kern/73673: [if_tun] ifconfig tun0 destroy report: ifconfig: SIOCIFDESTROY: Invalid argument

[David Woodhouse]

The following reply was made to PR kern/73673; it has been noted by GNATS.

From: David Woodhouse <dwmw2 at infradead.org>
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/73673: [if_tun] ifconfig tun0 destroy report: ifconfig:
 SIOCIFDESTROY: Invalid argument
Date: Thu, 08 Dec 2011 02:11:59 +0000

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 In vpnc-script (as used by vpnc and openconnect VPN clients), we have
 'ifconfig $TUNDEV destroy' for FreeBSD and NetBSD.
 
 My testing on FreeBSD shows that this seems to hang, *not* give the
 -EINVAL error as described here. It hangs until the VPN program has
 actually closed its open file handle to the tun device.
 
 In practice, since the VPN program spawns vpnc-script to shut down the
 routing &c *before* closing the tun device, this deadlocks.
 
 Simply removing the 'ifconfig $TUNDEV destroy' seems to leave a stale
 device lying around. Running it *later* does appear to work, and cleans
 up the unwanted device.
 
 I note that this bug is fairly old; is 'ifconfig $TUNDEV destroy' now
 expected to work... and is it expected to hang in this situation?
 
 FreeBSD freebsd.infradead.org 8.2-RELEASE FreeBSD 8.2-RELEASE #0: Thu
 Feb 17 02:41:51 UTC 2011
 root at mason.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  amd64
 
 
 --=20
 dwmw2
 
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