Patrick McHardy wrote:
> [NET_SCHED]: qdisc: avoid dequeue while throttled
It just occured to me that this doesn't work properly with qdiscs
that have multiple classes since they all don't properly maintain
the TCQ_F_THROTTLED flag. They set it on dequeue when no active
class is willing to give out packets, but when enqueueing to a
non-active class (thereby activating it) it is still set even though
we don't know if that class could be dequeued.
So this updated patch unsets the TCQ_F_THROTTLED flag whenever we
activate a class. Additionally it removes the unsetting of
TCQ_F_THROTTLED on successful dequeue since we're now guaranteed
that it was not set before.
[NET_SCHED]: qdisc: avoid dequeue while throttled
Avoid dequeueing while the device is throttled.
Signed-off-by: Patrick McHardy <[EMAIL PROTECTED]>
---
commit 073456c84a46736a3aa1ae4cc9d953a9e97b327c
tree 805a29224001180c88a429e65812b97a489c427a
parent e2459acd7dee06fb4d5e980f26c23d31db0e5de1
author Patrick McHardy <[EMAIL PROTECTED]> Fri, 23 Mar 2007 15:37:51 +0100
committer Patrick McHardy <[EMAIL PROTECTED]> Fri, 23 Mar 2007 15:37:51 +0100
net/sched/sch_cbq.c | 5 +++--
net/sched/sch_generic.c | 4 ++++
net/sched/sch_hfsc.c | 5 +++--
net/sched/sch_htb.c | 6 ++++--
net/sched/sch_netem.c | 4 ----
net/sched/sch_tbf.c | 1 -
6 files changed, 14 insertions(+), 11 deletions(-)
diff --git a/net/sched/sch_cbq.c b/net/sched/sch_cbq.c
index a294542..151f8e3 100644
--- a/net/sched/sch_cbq.c
+++ b/net/sched/sch_cbq.c
@@ -424,8 +424,10 @@ cbq_enqueue(struct sk_buff *skb, struct Qdisc *sch)
sch->bstats.packets++;
sch->bstats.bytes+=len;
cbq_mark_toplevel(q, cl);
- if (!cl->next_alive)
+ if (!cl->next_alive) {
cbq_activate_class(cl);
+ sch->flags &= ~TCQ_F_THROTTLED;
+ }
return ret;
}
@@ -1030,7 +1032,6 @@ cbq_dequeue(struct Qdisc *sch)
skb = cbq_dequeue_1(sch);
if (skb) {
sch->q.qlen--;
- sch->flags &= ~TCQ_F_THROTTLED;
return skb;
}
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 52eb343..39c5312 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -93,6 +93,10 @@ static inline int qdisc_restart(struct net_device *dev)
struct Qdisc *q = dev->qdisc;
struct sk_buff *skb;
+ smp_rmb();
+ if (q->flags & TCQ_F_THROTTLED)
+ return q->q.qlen;
+
/* Dequeue packet */
if (((skb = dev->gso_skb)) || ((skb = q->dequeue(q)))) {
unsigned nolock = (dev->features & NETIF_F_LLTX);
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 22cec11..c6da436 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1597,8 +1597,10 @@ hfsc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
return err;
}
- if (cl->qdisc->q.qlen == 1)
+ if (cl->qdisc->q.qlen == 1) {
set_active(cl, len);
+ sch->flags &= ~TCQ_F_THROTTLED;
+ }
cl->bstats.packets++;
cl->bstats.bytes += len;
@@ -1672,7 +1674,6 @@ hfsc_dequeue(struct Qdisc *sch)
}
out:
- sch->flags &= ~TCQ_F_THROTTLED;
sch->q.qlen--;
return skb;
diff --git a/net/sched/sch_htb.c b/net/sched/sch_htb.c
index 71db121..1387b7b 100644
--- a/net/sched/sch_htb.c
+++ b/net/sched/sch_htb.c
@@ -615,6 +615,8 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
/* enqueue to helper queue */
if (q->direct_queue.qlen < q->direct_qlen) {
__skb_queue_tail(&q->direct_queue, skb);
+ if (q->direct_queue.qlen == 1)
+ sch->flags &= ~TCQ_F_THROTTLED;
q->direct_pkts++;
} else {
kfree_skb(skb);
@@ -637,6 +639,8 @@ static int htb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
cl->bstats.packets++;
cl->bstats.bytes += skb->len;
htb_activate(q, cl);
+ if (cl->un.leaf.q->q.qlen == 1)
+ sch->flags &= ~TCQ_F_THROTTLED;
}
sch->q.qlen++;
@@ -958,7 +962,6 @@ static struct sk_buff *htb_dequeue(struct Qdisc *sch)
/* try to dequeue direct packets as high prio (!) to minimize cpu work */
skb = __skb_dequeue(&q->direct_queue);
if (skb != NULL) {
- sch->flags &= ~TCQ_F_THROTTLED;
sch->q.qlen--;
return skb;
}
@@ -991,7 +994,6 @@ static struct sk_buff *htb_dequeue(struct Qdisc *sch)
skb = htb_dequeue_tree(q, prio, level);
if (likely(skb != NULL)) {
sch->q.qlen--;
- sch->flags &= ~TCQ_F_THROTTLED;
goto fin;
}
}
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 5d9d8bc..4c7a8d8 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -273,10 +273,6 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
struct netem_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
- smp_mb();
- if (sch->flags & TCQ_F_THROTTLED)
- return NULL;
-
skb = q->qdisc->dequeue(q->qdisc);
if (skb) {
const struct netem_skb_cb *cb
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 5386295..ed7e581 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -218,7 +218,6 @@ static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
q->tokens = toks;
q->ptokens = ptoks;
sch->q.qlen--;
- sch->flags &= ~TCQ_F_THROTTLED;
return skb;
}
