[PATCH bpf-next 2/2] selftests/bpf: Add a test where map key_type_id with decl_tag type

[Yonghong Song <yhs@fb.com>]

Add a selftest where map creation key type_id is a decl_tag
pointing to a struct. Without previous patch, a kernel warning will
appear similar to the one in the previous patch. With the previous
patch, the kernel warning is silenced.

Signed-off-by: Yonghong Song <yhs@fb.com>
---
 tools/testing/selftests/bpf/prog_tests/btf.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/btf.c b/tools/testing/selftests/bpf/prog_tests/btf.c
index 210d643fda6c..69521e1dc330 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf.c
@@ -3990,6 +3990,26 @@ static struct btf_raw_test raw_tests[] = {
 	.btf_load_err = true,
 	.err_str = "Invalid arg#1",
 },
+{
+	.descr = "decl_tag test #18, struct member, decl_tag as the value type",
+	.raw_types = {
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),	/* [1] */
+		BTF_STRUCT_ENC(0, 2, 8),			/* [2] */
+		BTF_MEMBER_ENC(NAME_TBD, 1, 0),
+		BTF_MEMBER_ENC(NAME_TBD, 1, 32),
+		BTF_DECL_TAG_ENC(NAME_TBD, 2, -1),		/* [3] */
+		BTF_END_RAW,
+	},
+	BTF_STR_SEC("\0m1\0m2\0tag"),
+	.map_type = BPF_MAP_TYPE_ARRAY,
+	.map_name = "tag_type_check_btf",
+	.key_size = sizeof(int),
+	.value_size = 8,
+	.key_type_id = 1,
+	.value_type_id = 3,
+	.max_entries = 1,
+	.map_create_err = true,
+},
 {
 	.descr = "type_tag test #1",
 	.raw_types = {
-- 
2.34.1