Return-path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:56840 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754666Ab2ITMqx (ORCPT ); Thu, 20 Sep 2012 08:46:53 -0400 Received: by pbbrr4 with SMTP id rr4so132615pbb.19 for ; Thu, 20 Sep 2012 05:46:52 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1347361823.26457.3.camel@sauron.fi.intel.com> <1DC40B07CD6EC041A66726C271A73AE6195AE9C8@IRSMSX102.ger.corp.intel.com> <1347631355.5263.19.camel@sauron.fi.intel.com> <1347640763.5263.24.camel@sauron.fi.intel.com> <1347892887.7112.9.camel@sauron.fi.intel.com> <1348142775.2388.10.camel@sauron.fi.intel.com> <1348144524.4161.26.camel@jlt4.sipsolutions.net> Date: Thu, 20 Sep 2012 14:46:52 +0200 Message-ID: (sfid-20120920_144701_552250_F7103BC5) Subject: Re: regression: tethering fails in 3.5 with iwlwifi From: Eric Dumazet To: Johannes Berg Cc: artem.bityutskiy@linux.intel.com, linux-wireless@vger.kernel.org, netdev Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: Or its the lines with CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS ? What arch is it ? On Thu, Sep 20, 2012 at 2:45 PM, Eric Dumazet wrote: > I guess you only need to make sure 14 bytes of ethernet header are > available before eth_type_trans(skb, dev); > > diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c > index 61c621e..ffe5f84 100644 > --- a/net/mac80211/rx.c > +++ b/net/mac80211/rx.c > @@ -1795,9 +1795,13 @@ ieee80211_deliver_skb(struct ieee80211_rx_data *rx) > > if (skb) { > /* deliver to local stack */ > - skb->protocol = eth_type_trans(skb, dev); > - memset(skb->cb, 0, sizeof(skb->cb)); > - netif_receive_skb(skb); > + if (pskb_may_pull(skb, sizeof(struct ethhdr))) { > + skb->protocol = eth_type_trans(skb, dev); > + memset(skb->cb, 0, sizeof(skb->cb)); > + netif_receive_skb(skb); > + } else { > + kfree_skb(skb); > + } > } > } > > > On Thu, Sep 20, 2012 at 2:40 PM, Eric Dumazet wrote: >> OK, but which netif_receive_skb(), as I count 5 occurrences in >> net/mac80211/rx.c ? >> >> Instead of skb_linearize() calls >> >> you could try several values of XXX in >> >> pskb_may_pull(skb, XXX) >> >> So that you make sure XXX bytes are available in skb->head, and not >> the whole frame. >> >> One you know the limit for XXX, it might give a clue where a >> pskb_may_pull(skb, XXX) is missing. >> >> On Thu, Sep 20, 2012 at 2:35 PM, Johannes Berg >> wrote: >>> Hi, >>> >>>> > 56138f5 iwlwifi: dont pull too much payload in skb head >>>> > 3edaf3e mac80211: manage AP netdev carrier state >>>> >>>> The second patch (AP carrier state) actually exposed a connman issue >>>> which I fixed and submitted a connman patch: >>>> http://lists.connman.net/pipermail/connman/2012-September/011232.html >>>> >>>> However, Eric's patch still causes tethering problems to me. >>> >>> >>> Let me recap a bit. Artem is using connman, which sets up the wifi >>> interface as part of a bridge. It runs wpa_supplicant to create an AP >>> (only AP and mesh mode interfaces can be bridged anyway). >>> >>> >>> Eric, you said: >>> >>>> I would say some part of the stack assumes a header (I dont know wich >>>> one ?) is pulled in skb->head/data, and thats a bug. >>>> >>>> Always use pskb_may_pull(skb, XXX) to make sure you can access XXX >>>> bytes in skb->data >>> >>> I thought we'd figure out which part of the stack assumes a header, so I >>> asked Artem to test a one-line patch which adds "skb_linearize()" before >>> "netif_receive_skb()" in mac80211. This makes it work, but I'm not sure >>> where after that the bad assumption might be. >>> >>> johannes >>>