netdev - Re: regression: tethering fails in 3.5 with iwlwifi

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Message-ID: <CANn89i+9Th=xVgDgoy7tHwKtLNpOC8rgJkA09nQ1Yf0zvqBw6w@mail.gmail.com>
Date:	Thu, 20 Sep 2012 15:04:50 +0200
From:	Eric Dumazet <edumazet@...gle.com>
To:	artem.bityutskiy@...ux.intel.com
Cc:	Johannes Berg <johannes@...solutions.net>,
	linux-wireless@...r.kernel.org, netdev <netdev@...r.kernel.org>
Subject: Re: regression: tethering fails in 3.5 with iwlwifi

Try to pull 40 bytes : Thats OK for tcp performance, because 40 bytes
is the minimum size of IP+TCP headers

pskb_may_pull(skb, 40);

(instead of your  skb_linearize(skb);)


On Thu, Sep 20, 2012 at 2:58 PM, Artem Bityutskiy
<artem.bityutskiy@...ux.intel.com> wrote:
> On Thu, 2012-09-20 at 14:45 +0200, 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);
>> +                       }
>>                 }
>>         }
>
> Does not help, this one does:
>
> diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
> index 61c621e..6888586 100644
> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -1797,6 +1797,7 @@ ieee80211_deliver_skb(struct ieee80211_rx_data *rx)
>                         /* deliver to local stack */
>                         skb->protocol = eth_type_trans(skb, dev);
>                         memset(skb->cb, 0, sizeof(skb->cb));
> +                       skb_linearize(skb);
>                         netif_receive_skb(skb);
>                 }
>
> --
> Best Regards,
> Artem Bityutskiy
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