svn commit: r353103 - head/sys/net

[John Baldwin]

On 10/4/19 6:43 AM, Kyle Evans wrote:
> Author: kevans
> Date: Fri Oct  4 13:43:07 2019
> New Revision: 353103
> URL: https://svnweb.freebsd.org/changeset/base/353103
> 
> Log:
>   tuntap(4): loosen up tunclose restrictions
>   
>   Realistically, this cannot work. We don't allow the tun to be opened twice,
>   so it must be done via fd passing, fork, dup, some mechanism like these.
>   Applications demonstrably do not enforce strict ordering when they're
>   handing off tun devices, so the parent closing before the child will easily
>   leave the tun/tap device in a bad state where it can't be destroyed and a
>   confused user because they did nothing wrong.
>   
>   Concede that we can't leave the tun/tap device in this kind of state because
>   of software not playing the TUNSIFPID game, but it is still good to find and
>   fix this kind of thing to keep ifconfig(8) up-to-date and help ensure good
>   discipline in tun handling.

Why are you using d_close for last close anyway?  It's not really reliable compared
to using cdevpriv and a cdevpriv dtor.

-- 
John Baldwin