From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from nbd.name ([88.198.39.176]:44679 "EHLO ds10.nbd.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751978Ab0IVIcH (ORCPT ); Wed, 22 Sep 2010 04:32:07 -0400 Message-ID: <4C99BEFC.2060209@openwrt.org> Date: Wed, 22 Sep 2010 10:31:56 +0200 From: Felix Fietkau MIME-Version: 1.0 To: Ben Greear CC: Johannes Berg , "ath9k-devel@lists.ath9k.org" , "linux-wireless@vger.kernel.org" Subject: Re: [ath9k-devel] ath9k, multiple stations, and AMPDUs References: <4C9841BA.4080700@candelatech.com> <4C98848C.70005@openwrt.org> <4C98A022.7020106@candelatech.com> <4C98A2C4.8060108@openwrt.org> <4C98EAA1.7050908@candelatech.com> <4C98F2D8.8020602@openwrt.org> <1285097307.12764.11.camel@jlt3.sipsolutions.net> <4C990859.70709@openwrt.org> <4C99135A.3090103@candelatech.com> <4C99348F.2090504@openwrt.org> <4C99870C.20006@candelatech.com> In-Reply-To: <4C99870C.20006@candelatech.com> Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: On 2010-09-22 6:33 AM, Ben Greear wrote: > On 09/21/2010 03:41 PM, Felix Fietkau wrote: >> On 2010-09-21 10:19 PM, Ben Greear wrote: >>> On 09/21/2010 12:32 PM, Felix Fietkau wrote: >>>> On 2010-09-21 9:28 PM, Johannes Berg wrote: >>>>> On Tue, 2010-09-21 at 20:00 +0200, Felix Fietkau wrote: >>>>> >>>>>>> Could we just poke a pointer to the STA into the ath_buf structure? >>>>> >>>>>> No, that doesn't work because of RCU. >>>>> >>>>> Well, it could work, if you walk all the structures upon sta_notify and >>>>> remove now stale pointers (or just drop the frames or something). >>>> I think it would be much better to just add the helper function that >>>> checks the RA on STA lookup. Keeps things simple, especially since >>>> nothing else in the tx path needs the vif. >>> >>> How about this. Seems to do the trick on my system: >>> >>> >>> diff --git a/drivers/net/wireless/ath/ath9k/xmit.c b/drivers/net/wireless/ath/ath9k/xmit.c >>> index 85a7323..09815a1 100644 >>> --- a/drivers/net/wireless/ath/ath9k/xmit.c >>> +++ b/drivers/net/wireless/ath/ath9k/xmit.c >>> @@ -328,8 +328,7 @@ static void ath_tx_complete_aggr(struct ath_softc *sc, struct ath_txq *txq, >>> >>> rcu_read_lock(); >>> >>> - /* XXX: use ieee80211_find_sta! */ >>> - sta = ieee80211_find_sta_by_hw(hw, hdr->addr1); >>> + sta = tx_info->control.sta; >> As I mentioned in another email: at the time we get the tx status >> report, we have to consider the sta pointer stale. It may or may not >> still be valid. > > How about this one. I think it ensures that the sta will never be stale, No, it doesn't. At least not in AP mode. > since it flushes the tx queue on vif removal. Minimal testing shows it > working, but of course I might be missing something. In AP mode, a vif has multiple sta. And draining the queue when a sta gets removed is not a good idea. - Felix