Date: Fri, 4 Feb 2011 14:40:21 +0300 From: Alexander Zagrebin <alex@zagrebin.ru> To: Bernhard Schmidt <bschmidt@freebsd.org> Cc: freebsd-net@freebsd.org Subject: Re: if_run in hostap mode: issue with stations in the power save mode Message-ID: <20110204114021.GA237@gw.zagrebin.ru> In-Reply-To: <201102040951.34201.bschmidt@freebsd.org> References: <20110204060808.GA97298@gw.zagrebin.ru> <201102040951.34201.bschmidt@freebsd.org>
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Hi!
On 04.02.2011 09:51:34 +0100, Bernhard Schmidt wrote:
> On Friday 04 February 2011 07:08:08 Alexander Zagrebin wrote:
> > I'm using an Ralink RT2870 based adapter (run(4) driver) in the
> > hostap mode. and I've noticed that if_run doesn't support stations
> > working in the power save mode (PSM). The reason is in lack of the
> > TIM in beacons. The attached patch adds this functionality and
> > completely fixes this issue. Despite the fact that patch is working,
> > it seems that it needs an additional work. For example, now the
> > result of ieee80211_beacon_update is ignored with a corresponding
> > message, but may be necessary to process it...
> >
> > Can somebody review it?
>
> That looks about right, good catch!
>
> Handling ieee80211_beacon_update()'s return value doesn't seem to be
> necessary, the mbuf's length is handled in the next few lines of code
> anyways, doesn't matter if it changed or not.
>
> Though, I have a some doubts about just restoring bo_flags is enough
> (Can't prove that with some obvious code, still..). It feels saner to me
> if we just reuse the whole mbuf, similar to what ath(4) does. Can you
> look at attached patch? Completely untested, so I'm not sure what does
> happen on e.g. changing the SSID.
I've thought about such solution, and it looks more right, but I've decided
just to add ieee80211_beacon_update() to make the patch clear.
I'll try your patch a bit later, but I already have a question:
on the first invocation of the run_update_beacon_cb() only
ieee80211_beacon_alloc() will be called. So dynamic beacon contents
will not updated. Is it a problem?
Also I have to note, that it seems that other wlan drivers can has this
problem too: only ral's and ath's code uses ieee80211_beacon_update().
Also, I've found a kern/124753. One of replies contains a log's fragment
with many records, like following:
kernel: ath0: [00:18:41:c0:06:54] power save mode on, 1 sta's in ps mode
kernel: ath0: [00:18:41:c0:06:54] save frame with age 0, 1 now queued
kernel: ath0: [00:18:41:c0:06:54] save frame with age 0, 2 now queued
kernel: ath0: [00:18:41:c0:06:54] power save mode off, 0 sta's in ps mode
kernel: ath0: [00:18:41:c0:06:54] flush ps queue, 2 packets queue
But there are no records, which have to be for a PSM enabled stations:
When a beacon is properly updated, then we have to see records about
1. TIM updating, like
ieee80211_beacon_update: TIM updated, pending 1, off 0, len 1
2. poll messages from a stations, like
wlan0: [18:86:ac:10:4b:88] recv ps-poll, send packet, queue empty
Thanks for your cooperation!
--
Alexander Zagrebin
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