Re: [PATCH 2/2] test/cbpf_filter: skip when openat2.h is not available

[Yang Xiuwei <yangxiuwei@kylinos.cn>]

Hi Jens,

On 2026-03-14 13:35 UTC, Jens Axboe wrote:
> liburing defines open_how if it's not in the system headers. I feel
> like all you need to do here is remove the openat2.h include, rather
> than disable the test entirely?

Thanks for the suggestion. I had actually tried that first: removing only the
#include <linux/openat2.h> and relying on liburing's compat for struct open_how.
It turned out that this test also uses the RESOLVE_IN_ROOT macro (and the
filter logic is built around it). Without the header, the build fails with
'RESOLVE_IN_ROOT' undeclared. RESOLVE_IN_ROOT and the other RESOLVE_* flags
come from <linux/openat2.h>; compat.h only provides struct open_how when the
header is missing, not those constants.

Defining RESOLVE_IN_ROOT (and friends) ourselves in compat or in the test
would duplicate kernel UAPI and could get out of sync if the kernel ever
changes them. So I went back to the more conservative approach: wrap the
test in #ifdef CONFIG_HAVE_OPEN_HOW and provide a stub main that returns
T_EXIT_SKIP when openat2.h is not available. The test then always compiles;
on systems without the header it simply skips at runtime.

If you have a better approach in mind, I'd be glad to follow that instead.

Best regards,
Yang Xiuwei