Re: [PATCH wireless-2.6] iwlagn: fix "Received BA when not expected"

[Stanislaw Gruszka <sgruszka@redhat.com>]

On Thu, Apr 28, 2011 at 01:37:41PM +0200, Johannes Berg wrote:
> On Thu, 2011-04-28 at 13:10 +0200, Stanislaw Gruszka wrote:
> > Need to use broadcast sta_id for management and multicast frames,
> > otherwise we broke BA session and get messages like that:
> > 
> > "Received BA when not expected"
> > 
> > or (on older kernels):
> > 
> > "BA scd_flow 0 does not match txq_id 10"
> 
> Hmm. Interesting. I believe you, but it's hard.

To be honest, I expected to get explanations from you (perhaps
with better fix) :-) However this one is intended to work on older
kernels, and is tested by me and one other user.

> > -	/* Find index into station table for destination station */
> > -	sta_id = iwl_sta_id_or_broadcast(priv, ctx, info->control.sta);
> 
> info->control.sta should be NULL here, at least for multicast frames
> (which never really happen in practise unless you use AP mode). And then
> this should return ctx->bcast_sta_id, just like you use below:
> 
> > +	/* If this frame is broadcast or management, use broadcast station id */
> > +	if (!ieee80211_is_data(fc) || is_multicast_ether_addr(hdr->addr1))
> > +		sta_id = ctx->bcast_sta_id;
> 
> So the reason has to be management frames. But why would those be
> affecting it? They aren't QoS frames, so there should be no influence on
> BA handling at all. This is a bit odd.
>
> 
> Maybe we should make it clear here that it's about non-data frames and
> remove the multicast check since that ought to be handled in the other
> path?

We call iwl_sta_modify_sleep_tx_count(priv, sta_id, 1); for any frame
as long as some other conditions are true.

Also multicast frames are important. When we send data and multicast
frame we probably modify 

priv->stations[sta_id].tid[tid]

with wrong sta_id (other station with unicast address), what make related
aggregation data wrong for that other station.

Stanislaw