Date: Fri, 19 Sep 2008 11:40:07 -0700 From: "Maksim Yevmenkin" <maksim.yevmenkin@gmail.com> To: "Ed Schouten" <ed@80386.nl> Cc: "current@freebsd.org" <current@freebsd.org> Subject: Re: Interface auto-cloning bug or feature? Message-ID: <bb4a86c70809191140o4629159dl85af689bbce2c5a9@mail.gmail.com> In-Reply-To: <20080919101700.GS81522@hoeg.nl> References: <48D2F942.4070801@FreeBSD.org> <20080919101700.GS81522@hoeg.nl>
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On 9/19/08, Ed Schouten <ed@80386.nl> wrote: > Hello Maxim, > > > * Maxim Sobolev <sobomax@FreeBSD.org> wrote: > > 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). > > > I'd say the best way to fix this would be to convert tun and tap to > devfs_[gs]et_cdevpriv() and turn tun and tap into single device nodes. > That's what we've already been doing to bpf, snp, audit_pipe, etc. > Unfortunately I'm no expert when it comes to our tun and tap > implementations. not so fast please :) the tap/tun/vkbd (and maybe others) have split personality. that is, on one side there is a network interface or keyboard, and on the other side is character device. those are always go in pairs. as far as i understand, of dev_stdclone/clone_create/clonedevs list/etc. is here to free up driver from managing resources (such as minor numbers). sure we can convert those drivers to devfs_set/get_cdevpriv, however, split personality drivers will still have to manage something similar to minor numbers (to name network interfaces/keyboards associated with the particular cdevpriv instance). also we need to make sure that any code still could use /dev/tunX/tapX names and get correct tunX/tapX interface (provided, of course, one is available). thanks, max
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