[Click] ToDevice and pkts "too small"

[Eddie Kohler]

Torquato,

This is a good point, and a reasonable patch sketch.  I checked in a version; 
let me know if it works for you!

Eddie


Torquato Bertani wrote:
> Hi all,
> I found a strange thing in ToDevice element. If I use a configuration
> like this one:
> 
> FromHost->Classifier(12/806, -)->Queue->ToDevice(eth0); //Send ARP
> pkts to ethernet
> 
> Click reports the error: ToDevice: too small: len 42 tailroom 4
> 
> I know that tailroom is too small to pad the pkt till 60 bytes. In
> this case why ToDevice doesn't call the function Packet::put()? This
> function will cal Packet::expensive_put() and then everything should
> work. I see that ToDevice call tha function skb_put() to pad the pkt
> till 60 bytes if tailroom is enough, is right or can be improved
> calling Packet::put() ?
> 
> I modified the code to use Packet::put() if tailroom isn't enough and
> it works but I'd like to know if it's correct or not.
> 
> Thanks
> 
> Thor
> 
> todevice.cc:399
> if (!_no_pad && skb1->len < 60) {
>         if (skb_tailroom(skb1) < 60 - skb1->len) {
>             WritablePacket *q = p->put(60 - skb1->len);
>             p = q;       //Is this correct?
> //          printk("ToDevice: too small: len %d tailroom %d\n",
> //                 skb1->len, skb_tailroom(skb1));
> //          kfree_skb(skb1);
> //          return -1;
>         } else {
>                 skb_put(skb1, 60 - skb1->len);
>         }
>     }
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