New "timeout" api, to replace callout

[Andre Oppermann]

Poul-Henning Kamp wrote:
> In message <477C1CF3.6070301 at freebsd.org>, Andre Oppermann writes:
> 
>> I fear we have to go for the latter.  Getting a non-sleeping callout
>> drain seems to be non-trivial.
> 
> There is a crucial difference between "non-sleeping" and "not sleeping
> on my lock" that you should be very careful about in this context.
> 
> Which is your requirement ?

Calling timeout_drain() must not sleep and not drop the lock in this
context (while making any pending timeout go away forever).

-- 
Andre