Re: [PATCH] mac80211: Tear down aggregation sessions for suspend/resume

[Johannes Berg <johannes@sipsolutions.net>]

[-- Attachment #1: Type: text/plain, Size: 1048 bytes --]

On Mon, 2009-03-16 at 10:23 +0530, Sujith wrote:

> > I think the deadlock went away, not sure what fixed it but I guess
> > the HT rework.  I tested it a couple of weeks ago on ath5k and Luis
> > did on ath9k so I say let's go ahead and apply the patch... in the
> > meantime I'll try again on ath5k just to be sure.

Ok.

> There is a window for a race. Something like this:
> 
> From mac80211:
> 
> __ieee80211_suspend()
>      tear_down_BA_sessions(TX, RX)
>           ampdu_action(STOP)
>                remove_vifs()
> 
> At this point, the driver executes its remove_interface routine.
> While we are doing this, a TX completion interrupt could be raised,
> (HW hasn't been stopped yet) and nothing stops the driver from calling
> ieee80211_start_tx_ba_session().
> 
> So the question is: should mac80211 deny ADDBA requests in this case ?

Interesting observation. We probably should indeed reject that, and also
if the peer asks for sending aggregation again right away like some
Broadcom APs will.

johannes

[-- Attachment #2: This is a digitally signed message part --]
[-- Type: application/pgp-signature, Size: 836 bytes --]