[PATCH bpf-next v2 2/2] selftests/bpf: Add regression test for BTF dump zero detection

[Luis Vieira <luisflavieira@gmail.com>]

Add a regression test for a nested struct whose first member is zero
and second member is non-zero.

This verifies that struct and union zero detection continues checking
later members instead of treating the entire nested value as zero.

Signed-off-by: Luis Vieira <luisflavieira@gmail.com>
---
 tools/testing/selftests/bpf/prog_tests/btf_dump.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/btf_dump.c b/tools/testing/selftests/bpf/prog_tests/btf_dump.c
index 17fa44cb9c91..5a5ee001ac8b 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf_dump.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf_dump.c
@@ -1146,6 +1146,11 @@ static void test_btf_dump_struct_data(struct btf *btf, struct btf_dump *d,
 			   "(union bpf_iter_link_info){.map = (struct){.map_fd = (__u32)1,},.cgroup = (struct){.order = (enum bpf_cgroup_iter_order)BPF_CGROUP_ITER_SELF_ONLY,.cgroup_fd = (__u32)1,},.task = (struct){.tid = (__u32)1,.pid = (__u32)1,},}",
 			   { .cgroup = { .order = 1, .cgroup_fd = 1, }});
 
+	/* nested structs with zero first member and non-zero second member */
+	TEST_BTF_DUMP_DATA(btf, d, "union", str, union bpf_iter_link_info, BTF_F_COMPACT,
+			   "(union bpf_iter_link_info){.cgroup = (struct){.cgroup_fd = (__u32)1,},.task = (struct){.pid = (__u32)1,},}",
+			   { .cgroup = { .cgroup_fd = 1 }});
+
 	/* struct skb with nested structs/unions; because type output is so
 	 * complex, we don't do a string comparison, just verify we return
 	 * the type size as the amount of data displayed.

-- 
2.43.0