Subject: mac80211 ad-hoc mode problems
From: Dan Williams <dcbw@redhat.com>
To: linux-wireless@vger.kernel.org
Content-Type: text/plain; charset=utf8
Date: Tue, 03 Jun 2008 21:41:04 -0400
Message-Id: <1212543664.4237.14.camel@localhost.localdomain> (sfid-20080604_034126_005983_906C2124)
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Sender: linux-wireless-owner@vger.kernel.org

Hi,

While adding adhoc shared network support to NM, I ran into a few
mac80211 problems.

1) doesn't send SIOCGIWAP event on successful adhoc activation (patch
forthcoming)

2) takes a _really_ long time to create an adhoc network.  This is
controlled by IEEE80211_IBSS_JOIN_TIMEOUT.  Why is that 20 seconds?  Th=
e
problem here is that wpa_supplicant has an association timer shorter
than =EF=BB=BFIEEE80211_IBSS_JOIN_TIMEOUT and will re-try the connectio=
n,
causing mac80211 to reset ifsta->ibss_join_req.  FullMAC drivers will
simply look in their scan list (and optionally perform one scan) and if
the IBSS isn't found, create it.  I'd really like to
take =EF=BB=BFIEEE80211_IBSS_JOIN_TIMEOUT down to 5 or 7 seconds.  This=
 is only
the initial IBSS creation, IBSS merging will still be in effect.  I
simply thing 20 seconds is really too long here.

3) doesn't send NULL SIOCGIWAP disassoc events when the device goes dow=
n
or the module is removed.  Where's the best place to put the event on
module remove?

4) Is the association expected to survive a up->down->up sequence?  If
not, then we should be sending NULL SIOCGIWAP event whenever dev_close(=
)
gets called.

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 woul=
d
cause failures when switching AP that were different modes from NM.
See:

http://lists.shmoo.com/pipermail/hostap/2008-June/017894.html

Dan

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