From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-gx0-f174.google.com ([209.85.161.174]:43381 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754119Ab0KBQzX convert rfc822-to-8bit (ORCPT ); Tue, 2 Nov 2010 12:55:23 -0400 Received: by gxk23 with SMTP id 23so4206315gxk.19 for ; Tue, 02 Nov 2010 09:55:22 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <8762whrqvm.fsf@gmail.com> References: <8762whrqvm.fsf@gmail.com> Date: Tue, 2 Nov 2010 17:55:22 +0100 Message-ID: Subject: Re: [ath9k-devel] ath9k: race conditions in dma From: =?ISO-8859-1?Q?Bj=F6rn_Smedman?= To: Ben Gamari Cc: linux-wireless , ath9k-devel@lists.ath9k.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Mon, Nov 1, 2010 at 4:43 PM, Ben Gamari wrote: > On Mon, 1 Nov 2010 16:17:23 +0100, Björn Smedman wrote: >> Hi all, >> >> I have an application that creates and destroys a lot of ap vifs and >> does a lot of monitor frame injection. The recent ath9k rx locking >> fixes have helped with stability in this use-case but there still >> seems to be some tx/beacon related race condition(s). These manifests >> themselves as follows on an AR913x based router running >> compat-wireless-2010-10-19 (with locking fixes etc from openwrt): >> >> 1. TX DMA hangs under simultaneous high RX and TX load >> 2. TX is completely hung but chip is never reset > > I have also observed both of these behaviors with just a standard > hostapd single VIF configuration. Quite annoying. It seems to be better > with recent wireless-testing trees. > > - Ben I just posted "[RFC] ath9k: fix tx queue selection" with a patch that fixes (or at least reduces) these two for me. I'm not sure it is the whole story but at least in theory 1 could be caused by locking one tx queue and actually transmitting on another. 2 is probably caused by stopping one mac80211 queue and then starting another. Ben, if you can easily trigger these problems on wireless-testing, could you test with my patch and see if it helps? I'm especially interested to see if it really fixes problem 1. /Björn From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Bj=F6rn_Smedman?= Date: Tue, 2 Nov 2010 17:55:22 +0100 Subject: [ath9k-devel] ath9k: race conditions in dma In-Reply-To: <8762whrqvm.fsf@gmail.com> References: <8762whrqvm.fsf@gmail.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ath9k-devel@lists.ath9k.org On Mon, Nov 1, 2010 at 4:43 PM, Ben Gamari wrote: > On Mon, 1 Nov 2010 16:17:23 +0100, Bj?rn Smedman wrote: >> Hi all, >> >> I have an application that creates and destroys a lot of ap vifs and >> does a lot of monitor frame injection. The recent ath9k rx locking >> fixes have helped with stability in this use-case but there still >> seems to be some tx/beacon related race condition(s). These manifests >> themselves as follows on an AR913x based router running >> compat-wireless-2010-10-19 (with locking fixes etc from openwrt): >> >> 1. TX DMA hangs under simultaneous high RX and TX load >> 2. TX is completely hung but chip is never reset > > I have also observed both of these behaviors with just a standard > hostapd single VIF configuration. Quite annoying. It seems to be better > with recent wireless-testing trees. > > - Ben I just posted "[RFC] ath9k: fix tx queue selection" with a patch that fixes (or at least reduces) these two for me. I'm not sure it is the whole story but at least in theory 1 could be caused by locking one tx queue and actually transmitting on another. 2 is probably caused by stopping one mac80211 queue and then starting another. Ben, if you can easily trigger these problems on wireless-testing, could you test with my patch and see if it helps? I'm especially interested to see if it really fixes problem 1. /Bj?rn