Date: Wed, 15 Nov 1995 17:55:22 +0100 From: Poul-Henning Kamp <phk@critter.tfs.com> To: "Garrett A. Wollman" <wollman@lcs.mit.edu> Cc: Peter Wemm <peter@jhome.dialix.com>, Bruce Evans <bde@zeta.org.au>, CVS-commiters@freefall.freebsd.org, cvs-sys@freefall.freebsd.org Subject: Re: cvs commit: src/sys/kern kern_sysctl.c Message-ID: <3126.816454522@critter.tfs.com> In-Reply-To: Your message of "Wed, 15 Nov 1995 11:41:59 EST." <9511151641.AA26165@halloran-eldar.lcs.mit.edu>
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> <<On Wed, 15 Nov 1995 10:19:27 +0100, Poul-Henning Kamp <phk@critter.tfs.com> said: > > > The old implementation would lock the (old,oldlen) so that it could > > do the copyout without a context-switch. > > > In all cases but kern.vnode. > > > I really hate that exception, but on the other hand I'm not sure I really > > think we should have that feature anyway. It's going to be quite an effort > > to implement atomicity on a SMP system, and I really don't think it is the > > right way to solve the problem. I can see that it's a lot easier in the > > user-land, but boy is it a mess in the kernel. > > The purpose of this is to prevent race conditions even in a > uniprocessor system. what race-conditions ? -- Poul-Henning Kamp | phk@FreeBSD.ORG FreeBSD Core-team. http://www.freebsd.org/~phk | phk@login.dknet.dk Private mailbox. whois: [PHK] | phk@ref.tfs.com TRW Financial Systems, Inc. Future will arrive by its own means, progress not so.
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