[LARTC] [HTB] htb_dequeue_tree assertion (kernel 2.4.21-ac4)

[Wilfried Weissmann]

Hello,

I think the BUG_TRAP() in the htb_dequeue_tree() is wrong. First it 
checks if the class pointer "cl" is NULL, which is obviously right. But 
I do not understand why we also check whenever the queue length of the 
leaf queue is zero "cl->un.leaf.q->q.qlen". I would have put that in the 
expression of the "if" statements that comes afterwards. A queue length 
of 0 is not an error condition that should be reported (please, correct 
me if I misunderstood the code).
I can pretty much reliably trigger the assertion with a well utilized 
gigabit ethernet link when I flush and reactivate the TC configuration 
every 3 seconds. It looks like the error occurs only when confiuration 
changes are made.
I will some some more tests on monday when I am back at the office to 
verify that the queue length is (not) the problem.

bye,
wilfried

static struct sk_buff *
htb_dequeue_tree(struct htb_sched *q,int prio,int level)
{
	struct sk_buff *skb = NULL;
	//struct htb_sched *q = (struct htb_sched *)sch->data;
	struct htb_class *cl,*start;
	/* look initial class up in the row */
	start = cl = htb_lookup_leaf (q->row[level]+prio,prio,q->ptr[level]+prio);
	
	do {
		BUG_TRAP(cl && cl->un.leaf.q->q.qlen); if (!cl) return NULL;
		HTB_DBG(4,1,"htb_deq_tr prio=%d lev=%d cl=%X defic=%d\n",
				prio,level,cl->classid,cl->un.leaf.deficit[level]);
	
		if (likely((skb = cl->un.leaf.q->dequeue(cl->un.leaf.q)) != NULL))
			break;
		if (!cl->warned) {