Date: Tue, 20 Jul 2004 13:10:29 -0600 From: Scott Long <scottl@samsco.org> To: Brian Fundakowski Feldman <green@freebsd.org> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk> Subject: Re: kldunload DIAGNOSTIC idea... Message-ID: <40FD6E25.1080808@samsco.org> In-Reply-To: <20040720185236.GD1009@green.homeunix.org> References: <20040720183213.GC1009@green.homeunix.org> <75604.1090348797@critter.freebsd.dk> <20040720185236.GD1009@green.homeunix.org>
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Brian Fundakowski Feldman wrote: > 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. > busdma callbacks, cam callbacks, netisr callbacks, and on and on and on. Scott
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