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From: Hans Petter Selasky <hselasky@c2i.net>
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Date: Sun, 5 Aug 2012 10:33:13 +0200
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Cc: Konstantin Belousov <kostikbel@gmail.com>, Ed Schouten <ed@80386.nl>
Subject: Re: ttydev_cdevsw has no d_purge
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On Friday 03 August 2012 10:32:47 Ed Schouten wrote:
> 2012/8/1 Hans Petter Selasky <hselasky@c2i.net>:
> > I think the problem is like this, that in order to re-use the unit
> > numbers for USB serial tty devices, the USB stack needs to wait until a
> > TTY is actually freed, right? Else you will have a panic on creating
> > devfs entries having the same name.
> 
> Indeed. So the USB code could simply pick a different unit number.

Hi Ed,

USB could use a different Unit number. Some questions:

When can the previous unit number be re-used? Is there a callback for this?

When can the USB serial code assume that it will not be called again and that 
all callbacks are drained?

--HPS