[Click] todevice and madwifi-ng in monitor mode

[Eddie Kohler]

David,

Thanks very much for this patch!

Eddie


David Claffey wrote:
> Hi Torquato,
> 
> Good to hear it helped.  I actually fixed another problem in skbmgr.cc as well. 
>   Recycled skbs need to have the  skb->dst pointer set to NULL.  I had some 
> packets coming from linux with this pointer non-NULL. The next use of the 
> recycled skb will call dst_release with the refcnt 0, then -1 ,then -2, etc, 
> causing a hugh stream of printks.
> The patch is below.
> 
> - David
> 
> --- click/linuxmodule/skbmgr.cc
> +++ tmp/linuxmodule/skbmgr.cc
> @@ -248,6 +248,7 @@
>     // datarefp (expensive to set).
>     if (!(skb->pkt_type & PACKET_CLEAN)) {
>       dst_release(skb->dst);
> +    skb->dst = NULL; // stale pointer will cause problems for recycled skbs; 
> dst_run_gc will cleanup mem
>       if (skb->destructor) {
>         skb->destructor(skb);
>         skb->destructor = NULL;
> 
> 
> Torquato Bertani wrote:
>> Hi David,
>> thanks for your patch. Now my kernel doesn't crash anymore!
>> Bye
>>
>> On 4/12/06, David Claffey <dclaffey at jjplus.com> wrote:
>>> I have the click linuxmodule and the madwifi-ng driver running on linux-2.6.12.
>>>   I'm using todevice() to send packets out the ath device in monitor mode.  But
>>> this only works after adding the following patch:
>>> --- click/elements/linuxmodule/todevice.cc
>>> +++ tmp/elements/linuxmodule/todevice.cc
>>> @@ -383,6 +383,12 @@
>>>         skb_put(skb1, 60 - skb1->len);
>>>       }
>>>
>>> +    skb1->dev = _dev;
>>> +
>>>       int ret;
>>>   #if HAVE_LINUX_POLLING
>>>       if (_dev->polling > 0)
>>>         ret = _dev->tx_queue(_dev, skb1);
>>>      else
>>> #endif
>>>         {
>>>             ret = _dev->hard_start_xmit(skb1, _dev);
>>>             _hard_start++;
>>>         }
>>>
>>> Todevice() passes the skb to ieee80211_hardstart(struct sk_buff *skb, struct
>>> net_device *dev) which then calls ieee80211_monitor_encap(struct ieee80211vap
>>> *vap, struct sk_buff *skb).  The problem arises when ieee80211_monitor_encap()
>>> references skb->dev->type with skb->dev NULL. Can anyone suggest which function
>>> should set skb->dev, todevice or ieee80211_hardstart?
>>>
>>> - David
>>> _______________________________________________
>>> click mailing list
>>> click at amsterdam.lcs.mit.edu
>>> https://amsterdam.lcs.mit.edu/mailman/listinfo/click
>>>
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