Subject: Re: mac80211 ad-hoc mode problems
From: Johannes Berg <johannes@sipsolutions.net>
To: Dan Williams <dcbw@redhat.com>
Cc: linux-wireless@vger.kernel.org, Jouni Malinen <j@w1.fi>
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Date: Wed, 04 Jun 2008 17:44:12 +0200
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> > > 4) Is the association expected to survive a up->down->up sequence?  I=
f
> > > not, then we should be sending NULL SIOCGIWAP event whenever dev_clos=
e()
> > > gets called.
> >=20
> > No, it's not, yes, we probably should send that event somewhere. Is it
> > ok to send the event while not associated?
>=20
> Yeah, there's no ordering or pairing guarantee for SIOCGIWAP events
> since there isn't an association transaction model with WEXT.

Yeah, true. You can either stick it right into ieee80211_stop, make a
new mlme-stop function that is called from there, or maybe do it when
the AP's sta_info struct is removed?

> > > 5) mac80211 requires the device to be down when changing modes.  That=
's
> > > fine; but requires a patch to wpa_supplicant to handle this.  This wo=
uld
> > > cause failures when switching AP that were different modes from NM.
> > > See:
> > >=20
> > > http://lists.shmoo.com/pipermail/hostap/2008-June/017894.html
> >=20
> > Don't understand. How can you switch to an IBSS AP? :)
>=20
> Sorry, when switching from BSS -> IBSS, like picking an IBSS from the
> NetworkManager menu while you're connected to an AP.  Or, creating a new
> IBSS while connected.

Ok, but that means you disconnect so you lose all configuration anyway.

> > It's probably fairly easy to remove this restriction because they all
> > use ieee80211_if_sta internally (sta, ibss, mesh) but since I don't car=
e
> > too much about IBSS and see mesh as being quite different, I have no
> > motivation to try (and test) this.
>=20
> I think it's fine to leave it as-is.  At least prism54 required the
> interface to be !IFF_UP while changing modes, and I think madwifi has
> required this too at some point.  This can be handled in the supplicant,
> Jouni and I have already worked out what should be done and I'm going to
> update the linked patch.

Sure. As far as I understand, even if mac80211 would change in the
future the patch Jouni asked for would then not down the interface.

johannes

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