Date: Sun, 2 Apr 2000 18:32:20 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Alfred Perlstein <bright@wintelcom.net> 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 Message-ID: <200004030132.SAA52156@apollo.backplane.com> 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>
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: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
<dillon@backplane.com>
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