From owner-cvs-all  Wed Jun 30 10:58:15 1999
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Date: Wed, 30 Jun 1999 13:58:03 -0400 (EDT)
From: "Brian F. Feldman" <green@unixhelp.org>
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To: Julian Elischer <julian@whistle.com>
Cc: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>,
	Peter Wemm <peter@FreeBSD.org>, cvs-committers@FreeBSD.org,
	cvs-all@FreeBSD.org
Subject: Re: cvs commit: src/sys/kern init_main.c kern_fork.c kern_linker.c
         vfs_aio.c src/sys/sys proc.h
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On Wed, 30 Jun 1999, Julian Elischer wrote:

> 
> 
> On Wed, 30 Jun 1999, Garrett Wollman wrote:
> 
> > <<On Wed, 30 Jun 1999 08:33:43 -0700 (PDT), Peter Wemm <peter@FreeBSD.org> said:
> > 
> > >   syscalls set p->p_retval[] themselves.  Simplify the SYSINIT_KT() code
> > >   and other kernel thread creators to not need to use pfind() to find the
> > >   child based on the pid.  While here, partly tidy up some of the fork1()
> > 
> > On an almost-unrelated tangent...
> > 
> > Because proc structures are now stored in type-stable memory (via the
> > zone allocator), other places in the kernel which now reference
> > processes by pid and pfind should be able to keep a reference to the
> > proc instead.  (There does need to be a version number which gets
> > incremented when proc structs are recycled, but this should still be
> > cheaper than pfind().)  This would benefit network applications
> > written around a poll or select loop, since the simple case of
> > selwakeup() uses pfind() to locate the specific process to wake up.
> 
> Bill Jolitz added the PID stuff because there can be races where
> the proc structure is re-used..
> I can't remember the exact case but my gut feeling is that whatever it was
> is still there..

I thought about this a LOT, and it's not a great idea to hold a pointer to
the proc...

> 
> julian
> 
> 
> 
> > 
> > -GAWollman
> > 
> > --
> > Garrett A. Wollman   | O Siem / We are all family / O Siem / We're all the same
> > wollman@lcs.mit.edu  | O Siem / The fires of freedom 
> > Opinions not those of| Dance in the burning flame
> > MIT, LCS, CRS, or NSA|                     - Susan Aglukark and Chad Irschick
> > 
> > 
> 
> 
> 

 Brian Fundakowski Feldman      _ __ ___ ____  ___ ___ ___  
 green@FreeBSD.org                   _ __ ___ | _ ) __|   \ 
     FreeBSD: The Power to Serve!        _ __ | _ \._ \ |) |
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