Date: Thu, 02 Nov 2006 10:10:17 -0700 From: Scott Long <scottl@samsco.org> To: John Baldwin <jhb@freebsd.org> Cc: Perforce Change Reviews <perforce@freebsd.org>, Scott Long <scottl@freebsd.org>, Hans Petter Selasky <hselasky@c2i.net> Subject: Re: PERFORCE change 108878 for review Message-ID: <454A2679.4030609@samsco.org> In-Reply-To: <200611021151.19396.jhb@freebsd.org> References: <200611010112.kA11C1Jt066210@repoman.freebsd.org> <200611011047.07627.jhb@freebsd.org> <200611021222.48108.hselasky@c2i.net> <200611021151.19396.jhb@freebsd.org>
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John Baldwin wrote: > On Thursday 02 November 2006 06:22, Hans Petter Selasky wrote: > >>On Wednesday 01 November 2006 16:47, John Baldwin wrote: >> >>>On Tuesday 31 October 2006 20:12, Scott Long wrote: >>> >>>>http://perforce.freebsd.org/chv.cgi?CH=108878 >>>> >>>>Change 108878 by scottl@scottl-x64 on 2006/11/01 01:11:30 >>>> >>>> For some wonderful reason, you cannot pass &Giant to msleep. Work >>>> around that in a crude fashion. Also add some more assertions. >>> >>>Ah, yes, that would be most unhappy. I guess mostly the idea is that Giant >>>should be rather implicit and explicitly using Giant for an object lock is >>>discouraged. I'm not sure that is what you are doing though. I think >>>maybe you are borrowing Giant that's already held? >> >>I use this patch: >> >>/* preliminary fix for a bug in msleep on FreeBSD, >> * which cannot sleep with Giant: >> */ >>#define msleep(i,m,p,w,t) msleep(i,(((m) == &Giant) ? NULL : (m)),p,w,t) >> >>Really this issue should be fixed. It happens just because GIANT_DROP is done >>too early in "msleep()". > > > Giant is special in msleep() and friends to make sure it is first in the > lock order, but unlock doesn't matter for lock order, and actually, the > current order is less intuitive. I think it's the way it is now because we > inherited it from BSD/OS. Also in theory old code under Giant should be > using tsleep() and not msleep() anyway. It actually won't hurt to move > DROP_GIANT later though. > > How about this: > This won't work for what I'm using it for. It's not a big deal, though. Scott
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