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net: sched: avoid duplicates in qdisc dump 

tc_dump_qdisc() performs dumping of the per-device qdiscs in two phases;
first, the "standard" dev->qdisc is being dumped. Second, if there is/are
ingress queue(s), they are being dumped as well.

After conversion of netdevice's qdisc linked-list into hashtable, these
two sets are not in two disjunctive sets/lists any more, but are both
"reachable" directly from netdevice's hashtable. As a consequence, the
"full-depth" dump of the ingress qdiscs results in immediately hitting the
netdevice hashtable again, and duplicating the dump that has already been
performed for dev->qdisc.
What in fact needs to be dumped in case of ingress queue is "just" the
top-level ingress qdisc, as everything else has been dumped already.

Fix this by extending tc_dump_qdisc_root() in a way that it can be instructed
whether it should (while performing the "full" per-netdev qdisc dump) perform
the whole recursion, or just dump "additional" top-level (ingress) qdiscs
without performing any kind of recursion.

This fixes duplicate dumps such as

	qdisc mq 0: root
	qdisc pfifo_fast 0: parent :4 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
	qdisc pfifo_fast 0: parent :3 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
	qdisc pfifo_fast 0: parent :2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
	qdisc pfifo_fast 0: parent :1 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
	qdisc clsact ffff: parent ffff:fff1
	qdisc pfifo_fast 0: parent :4 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
	qdisc pfifo_fast 0: parent :3 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
	qdisc pfifo_fast 0: parent :2 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1
	qdisc pfifo_fast 0: parent :1 bands 3 priomap  1 2 2 2 1 2 0 0 1 1 1 1 1 1 1 1

Fixes: 59cc1f61f ("net: sched: convert qdisc linked list to hashtable")
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jiri Kosina 2016-08-16 23:53:46 +02:00 committed by David S. Miller
parent 69012ae425
commit ea32746953
1 changed files with 10 additions and 4 deletions
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14
net/sched/sch_api.c
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@ -1435,7 +1435,7 @@ err_out:
static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
struct netlink_callback *cb,
int *q_idx_p, int s_q_idx)
int *q_idx_p, int s_q_idx, bool recur)
{
int ret = 0, q_idx = *q_idx_p;
struct Qdisc *q;
@ -1455,7 +1455,13 @@ static int tc_dump_qdisc_root(struct Qdisc *root, struct sk_buff *skb,
q_idx++;
}
if (!qdisc_dev(root))
/* If dumping singletons, there is no qdisc_dev(root) and the singleton
* itself has already been dumped.
*
* If we've already dumped the top-level (ingress) qdisc above and the global
* qdisc hashtable, we don't want to hit it again
*/
if (!qdisc_dev(root) || !recur)
goto out;
hash_for_each(qdisc_dev(root)->qdisc_hash, b, q, hash) {
@ -1499,13 +1505,13 @@ static int tc_dump_qdisc(struct sk_buff *skb, struct netlink_callback *cb)
s_q_idx = 0;
q_idx = 0;
if (tc_dump_qdisc_root(dev->qdisc, skb, cb, &q_idx, s_q_idx) < 0)
if (tc_dump_qdisc_root(dev->qdisc, skb, cb, &q_idx, s_q_idx, true) < 0)
goto done;
dev_queue = dev_ingress_queue(dev);
if (dev_queue &&
tc_dump_qdisc_root(dev_queue->qdisc_sleeping, skb, cb,
&q_idx, s_q_idx) < 0)
&q_idx, s_q_idx, false) < 0)
goto done;
cont: