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Date: Thu, 31 May 2007 11:11:31 +1000 (EST)
From: Bruce Evans <brde@optusnet.com.au>
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To: Julian Elischer <julian@elischer.org>
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Cc: freebsd-arch@freebsd.org
Subject: Re: Updated rusage patch
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On Wed, 30 May 2007, Julian Elischer wrote:

> Bruce Evans wrote:
>
>> - RELENG_4: statclock() uses splhigh() but not interrupt atomicity.
>>             exit1() uses no locking and thus races with statclock().
>>   above: statclock() still uses sched_lock but not interrupt atomicity.
>
>
> sched_lock blocks interrupts
>
>>          exit1() uses no locking and thus races with statclock().
             ^^^^^^^^^^^^^^^^^^^^^^^

exit1() uses no locking and is thus unaffected by sched_lock.  More
precisely, it uses mounds of locking, but at the point that it races
with statclock() it holds only PROC_LOCK(p).  It acquires sched_lock
for the first time much later.

Bruce