From owner-freebsd-arch  Tue Oct  3 13: 1: 7 2000
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To: Alfred Perlstein <bright@wintelcom.net>
Cc: John Baldwin <jhb@freebsd.org>, arch@freebsd.org,
	John Polstra <jdp@polstra.com>, Daniel Eischen <eischen@vigrid.com>,
	Matt Dillon <dillon@earth.backplane.com>, Greg Lehey <grog@lemis.com>
Subject: Re: Mutexes and semaphores 
In-reply-to: Your message of "Tue, 03 Oct 2000 12:16:04 PDT."
             <20001003121604.H27736@fw.wintelcom.net> 
From: Chuck Paterson <cp@bsdi.com>
Date: Tue, 03 Oct 2000 14:01:02 -0600
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concerning asmlinkage long sys_getppid(void)


	I would point out that the kernel could be pre-empted
for an arbitrary long period of time and that by the time
you look at the pointer it may no longer point at anything
usefull, and could even fault. With the multi-threaded kernel this
can happen just from interrupts, you don't even have to wander
into the much less likely, but still possible, case of having
a top half preempt.

Chuck



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