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authorEric Dumazet <eric.dumazet@gmail.com>2011-12-28 23:12:02 +0000
committerDavid S. Miller <davem@davemloft.net>2011-12-30 17:12:23 -0500
commit50612537e9ab29693122fab20fc1eed235054ffe (patch)
tree389279a18e07ce046ef694b37f44ccbc7fe796a1 /net/sched/sch_netem.c
parent32b293a53deeb220769f9a29357cb151cfb8ee26 (diff)
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netem: fix classful handling
Commit 10f6dfcfde (Revert "sch_netem: Remove classful functionality") reintroduced classful functionality to netem, but broke basic netem behavior : netem uses an t(ime)fifo queue, and store timestamps in skb->cb[] If qdisc is changed, time constraints are not respected and other qdisc can destroy skb->cb[] and block netem at dequeue time. Fix this by always using internal tfifo, and optionally attach a child qdisc to netem (or a tree of qdiscs) Example of use : DEV=eth3 tc qdisc del dev $DEV root tc qdisc add dev $DEV root handle 30: est 1sec 8sec netem delay 20ms 10ms tc qdisc add dev $DEV handle 40:0 parent 30:0 tbf \ burst 20480 limit 20480 mtu 1514 rate 32000bps qdisc netem 30: root refcnt 18 limit 1000 delay 20.0ms 10.0ms Sent 190792 bytes 413 pkt (dropped 0, overlimits 0 requeues 0) rate 18416bit 3pps backlog 0b 0p requeues 0 qdisc tbf 40: parent 30: rate 256000bit burst 20Kb/8 mpu 0b lat 0us Sent 190792 bytes 413 pkt (dropped 6, overlimits 10 requeues 0) backlog 0b 5p requeues 0 Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> CC: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sched/sch_netem.c')
-rw-r--r--net/sched/sch_netem.c202
1 files changed, 81 insertions, 121 deletions
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index a92c1b3..06a5ceb 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -67,7 +67,11 @@
*/
struct netem_sched_data {
+ /* internal t(ime)fifo qdisc uses sch->q and sch->limit */
+
+ /* optional qdisc for classful handling (NULL at netem init) */
struct Qdisc *qdisc;
+
struct qdisc_watchdog watchdog;
psched_tdiff_t latency;
@@ -117,7 +121,9 @@ struct netem_sched_data {
};
-/* Time stamp put into socket buffer control block */
+/* Time stamp put into socket buffer control block
+ * Only valid when skbs are in our internal t(ime)fifo queue.
+ */
struct netem_skb_cb {
psched_time_t time_to_send;
};
@@ -324,6 +330,31 @@ static psched_time_t packet_len_2_sched_time(unsigned int len, struct netem_sche
return PSCHED_NS2TICKS(ticks);
}
+static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
+{
+ struct sk_buff_head *list = &sch->q;
+ psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
+ struct sk_buff *skb;
+
+ if (likely(skb_queue_len(list) < sch->limit)) {
+ skb = skb_peek_tail(list);
+ /* Optimize for add at tail */
+ if (likely(!skb || tnext >= netem_skb_cb(skb)->time_to_send))
+ return qdisc_enqueue_tail(nskb, sch);
+
+ skb_queue_reverse_walk(list, skb) {
+ if (tnext >= netem_skb_cb(skb)->time_to_send)
+ break;
+ }
+
+ __skb_queue_after(list, skb, nskb);
+ sch->qstats.backlog += qdisc_pkt_len(nskb);
+ return NET_XMIT_SUCCESS;
+ }
+
+ return qdisc_reshape_fail(nskb, sch);
+}
+
/*
* Insert one skb into qdisc.
* Note: parent depends on return value to account for queue length.
@@ -399,7 +430,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
now = psched_get_time();
if (q->rate) {
- struct sk_buff_head *list = &q->qdisc->q;
+ struct sk_buff_head *list = &sch->q;
delay += packet_len_2_sched_time(skb->len, q);
@@ -417,7 +448,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
cb->time_to_send = now + delay;
++q->counter;
- ret = qdisc_enqueue(skb, q->qdisc);
+ ret = tfifo_enqueue(skb, sch);
} else {
/*
* Do re-ordering by putting one out of N packets at the front
@@ -426,7 +457,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
cb->time_to_send = psched_get_time();
q->counter = 0;
- __skb_queue_head(&q->qdisc->q, skb);
+ __skb_queue_head(&sch->q, skb);
q->qdisc->qstats.backlog += qdisc_pkt_len(skb);
q->qdisc->qstats.requeues++;
ret = NET_XMIT_SUCCESS;
@@ -439,19 +470,20 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch)
}
}
- sch->q.qlen++;
return NET_XMIT_SUCCESS;
}
static unsigned int netem_drop(struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
- unsigned int len = 0;
+ unsigned int len;
- if (q->qdisc->ops->drop && (len = q->qdisc->ops->drop(q->qdisc)) != 0) {
- sch->q.qlen--;
+ len = qdisc_queue_drop(sch);
+ if (!len && q->qdisc && q->qdisc->ops->drop)
+ len = q->qdisc->ops->drop(q->qdisc);
+ if (len)
sch->qstats.drops++;
- }
+
return len;
}
@@ -463,16 +495,16 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
if (qdisc_is_throttled(sch))
return NULL;
- skb = q->qdisc->ops->peek(q->qdisc);
+tfifo_dequeue:
+ skb = qdisc_peek_head(sch);
if (skb) {
const struct netem_skb_cb *cb = netem_skb_cb(skb);
- psched_time_t now = psched_get_time();
/* if more time remaining? */
- if (cb->time_to_send <= now) {
- skb = qdisc_dequeue_peeked(q->qdisc);
+ if (cb->time_to_send <= psched_get_time()) {
+ skb = qdisc_dequeue_tail(sch);
if (unlikely(!skb))
- return NULL;
+ goto qdisc_dequeue;
#ifdef CONFIG_NET_CLS_ACT
/*
@@ -483,15 +515,37 @@ static struct sk_buff *netem_dequeue(struct Qdisc *sch)
skb->tstamp.tv64 = 0;
#endif
- sch->q.qlen--;
+ if (q->qdisc) {
+ int err = qdisc_enqueue(skb, q->qdisc);
+
+ if (unlikely(err != NET_XMIT_SUCCESS)) {
+ if (net_xmit_drop_count(err)) {
+ sch->qstats.drops++;
+ qdisc_tree_decrease_qlen(sch, 1);
+ }
+ }
+ goto tfifo_dequeue;
+ }
+deliver:
qdisc_unthrottled(sch);
qdisc_bstats_update(sch, skb);
return skb;
}
+ if (q->qdisc) {
+ skb = q->qdisc->ops->dequeue(q->qdisc);
+ if (skb)
+ goto deliver;
+ }
qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send);
}
+qdisc_dequeue:
+ if (q->qdisc) {
+ skb = q->qdisc->ops->dequeue(q->qdisc);
+ if (skb)
+ goto deliver;
+ }
return NULL;
}
@@ -499,8 +553,9 @@ static void netem_reset(struct Qdisc *sch)
{
struct netem_sched_data *q = qdisc_priv(sch);
- qdisc_reset(q->qdisc);
- sch->q.qlen = 0;
+ qdisc_reset_queue(sch);
+ if (q->qdisc)
+ qdisc_reset(q->qdisc);
qdisc_watchdog_cancel(&q->watchdog);
}
@@ -690,11 +745,7 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt)
if (ret < 0)
return ret;
- ret = fifo_set_limit(q->qdisc, qopt->limit);
- if (ret) {
- pr_info("netem: can't set fifo limit\n");
- return ret;
- }
+ sch->limit = qopt->limit;
q->latency = qopt->latency;
q->jitter = qopt->jitter;
@@ -735,88 +786,6 @@ static int netem_change(struct Qdisc *sch, struct nlattr *opt)
return ret;
}
-/*
- * Special case version of FIFO queue for use by netem.
- * It queues in order based on timestamps in skb's
- */
-struct fifo_sched_data {
- u32 limit;
- psched_time_t oldest;
-};
-
-static int tfifo_enqueue(struct sk_buff *nskb, struct Qdisc *sch)
-{
- struct fifo_sched_data *q = qdisc_priv(sch);
- struct sk_buff_head *list = &sch->q;
- psched_time_t tnext = netem_skb_cb(nskb)->time_to_send;
- struct sk_buff *skb;
-
- if (likely(skb_queue_len(list) < q->limit)) {
- /* Optimize for add at tail */
- if (likely(skb_queue_empty(list) || tnext >= q->oldest)) {
- q->oldest = tnext;
- return qdisc_enqueue_tail(nskb, sch);
- }
-
- skb_queue_reverse_walk(list, skb) {
- const struct netem_skb_cb *cb = netem_skb_cb(skb);
-
- if (tnext >= cb->time_to_send)
- break;
- }
-
- __skb_queue_after(list, skb, nskb);
-
- sch->qstats.backlog += qdisc_pkt_len(nskb);
-
- return NET_XMIT_SUCCESS;
- }
-
- return qdisc_reshape_fail(nskb, sch);
-}
-
-static int tfifo_init(struct Qdisc *sch, struct nlattr *opt)
-{
- struct fifo_sched_data *q = qdisc_priv(sch);
-
- if (opt) {
- struct tc_fifo_qopt *ctl = nla_data(opt);
- if (nla_len(opt) < sizeof(*ctl))
- return -EINVAL;
-
- q->limit = ctl->limit;
- } else
- q->limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
-
- q->oldest = PSCHED_PASTPERFECT;
- return 0;
-}
-
-static int tfifo_dump(struct Qdisc *sch, struct sk_buff *skb)
-{
- struct fifo_sched_data *q = qdisc_priv(sch);
- struct tc_fifo_qopt opt = { .limit = q->limit };
-
- NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
- return skb->len;
-
-nla_put_failure:
- return -1;
-}
-
-static struct Qdisc_ops tfifo_qdisc_ops __read_mostly = {
- .id = "tfifo",
- .priv_size = sizeof(struct fifo_sched_data),
- .enqueue = tfifo_enqueue,
- .dequeue = qdisc_dequeue_head,
- .peek = qdisc_peek_head,
- .drop = qdisc_queue_drop,
- .init = tfifo_init,
- .reset = qdisc_reset_queue,
- .change = tfifo_init,
- .dump = tfifo_dump,
-};
-
static int netem_init(struct Qdisc *sch, struct nlattr *opt)
{
struct netem_sched_data *q = qdisc_priv(sch);
@@ -828,18 +797,9 @@ static int netem_init(struct Qdisc *sch, struct nlattr *opt)
qdisc_watchdog_init(&q->watchdog, sch);
q->loss_model = CLG_RANDOM;
- q->qdisc = qdisc_create_dflt(sch->dev_queue, &tfifo_qdisc_ops,
- TC_H_MAKE(sch->handle, 1));
- if (!q->qdisc) {
- pr_notice("netem: qdisc create tfifo qdisc failed\n");
- return -ENOMEM;
- }
-
ret = netem_change(sch, opt);
- if (ret) {
+ if (ret)
pr_info("netem: change failed\n");
- qdisc_destroy(q->qdisc);
- }
return ret;
}
@@ -848,7 +808,8 @@ static void netem_destroy(struct Qdisc *sch)
struct netem_sched_data *q = qdisc_priv(sch);
qdisc_watchdog_cancel(&q->watchdog);
- qdisc_destroy(q->qdisc);
+ if (q->qdisc)
+ qdisc_destroy(q->qdisc);
dist_free(q->delay_dist);
}
@@ -952,7 +913,7 @@ static int netem_dump_class(struct Qdisc *sch, unsigned long cl,
{
struct netem_sched_data *q = qdisc_priv(sch);
- if (cl != 1) /* only one class */
+ if (cl != 1 || !q->qdisc) /* only one class */
return -ENOENT;
tcm->tcm_handle |= TC_H_MIN(1);
@@ -966,14 +927,13 @@ static int netem_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
{
struct netem_sched_data *q = qdisc_priv(sch);
- if (new == NULL)
- new = &noop_qdisc;
-
sch_tree_lock(sch);
*old = q->qdisc;
q->qdisc = new;
- qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
- qdisc_reset(*old);
+ if (*old) {
+ qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
+ qdisc_reset(*old);
+ }
sch_tree_unlock(sch);
return 0;