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Diffstat (limited to 'net/ipv4/fib_notifier.c')
-rw-r--r--net/ipv4/fib_notifier.c86
1 files changed, 86 insertions, 0 deletions
diff --git a/net/ipv4/fib_notifier.c b/net/ipv4/fib_notifier.c
new file mode 100644
index 000000000000..e0714d975947
--- /dev/null
+++ b/net/ipv4/fib_notifier.c
@@ -0,0 +1,86 @@
+#include <linux/rtnetlink.h>
+#include <linux/notifier.h>
+#include <linux/rcupdate.h>
+#include <linux/kernel.h>
+#include <net/net_namespace.h>
+#include <net/netns/ipv4.h>
+#include <net/ip_fib.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);
+}
+
+int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
+ struct fib_notifier_info *info)
+{
+ net->ipv4.fib_seq++;
+ info->net = net;
+ return atomic_notifier_call_chain(&fib_chain, event_type, info);
+}
+
+static unsigned int fib_seq_sum(void)
+{
+ unsigned int fib_seq = 0;
+ struct net *net;
+
+ rtnl_lock();
+ for_each_net(net)
+ fib_seq += net->ipv4.fib_seq;
+ rtnl_unlock();
+
+ return fib_seq;
+}
+
+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;
+
+ do {
+ unsigned int fib_seq = fib_seq_sum();
+ struct net *net;
+
+ /* Mutex semantics guarantee that every change done to
+ * FIB tries before we read the change sequence counter
+ * is now visible to us.
+ */
+ rcu_read_lock();
+ for_each_net_rcu(net) {
+ fib_rules_notify(net, nb);
+ fib_notify(net, nb);
+ }
+ rcu_read_unlock();
+
+ if (fib_dump_is_consistent(nb, cb, fib_seq))
+ return 0;
+ } while (++retries < FIB_DUMP_MAX_RETRIES);
+
+ return -EBUSY;
+}
+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);