Date: Fri, 20 Aug 2004 12:08:18 +0400 From: Roman Kurakin <rik@cronyx.ru> To: Robert Watson <rwatson@freebsd.org> Cc: freebsd-current@freebsd.org Subject: Re: Tracking down LORs Message-ID: <4125B172.9060303@cronyx.ru> In-Reply-To: <Pine.NEB.3.96L.1040820001041.20697B-100000@fledge.watson.org> References: <Pine.NEB.3.96L.1040820001041.20697B-100000@fledge.watson.org>
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Robert Watson wrote: >On Fri, 20 Aug 2004, Roman Kurakin wrote: > > > >> Currently I am trying to track down a couple of LORS in my code. >>But it seems that I do not undestand smth or all things id realy so bad. >> >> > >I find it's very helpful to add lock orders to the hard-coded lock order >table in subr_witness.c. Without hard-coded entries, WITNESS will >dynamically build an order based on observed lock use. This is generally >fine, but once in a while the "wrong" order will be used before the >"right" order, so the lock order warning will print for the "right" order, >leaving less useful debugging information. The table allows the >definition of partial orders, so you can specify relationships between >subsets of mutexes of interest. WITNESS will flesh out remaining orders >through dynamic discovery. > > I'll try to go this way, since I am in dead end. rik >Robert N M Watson FreeBSD Core Team, TrustedBSD Projects >robert@fledge.watson.org Principal Research Scientist, McAfee Research > > > > >> So I want to ask some questions to find out if my thoughts >>correct or wrong. >> >>1. If I am right LOR means that we have at least two mutexs. >>Lets call them a and b. If we set a, then b in first case >>and b then a in second we could get dead loop, and thus LOR. >> >>2. If I have some driver that have mutex a, and we have some >>sytem code that could call this driver with Giant (b), we would >>get LOR if driver lock a and some other part of system will >>try to lock Giant? >> >>or I am wrong? >> >>rik >> >> >> >>_______________________________________________ >>freebsd-current@freebsd.org mailing list >>http://lists.freebsd.org/mailman/listinfo/freebsd-current >>To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" >> >> >> > >_______________________________________________ >freebsd-current@freebsd.org mailing list >http://lists.freebsd.org/mailman/listinfo/freebsd-current >To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" > > > >
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