selftests/bpf: Create iter_tcp_destroy test program

Prepare for bucket resume tests for established TCP sockets by creating
a program to immediately destroy and remove sockets from the TCP ehash
table, since close() is not deterministic.

Signed-off-by: Jordan Rife <[email protected]>

Author: jrife

tools/testing/selftests/bpf/progs/sock_iter_batch.c

@@ -70,6 +70,28 @@ int iter_tcp_soreuse(struct bpf_iter__tcp *ctx)
 	return 0;
 }
 
+int bpf_sock_destroy(struct sock_common *sk) __ksym;
+volatile const __u64 destroy_cookie;
+
+SEC("iter/tcp")
+int iter_tcp_destroy(struct bpf_iter__tcp *ctx)
+{
+	struct sock_common *sk_common = (struct sock_common *)ctx->sk_common;
+	__u64 sock_cookie;
+
+	if (!sk_common)
+		return 0;
+
+	sock_cookie = bpf_get_socket_cookie(sk_common);
+	if (sock_cookie != destroy_cookie)
+		return 0;
+
+	bpf_sock_destroy(sk_common);
+	bpf_seq_write(ctx->meta->seq, &sock_cookie, sizeof(sock_cookie));
+
+	return 0;
+}
+
 #define udp_sk(ptr) container_of(ptr, struct udp_sock, inet.sk)
 
 SEC("iter/udp")