selftests/bpf: Check inner map deletion

Add a test case to check whether an unsuccessful creation of an outer
map of a BTF-defined map-in-map destroys the inner map.

As bpf_object__create_map() is a static function, we cannot just call it
from the test case and then check whether a map accessible via
map->inner_map_fd has been closed. Instead, we iterate over all maps and
check whether the map "$MAP_NAME.inner" does not exist.

Signed-off-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210719173838.423148-3-m@lambda.lt

1 files changed, 26 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/test_map_in_map_invalid.c b/tools/testing/selftests/bpf/progs/test_map_in_map_invalid.c
new file mode 100644
index 000000000000..703c08e06442
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_map_in_map_invalid.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Isovalent, Inc. */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+struct inner {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__type(key, __u32);
+	__type(value, int);
+	__uint(max_entries, 4);
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS);
+	__uint(max_entries, 0); /* This will make map creation to fail */
+	__uint(key_size, sizeof(__u32));
+	__array(values, struct inner);
+} mim SEC(".maps");
+
+SEC("xdp")
+int xdp_noop0(struct xdp_md *ctx)
+{
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";