Re: light weight user level semaphores

Alon Ziv
2001-04-22T14:19:51Z

Well, that's the reason for my small-negative-integer semaphore-FD idea...
(It won't support select() easily, but poll() is prob'ly good enough)
Still, there is the problem of read()/write()/etc. semantics; sure, we can
declare that 'negative FDs' have their own semantics which just happen to
include poll(), but it sure looks like a kludge...

-az

----- Original Message -----
From: "Alan Cox" <alan@lxorguk.ukuu.org.uk>
To: "Alon Ziv" <alonz@nolaviz.org>
Cc: <linux-kernel@vger.kernel.org>
Sent: Sunday, April 22, 2001 14:44
Subject: Re: light weight user level semaphores

> > All of this FD allocation stuff is truly distrurbing.
> > This appears to be the one place where Win32 got it (almost) right---
> > quite about every kernel object looks to userland just like an opaque
> > handle, and the same operations apply to all of them.
>
> Unix got this right, then AT&T broke it in System III. One very good
reason
> for pipe based semaphore stuff is precisely that it works in
poll/select/SIGIO
>
> Alan
>
>
>