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Date: Mon, 19 Jul 2004 16:33:55 -0600 (MDT)
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To: pjd@FreeBSD.ORG
From: "M. Warner Losh" <imp@bsdimp.com>
In-Reply-To: <20040719145745.GH57678@darkness.comp.waw.pl>
References: <20040719145745.GH57678@darkness.comp.waw.pl>
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cc: freebsd-current@FreeBSD.ORG
Subject: Re: Unloading USB driver while device is attached.
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In message: <20040719145745.GH57678@darkness.comp.waw.pl>
            Pawel Jakub Dawidek <pjd@freebsd.org> writes:
: Hello.
: 
: Could someone investigate what's going on for the situation from the
: subject? This panic is trivial to reproduce:
: 
: 	# kldload umass.ko
: 	<plug in your USB bar>
: 	# kldunload umass
: 	# kldload umass
: 	<panic>
: 
: It is not umass related! I think this problem is in our USB implementation.
: 
: One more note with could be helpful.
: When device is already inserted and I load USB driver, <drvname>_match
: isn't called, but when driver was unloaded while device was in and it is
: loaded again (as in my example) <drvname>_match is called and we have
: a problem, because there are some stale data, I think (not everything
: is cleaned up on kldunload?).
: Ok, one more note.
: You can also set 'break <drvname>_match' in DDB and try to compare
: backtraces when device is removed while driver is loaded and when you
: unload USB driver.

I do know that loading the driver won't attach umass unless you remove
and insert it again.

Warner