1 files changed, 47 insertions, 0 deletions
diff --git a/include/net/netns/generic.h b/include/net/netns/generic.h
new file mode 100644
index 00000000..d55f4344
--- /dev/null
+++ b/include/net/netns/generic.h
@@ -0,0 +1,47 @@
+/*
+ * generic net pointers
+ */
+
+#ifndef __NET_GENERIC_H__
+#define __NET_GENERIC_H__
+
+#include <linux/rcupdate.h>
+
+/*
+ * Generic net pointers are to be used by modules to put some private
+ * stuff on the struct net without explicit struct net modification
+ *
+ * The rules are simple:
+ * 1. set pernet_operations->id.  After register_pernet_device you
+ *    will have the id of your private pointer.
+ * 2. set pernet_operations->size to have the code allocate and free
+ *    a private structure pointed to from struct net.
+ * 3. do not change this pointer while the net is alive;
+ * 4. do not try to have any private reference on the net_generic object.
+ *
+ * After accomplishing all of the above, the private pointer can be
+ * accessed with the net_generic() call.
+ */
+
+struct net_generic {
+	unsigned int len;
+	struct rcu_head rcu;
+
+	void *ptr[0];
+};
+
+static inline void *net_generic(const struct net *net, int id)
+{
+	struct net_generic *ng;
+	void *ptr;
+
+	rcu_read_lock();
+	ng = rcu_dereference(net->gen);
+	BUG_ON(id == 0 || id > ng->len);
+	ptr = ng->ptr[id - 1];
+	rcu_read_unlock();
+
+	BUG_ON(!ptr);
+	return ptr;
+}
+#endif