxrpc_conn_id_lock);
}
}
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