From owner-freebsd-current Sun Apr 2 18:32:46 2000 Delivered-To: freebsd-current@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id 30D0637BCDA for ; Sun, 2 Apr 2000 18:32:22 -0700 (PDT) (envelope-from dillon@apollo.backplane.com) Received: (from dillon@localhost) by apollo.backplane.com (8.9.3/8.9.1) id SAA52156; Sun, 2 Apr 2000 18:32:20 -0700 (PDT) (envelope-from dillon) Date: Sun, 2 Apr 2000 18:32:20 -0700 (PDT) From: Matthew Dillon Message-Id: <200004030132.SAA52156@apollo.backplane.com> To: Alfred Perlstein Cc: current@FreeBSD.ORG Subject: Re: cvs commit: src/sys/i386/i386 support.s src/sys/kern init_sysent.c kern_prot.c kern_sig.c References: <200004021752.KAA13175@freefall.freebsd.org> <20000402163552.P21029@fw.wintelcom.net> <200004022312.QAA51299@apollo.backplane.com> <20000402164700.R21029@fw.wintelcom.net> <200004022338.QAA51565@apollo.backplane.com> <20000402172349.T21029@fw.wintelcom.net> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG :Good call. : :Ugh, I should think about this more, but i'll just grasp at straws :and suggest that p_pptr is set to volatile variable, and we re-read :it after we snarf the pid from the pointer and make sure it hasn't :changed out from under us. : :Either that or store it in the child's proc struct as well. : :-- :-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org] Re-reading is still somewhat dangerous due to the non-deterministic nature of the possible changes, whereas with monotonically increasing timers re-reading can be made to work in an SMP-safe fashion. In general it isn't worth getting that convoluted. I think the MP-safe code can make certain assumptions about the consistency of curproc, but outside of that we have to be very very careful. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message