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Message-ID: <Pine.LNX.4.64.0706230804060.4666@localhost.localdomain>
Date:	Sat, 23 Jun 2007 08:06:37 -0400 (EDT)
From:	"Robert P. J. Day" <rpjday@...dspring.com>
To:	Arnd Bergmann <arnd@...db.de>
cc:	Florin Iucha <florin@...ha.net>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: "upping" a semaphore from interrupt context?

On Sat, 23 Jun 2007, Arnd Bergmann wrote:

> On Saturday 23 June 2007, Robert P. J. Day wrote:
> > On Fri, 22 Jun 2007, Arnd Bergmann wrote:
> > >
> > > yes, but you should not. The use of semaphores is not
> > > recommended for new code, it should be replaced with either a
> > > mutex or a completion.
> >
> > can you clarify this?  it sounds like you're saying that the
> > current implementation of semaphores is entirely superfluous.  but
> > surely it isn't possible to replace all semaphores with either
> > mutexes or completions, is it?
>
> No, not all of them, but the vast majority. There are multiple
> differences, the most important one being the 'counting' in
> semaphores.

right, that was exactly the feature i was thinking of.  ok, i'm clear
on this now -- while the *majority* of semaphores can be more properly
replaced by mutexes or completions, there will always be a need for a
general-purpose counting semaphore.

rday
-- 
========================================================================
Robert P. J. Day
Linux Consulting, Training and Annoying Kernel Pedantry
Waterloo, Ontario, CANADA

http://fsdev.net/wiki/index.php?title=Main_Page
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