1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Linux WiMAX
  4 * Mappping of generic netlink family IDs to net devices
  5 *
  6 * Copyright (C) 2005-2006 Intel Corporation <linux-wimax@intel.com>
  7 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
  8 *
  9 * We assign a single generic netlink family ID to each device (to
 10 * simplify lookup).
 11 *
 12 * We need a way to map family ID to a wimax_dev pointer.
 13 *
 14 * The idea is to use a very simple lookup. Using a netlink attribute
 15 * with (for example) the interface name implies a heavier search over
 16 * all the network devices; seemed kind of a waste given that we know
 17 * we are looking for a WiMAX device and that most systems will have
 18 * just a single WiMAX adapter.
 19 *
 20 * We put all the WiMAX devices in the system in a linked list and
 21 * match the generic link family ID against the list.
 22 *
 23 * By using a linked list, the case of a single adapter in the system
 24 * becomes (almost) no overhead, while still working for many more. If
 25 * it ever goes beyond two, I'll be surprised.
 26 */
 27#include <linux/device.h>
 28#include <net/genetlink.h>
 29#include <linux/netdevice.h>
 30#include <linux/list.h>
 31#include <linux/wimax.h>
 32#include "wimax-internal.h"
 33
 34
 35#define D_SUBMODULE id_table
 36#include "debug-levels.h"
 37
 38
 39static DEFINE_SPINLOCK(wimax_id_table_lock);
 40static struct list_head wimax_id_table = LIST_HEAD_INIT(wimax_id_table);
 41
 42
 43/*
 44 * wimax_id_table_add - add a gennetlink familiy ID / wimax_dev mapping
 45 *
 46 * @wimax_dev: WiMAX device descriptor to associate to the Generic
 47 *     Netlink family ID.
 48 *
 49 * Look for an empty spot in the ID table; if none found, double the
 50 * table's size and get the first spot.
 51 */
 52void wimax_id_table_add(struct wimax_dev *wimax_dev)
 53{
 54	d_fnstart(3, NULL, "(wimax_dev %p)\n", wimax_dev);
 55	spin_lock(&wimax_id_table_lock);
 56	list_add(&wimax_dev->id_table_node, &wimax_id_table);
 57	spin_unlock(&wimax_id_table_lock);
 58	d_fnend(3, NULL, "(wimax_dev %p)\n", wimax_dev);
 59}
 60
 61
 62/*
 63 * wimax_get_netdev_by_info - lookup a wimax_dev from the gennetlink info
 64 *
 65 * The generic netlink family ID has been filled out in the
 66 * nlmsghdr->nlmsg_type field, so we pull it from there, look it up in
 67 * the mapping table and reference the wimax_dev.
 68 *
 69 * When done, the reference should be dropped with
 70 * 'dev_put(wimax_dev->net_dev)'.
 71 */
 72struct wimax_dev *wimax_dev_get_by_genl_info(
 73	struct genl_info *info, int ifindex)
 74{
 75	struct wimax_dev *wimax_dev = NULL;
 76
 77	d_fnstart(3, NULL, "(info %p ifindex %d)\n", info, ifindex);
 78	spin_lock(&wimax_id_table_lock);
 79	list_for_each_entry(wimax_dev, &wimax_id_table, id_table_node) {
 80		if (wimax_dev->net_dev->ifindex == ifindex) {
 81			dev_hold(wimax_dev->net_dev);
 82			goto found;
 83		}
 84	}
 85	wimax_dev = NULL;
 86	d_printf(1, NULL, "wimax: no devices found with ifindex %d\n",
 87		 ifindex);
 88found:
 89	spin_unlock(&wimax_id_table_lock);
 90	d_fnend(3, NULL, "(info %p ifindex %d) = %p\n",
 91		info, ifindex, wimax_dev);
 92	return wimax_dev;
 93}
 94
 95
 96/*
 97 * wimax_id_table_rm - Remove a gennetlink familiy ID / wimax_dev mapping
 98 *
 99 * @id: family ID to remove from the table
100 */
101void wimax_id_table_rm(struct wimax_dev *wimax_dev)
102{
103	spin_lock(&wimax_id_table_lock);
104	list_del_init(&wimax_dev->id_table_node);
105	spin_unlock(&wimax_id_table_lock);
106}
107
108
109/*
110 * Release the gennetlink family id / mapping table
111 *
112 * On debug, verify that the table is empty upon removal. We want the
113 * code always compiled, to ensure it doesn't bit rot. It will be
114 * compiled out if CONFIG_BUG is disabled.
115 */
116void wimax_id_table_release(void)
117{
118	struct wimax_dev *wimax_dev;
119
120#ifndef CONFIG_BUG
121	return;
122#endif
123	spin_lock(&wimax_id_table_lock);
124	list_for_each_entry(wimax_dev, &wimax_id_table, id_table_node) {
125		pr_err("BUG: %s wimax_dev %p ifindex %d not cleared\n",
126		       __func__, wimax_dev, wimax_dev->net_dev->ifindex);
127		WARN_ON(1);
128	}
129	spin_unlock(&wimax_id_table_lock);
130}