linux-kernel - Re: [ 104/173] rt2x00: Dont let mac80211 send a BAR when an AMPDU subframe fails

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Message-ID: <1358056981.4514.73.camel@deadeye.wl.decadent.org.uk>
Date:	Sun, 13 Jan 2013 06:03:01 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	Stanislaw Gruszka <sgruszka@...hat.com>
Cc:	Andreas Hartmann <andihartmann@...19freenet.de>,
	Johannes Berg <johannes@...solutions.net>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Helmut Schaa <helmut.schaa@...glemail.com>,
	"John W. Linville" <linville@...driver.com>
Subject: Re: [ 104/173] rt2x00: Dont let mac80211 send a BAR when an AMPDU
 subframe fails

On Mon, 2013-01-07 at 20:20 +0100, Stanislaw Gruszka wrote:
> On Mon, Jan 07, 2013 at 07:38:35PM +0100, Andreas Hartmann wrote:
> > Stanislaw Gruszka wrote:
> > > On Mon, Jan 07, 2013 at 04:04:01PM +0100, Andreas Hartmann wrote:
> > >> Ben Hutchings wrote:
> > >>> On Mon, 2013-01-07 at 09:10 +0100, Stanislaw Gruszka wrote:
> > >>>> On Mon, Jan 07, 2013 at 09:05:32AM +0100, Stanislaw Gruszka wrote:
> > >>>>>> To be clear, I have all of these in the queue:
> > >>>>>>
> > >>>>>> be03d4a45c09 rt2x00: Don't let mac80211 send a BAR when an AMPDU subframe fails
> > >>>>>> 5b632fe85ec8 mac80211: introduce IEEE80211_HW_TEARDOWN_AGGR_ON_BAR_FAIL
> > >>>>>> ab9d6e4ffe19 Revert: "rt2x00: Don't let mac80211 send a BAR when an AMPDU subframe fails"
> > >>>>>>
> > >>>>>> and I'm intending to drop/defer them all.
> > >>>>>
> > >>>>> Patch 3 is a revert of patch 1 (questioned patch). Please apply all 3 patches,
> > >>>>> or only patch 2.
> > >>>>
> > >>>> No, actually all 3 patches have to be applied. Because last one, except
> > >>>> revert, include flag IEEE80211_HW_TEARDOWN_AGGR_ON_BAR_FAIL setting in rt2x00
> > >>>> driver, which make patch 2 work.
> > >>>
> > >>> Andreas said that that after ab9d6e4ffe19 there was still a regression.
> > > 
> > > That's not true. There will be no regression after ab9d6e4ffe20. The
> > > only thing is that solution is not perfect. But perfect solution require
> > > lot of changes i.e. is not -stable appropriate (and does not exist currently).
> > > 
> > >>> But maybe he was confused.  I know I'm confused.
> > >> :-))
> > >>
> > >> No, the thing is:
> > >> rt2800pci misses an appropriate handling of aggregation (which meets the
> > >> requirements of mac80211).
> > >>
> > >> Both workarounds, mine and the new workaround from Stanislaw (which is
> > >> nothing more than a restricted version of my initial workaround), work
> > > 
> > > Your workaround broke STA mode on some environment.
> > 
> > Why are you sure, that this workaround doesn't break some other devices
> > running in AP mode? We believed at that time too, it wouldn't harm even
> > STA. But this was wrong for some (which?) devices.
> 
> Because it make behaviour the same as it was before 3.2, which introduce
> those issues.

After reviewing the various changes, I agree that applying the three
patches looks like it will restore the old (3.1) behaviour of rt2x00.  I
have reinstated them in the queue for the next 3.2 update.

Ben.

-- 
Ben Hutchings
Klipstein's 4th Law of Prototyping and Production:
                                    A fail-safe circuit will destroy others.

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