Date: Tue, 19 Oct 2004 14:25:00 -0700 From: Julian Elischer <julian@elischer.org> To: John Baldwin <jhb@freebsd.org> Cc: Kris Kennaway <kris@obsecurity.org> Subject: Re: WITNESS bug Message-ID: <4175862C.6030403@elischer.org> In-Reply-To: <200410191650.28544.jhb@FreeBSD.org> References: <20041019023713.GA1072@green.homeunix.org> <16757.4854.809996.993051@jerusalem.litteratus.org> <20041019160122.GC55255@xor.obsecurity.org> <200410191650.28544.jhb@FreeBSD.org>
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John Baldwin wrote: >On Tuesday 19 October 2004 12:01 pm, Kris Kennaway wrote: > > >>On Tue, Oct 19, 2004 at 09:13:26AM -0400, Robert Huff wrote: >> >> >>>Brian Fundakowski Feldman writes: >>> >>> >>>> You should never not run with WITNESS_SKIPSPIN if you use >>>> modules. Any spin mutexes not listed statically in the witness >>>> code will cause your machine to immediately panic. >>>> >>>> >>> If this is true (and I'm not disputing it), shouldn't it be >>>noted in GENERIC and/or NOTES? For that matter, what's the penalty >>>for not automatically including it as part of WITNESS? >>> >>> >>Sometimes you don't want to use it, e.g. if you actually want to trace >>spinlock operations with witness. >> >> > >True spin mutexes should be rarely used anyways, so I don't think modules >needing spin mutexes is all that big of an issue. Almost all mutexes should >just be regular mutexes. > netgraph uses a spin mutex for it's node locks > > >
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