v4.19.13 snapshot.
diff --git a/include/net/sock_reuseport.h b/include/net/sock_reuseport.h
new file mode 100644
index 0000000..8a5f70c
--- /dev/null
+++ b/include/net/sock_reuseport.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _SOCK_REUSEPORT_H
+#define _SOCK_REUSEPORT_H
+
+#include <linux/filter.h>
+#include <linux/skbuff.h>
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <net/sock.h>
+
+extern spinlock_t reuseport_lock;
+
+struct sock_reuseport {
+ struct rcu_head rcu;
+
+ u16 max_socks; /* length of socks */
+ u16 num_socks; /* elements in socks */
+ /* The last synq overflow event timestamp of this
+ * reuse->socks[] group.
+ */
+ unsigned int synq_overflow_ts;
+ /* ID stays the same even after the size of socks[] grows. */
+ unsigned int reuseport_id;
+ bool bind_inany;
+ struct bpf_prog __rcu *prog; /* optional BPF sock selector */
+ struct sock *socks[0]; /* array of sock pointers */
+};
+
+extern int reuseport_alloc(struct sock *sk, bool bind_inany);
+extern int reuseport_add_sock(struct sock *sk, struct sock *sk2,
+ bool bind_inany);
+extern void reuseport_detach_sock(struct sock *sk);
+extern struct sock *reuseport_select_sock(struct sock *sk,
+ u32 hash,
+ struct sk_buff *skb,
+ int hdr_len);
+extern int reuseport_attach_prog(struct sock *sk, struct bpf_prog *prog);
+int reuseport_get_id(struct sock_reuseport *reuse);
+
+#endif /* _SOCK_REUSEPORT_H */