Date: Thu, 18 Sep 2008 17:58:42 -0700 From: Maxim Sobolev <sobomax@FreeBSD.org> To: "current@freebsd.org" <current@FreeBSD.org> Subject: Interface auto-cloning bug or feature? Message-ID: <48D2F942.4070801@FreeBSD.org>
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Hi,
I've noticed that stat/open call on /dev/tun always creates new
interface, despite the fact that existing spare interfaces may be
available. I believe that it's a bug, since the whole purpose of
auto-cloning is to create new instance only when no existing one could
be allocated. At least that's my reading of the manual page for the tun(4).
<quote>
If the sysctl(8) variable net.link.tun.devfs_cloning is non-zero,
the tun
interface permits opens on the special control device /dev/tun. When
this device is opened, tun will return a handle for the lowest
unused tun
device (use devname(3) to determine which).
</quote>
-Maxim
[root@sp1 /usr/home/sobomax]# ifconfig -a
tun0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
[root@sp1 /usr/home/sobomax]# stat /dev/tun
67174144 96 crw------- 1 uucp dialer 96 0 "May 2 22:21:28 2008" "May 2
22:21:28 2008" "May 2 22:21:28 2008" "Dec 31 23:59:59 1969" 4096 0 0
/dev/tun
[root@sp1 /usr/home/sobomax]# ifconfig -a
tun0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
tun1: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
[root@sp1 /usr/home/sobomax]# stat /dev/tun
67174144 99 crw------- 1 uucp dialer 99 0 "May 2 22:21:28 2008" "May 2
22:21:28 2008" "May 2 22:21:28 2008" "Dec 31 23:59:59 1969" 4096 0 0
/dev/tun
[root@sp1 /usr/home/sobomax]# ifconfig -a
tun0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
tun1: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
tun2: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
[root@sp1 /usr/home/sobomax]# stat /dev/tun
67174144 105 crw------- 1 uucp dialer 105 0 "May 2 22:21:28 2008" "May
2 22:21:28 2008" "May 2 22:21:28 2008" "Dec 31 23:59:59 1969" 4096 0
0 /dev/tun
[root@sp1 /usr/home/sobomax]# ifconfig -a
tun0: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
tun1: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
tun2: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
tun3: flags=8010<POINTOPOINT,MULTICAST> mtu 1500
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