![Jiri Kosina](/assets/img/avatar_default.png)
The original reason [1] for having hidden qdiscs (potential scalability
issues in qdisc_match_from_root() with single linked list in case of large
amount of qdiscs) has been invalidated by 59cc1f61f0
("net: sched: convert
qdisc linked list to hashtable").
This allows us for bringing more clarity and determinism into the dump by
making default pfifo qdiscs visible.
We're not turning this on by default though, at it was deemed [2] too
intrusive / unnecessary change of default behavior towards userspace.
Instead, TCA_DUMP_INVISIBLE netlink attribute is introduced, which allows
applications to request complete qdisc hierarchy dump, including the
ones that have always been implicit/invisible.
Singleton noop_qdisc stays invisible, as teaching the whole infrastructure
about singletons would require quite some surgery with very little gain
(seeing no qdisc or seeing noop qdisc in the dump is probably setting
the same user expectation).
[1] http://lkml.kernel.org/r/1460732328.10638.74.camel@edumazet-glaptop3.roam.corp.google.com
[2] http://lkml.kernel.org/r/20161021.105935.1907696543877061916.davem@davemloft.net
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>
423 lines
9.1 KiB
C
423 lines
9.1 KiB
C
/*
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* Copyright (c) 2008, Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions 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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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, see <http://www.gnu.org/licenses/>.
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*
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* Author: Alexander Duyck <alexander.h.duyck@intel.com>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/types.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 <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <net/pkt_cls.h>
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struct multiq_sched_data {
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u16 bands;
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u16 max_bands;
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u16 curband;
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struct tcf_proto __rcu *filter_list;
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struct Qdisc **queues;
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};
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static struct Qdisc *
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multiq_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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u32 band;
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struct tcf_result res;
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struct tcf_proto *fl = rcu_dereference_bh(q->filter_list);
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int err;
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*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
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err = tc_classify(skb, fl, &res, false);
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#ifdef CONFIG_NET_CLS_ACT
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switch (err) {
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case TC_ACT_STOLEN:
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case TC_ACT_QUEUED:
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*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
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case TC_ACT_SHOT:
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return NULL;
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}
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#endif
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band = skb_get_queue_mapping(skb);
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if (band >= q->bands)
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return q->queues[0];
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return q->queues[band];
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}
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static int
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multiq_enqueue(struct sk_buff *skb, struct Qdisc *sch,
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struct sk_buff **to_free)
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{
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struct Qdisc *qdisc;
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int ret;
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qdisc = multiq_classify(skb, sch, &ret);
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#ifdef CONFIG_NET_CLS_ACT
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if (qdisc == NULL) {
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if (ret & __NET_XMIT_BYPASS)
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qdisc_qstats_drop(sch);
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__qdisc_drop(skb, to_free);
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return ret;
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}
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#endif
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ret = qdisc_enqueue(skb, qdisc, to_free);
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if (ret == NET_XMIT_SUCCESS) {
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sch->q.qlen++;
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return NET_XMIT_SUCCESS;
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}
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if (net_xmit_drop_count(ret))
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qdisc_qstats_drop(sch);
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return ret;
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}
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static struct sk_buff *multiq_dequeue(struct Qdisc *sch)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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struct Qdisc *qdisc;
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struct sk_buff *skb;
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int band;
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for (band = 0; band < q->bands; band++) {
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/* cycle through bands to ensure fairness */
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q->curband++;
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if (q->curband >= q->bands)
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q->curband = 0;
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/* Check that target subqueue is available before
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* pulling an skb to avoid head-of-line blocking.
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*/
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if (!netif_xmit_stopped(
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netdev_get_tx_queue(qdisc_dev(sch), q->curband))) {
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qdisc = q->queues[q->curband];
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skb = qdisc->dequeue(qdisc);
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if (skb) {
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qdisc_bstats_update(sch, skb);
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sch->q.qlen--;
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return skb;
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}
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}
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}
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return NULL;
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}
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static struct sk_buff *multiq_peek(struct Qdisc *sch)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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unsigned int curband = q->curband;
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struct Qdisc *qdisc;
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struct sk_buff *skb;
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int band;
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for (band = 0; band < q->bands; band++) {
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/* cycle through bands to ensure fairness */
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curband++;
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if (curband >= q->bands)
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curband = 0;
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/* Check that target subqueue is available before
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* pulling an skb to avoid head-of-line blocking.
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*/
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if (!netif_xmit_stopped(
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netdev_get_tx_queue(qdisc_dev(sch), curband))) {
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qdisc = q->queues[curband];
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skb = qdisc->ops->peek(qdisc);
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if (skb)
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return skb;
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}
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}
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return NULL;
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}
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static void
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multiq_reset(struct Qdisc *sch)
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{
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u16 band;
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struct multiq_sched_data *q = qdisc_priv(sch);
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for (band = 0; band < q->bands; band++)
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qdisc_reset(q->queues[band]);
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sch->q.qlen = 0;
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q->curband = 0;
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}
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static void
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multiq_destroy(struct Qdisc *sch)
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{
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int band;
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struct multiq_sched_data *q = qdisc_priv(sch);
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tcf_destroy_chain(&q->filter_list);
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for (band = 0; band < q->bands; band++)
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qdisc_destroy(q->queues[band]);
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kfree(q->queues);
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}
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static int multiq_tune(struct Qdisc *sch, struct nlattr *opt)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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struct tc_multiq_qopt *qopt;
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int i;
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if (!netif_is_multiqueue(qdisc_dev(sch)))
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return -EOPNOTSUPP;
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if (nla_len(opt) < sizeof(*qopt))
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return -EINVAL;
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qopt = nla_data(opt);
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qopt->bands = qdisc_dev(sch)->real_num_tx_queues;
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sch_tree_lock(sch);
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q->bands = qopt->bands;
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for (i = q->bands; i < q->max_bands; i++) {
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if (q->queues[i] != &noop_qdisc) {
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struct Qdisc *child = q->queues[i];
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q->queues[i] = &noop_qdisc;
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qdisc_tree_reduce_backlog(child, child->q.qlen,
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child->qstats.backlog);
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qdisc_destroy(child);
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}
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}
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sch_tree_unlock(sch);
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for (i = 0; i < q->bands; i++) {
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if (q->queues[i] == &noop_qdisc) {
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struct Qdisc *child, *old;
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child = qdisc_create_dflt(sch->dev_queue,
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&pfifo_qdisc_ops,
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TC_H_MAKE(sch->handle,
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i + 1));
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if (child) {
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sch_tree_lock(sch);
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old = q->queues[i];
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q->queues[i] = child;
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if (child != &noop_qdisc)
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qdisc_hash_add(child, true);
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if (old != &noop_qdisc) {
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qdisc_tree_reduce_backlog(old,
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old->q.qlen,
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old->qstats.backlog);
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qdisc_destroy(old);
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}
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sch_tree_unlock(sch);
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}
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}
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}
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return 0;
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}
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static int multiq_init(struct Qdisc *sch, struct nlattr *opt)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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int i, err;
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q->queues = NULL;
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if (opt == NULL)
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return -EINVAL;
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q->max_bands = qdisc_dev(sch)->num_tx_queues;
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q->queues = kcalloc(q->max_bands, sizeof(struct Qdisc *), GFP_KERNEL);
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if (!q->queues)
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return -ENOBUFS;
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for (i = 0; i < q->max_bands; i++)
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q->queues[i] = &noop_qdisc;
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err = multiq_tune(sch, opt);
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if (err)
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kfree(q->queues);
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return err;
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}
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static int multiq_dump(struct Qdisc *sch, struct sk_buff *skb)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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unsigned char *b = skb_tail_pointer(skb);
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struct tc_multiq_qopt opt;
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opt.bands = q->bands;
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opt.max_bands = q->max_bands;
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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 int multiq_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
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struct Qdisc **old)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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unsigned long band = arg - 1;
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if (new == NULL)
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new = &noop_qdisc;
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*old = qdisc_replace(sch, new, &q->queues[band]);
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return 0;
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}
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static struct Qdisc *
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multiq_leaf(struct Qdisc *sch, unsigned long arg)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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unsigned long band = arg - 1;
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return q->queues[band];
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}
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static unsigned long multiq_get(struct Qdisc *sch, u32 classid)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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unsigned long band = TC_H_MIN(classid);
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if (band - 1 >= q->bands)
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return 0;
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return band;
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}
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static unsigned long multiq_bind(struct Qdisc *sch, unsigned long parent,
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u32 classid)
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{
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return multiq_get(sch, classid);
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}
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static void multiq_put(struct Qdisc *q, unsigned long cl)
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{
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}
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static int multiq_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 multiq_sched_data *q = qdisc_priv(sch);
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tcm->tcm_handle |= TC_H_MIN(cl);
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tcm->tcm_info = q->queues[cl - 1]->handle;
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return 0;
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}
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static int multiq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
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struct gnet_dump *d)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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struct Qdisc *cl_q;
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cl_q = q->queues[cl - 1];
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if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
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d, NULL, &cl_q->bstats) < 0 ||
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gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)
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return -1;
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return 0;
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}
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static void multiq_walk(struct Qdisc *sch, struct qdisc_walker *arg)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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int band;
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if (arg->stop)
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return;
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for (band = 0; band < q->bands; band++) {
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if (arg->count < arg->skip) {
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arg->count++;
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continue;
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}
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if (arg->fn(sch, band + 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 struct tcf_proto __rcu **multiq_find_tcf(struct Qdisc *sch,
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unsigned long cl)
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{
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struct multiq_sched_data *q = qdisc_priv(sch);
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if (cl)
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return NULL;
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return &q->filter_list;
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}
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static const struct Qdisc_class_ops multiq_class_ops = {
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.graft = multiq_graft,
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.leaf = multiq_leaf,
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.get = multiq_get,
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.put = multiq_put,
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.walk = multiq_walk,
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.tcf_chain = multiq_find_tcf,
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.bind_tcf = multiq_bind,
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.unbind_tcf = multiq_put,
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.dump = multiq_dump_class,
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.dump_stats = multiq_dump_class_stats,
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};
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static struct Qdisc_ops multiq_qdisc_ops __read_mostly = {
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.next = NULL,
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.cl_ops = &multiq_class_ops,
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.id = "multiq",
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.priv_size = sizeof(struct multiq_sched_data),
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.enqueue = multiq_enqueue,
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.dequeue = multiq_dequeue,
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.peek = multiq_peek,
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.init = multiq_init,
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.reset = multiq_reset,
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.destroy = multiq_destroy,
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.change = multiq_tune,
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.dump = multiq_dump,
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.owner = THIS_MODULE,
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};
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static int __init multiq_module_init(void)
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{
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return register_qdisc(&multiq_qdisc_ops);
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}
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static void __exit multiq_module_exit(void)
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{
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unregister_qdisc(&multiq_qdisc_ops);
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}
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module_init(multiq_module_init)
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module_exit(multiq_module_exit)
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MODULE_LICENSE("GPL");
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