[LTP] [PATCH] Introduce ioctl_pidfd_get_info_supported() function

[Petr Vorel]

Hi Avinesh,

thanks for fixing this!
...
>  	if (ret == -1) {
> +		if (errno == ENOTTY)
> +			return -1;
> +
> +		if (errno == EINVAL || errno == ESRCH)
> +			return 0;
> +
> +		tst_brk(TBROK | TERRNO, "unexpected ioctl(PIDFD_GET_INFO) error");
>  	}

> -	SAFE_CLOSE(pidfd);
> +	return info.mask;

Because ioctl_pidfd_get_info_supported() returns 3 different states
(-1 (not supported), 0 (supported) and >= 0 (mask) it wouldn't harm to document
return type.

All the more so because ioctl_pidfd_info_exit_supported() uses reversed
conditions for supported (1) / not supported (0).

I understand chosen values, but because names suggest the same functionality doc
would help.

> +}
> +
> +static inline int ioctl_pidfd_info_exit_supported(void)
This could be bool, that's itself a documentation (just 2 possible values, not
more).

Kind regards,
Petr

> +{
> +	long mask;
> +
> +	if (tst_kvercmp(6, 15, 0) >= 0)
> +		return 1;
> +
> +	mask = ioctl_pidfd_get_info_supported();
> +	if (mask == -1)
> +		return 0;

> -	return supported;
> +	return !!(mask & PIDFD_INFO_EXIT);
>  }