[LTP] [PATCH v2] Introduce ioctl_pidfd_get_info_supported() function

[Petr Vorel]

Hi Avinesh,

...
>  	if (ret == -1) {
> -		/* - ENOTTY: old kernels not implementing fs/pidfs.c:pidfd_ioctl
> -		 * - EINVAL: until v6.13 kernel
> -		 * - ESRCH: all kernels between v6.13 and v6.15
> +		/* - ENOTTY: kernel too old, ioctl(PIDFD_GET_INFO) not implemented; return -1 */
> +		if (errno == ENOTTY)
> +			return -1;
> +
> +		/* - EINVAL: ioctl(PIDFD_GET_INFO) exists but invalid args
> +		 * - ESRCH: ioctl(PIDFD_GET_INFO) exists but task already exited
> +		 * both mean supported, but info.mask is not set; return 0
>  		 */
I originally mean to move the docs above function signature (to the top)
and add it for both, but I suppose this is perfectly ok (it was here before).

Thanks for improving it.

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Kind regards,
Petr

> -		if (errno != ENOTTY &&
> -			errno != EINVAL &&
> -			errno != ESRCH)
> -			tst_brk(TBROK | TERRNO, "ioctl error");
> -	} else {
> -		if (info.mask & PIDFD_INFO_EXIT)
> -			supported = 1;
> +		if (errno == EINVAL || errno == ESRCH)
> +			return 0;
> +
> +		tst_brk(TBROK | TERRNO, "unexpected ioctl(PIDFD_GET_INFO) error");
>  	}

> -	SAFE_CLOSE(pidfd);
> +	/* ioctl(PIDFD_GET_INFO) successful; return mask */
> +	return info.mask;
> +}
> +
> +static inline bool ioctl_pidfd_info_exit_supported(void)
> +{
...