Re: ttydev_cdevsw has no d_purge

On Aug 8, 2012, at 11:41 AM, Hans Petter Selasky wrote:

> On Wednesday 08 August 2012 19:24:18 Ed Schouten wrote:
>>> Ed: I would really like to see a custom argument for the tsw_free(),
>>> because it only needs to know the unit number, and the xsc for UCOM =
is
>>> freed when this is called and cannot be referred. Is it possible to =
have
>>> a separate "void *" for the tsw_free() function? Is this something =
which
>>> you can implement?
>>=20
>> We could extend the TTY code to allow the softc to be changed, e.g.
>> tty_set_softc(). This function could be called right before calling
>> tty_rel_gone(). Still, I would prefer it if these kind of things =
would
>=20
> Are you sure that the new softc won't be used in any callbacks when=20
> tty_rel_gone() is called, except for tsw_free() ?
>=20
>> not be part of the API. Is there really no way the deallocation of =
the
>> softc can be delayed until tsw_free() is called?
>=20
> Yes, but that is inconvenient. We use the automatically allocated =
softc given=20
> to the driver by newbus. When detach() returns, the softc is freed. =
Then we=20
> need to block in detach, and that is causing the problem!

I thought the detach protocol was such that you shouldn't return from =
detach until all dangling references were gone.  you could use tsw_free =
to wake up the detach sleeper, no?

Warner

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