selftests/bpf: Add bpf_red scheduler & test

This patch implements the redundant BPF MPTCP scheduler, named bpf_red,
which sends all packets redundantly on all available subflows.

Using MPTCP_SCHED_TEST macro to add a new test for this bpf_red
scheduler, the arguments "1 1" means data has been sent on both
net devices. Run this test by RUN_MPTCP_TEST macro.

Signed-off-by: Geliang Tang <[email protected]>
Reviewed-by: Mat Martineau <[email protected]>
Reviewed-by: Matthieu Baerts (NGI0) <[email protected]>

Author: Geliang Tang

tools/testing/selftests/bpf/prog_tests/mptcp.c

@@ -14,6 +14,7 @@
 #include "mptcp_bpf_first.skel.h"
 #include "mptcp_bpf_bkup.skel.h"
 #include "mptcp_bpf_rr.skel.h"
+#include "mptcp_bpf_red.skel.h"
 
 #define NS_TEST "mptcp_ns"
 #define ADDR_1	"10.0.1.1"
@@ -639,6 +640,18 @@ static void test_rr(void)
 	mptcp_bpf_rr__destroy(skel);
 }
 
+static void test_red(void)
+{
+	struct mptcp_bpf_red *skel;
+
+	skel = mptcp_bpf_red__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "open_and_load: red"))
+		return;
+
+	test_bpf_sched(skel->maps.red, "red", WITH_DATA, WITH_DATA);
+	mptcp_bpf_red__destroy(skel);
+}
+
 void test_mptcp(void)
 {
 	if (test__start_subtest("base"))
@@ -655,4 +668,6 @@ void test_mptcp(void)
 		test_bkup();
 	if (test__start_subtest("rr"))
 		test_rr();
+	if (test__start_subtest("red"))
+		test_red();
 }

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

@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022, SUSE. */
+
+#include "mptcp_bpf.h"
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops")
+void BPF_PROG(mptcp_sched_red_init, struct mptcp_sock *msk)
+{
+}
+
+SEC("struct_ops")
+void BPF_PROG(mptcp_sched_red_release, struct mptcp_sock *msk)
+{
+}
+
+SEC("struct_ops")
+int BPF_PROG(bpf_red_get_send, struct mptcp_sock *msk)
+{
+	struct mptcp_subflow_context *subflow;
+
+	bpf_for_each(mptcp_subflow, subflow, (struct sock *)msk)
+		mptcp_subflow_set_scheduled(subflow, true);
+
+	return 0;
+}
+
+SEC(".struct_ops.link")
+struct mptcp_sched_ops red = {
+	.init		= (void *)mptcp_sched_red_init,
+	.release	= (void *)mptcp_sched_red_release,
+	.get_send	= (void *)bpf_red_get_send,
+	.name		= "bpf_red",
+};