Date: Thu, 18 May 2000 21:07:43 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: Wes Peters <wes@softweyr.com> Cc: arch@FreeBSD.ORG Subject: Re: A new api for asynchronous task execution Message-ID: <Pine.BSF.4.21.0005182105470.73457-100000@salmon.nlsystems.com> In-Reply-To: <392410CB.6B86AA@softweyr.com>
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On Thu, 18 May 2000, Wes Peters wrote: > Doug Rabson wrote: > > > > The BSD/OS mutex code includes a compile-time-selected debugging feature > > which automatically detects locking hierarchy violations. Anyway, using a > > mutex here doesn't add to locking complexity since the mutex would be > > exited before calling the task's callback and re-entered after. > > Wouldn't it make more sense to provide an inversion-proof semaphore? > Or is that what they're doing? I'm sure Chuck can describe it better than me. As I understand it, the BSD/OS object is a simple counting mutex which comes in both blocking and spinning forms. There is a set of strict rules for mutex nesting which the debugging code uses to detect e.g. deadly embrace etc. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 20 8442 9037 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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