Commit Graph

57 Commits

Author SHA1 Message Date
Jarek Poplawski f30ab418a1 pkt_sched: Remove qdisc->ops->requeue() etc.
After implementing qdisc->ops->peek() and changing sch_netem into
classless qdisc there are no more qdisc->ops->requeue() users. This
patch removes this method with its wrappers (qdisc_requeue()), and
also unused qdisc->requeue structure. There are a few minor fixes of
warnings (htb_enqueue()) and comments btw.

The idea to kill ->requeue() and a similar patch were first developed
by David S. Miller.

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-13 22:56:30 -08:00
Jarek Poplawski 61c9eaf900 pkt_sched: Fix qdisc len in qdisc_peek_dequeued()
A packet dequeued and stored as gso_skb in qdisc_peek_dequeued() should
be seen as part of the queue for sch->q.qlen queries until it's really
dequeued with qdisc_dequeue_peeked(), so qlen needs additional updating
in these functions. (Updating qstats.backlog shouldn't matter here.)

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-05 16:02:34 -08:00
Jarek Poplawski 77be155cba pkt_sched: Add peek emulation for non-work-conserving qdiscs.
This patch adds qdisc_peek_dequeued() wrapper to emulate peek method
with qdisc->dequeue() and storing "peeked" skb in qdisc->gso_skb until
dequeuing. This is mainly for compatibility reasons not to break some
strange configs because peeking is expected for non-work-conserving
parent qdiscs to query work-conserving child qdiscs.

This implementation requires using qdisc_dequeue_peeked() wrapper
instead of directly calling qdisc->dequeue() for all qdiscs ever
querried with qdisc->ops->peek() or qdisc_peek_dequeued().

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-31 00:47:01 -07:00
Patrick McHardy 48a8f519e0 pkt_sched: Add ->peek() methods for fifo, prio and SFQ qdiscs.
From: Patrick McHardy <kaber@trash.net>

Just as a demonstration how easy adding a peek operation to the
work-conserving qdiscs actually is. It doesn't need to keep or change
any internal state in many cases thanks to the guarantee that the
packet will either be dequeued or, if another packet arrives, the
upper qdisc will immediately ->peek again to reevaluate the state.

(This is only slightly modified Patrick's patch.)

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-31 00:44:18 -07:00
Jarek Poplawski 90d841fd0a pkt_sched: sch_generic: Add Qdisc_ops peek() method.
Add Qdisc_ops peek() method in order to replace requeuing.

Based on ideas and patches of Herbert Xu, Patrick McHardy and
David S. Miller.

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-31 00:43:45 -07:00
Jarek Poplawski 554794de79 pkt_sched: Fix handling of gso skbs on requeuing
Jay Cliburn noticed and diagnosed a bug triggered in
dev_gso_skb_destructor() after last change from qdisc->gso_skb
to qdisc->requeue list. Since gso_segmented skbs can't be queued
to another list this patch brings back qdisc->gso_skb for them.

Reported-by: Jay Cliburn <jcliburn@gmail.com>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-10-06 09:54:39 -07:00
David S. Miller 242f8bfefe pkt_sched: Make qdisc->gso_skb a list.
The idea is that we can use this to get rid of
->requeue().

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-09-22 22:15:30 -07:00
Jarek Poplawski fe439dd09d pkt_sched: Fix sch_tree_lock()
Use new qdisc_root_sleeping_lock() instead of qdisc_root_lock() as
sch_tree_lock() because this lock could be used while dev is
deactivated, but we never need to use this with noop_qdisc as a root.

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-27 02:27:10 -07:00
Jarek Poplawski f6f9b93f16 pkt_sched: Fix gen_estimator locks
While passing a qdisc root lock to gen_new_estimator() and
gen_replace_estimator() dev could be deactivated or even before
grafting proper root qdisc as qdisc_sleeping (e.g. qdisc_create), so
using qdisc_root_lock() is not enough. This patch adds
qdisc_root_sleeping_lock() for this, plus additional checks, where
necessary.

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-27 02:25:17 -07:00
Jarek Poplawski 2540e0511e pkt_sched: Fix qdisc_watchdog() vs. dev_deactivate() race
dev_deactivate() can skip rescheduling of a qdisc by qdisc_watchdog()
or other timer calling netif_schedule() after dev_queue_deactivate().
We prevent this checking aliveness before scheduling the timer. Since
during deactivation the root qdisc is available only as qdisc_sleeping
additional accessor qdisc_root_sleeping() is created.

With feedback from Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-21 05:11:14 -07:00
David S. Miller 1e0d5a5747 pkt_sched: No longer destroy qdiscs from RCU.
We can now kill them synchronously with all of the
previous dev_deactivate() cures.

This makes netdev destruction and shutdown saner as
the qdiscs hold references to the device.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-17 22:31:26 -07:00
David S. Miller a9312ae893 pkt_sched: Add 'deactivated' state.
This new state lets dev_deactivate() mark a qdisc as having been
deactivated.

dev_queue_xmit() and ing_filter() check for this bit and do not
try to process the qdisc if the bit is set.

dev_deactivate() polls the qdisc after setting the bit, waiting
for both __QDISC_STATE_RUNNING and __QDISC_STATE_SCHED to clear.

This isn't perfect yet, but subsequent changesets will make it so.
This part is just one piece of the puzzle.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-17 21:51:03 -07:00
Jarek Poplawski c27f339af9 net_sched: Add qdisc __NET_XMIT_BYPASS flag
Patrick McHardy <kaber@trash.net> noticed that it would be nice to
handle NET_XMIT_BYPASS by NET_XMIT_SUCCESS with an internal qdisc flag
__NET_XMIT_BYPASS and to remove the mapping from dev_queue_xmit().

David Miller <davem@davemloft.net> spotted a serious bug in the first
version of this patch.

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-04 22:39:11 -07:00
Jarek Poplawski 378a2f090f net_sched: Add qdisc __NET_XMIT_STOLEN flag
Patrick McHardy <kaber@trash.net> noticed:
"The other problem that affects all qdiscs supporting actions is
TC_ACT_QUEUED/TC_ACT_STOLEN getting mapped to NET_XMIT_SUCCESS
even though the packet is not queued, corrupting upper qdiscs'
qlen counters."

and later explained:
"The reason why it translates it at all seems to be to not increase
the drops counter. Within a single qdisc this could be avoided by
other means easily, upper qdiscs would still increase the counter
when we return anything besides NET_XMIT_SUCCESS though.

This means we need a new NET_XMIT return value to indicate this to
the upper qdiscs. So I'd suggest to introduce NET_XMIT_STOLEN,
return that to upper qdiscs and translate it to NET_XMIT_SUCCESS
in dev_queue_xmit, similar to NET_XMIT_BYPASS."

David Miller <davem@davemloft.net> noticed:
"Maybe these NET_XMIT_* values being passed around should be a set of
bits. They could be composed of base meanings, combined with specific
attributes.

So you could say "NET_XMIT_DROP | __NET_XMIT_NO_DROP_COUNT"

The attributes get masked out by the top-level ->enqueue() caller,
such that the base meanings are the only thing that make their
way up into the stack. If it's only about communication within the
qdisc tree, let's simply code it that way."

This patch is trying to realize these ideas.

Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-04 22:31:03 -07:00
David S. Miller 7e43f1128d pkt_sched: Make sure RTNL is held in qdisc_root_lock().
It is the only legal environment in which this can be
used.

Add some commentary explaining the situation.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-08-02 23:27:37 -07:00
David S. Miller 3a682fbd73 pkt_sched: Fix build with NET_SCHED disabled.
The stab bits can't be referenced uniless the full
packet scheduler layer is enabled.

Reported by Stephen Rothwell.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-20 18:13:01 -07:00
Jussi Kivilinna 175f9c1bba net_sched: Add size table for qdiscs
Add size table functions for qdiscs and calculate packet size in
qdisc_enqueue().

Based on patch by Patrick McHardy
 http://marc.info/?l=linux-netdev&m=115201979221729&w=2

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-20 00:08:47 -07:00
Jussi Kivilinna 0abf77e55a net_sched: Add accessor function for packet length for qdiscs
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-20 00:08:27 -07:00
Jussi Kivilinna 5f86173bdf net_sched: Add qdisc_enqueue wrapper
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-20 00:08:04 -07:00
David S. Miller 72b25a913e pkt_sched: Get rid of u32_list.
The u32_list is just an indirect way of maintaining a reference
to a U32 node on a per-qdisc basis.

Just add an explicit node pointer for u32 to struct Qdisc an do
away with this global list.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-18 20:54:17 -07:00
David S. Miller 93245dd6d3 pkt_sched: Don't used locked skb_queue_purge() in __qdisc_reset_queue()
We have to have exclusive access to the given qdisc anyways, so
doing even more locking is superfluous.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:32 -07:00
David S. Miller 8387400092 pkt_sched: Kill netdev_queue lock.
We can simply use the qdisc->q.lock for all of the
qdisc tree synchronization.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:30 -07:00
David S. Miller c7e4f3bbb4 pkt_sched: Kill qdisc_lock_tree and qdisc_unlock_tree.
No longer used.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:29 -07:00
David S. Miller 78a5b30b73 pkt_sched: Rework {sch,tbf}_tree_lock().
Make sch_tree_lock() lock the qdisc's root.  All of the
users hold the RTNL semaphore and the root qdisc is not
changing.

Implement tbf_tree_{lock,unlock}() simply in terms of
sch_tree_{lock,unlock}().

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:28 -07:00
David S. Miller 37437bb2e1 pkt_sched: Schedule qdiscs instead of netdev_queue.
When we have shared qdiscs, packets come out of the qdiscs
for multiple transmit queues.

Therefore it doesn't make any sense to schedule the transmit
queue when logically we cannot know ahead of time the TX
queue of the SKB that the qdisc->dequeue() will give us.

Just for sanity I added a BUG check to make sure we never
get into a state where the noop_qdisc is scheduled.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:20 -07:00
David S. Miller 7698b4fcab pkt_sched: Add and use qdisc_root() and qdisc_root_lock().
When code wants to lock the qdisc tree state, the logic
operation it's doing is locking the top-level qdisc that
sits of the root of the netdev_queue.

Add qdisc_root_lock() to represent this and convert the
easiest cases.

In order for this to work out in all cases, we have to
hook up the noop_qdisc to a dummy netdev_queue.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:19 -07:00
David S. Miller e2627c8c22 pkt_sched: Make QDISC_RUNNING a qdisc state.
Currently it is associated with a netdev_queue, but when we have
qdisc sharing that no longer makes any sense.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:18 -07:00
David S. Miller d3b753db7c pkt_sched: Move gso_skb into Qdisc.
We liberate any dangling gso_skb during qdisc destruction.

It really only matters for the root qdisc.  But when qdiscs
can be shared by multiple netdev_queue objects, we can't
have the gso_skb in the netdev_queue any more.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:18 -07:00
David S. Miller e8a0464cc9 netdev: Allocate multiple queues for TX.
alloc_netdev_mq() now allocates an array of netdev_queue
structures for TX, based upon the queue_count argument.

Furthermore, all accesses to the TX queues are now vectored
through the netdev_get_tx_queue() and netdev_for_each_tx_queue()
interfaces.  This makes it easy to grep the tree for all
things that want to get to a TX queue of a net device.

Problem spots which are not really multiqueue aware yet, and
only work with one queue, can easily be spotted by grepping
for all netdev_get_tx_queue() calls that pass in a zero index.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-17 19:21:00 -07:00
David S. Miller 052979499c pkt_sched: Add qdisc_tx_is_noop() helper and use in IPV6.
This indicates if the NOOP scheduler is what is active for TX on a
given device.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-08 23:01:27 -07:00
David S. Miller 6fa9864b53 net: Clean up explicit ->tx_queue references in link watch.
First, we add a qdisc_tx_changing() helper which returns true if the
qdisc attachment is in transition.

Second, we remove an assertion warning which is of limited value and
is hard to express precisely in a multiqueue environment.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-08 23:01:06 -07:00
David S. Miller 3e745dd695 pkt_sched: Add qdisc_all_tx_empty()
This is a helper function, currently used by IRDA.

This is being added so that we can contain and isolate as many
explicit ->tx_queue references in the tree as possible.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-08 23:00:25 -07:00
David S. Miller 5aa709954a pkt_sched: Add qdisc_reset_all_tx().
Isolate callers that want to simply reset all the TX qdiscs from the
details of TX queues.

Use this in the ISDN code.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-08 22:59:10 -07:00
David S. Miller 68dfb42798 pkt_sched: Kill stats_lock member of struct Qdisc.
It is always equal to qdisc->dev_queue->lock

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-08 22:57:31 -07:00
David S. Miller 5ce2d488fe pkt_sched: Remove 'dev' member of struct Qdisc.
It can be obtained via the netdev_queue.  So create a helper routine,
qdisc_dev(), to make the transformations nicer looking.

Now, qdisc_alloc() now no longer needs a net_device pointer argument.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-08 17:06:30 -07:00
David S. Miller bb949fbd18 netdev: Create netdev_queue abstraction.
A netdev_queue is an entity managed by a qdisc.

Currently there is one RX and one TX queue, and a netdev_queue merely
contains a backpointer to the net_device.

The Qdisc struct is augmented with a netdev_queue pointer as well.

Eventually the 'dev' Qdisc member will go away and we will have the
resulting hierarchy:

	net_device --> netdev_queue --> Qdisc

Also, qdisc_alloc() and qdisc_create_dflt() now take a netdev_queue
pointer argument.

Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-08 16:55:56 -07:00
Patrick McHardy 6fe1c7a555 net-sched: add dynamically sized qdisc class hash helpers
Currently all qdiscs which allow to create classes uses a fixed sized hash
table with size 16 to hash the classes. This causes a large bottleneck
when using thousands of classes and unbound filters.

Add helpers for dynamically sized class hashes to fix this. The following
patches will convert the qdiscs to use them.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-05 23:21:31 -07:00
Patrick McHardy ff31ab56c0 net-sched: change tcf_destroy_chain() to clear start of filter list
Pass double tcf_proto pointers to tcf_destroy_chain() to make it
clear the start of the filter list for more consistency.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-07-01 19:52:38 -07:00
Patrick McHardy add93b610a [NET_SCHED]: Convert classifiers from rtnetlink to new netlink API
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 15:11:11 -08:00
Patrick McHardy 1e90474c37 [NET_SCHED]: Convert packet schedulers from rtnetlink to new netlink API
Convert packet schedulers to use the netlink API. Unfortunately a gradual
conversion is not possible without breaking compilation in the middle or
adding lots of casts, so this patch converts them all in one step. The
patch has been mostly generated automatically with some minor edits to
at least allow seperate conversion of classifiers and actions.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 15:11:10 -08:00
Eric Dumazet 20fea08b5f [NET]: Move Qdisc_class_ops and Qdisc_ops in appropriate sections.
Qdisc_class_ops are const, and Qdisc_ops are mostly read.

Using "const" and "__read_mostly" qualifiers helps to reduce false
sharing.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28 14:53:58 -08:00
Paul Moore 02f1c89d6e [NET]: Clone the sk_buff 'iif' field in __skb_clone()
Both NetLabel and SELinux (other LSMs may grow to use it as well) rely
on the 'iif' field to determine the receiving network interface of
inbound packets.  Unfortunately, at present this field is not
preserved across a skb clone operation which can lead to garbage
values if the cloned skb is sent back through the network stack.  This
patch corrects this problem by properly copying the 'iif' field in
__skb_clone() and removing the 'iif' field assignment from
skb_act_clone() since it is no longer needed.

Also, while we are here, put the assignments in the same order as the
offsets to reduce cacheline bounces.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-08 23:30:17 -08:00
Jamal Hadi Salim 12da81d11a [NET_CLS_ACT]: Introduce skb_act_clone
Reworked skb_clone looks uglier with the single ifdef
CONFIG_NET_CLS_ACT This patch introduces skb_act_clone which will
replace skb_clone in tc actions

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-26 02:47:23 -07:00
Jesper Dangaard Brouer e08b09983f [NET_SCHED]: Making rate table lookups more flexible.
This is done in order to, add support to changing the rate table to
use the upper-boundry L2T (length to time) value. Currently we use the
lower-boundry, which result in under-estimating the actual bandwidth
usage.

Extend the tc_ratespec struct, with two parameters: 1) "cell_align"
that allow adjusting the alignment of the rate table. 2) "overhead"
that allow adding a packet overhead before the lookup.

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:49:20 -07:00
Jesper Dangaard Brouer e9bef55d3d [NET_SCHED]: Cleanup L2T macros and handle oversized packets
Change L2T (length to time) macros, in all rate based schedulers, to
call a common function qdisc_l2t() that does the rate table lookup.
This function handles if the packet size lookup is larger than the
rate table, which often occurs with TSO enabled.

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Acked-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:49:20 -07:00
Patrick McHardy c3bc7cff8f [NET_SCHED]: Kill CONFIG_NET_CLS_POLICE
The NET_CLS_ACT option is now a full replacement for NET_CLS_POLICE,
remove the old code. The config option will be kept around to select
the equivalent NET_CLS_ACT options for a short time to allow easier
upgrades.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-15 00:03:05 -07:00
Patrick McHardy 73ca4918fb [NET_SCHED]: act_api: qdisc internal reclassify support
The behaviour of NET_CLS_POLICE for TC_POLICE_RECLASSIFY was to return
it to the qdisc, which could handle it internally or ignore it. With
NET_CLS_ACT however, tc_classify starts over at the first classifier
and never returns it to the qdisc. This makes it impossible to support
qdisc-internal reclassification, which in turn makes it impossible to
remove the old NET_CLS_POLICE code without breaking compatibility since
we have two qdiscs (CBQ and ATM) that support this.

This patch adds a tc_classify_compat function that handles
reclassification the old way and changes CBQ and ATM to use it.

This again is of course not fully backwards compatible with the previous
NET_CLS_ACT behaviour. Unfortunately there is no way to fully maintain
compatibility *and* support qdisc internal reclassification with
NET_CLS_ACT, but this seems like the better choice over keeping the two
incompatible options around forever.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-15 00:02:31 -07:00
Patrick McHardy a48b5a6144 [NET_SCHED]: Unline tcf_destroy
Uninline tcf_destroy and add a helper function to destroy an entire filter
chain.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:27:56 -07:00
Thomas Graf be577ddc2b [PKT_SCHED] qdisc: Use rtnl registration interface
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-04-25 22:27:09 -07:00
Patrick McHardy 43effa1e57 [NET_SCHED]: Fix endless loops caused by inaccurate qlen counters (part 1)
There are multiple problems related to qlen adjustment that can lead
to an upper qdisc getting out of sync with the real number of packets
queued, leading to endless dequeueing attempts by the upper layer code.

All qdiscs must maintain an accurate q.qlen counter. There are basically
two groups of operations affecting the qlen: operations that propagate
down the tree (enqueue, dequeue, requeue, drop, reset) beginning at the
root qdisc and operations only affecting a subtree or single qdisc
(change, graft, delete class). Since qlen changes during operations from
the second group don't propagate to ancestor qdiscs, their qlen values
become desynchronized.

This patch adds a function to propagate qlen changes up the qdisc tree,
optionally calling a callback function to perform qdisc-internal
maintenance when the child qdisc becomes empty. The follow-up patches
will convert all qdiscs to use this function where necessary.

Noticed by Timo Steinbach <tsteinbach@astaro.com>.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 21:31:42 -08:00