tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#include <linux/rtnetlink.h>
2#include <linux/notifier.h>
3#include <linux/rcupdate.h>
4#include <linux/kernel.h>
5#include <linux/module.h>
6#include <linux/init.h>
7#include <net/net_namespace.h>
8#include <net/fib_notifier.h>
9
10static ATOMIC_NOTIFIER_HEAD(fib_chain);
11
12int call_fib_notifier(struct notifier_block *nb, struct net *net,
13 enum fib_event_type event_type,
14 struct fib_notifier_info *info)
15{
16 info->net = net;
17 return nb->notifier_call(nb, event_type, info);
18}
19EXPORT_SYMBOL(call_fib_notifier);
20
21int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
22 struct fib_notifier_info *info)
23{
24 info->net = net;
25 return atomic_notifier_call_chain(&fib_chain, event_type, info);
26}
27EXPORT_SYMBOL(call_fib_notifiers);
28
29static unsigned int fib_seq_sum(void)
30{
31 struct fib_notifier_ops *ops;
32 unsigned int fib_seq = 0;
33 struct net *net;
34
35 rtnl_lock();
36 for_each_net(net) {
37 rcu_read_lock();
38 list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) {
39 if (!try_module_get(ops->owner))
40 continue;
41 fib_seq += ops->fib_seq_read(net);
42 module_put(ops->owner);
43 }
44 rcu_read_unlock();
45 }
46 rtnl_unlock();
47
48 return fib_seq;
49}
50
51static int fib_net_dump(struct net *net, struct notifier_block *nb)
52{
53 struct fib_notifier_ops *ops;
54
55 list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) {
56 int err;
57
58 if (!try_module_get(ops->owner))
59 continue;
60 err = ops->fib_dump(net, nb);
61 module_put(ops->owner);
62 if (err)
63 return err;
64 }
65
66 return 0;
67}
68
69static bool fib_dump_is_consistent(struct notifier_block *nb,
70 void (*cb)(struct notifier_block *nb),
71 unsigned int fib_seq)
72{
73 atomic_notifier_chain_register(&fib_chain, nb);
74 if (fib_seq == fib_seq_sum())
75 return true;
76 atomic_notifier_chain_unregister(&fib_chain, nb);
77 if (cb)
78 cb(nb);
79 return false;
80}
81
82#define FIB_DUMP_MAX_RETRIES 5
83int register_fib_notifier(struct notifier_block *nb,
84 void (*cb)(struct notifier_block *nb))
85{
86 int retries = 0;
87 int err;
88
89 do {
90 unsigned int fib_seq = fib_seq_sum();
91 struct net *net;
92
93 rcu_read_lock();
94 for_each_net_rcu(net) {
95 err = fib_net_dump(net, nb);
96 if (err)
97 goto err_fib_net_dump;
98 }
99 rcu_read_unlock();
100
101 if (fib_dump_is_consistent(nb, cb, fib_seq))
102 return 0;
103 } while (++retries < FIB_DUMP_MAX_RETRIES);
104
105 return -EBUSY;
106
107err_fib_net_dump:
108 rcu_read_unlock();
109 return err;
110}
111EXPORT_SYMBOL(register_fib_notifier);
112
113int unregister_fib_notifier(struct notifier_block *nb)
114{
115 return atomic_notifier_chain_unregister(&fib_chain, nb);
116}
117EXPORT_SYMBOL(unregister_fib_notifier);
118
119static int __fib_notifier_ops_register(struct fib_notifier_ops *ops,
120 struct net *net)
121{
122 struct fib_notifier_ops *o;
123
124 list_for_each_entry(o, &net->fib_notifier_ops, list)
125 if (ops->family == o->family)
126 return -EEXIST;
127 list_add_tail_rcu(&ops->list, &net->fib_notifier_ops);
128 return 0;
129}
130
131struct fib_notifier_ops *
132fib_notifier_ops_register(const struct fib_notifier_ops *tmpl, struct net *net)
133{
134 struct fib_notifier_ops *ops;
135 int err;
136
137 ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
138 if (!ops)
139 return ERR_PTR(-ENOMEM);
140
141 err = __fib_notifier_ops_register(ops, net);
142 if (err)
143 goto err_register;
144
145 return ops;
146
147err_register:
148 kfree(ops);
149 return ERR_PTR(err);
150}
151EXPORT_SYMBOL(fib_notifier_ops_register);
152
153void fib_notifier_ops_unregister(struct fib_notifier_ops *ops)
154{
155 list_del_rcu(&ops->list);
156 kfree_rcu(ops, rcu);
157}
158EXPORT_SYMBOL(fib_notifier_ops_unregister);
159
160static int __net_init fib_notifier_net_init(struct net *net)
161{
162 INIT_LIST_HEAD(&net->fib_notifier_ops);
163 return 0;
164}
165
166static void __net_exit fib_notifier_net_exit(struct net *net)
167{
168 WARN_ON_ONCE(!list_empty(&net->fib_notifier_ops));
169}
170
171static struct pernet_operations fib_notifier_net_ops = {
172 .init = fib_notifier_net_init,
173 .exit = fib_notifier_net_exit,
174};
175
176static int __init fib_notifier_init(void)
177{
178 return register_pernet_subsys(&fib_notifier_net_ops);
179}
180
181subsys_initcall(fib_notifier_init);