Re: [PATCH] pid: restore the old behaviour of the ns_last_pid sysctl

[Oleg Nesterov]

On 11/03, Andrei Vagin wrote:
>
> @@ -297,8 +298,18 @@ static int pid_ns_ctl_handler(struct ctl_table *table, int write,
>  	 * it should synchronize its usage with external means.
>  	 */
>  
> -	tmp.data = &pid_ns->idr.idr_next;
> -	return proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
> +	next = idr_get_cursor(&pid_ns->idr) - 1;
> +
> +	tmp.data = &next;
> +	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!write)
> +		return 0;
> +
> +	idr_set_cursor(&pid_ns->idr, next + 1);
> +	return 0;

Ah yes, we should also take "write" into account, I forgot it is readable.
Can't resist, to me

	err = proc_dointvec_minmax(...);
	if (!err && write)
		idr_set_cursor(...);

	return err;

looks a bit more readable, but this is matter of taste of course.


Acked-by: Oleg Nesterov <oleg@xxxxxxxxxx>