Can someone please tell me whether the AIX untimeout() kernel service
will wait if the timeout callout is currently being processed?

On Solaris the untimeout() call will wait if the timeout callout is
currently running and will not return until the callout completes. If
the timeout callout hasn't yet fired when untimeout() is called then
it will never fire.

Does the AIX kernel confrom to this?

Thanks.