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#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)
{
info->net = net;
return nb->notifier_call(nb, event_type, info);
}
EXPORT_SYMBOL(call_fib_notifier);
int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
struct fib_notifier_info *info)
{
info->net = net;
return atomic_notifier_call_chain(&fib_chain, event_type, info);
}
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();
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();
}
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);
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