Re: [RFC/RFT 06/11] mac80211: document TX aggregation (and small cleanup)

[Johannes Berg <johannes@sipsolutions.net>]

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On Thu, 2009-01-29 at 23:51 +0200, Jouni Malinen wrote:
> On Thu, Jan 29, 2009 at 01:54:56AM +0100, Johannes Berg wrote:
> 
> > + * DOC: TX aggregation
> 
> > + * When TX aggregation is started by some subsystem (usually the rate control
> > + * control algorithm would be appropriate) by calling the
> > + * ieee80211_start_tx_ba_session() function, the driver will be notified via
> > + * its @ampdu_action function, with the %IEEE80211_AMPDU_TX_START action.
> 
> Does rate control (btw, remove the duplicated "control" from the text)

Oops, thanks.

> algorithm have knowledge of whether PTK has already been configured?
> There is going to be a somewhat unfortunate timing issue with trying to
> set up aggregation before 4-way handshake has been completed if 802.11w
> is used (Action frames are dropped before the keys are set). Something
> in the system (either the request or mac80211's action on the request)
> would need to be delayed until the keys are in place in such a case.

Interesting issue, something I wasn't aware of. Yes, we'd need to delay
it in that case, not that it makes sense to set up aggregation that
early -- who knows it's going to be used? My AP at least will disable
your session if you're fairly idle (I guess to save reorder buffer
resources). We can simply delay it in mac80211, or we can just return
-EAGAIN. For iwl-agn-rs it wouldn't matter, it tries to enable
aggregation repeatedly even while it's already enabled =)

johannes

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