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Date:      Thu, 7 Dec 2000 17:19:53 -0500 (EST)
From:      Daniel Eischen <eischen@vigrid.com>
To:        Jason Evans <jasone@canonware.com>
Cc:        Dan Eischen <eischen@vigrid.com>, smp@freebsd.org
Subject:   Re: Userland atomic assignments
Message-ID:  <Pine.SUN.3.91.1001207171540.10405A-100000@pcnet1.pcnet.com>
In-Reply-To: <20001207140746.O2312@canonware.com>

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On 7 Dec 2000, Jason Evans wrote:
> On Thu, Dec 07, 2000 at 04:15:05PM -0500, Dan Eischen wrote:
> > What kind of atomic operations can we get in userland?
> > If I have a singly linked list, where nodes are only added
> > to the head or the tail and they are never removed, can I
> > walk the list without fear of catching a bad head or
> > node->next (when I'm at the end of the list) pointer?
> > 
> > In other words, can I get an atomic_set_ptr() operation
> > on each platform?  I can also see the need for an
> > atomic_set_int32() operation.
> 
> I don't think we have an official API for atomic operations in userland.
> There is <machine/atomic.h>, but it isn't documented as a userland API.  I
> agree that we need this or something similar in userland though.  Any ideas
> on the cleanest way to provide this?

Something along the lines of <machine/atomic.h> I'd guess.
I don't need compare and set, nor anything that complicated,
just a couple of atomic store operations.  I'm finding some
places in libc that could really use an atomic_store_ptr().

-- 
Dan Eischen



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