![Eric Dumazet](/assets/img/avatar_default.png)
qdisc_tree_decrease_qlen() suffers from two problems on multiqueue devices. One problem is that it updates sch->q.qlen and sch->qstats.drops on the mq/mqprio root qdisc, while it should not : Daniele reported underflows errors : [ 681.774821] PAX: sch->q.qlen: 0 n: 1 [ 681.774825] PAX: size overflow detected in function qdisc_tree_decrease_qlen net/sched/sch_api.c:769 cicus.693_49 min, count: 72, decl: qlen; num: 0; context: sk_buff_head; [ 681.774954] CPU: 2 PID: 19 Comm: ksoftirqd/2 Tainted: G O 4.2.6.201511282239-1-grsec #1 [ 681.774955] Hardware name: ASUSTeK COMPUTER INC. X302LJ/X302LJ, BIOS X302LJ.202 03/05/2015 [ 681.774956] ffffffffa9a04863 0000000000000000 0000000000000000 ffffffffa990ff7c [ 681.774959] ffffc90000d3bc38 ffffffffa95d2810 0000000000000007 ffffffffa991002b [ 681.774960] ffffc90000d3bc68 ffffffffa91a44f4 0000000000000001 0000000000000001 [ 681.774962] Call Trace: [ 681.774967] [<ffffffffa95d2810>] dump_stack+0x4c/0x7f [ 681.774970] [<ffffffffa91a44f4>] report_size_overflow+0x34/0x50 [ 681.774972] [<ffffffffa94d17e2>] qdisc_tree_decrease_qlen+0x152/0x160 [ 681.774976] [<ffffffffc02694b1>] fq_codel_dequeue+0x7b1/0x820 [sch_fq_codel] [ 681.774978] [<ffffffffc02680a0>] ? qdisc_peek_dequeued+0xa0/0xa0 [sch_fq_codel] [ 681.774980] [<ffffffffa94cd92d>] __qdisc_run+0x4d/0x1d0 [ 681.774983] [<ffffffffa949b2b2>] net_tx_action+0xc2/0x160 [ 681.774985] [<ffffffffa90664c1>] __do_softirq+0xf1/0x200 [ 681.774987] [<ffffffffa90665ee>] run_ksoftirqd+0x1e/0x30 [ 681.774989] [<ffffffffa90896b0>] smpboot_thread_fn+0x150/0x260 [ 681.774991] [<ffffffffa9089560>] ? sort_range+0x40/0x40 [ 681.774992] [<ffffffffa9085fe4>] kthread+0xe4/0x100 [ 681.774994] [<ffffffffa9085f00>] ? kthread_worker_fn+0x170/0x170 [ 681.774995] [<ffffffffa95d8d1e>] ret_from_fork+0x3e/0x70 mq/mqprio have their own ways to report qlen/drops by folding stats on all their queues, with appropriate locking. A second problem is that qdisc_tree_decrease_qlen() calls qdisc_lookup() without proper locking : concurrent qdisc updates could corrupt the list that qdisc_match_from_root() parses to find a qdisc given its handle. Fix first problem adding a TCQ_F_NOPARENT qdisc flag that qdisc_tree_decrease_qlen() can use to abort its tree traversal, as soon as it meets a mq/mqprio qdisc children. Second problem can be fixed by RCU protection. Qdisc are already freed after RCU grace period, so qdisc_list_add() and qdisc_list_del() simply have to use appropriate rcu list variants. A future patch will add a per struct netdev_queue list anchor, so that qdisc_tree_decrease_qlen() can have more efficient lookups. Reported-by: Daniele Fucini <dfucini@gmail.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Cong Wang <cwang@twopensource.com> Cc: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
429 lines
10 KiB
C
429 lines
10 KiB
C
/*
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* net/sched/sch_mqprio.c
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*
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* Copyright (c) 2010 John Fastabend <john.r.fastabend@intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/skbuff.h>
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#include <linux/module.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <net/sch_generic.h>
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struct mqprio_sched {
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struct Qdisc **qdiscs;
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int hw_owned;
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};
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static void mqprio_destroy(struct Qdisc *sch)
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{
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struct net_device *dev = qdisc_dev(sch);
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struct mqprio_sched *priv = qdisc_priv(sch);
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unsigned int ntx;
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if (priv->qdiscs) {
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for (ntx = 0;
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ntx < dev->num_tx_queues && priv->qdiscs[ntx];
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ntx++)
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qdisc_destroy(priv->qdiscs[ntx]);
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kfree(priv->qdiscs);
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}
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if (priv->hw_owned && dev->netdev_ops->ndo_setup_tc)
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dev->netdev_ops->ndo_setup_tc(dev, 0);
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else
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netdev_set_num_tc(dev, 0);
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}
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static int mqprio_parse_opt(struct net_device *dev, struct tc_mqprio_qopt *qopt)
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{
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int i, j;
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/* Verify num_tc is not out of max range */
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if (qopt->num_tc > TC_MAX_QUEUE)
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return -EINVAL;
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/* Verify priority mapping uses valid tcs */
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for (i = 0; i < TC_BITMASK + 1; i++) {
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if (qopt->prio_tc_map[i] >= qopt->num_tc)
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return -EINVAL;
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}
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/* net_device does not support requested operation */
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if (qopt->hw && !dev->netdev_ops->ndo_setup_tc)
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return -EINVAL;
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/* if hw owned qcount and qoffset are taken from LLD so
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* no reason to verify them here
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*/
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if (qopt->hw)
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return 0;
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for (i = 0; i < qopt->num_tc; i++) {
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unsigned int last = qopt->offset[i] + qopt->count[i];
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/* Verify the queue count is in tx range being equal to the
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* real_num_tx_queues indicates the last queue is in use.
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*/
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if (qopt->offset[i] >= dev->real_num_tx_queues ||
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!qopt->count[i] ||
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last > dev->real_num_tx_queues)
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return -EINVAL;
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/* Verify that the offset and counts do not overlap */
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for (j = i + 1; j < qopt->num_tc; j++) {
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if (last > qopt->offset[j])
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return -EINVAL;
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}
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}
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return 0;
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}
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static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
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{
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struct net_device *dev = qdisc_dev(sch);
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struct mqprio_sched *priv = qdisc_priv(sch);
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struct netdev_queue *dev_queue;
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struct Qdisc *qdisc;
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int i, err = -EOPNOTSUPP;
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struct tc_mqprio_qopt *qopt = NULL;
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BUILD_BUG_ON(TC_MAX_QUEUE != TC_QOPT_MAX_QUEUE);
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BUILD_BUG_ON(TC_BITMASK != TC_QOPT_BITMASK);
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if (sch->parent != TC_H_ROOT)
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return -EOPNOTSUPP;
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if (!netif_is_multiqueue(dev))
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return -EOPNOTSUPP;
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if (!opt || nla_len(opt) < sizeof(*qopt))
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return -EINVAL;
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qopt = nla_data(opt);
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if (mqprio_parse_opt(dev, qopt))
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return -EINVAL;
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/* pre-allocate qdisc, attachment can't fail */
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priv->qdiscs = kcalloc(dev->num_tx_queues, sizeof(priv->qdiscs[0]),
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GFP_KERNEL);
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if (priv->qdiscs == NULL) {
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err = -ENOMEM;
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goto err;
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}
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for (i = 0; i < dev->num_tx_queues; i++) {
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dev_queue = netdev_get_tx_queue(dev, i);
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qdisc = qdisc_create_dflt(dev_queue, default_qdisc_ops,
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TC_H_MAKE(TC_H_MAJ(sch->handle),
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TC_H_MIN(i + 1)));
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if (qdisc == NULL) {
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err = -ENOMEM;
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goto err;
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}
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priv->qdiscs[i] = qdisc;
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qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
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}
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/* If the mqprio options indicate that hardware should own
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* the queue mapping then run ndo_setup_tc otherwise use the
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* supplied and verified mapping
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*/
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if (qopt->hw) {
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priv->hw_owned = 1;
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err = dev->netdev_ops->ndo_setup_tc(dev, qopt->num_tc);
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if (err)
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goto err;
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} else {
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netdev_set_num_tc(dev, qopt->num_tc);
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for (i = 0; i < qopt->num_tc; i++)
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netdev_set_tc_queue(dev, i,
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qopt->count[i], qopt->offset[i]);
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}
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/* Always use supplied priority mappings */
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for (i = 0; i < TC_BITMASK + 1; i++)
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netdev_set_prio_tc_map(dev, i, qopt->prio_tc_map[i]);
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sch->flags |= TCQ_F_MQROOT;
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return 0;
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err:
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mqprio_destroy(sch);
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return err;
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}
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static void mqprio_attach(struct Qdisc *sch)
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{
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struct net_device *dev = qdisc_dev(sch);
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struct mqprio_sched *priv = qdisc_priv(sch);
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struct Qdisc *qdisc, *old;
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unsigned int ntx;
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/* Attach underlying qdisc */
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for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
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qdisc = priv->qdiscs[ntx];
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old = dev_graft_qdisc(qdisc->dev_queue, qdisc);
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if (old)
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qdisc_destroy(old);
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if (ntx < dev->real_num_tx_queues)
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qdisc_list_add(qdisc);
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}
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kfree(priv->qdiscs);
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priv->qdiscs = NULL;
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}
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static struct netdev_queue *mqprio_queue_get(struct Qdisc *sch,
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unsigned long cl)
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{
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struct net_device *dev = qdisc_dev(sch);
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unsigned long ntx = cl - 1 - netdev_get_num_tc(dev);
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if (ntx >= dev->num_tx_queues)
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return NULL;
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return netdev_get_tx_queue(dev, ntx);
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}
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static int mqprio_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
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struct Qdisc **old)
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{
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struct net_device *dev = qdisc_dev(sch);
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struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);
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if (!dev_queue)
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return -EINVAL;
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if (dev->flags & IFF_UP)
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dev_deactivate(dev);
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*old = dev_graft_qdisc(dev_queue, new);
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if (new)
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new->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
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if (dev->flags & IFF_UP)
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dev_activate(dev);
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return 0;
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}
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static int mqprio_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct net_device *dev = qdisc_dev(sch);
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struct mqprio_sched *priv = qdisc_priv(sch);
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unsigned char *b = skb_tail_pointer(skb);
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struct tc_mqprio_qopt opt = { 0 };
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struct Qdisc *qdisc;
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unsigned int i;
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sch->q.qlen = 0;
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memset(&sch->bstats, 0, sizeof(sch->bstats));
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memset(&sch->qstats, 0, sizeof(sch->qstats));
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for (i = 0; i < dev->num_tx_queues; i++) {
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qdisc = rtnl_dereference(netdev_get_tx_queue(dev, i)->qdisc);
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spin_lock_bh(qdisc_lock(qdisc));
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sch->q.qlen += qdisc->q.qlen;
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sch->bstats.bytes += qdisc->bstats.bytes;
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sch->bstats.packets += qdisc->bstats.packets;
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sch->qstats.backlog += qdisc->qstats.backlog;
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sch->qstats.drops += qdisc->qstats.drops;
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sch->qstats.requeues += qdisc->qstats.requeues;
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sch->qstats.overlimits += qdisc->qstats.overlimits;
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spin_unlock_bh(qdisc_lock(qdisc));
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}
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opt.num_tc = netdev_get_num_tc(dev);
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memcpy(opt.prio_tc_map, dev->prio_tc_map, sizeof(opt.prio_tc_map));
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opt.hw = priv->hw_owned;
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for (i = 0; i < netdev_get_num_tc(dev); i++) {
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opt.count[i] = dev->tc_to_txq[i].count;
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opt.offset[i] = dev->tc_to_txq[i].offset;
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}
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if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
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goto nla_put_failure;
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return skb->len;
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nla_put_failure:
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nlmsg_trim(skb, b);
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return -1;
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}
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static struct Qdisc *mqprio_leaf(struct Qdisc *sch, unsigned long cl)
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{
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struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);
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if (!dev_queue)
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return NULL;
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return dev_queue->qdisc_sleeping;
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}
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static unsigned long mqprio_get(struct Qdisc *sch, u32 classid)
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{
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struct net_device *dev = qdisc_dev(sch);
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unsigned int ntx = TC_H_MIN(classid);
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if (ntx > dev->num_tx_queues + netdev_get_num_tc(dev))
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return 0;
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return ntx;
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}
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static void mqprio_put(struct Qdisc *sch, unsigned long cl)
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{
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}
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static int mqprio_dump_class(struct Qdisc *sch, unsigned long cl,
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struct sk_buff *skb, struct tcmsg *tcm)
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{
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struct net_device *dev = qdisc_dev(sch);
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if (cl <= netdev_get_num_tc(dev)) {
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tcm->tcm_parent = TC_H_ROOT;
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tcm->tcm_info = 0;
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} else {
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int i;
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struct netdev_queue *dev_queue;
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dev_queue = mqprio_queue_get(sch, cl);
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tcm->tcm_parent = 0;
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for (i = 0; i < netdev_get_num_tc(dev); i++) {
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struct netdev_tc_txq tc = dev->tc_to_txq[i];
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int q_idx = cl - netdev_get_num_tc(dev);
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if (q_idx > tc.offset &&
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q_idx <= tc.offset + tc.count) {
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tcm->tcm_parent =
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TC_H_MAKE(TC_H_MAJ(sch->handle),
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TC_H_MIN(i + 1));
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break;
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}
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}
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tcm->tcm_info = dev_queue->qdisc_sleeping->handle;
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}
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tcm->tcm_handle |= TC_H_MIN(cl);
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return 0;
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}
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static int mqprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
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struct gnet_dump *d)
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__releases(d->lock)
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__acquires(d->lock)
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{
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struct net_device *dev = qdisc_dev(sch);
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if (cl <= netdev_get_num_tc(dev)) {
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int i;
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__u32 qlen = 0;
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struct Qdisc *qdisc;
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struct gnet_stats_queue qstats = {0};
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struct gnet_stats_basic_packed bstats = {0};
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struct netdev_tc_txq tc = dev->tc_to_txq[cl - 1];
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/* Drop lock here it will be reclaimed before touching
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* statistics this is required because the d->lock we
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* hold here is the look on dev_queue->qdisc_sleeping
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* also acquired below.
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*/
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spin_unlock_bh(d->lock);
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for (i = tc.offset; i < tc.offset + tc.count; i++) {
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struct netdev_queue *q = netdev_get_tx_queue(dev, i);
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qdisc = rtnl_dereference(q->qdisc);
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spin_lock_bh(qdisc_lock(qdisc));
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qlen += qdisc->q.qlen;
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bstats.bytes += qdisc->bstats.bytes;
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bstats.packets += qdisc->bstats.packets;
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qstats.backlog += qdisc->qstats.backlog;
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qstats.drops += qdisc->qstats.drops;
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qstats.requeues += qdisc->qstats.requeues;
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qstats.overlimits += qdisc->qstats.overlimits;
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spin_unlock_bh(qdisc_lock(qdisc));
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}
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/* Reclaim root sleeping lock before completing stats */
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spin_lock_bh(d->lock);
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if (gnet_stats_copy_basic(d, NULL, &bstats) < 0 ||
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gnet_stats_copy_queue(d, NULL, &qstats, qlen) < 0)
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return -1;
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} else {
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struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);
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sch = dev_queue->qdisc_sleeping;
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if (gnet_stats_copy_basic(d, NULL, &sch->bstats) < 0 ||
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gnet_stats_copy_queue(d, NULL,
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&sch->qstats, sch->q.qlen) < 0)
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return -1;
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}
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return 0;
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}
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static void mqprio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
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{
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struct net_device *dev = qdisc_dev(sch);
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unsigned long ntx;
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if (arg->stop)
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return;
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/* Walk hierarchy with a virtual class per tc */
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arg->count = arg->skip;
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for (ntx = arg->skip;
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ntx < dev->num_tx_queues + netdev_get_num_tc(dev);
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ntx++) {
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if (arg->fn(sch, ntx + 1, arg) < 0) {
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arg->stop = 1;
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break;
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}
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arg->count++;
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}
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}
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static const struct Qdisc_class_ops mqprio_class_ops = {
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.graft = mqprio_graft,
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.leaf = mqprio_leaf,
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.get = mqprio_get,
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.put = mqprio_put,
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.walk = mqprio_walk,
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.dump = mqprio_dump_class,
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.dump_stats = mqprio_dump_class_stats,
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};
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static struct Qdisc_ops mqprio_qdisc_ops __read_mostly = {
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.cl_ops = &mqprio_class_ops,
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.id = "mqprio",
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.priv_size = sizeof(struct mqprio_sched),
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.init = mqprio_init,
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.destroy = mqprio_destroy,
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.attach = mqprio_attach,
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.dump = mqprio_dump,
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.owner = THIS_MODULE,
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};
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static int __init mqprio_module_init(void)
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{
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return register_qdisc(&mqprio_qdisc_ops);
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}
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static void __exit mqprio_module_exit(void)
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{
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unregister_qdisc(&mqprio_qdisc_ops);
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}
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module_init(mqprio_module_init);
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module_exit(mqprio_module_exit);
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MODULE_LICENSE("GPL");
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