Date: Wed, 21 Jan 2009 17:57:13 +0200 From: Kostik Belousov <kostikbel@gmail.com> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-hackers@freebsd.org Subject: Re: MOD_UNLOAD and driver with cdev Message-ID: <20090121155713.GP58517@deviant.kiev.zoral.com.ua> In-Reply-To: <4977444E.8050306@icyb.net.ua> References: <49773938.5010000@icyb.net.ua> <20090121153908.GO58517@deviant.kiev.zoral.com.ua> <4977444E.8050306@icyb.net.ua>
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--FbmEh7Ek6NM6xKh/ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jan 21, 2009 at 05:50:38PM +0200, Andriy Gapon wrote: > on 21/01/2009 17:39 Kostik Belousov said the following: > > On Wed, Jan 21, 2009 at 05:03:20PM +0200, Andriy Gapon wrote: > >> Do I need to code for MOD_UNLOAD for driver module that also creates a= cdev? > >> I see in the current code that one strategy is to simply call > >> destroy_dev(). I guess detach routines are called automatically and > >> destroy_dev can be done there as well.. > > What are the detach routines ? Do you mean newbus device detach ? >=20 > Yes, device_detach. This seems to work and make_device_driver.sh also > suggests it this way. But I am not sure about possible races. >=20 > > Yes, the usual strategy is to call destroy_dev from unload handler. > >=20 > >> Is it reasonable to refuse unload if cdev is in use (in MOD_QUIESCE)? > >> How to check for that best? > >=20 > > This cannot be checked race-free. >=20 > So no point in trying? I would say no. You could use count_dev(), but my own experience shown that ability to unload driver is more important then unadvertently knock out filedescriptor from under the running program. --FbmEh7Ek6NM6xKh/ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkl3RdkACgkQC3+MBN1Mb4g3UACgnTrYA02QZeOjXrEJmrGnDCdE SEQAn1a85AOQLOH1HLVZ+ivEcpFxuPl2 =2Y5h -----END PGP SIGNATURE----- --FbmEh7Ek6NM6xKh/--
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