Date: Tue, 20 Jul 2004 14:52:36 -0400 From: Brian Fundakowski Feldman <green@freebsd.org> To: Poul-Henning Kamp <phk@phk.freebsd.dk> Cc: arch@freebsd.org Subject: Re: kldunload DIAGNOSTIC idea... Message-ID: <20040720185236.GD1009@green.homeunix.org> In-Reply-To: <75604.1090348797@critter.freebsd.dk> References: <20040720183213.GC1009@green.homeunix.org> <75604.1090348797@critter.freebsd.dk>
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On Tue, Jul 20, 2004 at 08:39:57PM +0200, Poul-Henning Kamp wrote: > In message <20040720183213.GC1009@green.homeunix.org>, Brian Fundakowski Feldma > n writes: > >On Tue, Jul 20, 2004 at 08:20:23PM +0200, Poul-Henning Kamp wrote: > >> > >> I'm pulling hair out trying to make it guaranteed safe to unload device > >> driver modules, and the major pain here is to make sure there is no > >> thread stuck somewhere inside the code. > >> > >> That gave me the idea for a simple little DIAGNOSTIC check for kldunload: > >> run through the proc/thread table and look for any thread with an > >> instruction counter inside the range of pages we are going to unload. > >> > >> Any takers ? > > > >You mean any thread with a stack trace that includes an instruction > >counter inside those pages, don't you? > > That would require us to unwind the stack which I think is overkill > for the purpose. > > The most likely case is that the thread is sleeping on something > inside the kld so just checking the instruction pointer would be > fine. > > Looking for sleep addresses inside the module might make sense too. It's probably not overkill -- at least in my experience most of the time a driver is "doing something" it is sleeping, so the address will be in mi_switch() or somewhere way out there. Sleep addresses on dynamic data addresses are also a lot more common than sleep addresses on static/code addresses. If someone is interested in doign this, it would be very informative, especially if it could catch sleeps, pending timeouts, pending callouts, etc. -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> green@FreeBSD.org \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\
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