From: presotto@plan9.bell-labs.com
To: 9fans@cse.psu.edu
Subject: Re: [9fans] Kernel question: i386 test-and-set problem
Date: Thu, 20 Jul 2000 13:09:30 -0400 [thread overview]
Message-ID: <200007201709.NAA13687@cse.psu.edu> (raw)
r->p is either 0 or a valid process number. Therefore, the r->p
access shouldn't cause a crash. We later check the p->r against r
under lock to make sure the process is still waiting on that
rendezvouz. The worst the unlocked access should do is miss
a sleep which was in the process of happening. That would have happened
even with the lock with a small delta in timing.
In v2 the lock was providing the coherence() that we put herein v3.
However, v2 also had deadlock problems twixt sleep and postnote
that v3 fixes.
next reply other threads:[~2000-07-20 17:09 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-07-20 17:09 presotto [this message]
-- strict thread matches above, loose matches on Subject: below --
2000-08-03 9:56 miller
2000-08-02 16:24 presotto
2000-08-02 15:43 jmk
2000-08-02 14:51 miller
2000-08-02 13:20 presotto
2000-08-02 8:32 miller
2000-07-31 17:26 presotto
2000-07-23 14:41 miller
2000-07-21 13:15 presotto
2000-07-21 9:10 miller
2000-07-20 13:54 miller
2000-07-20 2:03 jmk
2000-07-10 16:21 miller
2000-07-10 12:40 Russ Cox
2000-07-11 8:51 ` Jakub Jermar
2000-07-10 9:57 Jakub Jermar
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