Date: Wed, 30 May 2001 10:15:09 +0100 From: Brian Somers <brian@Awfulhak.org> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Brian Somers <brian@Awfulhak.org>, freebsd-arch@FreeBSD.ORG, brian@Awfulhak.org Subject: Re: How to handle cloning in a pseudo device. Message-ID: <200105300915.f4U9F9H32416@hak.lan.Awfulhak.org> In-Reply-To: Message from Poul-Henning Kamp <phk@critter.freebsd.dk> of "Wed, 30 May 2001 10:48:47 %2B0200." <39755.991212527@critter>
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> What you should do when people try to acccess /dev/tun is to
> create a hitherto unopened unit on the tunnel and mark the
> dev_t "CHEAP_CLONE".
>
> If people just do an ls -l /dev/tun they get a random line
> and that dev_t will be GC'ed pretty quickly.
The problem I had was this:
$ sudo kldload if_tun
$ touch /dev/tun
$ sudo kldunload if_tun
$ ls -l /dev/tun*
The machine froze at that point - I assumed because if_tun hadn't
destroy_dev()d tun0 (I haven't got the code any more so I can't give
any more info right now).
I'm not clear about when devfs_reclaim() gets called (resulting in an
auto-destroy_dev)) ? Is that done by the syncer or something ? I've
mucked about with setting a 5 second timeout after calling make_dev()
from the clone routine, but it doesn't exactly give me a warm feeling
of doing things right :-/
> If they open /dev/tun they get a device and the tunopen allocates
> a softc and the dev_t stays. When you close, remove the softc
> and the dev_t should be reclaimed again.
>
> --
> 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.
--
Brian <brian@Awfulhak.org> <brian@[uk.]FreeBSD.org>
<http://www.Awfulhak.org>; <brian@[uk.]OpenBSD.org>
Don't _EVER_ lose your sense of humour !
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