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
39 static DEFINE_SPINLOCK(wimax_id_table_lock);
40 static 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 */
52 void 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 */
72 struct 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);
88 found:
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 */
101 void 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 */
116 void 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 }