pkt_sched: sch_drr: fix drr_dequeue loop()
Jarek Poplawski points out:
If all child qdiscs of sch_drr are non-work-conserving (e.g. sch_tbf)
drr_dequeue() will busy-loop waiting for skbs instead of leaving the
job for a watchdog. Checking for list_empty() in each loop isn't
necessary either, because this can never be true except the first time.
Using non-work-conserving qdiscs as children of DRR makes no sense,
simply bail out in that case.
Reported-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c
index 37e6ab9..e7a7e87 100644
--- a/net/sched/sch_drr.c
+++ b/net/sched/sch_drr.c
@@ -373,11 +373,13 @@
struct sk_buff *skb;
unsigned int len;
- while (!list_empty(&q->active)) {
+ if (list_empty(&q->active))
+ goto out;
+ while (1) {
cl = list_first_entry(&q->active, struct drr_class, alist);
skb = cl->qdisc->ops->peek(cl->qdisc);
if (skb == NULL)
- goto skip;
+ goto out;
len = qdisc_pkt_len(skb);
if (len <= cl->deficit) {
@@ -390,9 +392,9 @@
}
cl->deficit += cl->quantum;
-skip:
list_move_tail(&cl->alist, &q->active);
}
+out:
return NULL;
}