bpf: selftests: Add dctcp fallback test

This patch makes the bpf_dctcp test to fallback to cubic by
using setsockopt(TCP_CONGESTION) when the tcp flow is not
ecn ready.

It also checks setsockopt() is not available to release().

The settimeo() from the network_helpers.h is used, so the local
one is removed.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210824173026.3979130-1-kafai@fb.com

1 files changed, 26 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/bpf_dctcp_release.c b/tools/testing/selftests/bpf/progs/bpf_dctcp_release.c
new file mode 100644
index 000000000000..d836f7c372f0
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/bpf_dctcp_release.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/tcp.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_tcp_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+const char cubic[] = "cubic";
+
+void BPF_STRUCT_OPS(dctcp_nouse_release, struct sock *sk)
+{
+	bpf_setsockopt(sk, SOL_TCP, TCP_CONGESTION,
+		       (void *)cubic, sizeof(cubic));
+}
+
+SEC(".struct_ops")
+struct tcp_congestion_ops dctcp_rel = {
+	.release	= (void *)dctcp_nouse_release,
+	.name		= "bpf_dctcp_rel",
+};