ath6kl_mgmt_tx with NULL chan (was Re: [PATCH 1/2] nl80211: allow sending CMD_FRAME without specifying any frequency)

[Antonio Quartulli <ordex@autistici.org>]

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On Mon, Jun 03, 2013 at 05:04:08PM +0200, Nicolas Cavallari wrote:
> On 03/06/2013 16:59, Johannes Berg wrote:
> > On Mon, 2013-06-03 at 08:39 +0200, Antonio Quartulli wrote:
> >> From: Antonio Quartulli <antonio@open-mesh.com>
> >>
> >> Users may want to send a frame on the current channel
> >> without specifying it.
> >>
> >> Make mgmt_tx pass a NULL channel to mac80211 if none has
> >> been specified by the user.
> > 
> > cfg80211 isn't just a mac80211 frontend ... ;-)
> > 
> > Also, as Nicolas said, ath6kl_mgmt_tx() will crash after this patch if
> > it's called in AP mode w/o a channel, so you need to think about that.
> 
> It will crash unconditionally. All ath6kl_mgmt_tx()'s code paths access
> chan->center_freq at some point.

Hello Nicolas,
I'm also CCing Kalle Valo since get_maintainer.pl told me he is the guy for
these kind of questions :-)

I'm looking at ath6kl_mgmt_tx() in ath6kl/cfg80211.c and I've seen that the
currently "configured" frequency can be obtained by reading the
ath6kl_vif->ch_hint field.

But, is this correct? I couldn't see any real relation between the ch_hint field
and the real frequency (probably because a lot of logic is hidden to the
driver).
I could only understand that the ch_hint field stores the frequency passed as
parameter during the connection, but I have found no guarantee that this is the
really used one.

Can someone please clarify on this?

Cheers,

-- 
Antonio Quartulli

..each of us alone is worth nothing..
Ernesto "Che" Guevara

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