[NET_SCHED] BUG in qdisc TBF (token bucket filter)

* [NET_SCHED] BUG in qdisc TBF (token bucket filter)
@ 2004-03-03 12:31 Jesper Dangaard Brouer
  2004-03-05  6:47 ` Dmitry Torokhov
  2004-04-06 14:17 ` [NET_SCHED] BUG in qdisc TBF (token bucket filter) Jesper Dangaard Brouer
  0 siblings, 2 replies; 9+ messages in thread
From: Jesper Dangaard Brouer @ 2004-03-03 12:31 UTC (permalink / raw)
  To: linux-kernel

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BUG in qdisc TBF (token bucket filter).

 Problem in    : Kernel 2.4.22 (and newer, tested till 2.4.25-rc2)
 Problem NOT in: kernel 2.4.21 (and older)

Problem:
--------
 After I add an tbf qdisc to an htb class, then the htb class disappear
 from the output-listing "tc -s class ls dev ethX".

tc-versions:
 I have tested with different version of the "tc" utility.
 And different versions of the htb patch.

 "tc utility, iproute2-ss010824" (debian's iproute)
 "tc utility, iproute2-ss020116" (with htb3.6-020525)

I've not tested if the tfb qdisc and htb class still works, but only
that the output-listing is wrong.  (I'm running 2.4.21 on my
router/firewall to be on the safe side.)

Howto reproduce:
----------------
 #Removing previous 'root' handle/classification
 /sbin/tc qdisc del dev eth0 root
 #
 /sbin/tc qdisc add dev eth0 root handle 1: htb default 10
 #
 /sbin/tc class add dev eth0 parent 1: classid 1:10 htb rate 500kbit

 # output-listing of class'es
 tc -s class ls dev eth0
 #
 # output:
 class htb 1:10 root prio 0 rate 500Kbit ceil 500Kbit burst 2239b cburst 2239b
  Sent 812 bytes 6 pkts (dropped 0, overlimits 0)
  lended: 6 borrowed: 0 giants: 0
  tokens: 27239 ctokens: 27239

 # the tbf line
 /sbin/tc qdisc add dev eth0 parent 1:10 handle 4210: tbf rate 500kbit \
          latency 50ms burst 2239b

 # output-listing of class'es
 tc -s class ls dev eth0
 #
 # output:
 <NOTHING>

The output-listing of class'es returns, if I remove the tbf qdisc again.

Diff between file /net/sched/sch_tbf.c in kernel 2.4.21 and 2.4.22 is
attached.


Hilsen
  Jesper Brouer

--
-------------------------------------------------------------------
System Administrator
Dept. of Computer Science, University of Copenhagen
E-mail: hawk@diku.dk, Direct Tel.: 353 21464
-------------------------------------------------------------------

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--- linux-2.4.21/net/sched/sch_tbf.c	Fri Dec 21 18:42:06 2001
+++ linux-2.4.22/net/sched/sch_tbf.c	Mon Aug 25 13:44:44 2003
@@ -7,6 +7,8 @@
  *		2 of the License, or (at your option) any later version.
  *
  * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
+ *		Dmitry Torokhov <dtor@mail.ru> - allow attaching inner qdiscs -
+ *						 original idea by Martin Devera
  *
  */
 
@@ -123,62 +125,63 @@
 	long	ptokens;		/* Current number of P tokens */
 	psched_time_t	t_c;		/* Time check-point */
 	struct timer_list wd_timer;	/* Watchdog timer */
+	struct Qdisc	*qdisc;		/* Inner qdisc, default - bfifo queue */
 };
 
 #define L2T(q,L)   ((q)->R_tab->data[(L)>>(q)->R_tab->rate.cell_log])
 #define L2T_P(q,L) ((q)->P_tab->data[(L)>>(q)->P_tab->rate.cell_log])
 
-static int
-tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch)
+static int tbf_enqueue(struct sk_buff *skb, struct Qdisc* sch)
 {
 	struct tbf_sched_data *q = (struct tbf_sched_data *)sch->data;
+	int ret;
 
-	if (skb->len > q->max_size)
-		goto drop;
-	__skb_queue_tail(&sch->q, skb);
-	if ((sch->stats.backlog += skb->len) <= q->limit) {
-		sch->stats.bytes += skb->len;
-		sch->stats.packets++;
-		return 0;
-	}
-
-	/* Drop action: undo the things that we just did,
-	 * i.e. make tail drop
-	 */
-
-	__skb_unlink(skb, &sch->q);
-	sch->stats.backlog -= skb->len;
-
-drop:
-	sch->stats.drops++;
+	if (skb->len > q->max_size || sch->stats.backlog + skb->len > q->limit) {
+		sch->stats.drops++;
 #ifdef CONFIG_NET_CLS_POLICE
-	if (sch->reshape_fail==NULL || sch->reshape_fail(skb, sch))
+		if (sch->reshape_fail == NULL || sch->reshape_fail(skb, sch))
 #endif
-		kfree_skb(skb);
-	return NET_XMIT_DROP;
-}
-
-static int
-tbf_requeue(struct sk_buff *skb, struct Qdisc* sch)
-{
-	__skb_queue_head(&sch->q, skb);
+			kfree_skb(skb);
+	
+		return NET_XMIT_DROP;
+	}
+	
+	if ((ret = q->qdisc->enqueue(skb, q->qdisc)) != 0) {
+		sch->stats.drops++;
+		return ret;
+	}	
+	
+	sch->q.qlen++;
 	sch->stats.backlog += skb->len;
+	sch->stats.bytes += skb->len;
+	sch->stats.packets++;
 	return 0;
 }
 
-static int
-tbf_drop(struct Qdisc* sch)
+static int tbf_requeue(struct sk_buff *skb, struct Qdisc* sch)
 {
-	struct sk_buff *skb;
+	struct tbf_sched_data *q = (struct tbf_sched_data *)sch->data;
+	int ret;
+	
+	if ((ret = q->qdisc->ops->requeue(skb, q->qdisc)) == 0) {
+		sch->q.qlen++; 
+		sch->stats.backlog += skb->len;
+	}
+	
+	return ret;
+}
 
-	skb = __skb_dequeue_tail(&sch->q);
-	if (skb) {
-		sch->stats.backlog -= skb->len;
+static unsigned int tbf_drop(struct Qdisc* sch)
+{
+	struct tbf_sched_data *q = (struct tbf_sched_data *)sch->data;
+	unsigned int len;
+	
+	if ((len = q->qdisc->ops->drop(q->qdisc)) != 0) {
+		sch->q.qlen--;
+		sch->stats.backlog -= len;
 		sch->stats.drops++;
-		kfree_skb(skb);
-		return 1;
 	}
-	return 0;
+	return len;
 }
 
 static void tbf_watchdog(unsigned long arg)
@@ -189,19 +192,19 @@
 	netif_schedule(sch->dev);
 }
 
-static struct sk_buff *
-tbf_dequeue(struct Qdisc* sch)
+static struct sk_buff *tbf_dequeue(struct Qdisc* sch)
 {
 	struct tbf_sched_data *q = (struct tbf_sched_data *)sch->data;
 	struct sk_buff *skb;
 	
-	skb = __skb_dequeue(&sch->q);
+	skb = q->qdisc->dequeue(q->qdisc);
 
 	if (skb) {
 		psched_time_t now;
 		long toks;
 		long ptoks = 0;
-
+		unsigned int len = skb->len;
+		
 		PSCHED_GET_TIME(now);
 
 		toks = PSCHED_TDIFF_SAFE(now, q->t_c, q->buffer, 0);
@@ -210,18 +213,19 @@
 			ptoks = toks + q->ptokens;
 			if (ptoks > (long)q->mtu)
 				ptoks = q->mtu;
-			ptoks -= L2T_P(q, skb->len);
+			ptoks -= L2T_P(q, len);
 		}
 		toks += q->tokens;
 		if (toks > (long)q->buffer)
 			toks = q->buffer;
-		toks -= L2T(q, skb->len);
+		toks -= L2T(q, len);
 
 		if ((toks|ptoks) >= 0) {
 			q->t_c = now;
 			q->tokens = toks;
 			q->ptokens = ptoks;
-			sch->stats.backlog -= skb->len;
+			sch->stats.backlog -= len;
+			sch->q.qlen--;
 			sch->flags &= ~TCQ_F_THROTTLED;
 			return skb;
 		}
@@ -245,20 +249,25 @@
 		   This is the main idea of all FQ algorithms
 		   (cf. CSZ, HPFQ, HFSC)
 		 */
-		__skb_queue_head(&sch->q, skb);
-
+		
+		if (q->qdisc->ops->requeue(skb, q->qdisc) != NET_XMIT_SUCCESS) {
+			/* When requeue fails skb is dropped */ 
+			sch->q.qlen--;
+			sch->stats.backlog -= len;
+			sch->stats.drops++;
+		}	
+		
 		sch->flags |= TCQ_F_THROTTLED;
 		sch->stats.overlimits++;
 	}
 	return NULL;
 }
 
-
-static void
-tbf_reset(struct Qdisc* sch)
+static void tbf_reset(struct Qdisc* sch)
 {
 	struct tbf_sched_data *q = (struct tbf_sched_data *)sch->data;
 
+	qdisc_reset(q->qdisc);
 	skb_queue_purge(&sch->q);
 	sch->stats.backlog = 0;
 	PSCHED_GET_TIME(q->t_c);
@@ -268,6 +277,31 @@
 	del_timer(&q->wd_timer);
 }
 
+static struct Qdisc *tbf_create_dflt_qdisc(struct net_device *dev, u32 limit)
+{
+	struct Qdisc *q = qdisc_create_dflt(dev, &bfifo_qdisc_ops);
+        struct rtattr *rta;
+	int ret;
+	
+	if (q) {
+		rta = kmalloc(RTA_LENGTH(sizeof(struct tc_fifo_qopt)), GFP_KERNEL);
+		if (rta) {
+			rta->rta_type = RTM_NEWQDISC;
+			rta->rta_len = RTA_LENGTH(sizeof(struct tc_fifo_qopt)); 
+			((struct tc_fifo_qopt *)RTA_DATA(rta))->limit = limit;
+			
+			ret = q->ops->change(q, rta);
+			kfree(rta);
+			
+			if (ret == 0)
+				return q;
+		}
+		qdisc_destroy(q);
+	}
+
+	return NULL;	
+}
+
 static int tbf_change(struct Qdisc* sch, struct rtattr *opt)
 {
 	int err = -EINVAL;
@@ -276,6 +310,7 @@
 	struct tc_tbf_qopt *qopt;
 	struct qdisc_rate_table *rtab = NULL;
 	struct qdisc_rate_table *ptab = NULL;
+	struct Qdisc *child = NULL;
 	int max_size,n;
 
 	if (rtattr_parse(tb, TCA_TBF_PTAB, RTA_DATA(opt), RTA_PAYLOAD(opt)) ||
@@ -308,8 +343,14 @@
 	}
 	if (max_size < 0)
 		goto done;
+	
+	if (q->qdisc == &noop_qdisc) {
+		if ((child = tbf_create_dflt_qdisc(sch->dev, qopt->limit)) == NULL)
+			goto done;
+	}
 
 	sch_tree_lock(sch);
+	if (child) q->qdisc = child;
 	q->limit = qopt->limit;
 	q->mtu = qopt->mtu;
 	q->max_size = max_size;
@@ -342,6 +383,8 @@
 	init_timer(&q->wd_timer);
 	q->wd_timer.function = tbf_watchdog;
 	q->wd_timer.data = (unsigned long)sch;
+
+	q->qdisc = &noop_qdisc;
 	
 	if ((err = tbf_change(sch, opt)) != 0) {
 		MOD_DEC_USE_COUNT;
@@ -359,6 +402,9 @@
 		qdisc_put_rtab(q->P_tab);
 	if (q->R_tab)
 		qdisc_put_rtab(q->R_tab);
+	
+	qdisc_destroy(q->qdisc);
+	q->qdisc = &noop_qdisc;
 
 	MOD_DEC_USE_COUNT;
 }
@@ -391,10 +437,93 @@
 	return -1;
 }
 
+static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
+	       		  struct sk_buff *skb, struct tcmsg *tcm)
+{
+	struct tbf_sched_data *q = (struct tbf_sched_data*)sch->data;
+
+	if (cl != 1) 	/* only one class */ 
+		return -ENOENT;
+    
+	tcm->tcm_parent = TC_H_ROOT;
+	tcm->tcm_handle = 1;
+	tcm->tcm_info = q->qdisc->handle;
+
+	return 0;
+}
+
+static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+		     struct Qdisc **old)
+{
+	struct tbf_sched_data *q = (struct tbf_sched_data *)sch->data;
+
+	if (new == NULL)
+		new = &noop_qdisc;
+
+	sch_tree_lock(sch);	
+	*old = xchg(&q->qdisc, new);
+	qdisc_reset(*old);
+	sch_tree_unlock(sch);
+	
+	return 0;
+}
+
+static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
+{
+	struct tbf_sched_data *q = (struct tbf_sched_data *)sch->data;
+	return q->qdisc;
+}
+
+static unsigned long tbf_get(struct Qdisc *sch, u32 classid)
+{
+	return 1;
+}
+
+static void tbf_put(struct Qdisc *sch, unsigned long arg)
+{
+}
+
+static int tbf_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 
+			struct rtattr **tca, unsigned long *arg)
+{
+	return -ENOSYS;
+}
+
+static int tbf_delete(struct Qdisc *sch, unsigned long arg)
+{
+	return -ENOSYS;
+}
+
+static void tbf_walk(struct Qdisc *sch, struct qdisc_walker *walker)
+{
+	struct tbf_sched_data *q = (struct tbf_sched_data *)sch->data;
+
+	if (!walker->stop) {
+		if (walker->count >= walker->skip) 
+			if (walker->fn(sch, (unsigned long)q, walker) < 0) { 
+				walker->stop = 1;
+				return;
+			}
+		walker->count++;
+	}
+}
+
+static struct Qdisc_class_ops tbf_class_ops =
+{
+	.graft		= 	tbf_graft,
+	.leaf		=	tbf_leaf,
+	.get		=	tbf_get,
+	.put		=	tbf_put,
+	.change		=	tbf_change_class,
+	.delete		=	tbf_delete,
+	.walk		=	tbf_walk,
+	.dump		=	tbf_dump_class,
+};
+
 struct Qdisc_ops tbf_qdisc_ops =
 {
 	NULL,
-	NULL,
+	&tbf_class_ops,
 	"tbf",
 	sizeof(struct tbf_sched_data),
 

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