On Wed, Jan 22, 2014 at 04:36:14PM +0100, Helmut Schaa wrote:
> On Wed, Jan 22, 2014 at 4:28 PM, Karl Beldan <karl.beldan@xxxxxxxxx> wrote:
> > On Wed, Jan 22, 2014 at 02:33:14PM +0100, Helmut Schaa wrote:
> >> On Wed, Jan 22, 2014 at 2:09 PM, Karl Beldan <karl.beldan@xxxxxxxxx> wrote:
> >> > On Wed, Jan 22, 2014 at 01:34:39PM +0100, Johannes Berg wrote:
> >> >> Hmm. I guess you're right about the spec, but I vaguely remember races
> >> >> in this with the delBA going out too soon or so?
> >> >>
> >> >
> >> > Indeed, this was intended by cf6bb79 ("Use appropriate TID for sending
> >> > BAR, ADDBA and DELBA frames") and I overlooked it .. will look into it,
> >> > thanks.
> >> > I Cced Helmut who authored the said commit.
> >>
> >> You're right. There were some issues with that, but that was 2 years ago :)
> >>
> >> Sending ADDBA over AV_VO should be safe.
> >> If a DELBA is sent as AC_VO it might get received before the last AMPDU
> >> of the BlockAck session. So, the pending AMPDUs will get dropped at the
> >> receiver.
> >>
> >> In theory this could also be avoided by properly flushing all pending AMPDUs
> >> of the TID in question from the hw queues or by waiting for the tx status
> >> of all pending AMPDUs.
> >>
> >
> > I just looked at the code with your change in mind and couldn't find any
> > issue caused by sending {add,del}ba on AC_VO.
> > As of today, a delba is sent only after a driver has called 'purposely'
> > ieee80211_stop_tx_ba_cb_irqsafe so I see no issue with the delba either,
> > do you see one today ?
>
> If the driver does the right thing by flushing the right frames in the
> hw tx queues
> I think this should be ok. At least rt2x00 is not doing that, but
> maybe that's just
> an issue in rt2x00 :(
>
I see you are one of the maintainers of the ralink drivers, do you
intend to fix it in those ?
Callers of ieee80211_stop_tx_ba_cb_irqsafe are:
ath9k
ath9k_htc
carl9170
wcn36xx
brcm80211
iwlegacy
iwlwifi
mwl8k
rt2x00
rtlwifi
Johannes, what is your impression ?
Karl
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