1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
#include <linux/rtnetlink.h>
#include <linux/notifier.h>
#include <linux/rcupdate.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <net/net_namespace.h>
#include <net/fib_notifier.h>
static ATOMIC_NOTIFIER_HEAD(fib_chain);
int call_fib_notifier(struct notifier_block *nb, struct net *net,
enum fib_event_type event_type,
struct fib_notifier_info *info)
{
int err;
info->net = net;
err = nb->notifier_call(nb, event_type, info);
return notifier_to_errno(err);
}
EXPORT_SYMBOL(call_fib_notifier);
int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
struct fib_notifier_info *info)
{
int err;
info->net = net;
err = atomic_notifier_call_chain(&fib_chain, event_type, info);
return notifier_to_errno(err);
}
EXPORT_SYMBOL(call_fib_notifiers);
static unsigned int fib_seq_sum(void)
{
struct fib_notifier_ops *ops;
unsigned int fib_seq = 0;
struct net *net;
rtnl_lock();
down_read(&net_rwsem);
for_each_net(net) {
rcu_read_lock();
list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) {
if (!try_module_get(ops->owner))
continue;
fib_seq += ops->fib_seq_read(net);
module_put(ops->owner);
}
rcu_read_unlock();
}
up_read(&net_rwsem);
rtnl_unlock();
return fib_seq;
}
static int fib_net_dump(struct net *net, struct notifier_block *nb)
{
struct fib_notifier_ops *ops;
list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) {
int err;
if (!try_module_get(ops->owner))
continue;
err = ops->fib_dump(net, nb);
module_put(ops->owner);
if (err)
return err;
}
return 0;
}
static bool fib_dump_is_consistent(struct notifier_block *nb,
void (*cb)(struct notifier_block *nb),
unsigned int fib_seq)
{
atomic_notifier_chain_register(&fib_chain, nb);
if (fib_seq == fib_seq_sum())
return true;
atomic_notifier_chain_unregister(&fib_chain, nb);
if (cb)
cb(nb);
return false;
}
#define FIB_DUMP_MAX_RETRIES 5
int register_fib_notifier(struct notifier_block *nb,
void (*cb)(struct notifier_block *nb))
{
int retries = 0;
int err;
do {
unsigned int fib_seq = fib_seq_sum();
struct net *net;
rcu_read_lock();
for_each_net_rcu(net) {
err = fib_net_dump(net, nb);
if (err)
goto err_fib_net_dump;
}
rcu_read_unlock();
if (fib_dump_is_consistent(nb, cb, fib_seq))
return 0;
} while (++retries < FIB_DUMP_MAX_RETRIES);
return -EBUSY;
err_fib_net_dump:
rcu_read_unlock();
return err;
}
EXPORT_SYMBOL(register_fib_notifier);
int unregister_fib_notifier(struct notifier_block *nb)
{
return atomic_notifier_chain_unregister(&fib_chain, nb);
}
EXPORT_SYMBOL(unregister_fib_notifier);
static int __fib_notifier_ops_register(struct fib_notifier_ops *ops,
struct net *net)
{
struct fib_notifier_ops *o;
list_for_each_entry(o, &net->fib_notifier_ops, list)
if (ops->family == o->family)
return -EEXIST;
list_add_tail_rcu(&ops->list, &net->fib_notifier_ops);
return 0;
}
struct fib_notifier_ops *
fib_notifier_ops_register(const struct fib_notifier_ops *tmpl, struct net *net)
{
struct fib_notifier_ops *ops;
int err;
ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
if (!ops)
return ERR_PTR(-ENOMEM);
err = __fib_notifier_ops_register(ops, net);
if (err)
goto err_register;
return ops;
err_register:
kfree(ops);
return ERR_PTR(err);
}
EXPORT_SYMBOL(fib_notifier_ops_register);
void fib_notifier_ops_unregister(struct fib_notifier_ops *ops)
{
list_del_rcu(&ops->list);
kfree_rcu(ops, rcu);
}
EXPORT_SYMBOL(fib_notifier_ops_unregister);
static int __net_init fib_notifier_net_init(struct net *net)
{
INIT_LIST_HEAD(&net->fib_notifier_ops);
return 0;
}
static void __net_exit fib_notifier_net_exit(struct net *net)
{
WARN_ON_ONCE(!list_empty(&net->fib_notifier_ops));
}
static struct pernet_operations fib_notifier_net_ops = {
.init = fib_notifier_net_init,
.exit = fib_notifier_net_exit,
};
static int __init fib_notifier_init(void)
{
return register_pernet_subsys(&fib_notifier_net_ops);
}
subsys_initcall(fib_notifier_init);
|
