Re: [PATCH 4/6 OPTION-A version 3] completion: Add new wait_for_completion_timeout_state

[Oleg Nesterov <oleg@redhat.com>]

On 03/26, Boaz Harrosh wrote:
>
> +int __sched
> +wait_for_completion_timeout_state(struct completion *x,
> +				  unsigned long timeout, int state)
> +{
> +	long t;
> +	int ret;
> +
> +	if (!timeout)
> +		timeout = MAX_SCHEDULE_TIMEOUT;
> +
> +	switch (state) {
> +	default:
> +		WARN_ON_ONCE(1);
> +		/* fall through */
> +	case 0:
> +		state = TASK_UNINTERRUPTIBLE;
> +		break;

Well, this looks strange, imho. If the caller wants TASK_UNINTERRUPTIBLE,
it should simply pass TASK_UNINTERRUPTIBLE.
wait_for_completion_timeout_state(state => 0) looks confusing, and this
is not symmetrical wrt other states.

> +	t = wait_for_common(x, timeout, state);
> +	if (likely(t > 0)) {
> +		ret = 0;
> +	} else  {
> +		if (t < 0)
> +			ret = t;
> +		else
> +			ret = -ETIMEDOUT;
> +	}
> +	return ret;

I tend to agree with Peter. This is the common helper, probably it
will have more users. We shouldn't throw out the positive return
value, it can be useful.

call_usermodehelper_exec() can simply do

	retval = wait_for_common(...);

	if (retval > 0)
		retval = sub_info->retval;
	else if (!retval)
		retval = -ETIMEDOUT;

Oleg.