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authorPatrick McHardy <kaber@trash.net>2006-11-29 20:35:48 -0500
committerDavid S. Miller <davem@sunset.davemloft.net>2006-12-03 00:31:42 -0500
commit43effa1e57fc4635e0301b27d78f9d83afe78974 (patch)
treedc4a22fdaad074a547438050fb428f32b1cb2ded /include/net
parent9f9afec48221fe4a19f84a9341f5b304bf7d7783 (diff)
[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>
Diffstat (limited to 'include/net')
-rw-r--r--include/net/sch_generic.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index b37572db12a..82086392735 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -60,6 +60,7 @@ struct Qdisc_class_ops
60 int (*graft)(struct Qdisc *, unsigned long cl, 60 int (*graft)(struct Qdisc *, unsigned long cl,
61 struct Qdisc *, struct Qdisc **); 61 struct Qdisc *, struct Qdisc **);
62 struct Qdisc * (*leaf)(struct Qdisc *, unsigned long cl); 62 struct Qdisc * (*leaf)(struct Qdisc *, unsigned long cl);
63 void (*qlen_notify)(struct Qdisc *, unsigned long);
63 64
64 /* Class manipulation routines */ 65 /* Class manipulation routines */
65 unsigned long (*get)(struct Qdisc *, u32 classid); 66 unsigned long (*get)(struct Qdisc *, u32 classid);
@@ -172,6 +173,7 @@ extern void dev_activate(struct net_device *dev);
172extern void dev_deactivate(struct net_device *dev); 173extern void dev_deactivate(struct net_device *dev);
173extern void qdisc_reset(struct Qdisc *qdisc); 174extern void qdisc_reset(struct Qdisc *qdisc);
174extern void qdisc_destroy(struct Qdisc *qdisc); 175extern void qdisc_destroy(struct Qdisc *qdisc);
176extern void qdisc_tree_decrease_qlen(struct Qdisc *qdisc, unsigned int n);
175extern struct Qdisc *qdisc_alloc(struct net_device *dev, struct Qdisc_ops *ops); 177extern struct Qdisc *qdisc_alloc(struct net_device *dev, struct Qdisc_ops *ops);
176extern struct Qdisc *qdisc_create_dflt(struct net_device *dev, 178extern struct Qdisc *qdisc_create_dflt(struct net_device *dev,
177 struct Qdisc_ops *ops, u32 parentid); 179 struct Qdisc_ops *ops, u32 parentid);