Return-path: Received: from mo-p00-ob.rzone.de ([81.169.146.161]:51710 "EHLO mo-p00-ob.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754567AbZIKQHy (ORCPT ); Fri, 11 Sep 2009 12:07:54 -0400 Message-ID: <4AAA75CB.6040803@hartkopp.net> Date: Fri, 11 Sep 2009 18:07:39 +0200 From: Oliver Hartkopp MIME-Version: 1.0 To: Michael Buesch CC: Kalle Valo , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, Johannes Berg , "John W. Linville" Subject: Re: mac80211: NOHZ: local_softirq_pending 08 References: <200909111648.50902.mb@bu3sch.de> <877hw534wd.fsf@litku.valot.fi> <200909111707.23971.mb@bu3sch.de> In-Reply-To: <200909111707.23971.mb@bu3sch.de> Content-Type: text/plain; charset=iso-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: Michael Buesch wrote: > On Friday 11 September 2009 16:57:54 Kalle Valo wrote: >> Michael Buesch writes: >> >>> Hi, >> Hallo, >> >>> mac80211 (or some other part of the networking stack) triggers this >>> warning in the NOHZ code: NOHZ: local_softirq_pending 08 >>> >>> 08 seems to be NET_RX_SOFTIRQ. >>> >>> It happens, because my test driver b43 handles all RX and TX-status >>> callbacks in process context. I guess some part of the networking >>> stack expects RX to be in tasklet and/or softirq context. >>> >>> We also have a report of this warning in wl1251, so it's probably not >>> a b43 problem. >> Yes, I see this with wl1251. It uses workqueues everywhere. >> > > This patch seems to fix it. > > Signed-off-by: Michael Buesch > > Index: wireless-testing/net/mac80211/cfg.c > =================================================================== > --- wireless-testing.orig/net/mac80211/cfg.c 2009-08-09 18:47:11.000000000 +0200 > +++ wireless-testing/net/mac80211/cfg.c 2009-09-11 16:59:12.000000000 +0200 > @@ -606,7 +606,7 @@ static void ieee80211_send_layer2_update > skb->dev = sta->sdata->dev; > skb->protocol = eth_type_trans(skb, sta->sdata->dev); > memset(skb->cb, 0, sizeof(skb->cb)); > - netif_rx(skb); > + ieee80211_netif_rx(skb); > } > > static void sta_apply_parameters(struct ieee80211_local *local, > Index: wireless-testing/net/mac80211/ieee80211_i.h > =================================================================== > --- wireless-testing.orig/net/mac80211/ieee80211_i.h 2009-08-23 00:06:41.000000000 +0200 > +++ wireless-testing/net/mac80211/ieee80211_i.h 2009-09-11 17:02:05.000000000 +0200 > @@ -1053,6 +1053,14 @@ void ieee80211_tx_pending(unsigned long > int ieee80211_monitor_start_xmit(struct sk_buff *skb, struct net_device *dev); > int ieee80211_subif_start_xmit(struct sk_buff *skb, struct net_device *dev); > > +/* rx handling */ > +static inline int ieee80211_netif_rx(struct sk_buff *skb) > +{ > + if (in_interrupt()) > + return netif_rx(skb); > + return netif_rx_ni(skb); > +} > + Hello Michael, i know this NOHZ warning from the CAN stack also - but now, i know what caused this warning. I fixed it in my local tree and it works. Thanks! As there are several users in the kernel do exact this test and call the appropriate netif_rx() function, i would suggest to create a static inline function: static inline int netif_rx_ti(struct sk_buff *skb) { if (in_interrupt()) return netif_rx(skb); return netif_rx_ni(skb); } ('ti' for test in_interrupt()) in include/linux/netdevice.h What do you think about that? Regards, Oliver