Re: [PATCH v5 bpf-next 11/11] bpf: Test BPF_SK_REUSEPORT_SELECT_OR_MIGRATE.

From:   Martin KaFai Lau <redacted>
Date:   Fri, 14 May 2021 19:05:15 -0700

On Mon, May 10, 2021 at 12:44:33PM +0900, Kuniyuki Iwashima wrote:

quoted

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index 12ee40284da0..2060bc122c53 100644

[ ... ]

quoted

+static int setup_fastopen(char *buf, int size, int *saved_len, bool restore)
+{
+	int err = 0, fd, len;
+
+	fd = open("/proc/sys/net/ipv4/tcp_fastopen", O_RDWR);
+	if (!ASSERT_NEQ(fd, -1, "open"))
+		return -1;
+
+	if (restore) {
+		len = write(fd, buf, *saved_len);
+		if (!ASSERT_EQ(len, *saved_len, "write - restore"))
+			err = -1;
+	} else {
+		*saved_len = read(fd, buf, size);
+		if (!ASSERT_GE(*saved_len, 1, "read")) {
+			err = -1;
+			goto close;
+		}
+
+		err = lseek(fd, 0, SEEK_SET);
+		if (!ASSERT_OK(err, "lseek"))
+			goto close;
+
+		/* (TFO_CLIENT_ENABLE | TFO_SERVER_ENABLE) */
+		len = write(fd, "3", 1);
+		if (!ASSERT_EQ(len, 1, "write - setup"))

Is it to trigger the tcp_try_fastopen() case?
I am not sure it is enough.  At least, I think not for the
very first connection before the cookie is saved.
The second run of the test may be able to trigger it.

setsockopt(TCP_FASTOPEN_NO_COOKIE) or another value in the
"/proc/sys/net/ipv4/tcp_fastopen" (ip-sysctl.rst) may be
needed.

Ah, right. I missed that point while testing in the same host.
TFO should be always forced without cookies.

quoted

+			err = -1;
+	}
+
+close:
+	close(fd);
+
+	return err;
+}
+

[ ... ]

quoted

diff --git a/tools/testing/selftests/bpf/progs/test_migrate_reuseport.c b/tools/testing/selftests/bpf/progs/test_migrate_reuseport.c
new file mode 100644
index 000000000000..72978b5d1fcb
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_migrate_reuseport.c

@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Check if we can migrate child sockets.
+ *
+ *   1. If reuse_md->migrating_sk is NULL (SYN packet),
+ *        return SK_PASS without selecting a listener.
+ *   2. If reuse_md->migrating_sk is not NULL (socket migration),
+ *        select a listener (reuseport_map[migrate_map[cookie]])
+ *
+ * Author: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
+ */
+
+#include <stddef.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_REUSEPORT_SOCKARRAY);
+	__uint(max_entries, 256);
+	__type(key, int);
+	__type(value, __u64);
+} reuseport_map SEC(".maps");
+
+struct {
+	__uint(type, BPF_MAP_TYPE_HASH);
+	__uint(max_entries, 256);
+	__type(key, __u64);
+	__type(value, int);
+} migrate_map SEC(".maps");
+
+int migrated_at_close SEC(".data");
+int migrated_at_send_synack SEC(".data");
+int migrated_at_recv_ack SEC(".data");

int migrated_at_close = 0;
int migrated_at_send_synack = 0;
int migrated_at_recv_ack = 0;

and then use skel->bss->migrated_at_* in migrate_reuseport.c.

I'll fix them.

Thank you.