Date: Thu, 07 Dec 2000 14:26:15 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: Daniel Eischen <eischen@vigrid.com> Cc: smp@FreeBSD.org, Jason Evans <jasone@canonware.com> Subject: Re: Userland atomic assignments Message-ID: <XFMail.001207142615.jhb@FreeBSD.org> In-Reply-To: <Pine.SUN.3.91.1001207171540.10405A-100000@pcnet1.pcnet.com>
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On 07-Dec-00 Daniel Eischen wrote: > 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(). a = b; should be atomic I think. If its not, then large portions of the kernel break, IIRC. > -- > Dan Eischen -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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