[Click] packet weirdness

[Roman Chertov]

After reading the doc for FastUDPsrc it seems that it operates on a 
single skb_buff.  The thing which confuses me is why incr_ports is 
allowed to be used in the pull function if packet modifications is not 
allowed without cloning.

Roman

Roman Chertov wrote:
> Hello,
> 	I have a machine with two NICs connected by a cross over cable.  I am 
> running Click from CVS on a 2.4.32 kernel.  I did a few modifications to 
> the Click linux module elements such that FastUDPsrc now puts a packet 
> sequence number into the packet's payload and then I set the timestamp 
> annotation. Then the packet gets sent to eth1.  A special element on the 
> eth2 recieve path looks at the packets and stores the sequence numbers 
> in an internal fixed size array.  To get the array data I have made a 
> read_handler for it.
> 
> If I set the packet generation rate to something low then I get a 
> non-repeating set of sequence numbers; however, if I set the rate to 0, 
> then I sometimes see a long series of repeating numbers.
> 
> Any input would be much appreciated,
> 
> Roman
> 
> Script.
> source :: FastUDPSource2(0, 10000, 60,
>                          00:0E:0C:AB:64:0C, 10.0.1.1, 1234,
>                          00:0E:0C:AB:63:70, 10.0.2.1, 1234);
> 
> to     :: ToDevice(eth1);
> from   :: PollDevice(eth2);
> ctr    :: AverageCounter;
> 
> classifier      :: Classifier(12/0800 /* IP packets */,
>                                - /* everything else */);
> ip_classifier   :: IPClassifier(dst udp port 1234 /* relevant UDP 
> packets */,
>                                  - /* everything else */);
> 
> 
> source -> SetTimestamp
>         -> to;
> 
> 
> from   -> classifier[0]
>         -> CheckIPHeader(14, CHECKSUM false) // don't check checksum for 
> speed
>         -> ip_classifier[0]
>         -> tt :: TimestampTrack(1000)
>         -> ctr
>         //-> Print
>         -> Discard;
> 
> classifier[1] -> ToHost;
> ip_classifier[1] -> ToHost;
> 
> Idle -> ToDevice(eth2);
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