[LTP] [PATCH v3 1/2] Add fanotify_get_supported_init_flags() helper function

[Amir Goldstein]

On Fri, Oct 20, 2023 at 6:07 PM Martin Doucha <mdoucha@suse.cz> wrote:
>
> Since FAN_ALL_INIT_FLAGS constant is deprecated, the kernel has added
> new fanotify feature flags and there is no other way to check
> for their support, we need to manually check which init flags needed
> by our tests are available.
>
> Signed-off-by: Martin Doucha <mdoucha@suse.cz>
> ---
>
> Changes since v1:
> - Fixed check for FAN_REPORT_NAME
> - Added longer patch description
>
> Changes since v2:
> - Added a table of flag dependencies so that each individual flag is tested
>   together with all additional required flags
>
> The helper function also checks that it wasn't called with a new uknown
> flag which might require dependency table update. In that case, the test
> will fail and advise the developer to review documentation and update
> the dependency table.
>

This is much more sane than the previous version :)
You may add:

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

>  testcases/kernel/syscalls/fanotify/fanotify.h | 43 +++++++++++++++++++
>  1 file changed, 43 insertions(+)
>
> diff --git a/testcases/kernel/syscalls/fanotify/fanotify.h b/testcases/kernel/syscalls/fanotify/fanotify.h
> index 75a081dc9..78424a350 100644
> --- a/testcases/kernel/syscalls/fanotify/fanotify.h
> +++ b/testcases/kernel/syscalls/fanotify/fanotify.h
> @@ -217,6 +217,49 @@ static inline int fanotify_init_flags_supported_by_kernel(unsigned int flags)
>         return fanotify_init_flags_supported_on_fs(flags, NULL);
>  }
>
> +#define TST_FANOTIFY_INIT_KNOWN_FLAGS                                      \
> +       (FAN_REPORT_DFID_NAME_TARGET | FAN_REPORT_TID | FAN_REPORT_PIDFD | \
> +       FAN_CLASS_NOTIF | FAN_CLASS_CONTENT | FAN_CLASS_PRE_CONTENT)
> +
> +/*
> + * Check support of given init flags one by one and return those which are
> + * supported.
> + */
> +static inline unsigned int fanotify_get_supported_init_flags(unsigned int flags,
> +       const char *fname)
> +{
> +       unsigned int i, flg, arg, ret = 0;
> +       static const struct { unsigned int flag, deps; } deplist[] = {
> +               {FAN_REPORT_NAME, FAN_REPORT_DIR_FID},
> +               {FAN_REPORT_TARGET_FID, FAN_REPORT_DFID_NAME_FID},
> +               {0, 0}
> +       };
> +
> +       if (flags & ~TST_FANOTIFY_INIT_KNOWN_FLAGS) {
> +               tst_brk(TBROK, "fanotify_init() feature check called with unknown flags %x, please update flag dependency table if needed",
> +                       flags & ~TST_FANOTIFY_INIT_KNOWN_FLAGS);
> +       }
> +
> +       for (flg = 1; flg; flg <<= 1) {
> +               if (!(flags & flg))
> +                       continue;
> +
> +               arg = flg;
> +
> +               for (i = 0; deplist[i].flag; i++) {
> +                       if (deplist[i].flag == flg) {
> +                               arg |= deplist[i].deps;
> +                               break;
> +                       }
> +               }
> +
> +               if (!fanotify_init_flags_supported_on_fs(arg, fname))
> +                       ret |= flg;
> +       }
> +
> +       return ret;
> +}
> +
>  typedef void (*tst_res_func_t)(const char *file, const int lineno,
>                                int ttype, const char *fmt, ...);
>
> --
> 2.42.0
>