Date: Wed, 15 Nov 2000 09:22:30 -0800 (PST) From: John Baldwin <jhb@FreeBSD.org> To: Mike Smith <msmith@FreeBSD.org> Cc: jake@io.yi.org, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org, Jake Burkholder <jburkhol@home.com> Subject: Re: cvs commit: src/sys/sys eventhandler.h Message-ID: <XFMail.001115092230.jhb@FreeBSD.org> In-Reply-To: <200011150658.eAF6wPF01843@mass.osd.bsdi.com>
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On 15-Nov-00 Mike Smith wrote: >> Holding the mutex over the whole traversal also means you rely on mutex >> recursion in order to be able to deregister from an event handler. > > True. I've been thinking about Garrett's point about flagging deleted > list elements too. > > I'm actually trying to work out what the issue is with witness; I can > only assume that it doesn't like the fact that an eventhandler mutex may > be acquired either before or after giant, and this exposes a weakness in > witness - that it can't deal with the situation where lock ordering > *doesn't* matter. No, it is unrelated to lock order. It has to do with tsleeping() with a mutex held. Specifically, during shutdown when we suspend the bugdaemon and syncer kernel threads. -- John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.baldwin.cx/~john/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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