/*
* Codel - The Controlled-Delay Active Queue Management algorithm
*
* Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
* Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
*
* Implemented on linux by :
* Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net>
* Copyright (C) 2012 Eric Dumazet <edumazet@google.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer,
* without modification.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* Alternatively, provided that this notice is retained in full, this
* software may be distributed under the terms of the GNU General
* Public License ("GPL") version 2, in which case the provisions of the
* GPL apply INSTEAD OF those given above.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/prefetch.h>
#include <net/pkt_sched.h>
#include <net/codel.h>
#define DEFAULT_CODEL_LIMIT 1000
struct codel_sched_data {
struct codel_params params;
struct codel_vars vars;
struct codel_stats stats;
u32 drop_overlimit;
};
/* This is the specific function called from codel_dequeue()
* to dequeue a packet from queue. Note: backlog is handled in
* codel, we dont need to reduce it here.
*/
static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
{
struct sk_buff *skb = __skb_dequeue(&sch->q);
prefetch(&skb->end); /* we'll need skb_shinfo() */
return skb;
}
static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch)
{
struct codel_sched_data *q = qdisc_priv(sch);
struct sk_buff *skb;
skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
/* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
* or HTB crashes. Defer it for next round.
*/
if (q->stats.drop_count && sch->q.qlen) {
qdisc_tree_decrease_qlen(sch, q->stats.drop_count);
q->stats.drop_count = 0;
}
if (skb)
qdisc_bstats_update(sch, skb);
return skb;
}
static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct codel_sched_data *q;
if (likely(qdisc_qlen(sch) < sch->limit)) {
codel_set_enqueue_time(skb);
return qdisc_enqueue_tail(skb, sch);
}
q = qdisc_priv(sch);
q->drop_overlimit++;
return qdisc_drop(skb, sch);
}
static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = {
[TCA_CODEL_TARGET] = { .type = NLA_U32 },
[TCA_CODEL_LIMIT] = { .type = NLA_U32 },
[TCA_CODEL_INTERVAL] = { .type = NLA_U32 },
[TCA_CODEL_ECN] = { .type = NLA_U32 },
};
static int codel_change(struct Qdisc *sch, struct nlattr *opt)
{
struct codel_sched_data *q = qdisc_priv(sch);
struct nlattr *tb[TCA_CODEL_MAX + 1];
unsigned int qlen;
int err;
if (!opt)
return -EINVAL;
err = nla_parse_nested(tb, TCA_CODEL_MAX, opt, codel_policy);
if (err < 0)
return err;
sch_tree_lock(sch);
if (tb[TCA_CODEL_TARGET]) {
u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]);
q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT;
}
if (tb[TCA_CODEL_INTERVAL]) {
u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]);
q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT;
}
if (tb[TCA_CODEL_LIMIT])
sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]);
if (tb[TCA_CODEL_ECN])
q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]);
qlen = sch->q.qlen;
while (sch->q.qlen > sch->limit) {
struct sk_buff *skb = __skb_dequeue(&sch->q);
sch->qstats.backlog -= qdisc_pkt_len(skb);
qdisc_drop(skb, sch);
}
qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen);
sch_tree_unlock(sch);
return 0;
}
static int codel_init(struct Qdisc *sch, struct nlattr *opt)
{
struct codel_sched_data *q = qdisc_priv(sch);
sch->limit = DEFAULT_CODEL_LIMIT;
codel_params_init(&q->params);
codel_vars_init(&q->vars);
codel_stats_init(&q->stats);
if (opt) {
int err = codel_change(sch, opt);
if (err)
return err;
}
if (sch->limit >= 1)
sch->flags |= TCQ_F_CAN_BYPASS;
else
sch->flags &= ~TCQ_F_CAN_BYPASS;
return 0;
}
static int codel_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct codel_sched_data *q = qdisc_priv(sch);
struct nlattr *opts;
opts = nla_nest_start(skb, TCA_OPTIONS);
if (opts == NULL)
goto nla_put_failure;
if (nla_put_u32(skb, TCA_CODEL_TARGET,
codel_time_to_us(q->params.target)) ||
nla_put_u32(skb, TCA_CODEL_LIMIT,
sch->limit) ||
nla_put_u32(skb, TCA_CODEL_INTERVAL,
codel_time_to_us(q->params.interval)) ||
nla_put_u32(skb, TCA_CODEL_ECN,
q->params.ecn))
goto nla_put_failure;
return nla_nest_end(skb, opts);
nla_put_failure:
nla_nest_cancel(skb, opts);
return -1;
}
static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
{
const struct codel_sched_data *q = qdisc_priv(sch);
struct tc_codel_xstats st = {
.maxpacket = q->stats.maxpacket,
.count = q->vars.count,
.lastcount = q->vars.lastcount,
.drop_overlimit = q->drop_overlimit,
.ldelay = codel_time_to_us(q->vars.ldelay),
.dropping = q->vars.dropping,
.ecn_mark = q->stats.ecn_mark,
};
if (q->vars.dropping) {
codel_tdiff_t delta = q->vars.drop_next - codel_get_time();
if (delta >= 0)
st.drop_next = codel_time_to_us(delta);
else
st.drop_next = -codel_time_to_us(-delta);
}
return gnet_stats_copy_app(d, &st, sizeof(st));
}
static void codel_reset(struct Qdisc *sch)
{
struct codel_sched_data *q = qdisc_priv(sch);
qdisc_reset_queue(sch);
codel_vars_init(&q->vars);
}
static struct Qdisc_ops codel_qdisc_ops __read_mostly = {
.id = "codel",
.priv_size = sizeof(struct codel_sched_data),
.enqueue = codel_qdisc_enqueue,
.dequeue = codel_qdisc_dequeue,
.peek = qdisc_peek_dequeued,
.init = codel_init,
.reset = codel_reset,
.change = codel_change,
.dump = codel_dump,
.dump_stats = codel_dump_stats,
.owner = THIS_MODULE,
};
static int __init codel_module_init(void)
{
return register_qdisc(&codel_qdisc_ops);
}
static void __exit codel_module_exit(void)
{
unregister_qdisc(&codel_qdisc_ops);
}
module_init(codel_module_init)
module_exit(codel_module_exit)
MODULE_DESCRIPTION("Controlled Delay queue discipline");
MODULE_AUTHOR("Dave Taht");
MODULE_AUTHOR("Eric Dumazet");
MODULE_LICENSE("Dual BSD/GPL");
