[PATCH bpf-next v2 3/5] selftests/bpf: Make sure TLD_DEFINE_KEY runs first

[Amery Hung <ameryhung@gmail.com>]

Without specifying constructor priority of the hidden constructor
function defined by TLD_DEFINE_KEY, __tld_create_key(..., dyn_data =
false) may run after tld_get_data() called from other constructors.
Threads calling tld_get_data() before __tld_create_key(..., dyn_data
= false) will not allocate enough memory for all TLDs and later result
in OOB access. Therefore, set it to the lowest value available to
users. Note that lower means higher priority and 0-100 is reserved to
the compiler.

Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Amery Hung <ameryhung@gmail.com>
---
 tools/testing/selftests/bpf/prog_tests/task_local_data.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/task_local_data.h b/tools/testing/selftests/bpf/prog_tests/task_local_data.h
index 366a6739c086..e242c455ddae 100644
--- a/tools/testing/selftests/bpf/prog_tests/task_local_data.h
+++ b/tools/testing/selftests/bpf/prog_tests/task_local_data.h
@@ -278,7 +278,7 @@ static tld_key_t __tld_create_key(const char *name, size_t size, bool dyn_data)
 #define TLD_DEFINE_KEY(key, name, size)			\
 tld_key_t key;						\
 							\
-__attribute__((constructor))				\
+__attribute__((constructor(101)))			\
 void __tld_define_key_##key(void)			\
 {							\
 	key = __tld_create_key(name, size, false);	\
-- 
2.52.0