I'm implementing a communication fault injection tool on Linux, it's
basically a layer that intercepts packets around dev_queue_xmit and
netif_rx and allows you to introduce faults at will.
One of its abilities is to delay packets a certain amount of time, to
simulate timing problems, network congestion, etc. At the moment, when a
certain packet is selected to be delayed, I set the skb->stamp values to
be xtime plus a certain amount of milliseconds, so that I can later test
if xtime is greater than the skb->stamp and then send the packet.
The routine that intercepts dev_queue_xmit puts the packets that should be
delayed on a sk_buff_head, and then I inserted code on timer_bh to check
the queue for possible transmitions.
Is this whole thing wrong? I mean, up to now I can only get delayed
crashes. It's interesting that even a call to skb_unlink inside timer_bh
crashes the system... what could be wrong? Can anyone suggest a better
approach to delaying packets at will?
I'm doing this on 2.2.9. Thanks for any comments, and please CC to me as
I'm not on the list.
Fábio
( Fábio Olivé Leite olive@inf.ufrgs.br )
( http://descartes.ucpel.tche.br/~olive )
( Quero escapar para o meta-nível! )
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