Date: Wed, 21 Jul 2004 13:37:50 +0200 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Doug Rabson <dfr@nlsystems.com> Cc: freebsd-arch@freebsd.org Subject: Re: kldunload DIAGNOSTIC idea... Message-ID: <82178.1090409870@critter.freebsd.dk> In-Reply-To: Your message of "Wed, 21 Jul 2004 12:20:54 BST." <1090408854.7114.8.camel@builder02.qubesoft.com>
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In message <1090408854.7114.8.camel@builder02.qubesoft.com>, Doug Rabson writes : >> There are three parts to it, a refcount on cdevsw which tells us if >> any thread is inside the driver using that route, a refcount on the >> individual cdev and a linkage between the two. > >The device_busy() counter is still simplest (as long as there is a >device_t at all). The implementation of devclass_delete_driver() will >automatically veto the unload (when its called from >driver_module_handler()). The problem is that I cannot find the device_t without dereferencing the struct cdev (either for si_driver[12] or the dev_t) and by then it is too late. There is no way we can avoid refcounting on the cdev. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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