1/*
  2 * Linux WiMAX
  3 * Mappping of generic netlink family IDs to net devices
  4 *
  5 *
  6 * Copyright (C) 2005-2006 Intel Corporation <linux-wimax@intel.com>
  7 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
  8 *
  9 * This program is free software; you can redistribute it and/or
 10 * modify it under the terms of the GNU General Public License version
 11 * 2 as published by the Free Software Foundation.
 12 *
 13 * This program is distributed in the hope that it will be useful,
 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 16 * GNU General Public License for more details.
 17 *
 18 * You should have received a copy of the GNU General Public License
 19 * along with this program; if not, write to the Free Software
 20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 21 * 02110-1301, USA.
 22 *
 23 *
 24 * We assign a single generic netlink family ID to each device (to
 25 * simplify lookup).
 26 *
 27 * We need a way to map family ID to a wimax_dev pointer.
 28 *
 29 * The idea is to use a very simple lookup. Using a netlink attribute
 30 * with (for example) the interface name implies a heavier search over
 31 * all the network devices; seemed kind of a waste given that we know
 32 * we are looking for a WiMAX device and that most systems will have
 33 * just a single WiMAX adapter.
 34 *
 35 * We put all the WiMAX devices in the system in a linked list and
 36 * match the generic link family ID against the list.
 37 *
 38 * By using a linked list, the case of a single adapter in the system
 39 * becomes (almost) no overhead, while still working for many more. If
 40 * it ever goes beyond two, I'll be surprised.
 41 */
 42#include <linux/device.h>
 43#include <net/genetlink.h>
 44#include <linux/netdevice.h>
 45#include <linux/list.h>
 46#include <linux/wimax.h>
 47#include "wimax-internal.h"
 48
 49
 50#define D_SUBMODULE id_table
 51#include "debug-levels.h"
 52
 53
 54static DEFINE_SPINLOCK(wimax_id_table_lock);
 55static struct list_head wimax_id_table = LIST_HEAD_INIT(wimax_id_table);
 56
 57
 58/*
 59 * wimax_id_table_add - add a gennetlink familiy ID / wimax_dev mapping
 60 *
 61 * @wimax_dev: WiMAX device descriptor to associate to the Generic
 62 *     Netlink family ID.
 63 *
 64 * Look for an empty spot in the ID table; if none found, double the
 65 * table's size and get the first spot.
 66 */
 67void wimax_id_table_add(struct wimax_dev *wimax_dev)
 68{
 69	d_fnstart(3, NULL, "(wimax_dev %p)\n", wimax_dev);
 70	spin_lock(&wimax_id_table_lock);
 71	list_add(&wimax_dev->id_table_node, &wimax_id_table);
 72	spin_unlock(&wimax_id_table_lock);
 73	d_fnend(3, NULL, "(wimax_dev %p)\n", wimax_dev);
 74}
 75
 76
 77/*
 78 * wimax_get_netdev_by_info - lookup a wimax_dev from the gennetlink info
 79 *
 80 * The generic netlink family ID has been filled out in the
 81 * nlmsghdr->nlmsg_type field, so we pull it from there, look it up in
 82 * the mapping table and reference the wimax_dev.
 83 *
 84 * When done, the reference should be dropped with
 85 * 'dev_put(wimax_dev->net_dev)'.
 86 */
 87struct wimax_dev *wimax_dev_get_by_genl_info(
 88	struct genl_info *info, int ifindex)
 89{
 90	struct wimax_dev *wimax_dev = NULL;
 91
 92	d_fnstart(3, NULL, "(info %p ifindex %d)\n", info, ifindex);
 93	spin_lock(&wimax_id_table_lock);
 94	list_for_each_entry(wimax_dev, &wimax_id_table, id_table_node) {
 95		if (wimax_dev->net_dev->ifindex == ifindex) {
 96			dev_hold(wimax_dev->net_dev);
 97			goto found;
 98		}
 99	}
100	wimax_dev = NULL;
101	d_printf(1, NULL, "wimax: no devices found with ifindex %d\n",
102		 ifindex);
103found:
104	spin_unlock(&wimax_id_table_lock);
105	d_fnend(3, NULL, "(info %p ifindex %d) = %p\n",
106		info, ifindex, wimax_dev);
107	return wimax_dev;
108}
109
110
111/*
112 * wimax_id_table_rm - Remove a gennetlink familiy ID / wimax_dev mapping
113 *
114 * @id: family ID to remove from the table
115 */
116void wimax_id_table_rm(struct wimax_dev *wimax_dev)
117{
118	spin_lock(&wimax_id_table_lock);
119	list_del_init(&wimax_dev->id_table_node);
120	spin_unlock(&wimax_id_table_lock);
121}
122
123
124/*
125 * Release the gennetlink family id / mapping table
126 *
127 * On debug, verify that the table is empty upon removal. We want the
128 * code always compiled, to ensure it doesn't bit rot. It will be
129 * compiled out if CONFIG_BUG is disabled.
130 */
131void wimax_id_table_release(void)
132{
133	struct wimax_dev *wimax_dev;
134
135#ifndef CONFIG_BUG
136	return;
137#endif
138	spin_lock(&wimax_id_table_lock);
139	list_for_each_entry(wimax_dev, &wimax_id_table, id_table_node) {
140		printk(KERN_ERR "BUG: %s wimax_dev %p ifindex %d not cleared\n",
141		       __func__, wimax_dev, wimax_dev->net_dev->ifindex);
142		WARN_ON(1);
143	}
144	spin_unlock(&wimax_id_table_lock);
145}