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Date: Sat, 14 Aug 2004 16:59:59 -0400 (EDT)
From: Robert Watson <rwatson@FreeBSD.org>
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To: Julian Elischer <julian@elischer.org>
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Subject: Re: cvs commit: src/sys/kern kern_proc.c
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On Sat, 14 Aug 2004, Julian Elischer wrote:

> >   Cause pfind() not to return processes in the PRS_NEW state.  As a result,
> >   threads consuming the result of pfind() will not need to check for a NULL
> >   credential pointer or other signs of an incompletely created process.
> >   However, this also means that pfind() cannot be used to test for the
> >   existence or find such a process.  Annotate pfind() to indicate that this
> >   is the case.  A review of curent consumers seems to indicate that this is
> >   not a problem for any of them.  This closes a number of race conditions
> >   that could result in NULL pointer dereferences and related failure modes.
> >   Other related races continue to exist, especially during iteration of the
> >   allproc list without due caution.
> 
> possibly part of the answer would be to not put the proc on any queues
> until it is more set up.. 

Tim had a set of modifications to keep them on a separate list, but I
think he also decided it was quite a bit more complicated than they had
hoped.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Principal Research Scientist, McAfee Research