Bug in netem reordering
From: Vijay Subramanian <hidden>
Date: 2012-01-05 00:44:52
Hi,
I am getting a crash when I test the reordering feature of netem. This
happens every time I run the following tc command and then pass some
traffic through the
interface. I am using the latest net-next kernel.
#tc qdisc add dev eth0 root netem delay 10ms reorder 25% 50%
Then wait for several packets to go through.
The problem seems to be in netem_enqueue(). Part of the code for
reordering is as follows:
} else {
/*
* Do re-ordering by putting one out of N packets at the front
* of the queue.
*/
cb->time_to_send = psched_get_time();
q->counter = 0;
__skb_queue_head(&sch->q, skb);
q->qdisc->qstats.backlog += qdisc_pkt_len(skb);
q->qdisc->qstats.requeues++;
ret = NET_XMIT_SUCCESS;
}
The issue is that q->qdisc is initialized to NULL (by netem_init? ).
When the else branch is executed as above after a few packets,
q->qdisc is NULL and we get a crash.
Can anyone else reproduce the problem?
Regards,
Vijay Subramanian