pkt_sched: sch_htb: Break all htb_do_events() after 2 jiffies

Currently htb_do_events() breaks events recounting for a level after 2
jiffies, but there is no reason to repeat this for next levels and
increase delays even more (with softirqs disabled). htb_dequeue_tree()
can add to this too, btw. In such a case q->now time is invalid anyway.

Thanks to Patrick McHardy for spotting an error around earlier version
of this patch.

Signed-off-by: Jarek Poplawski <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

net/sched/sch_htb.c

···
  * next pending event (0 for no event in pq).
  * Note: Applied are events whose have cl->pq_key <= q->now.
  */
-static psched_time_t htb_do_events(struct htb_sched *q, int level)
+static psched_time_t htb_do_events(struct htb_sched *q, int level,
+				   unsigned long start)
 {
 	/* don't run for longer than 2 jiffies; 2 is used instead of
 	   1 to simplify things when jiffy is going to be incremented
 	   too soon */
-	unsigned long stop_at = jiffies + 2;
+	unsigned long stop_at = start + 2;
 	while (time_before(jiffies, stop_at)) {
 		struct htb_class *cl;
 		long diff;
···
 	struct htb_sched *q = qdisc_priv(sch);
 	int level;
 	psched_time_t next_event;
+	unsigned long start_at;
 
 	/* try to dequeue direct packets as high prio (!) to minimize cpu work */
 	skb = __skb_dequeue(&q->direct_queue);
···
 	if (!sch->q.qlen)
 		goto fin;
 	q->now = psched_get_time();
+	start_at = jiffies;
 
 	next_event = q->now + 5 * PSCHED_TICKS_PER_SEC;
 
···
 		psched_time_t event;
 
 		if (q->now >= q->near_ev_cache[level]) {
-			event = htb_do_events(q, level);
+			event = htb_do_events(q, level, start_at);
 			if (!event)
 				event = q->now + PSCHED_TICKS_PER_SEC;
 			q->near_ev_cache[level] = event;