linux/net/sched/sch_skbprio.c
Thomas Gleixner 2874c5fd28 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:26:32 -07:00

317 lines
7.5 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/sched/sch_skbprio.c SKB Priority Queue.
*
* Authors: Nishanth Devarajan, <ndev2021@gmail.com>
* Cody Doucette, <doucette@bu.edu>
* original idea by Michel Machado, Cody Doucette, and Qiaobin Fu
*/
#include <linux/string.h>
#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 <net/pkt_sched.h>
#include <net/sch_generic.h>
#include <net/inet_ecn.h>
/* SKB Priority Queue
* =================================
*
* Skbprio (SKB Priority Queue) is a queueing discipline that prioritizes
* packets according to their skb->priority field. Under congestion,
* Skbprio drops already-enqueued lower priority packets to make space
* available for higher priority packets; it was conceived as a solution
* for denial-of-service defenses that need to route packets with different
* priorities as a mean to overcome DoS attacks.
*/
struct skbprio_sched_data {
/* Queue state. */
struct sk_buff_head qdiscs[SKBPRIO_MAX_PRIORITY];
struct gnet_stats_queue qstats[SKBPRIO_MAX_PRIORITY];
u16 highest_prio;
u16 lowest_prio;
};
static u16 calc_new_high_prio(const struct skbprio_sched_data *q)
{
int prio;
for (prio = q->highest_prio - 1; prio >= q->lowest_prio; prio--) {
if (!skb_queue_empty(&q->qdiscs[prio]))
return prio;
}
/* SKB queue is empty, return 0 (default highest priority setting). */
return 0;
}
static u16 calc_new_low_prio(const struct skbprio_sched_data *q)
{
int prio;
for (prio = q->lowest_prio + 1; prio <= q->highest_prio; prio++) {
if (!skb_queue_empty(&q->qdiscs[prio]))
return prio;
}
/* SKB queue is empty, return SKBPRIO_MAX_PRIORITY - 1
* (default lowest priority setting).
*/
return SKBPRIO_MAX_PRIORITY - 1;
}
static int skbprio_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
const unsigned int max_priority = SKBPRIO_MAX_PRIORITY - 1;
struct skbprio_sched_data *q = qdisc_priv(sch);
struct sk_buff_head *qdisc;
struct sk_buff_head *lp_qdisc;
struct sk_buff *to_drop;
u16 prio, lp;
/* Obtain the priority of @skb. */
prio = min(skb->priority, max_priority);
qdisc = &q->qdiscs[prio];
if (sch->q.qlen < sch->limit) {
__skb_queue_tail(qdisc, skb);
qdisc_qstats_backlog_inc(sch, skb);
q->qstats[prio].backlog += qdisc_pkt_len(skb);
/* Check to update highest and lowest priorities. */
if (prio > q->highest_prio)
q->highest_prio = prio;
if (prio < q->lowest_prio)
q->lowest_prio = prio;
sch->q.qlen++;
return NET_XMIT_SUCCESS;
}
/* If this packet has the lowest priority, drop it. */
lp = q->lowest_prio;
if (prio <= lp) {
q->qstats[prio].drops++;
q->qstats[prio].overlimits++;
return qdisc_drop(skb, sch, to_free);
}
__skb_queue_tail(qdisc, skb);
qdisc_qstats_backlog_inc(sch, skb);
q->qstats[prio].backlog += qdisc_pkt_len(skb);
/* Drop the packet at the tail of the lowest priority qdisc. */
lp_qdisc = &q->qdiscs[lp];
to_drop = __skb_dequeue_tail(lp_qdisc);
BUG_ON(!to_drop);
qdisc_qstats_backlog_dec(sch, to_drop);
qdisc_drop(to_drop, sch, to_free);
q->qstats[lp].backlog -= qdisc_pkt_len(to_drop);
q->qstats[lp].drops++;
q->qstats[lp].overlimits++;
/* Check to update highest and lowest priorities. */
if (skb_queue_empty(lp_qdisc)) {
if (q->lowest_prio == q->highest_prio) {
/* The incoming packet is the only packet in queue. */
BUG_ON(sch->q.qlen != 1);
q->lowest_prio = prio;
q->highest_prio = prio;
} else {
q->lowest_prio = calc_new_low_prio(q);
}
}
if (prio > q->highest_prio)
q->highest_prio = prio;
return NET_XMIT_CN;
}
static struct sk_buff *skbprio_dequeue(struct Qdisc *sch)
{
struct skbprio_sched_data *q = qdisc_priv(sch);
struct sk_buff_head *hpq = &q->qdiscs[q->highest_prio];
struct sk_buff *skb = __skb_dequeue(hpq);
if (unlikely(!skb))
return NULL;
sch->q.qlen--;
qdisc_qstats_backlog_dec(sch, skb);
qdisc_bstats_update(sch, skb);
q->qstats[q->highest_prio].backlog -= qdisc_pkt_len(skb);
/* Update highest priority field. */
if (skb_queue_empty(hpq)) {
if (q->lowest_prio == q->highest_prio) {
BUG_ON(sch->q.qlen);
q->highest_prio = 0;
q->lowest_prio = SKBPRIO_MAX_PRIORITY - 1;
} else {
q->highest_prio = calc_new_high_prio(q);
}
}
return skb;
}
static int skbprio_change(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
struct tc_skbprio_qopt *ctl = nla_data(opt);
sch->limit = ctl->limit;
return 0;
}
static int skbprio_init(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
struct skbprio_sched_data *q = qdisc_priv(sch);
int prio;
/* Initialise all queues, one for each possible priority. */
for (prio = 0; prio < SKBPRIO_MAX_PRIORITY; prio++)
__skb_queue_head_init(&q->qdiscs[prio]);
memset(&q->qstats, 0, sizeof(q->qstats));
q->highest_prio = 0;
q->lowest_prio = SKBPRIO_MAX_PRIORITY - 1;
sch->limit = 64;
if (!opt)
return 0;
return skbprio_change(sch, opt, extack);
}
static int skbprio_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct tc_skbprio_qopt opt;
opt.limit = sch->limit;
if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
return -1;
return skb->len;
}
static void skbprio_reset(struct Qdisc *sch)
{
struct skbprio_sched_data *q = qdisc_priv(sch);
int prio;
sch->qstats.backlog = 0;
sch->q.qlen = 0;
for (prio = 0; prio < SKBPRIO_MAX_PRIORITY; prio++)
__skb_queue_purge(&q->qdiscs[prio]);
memset(&q->qstats, 0, sizeof(q->qstats));
q->highest_prio = 0;
q->lowest_prio = SKBPRIO_MAX_PRIORITY - 1;
}
static void skbprio_destroy(struct Qdisc *sch)
{
struct skbprio_sched_data *q = qdisc_priv(sch);
int prio;
for (prio = 0; prio < SKBPRIO_MAX_PRIORITY; prio++)
__skb_queue_purge(&q->qdiscs[prio]);
}
static struct Qdisc *skbprio_leaf(struct Qdisc *sch, unsigned long arg)
{
return NULL;
}
static unsigned long skbprio_find(struct Qdisc *sch, u32 classid)
{
return 0;
}
static int skbprio_dump_class(struct Qdisc *sch, unsigned long cl,
struct sk_buff *skb, struct tcmsg *tcm)
{
tcm->tcm_handle |= TC_H_MIN(cl);
return 0;
}
static int skbprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
struct gnet_dump *d)
{
struct skbprio_sched_data *q = qdisc_priv(sch);
if (gnet_stats_copy_queue(d, NULL, &q->qstats[cl - 1],
q->qstats[cl - 1].qlen) < 0)
return -1;
return 0;
}
static void skbprio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
unsigned int i;
if (arg->stop)
return;
for (i = 0; i < SKBPRIO_MAX_PRIORITY; i++) {
if (arg->count < arg->skip) {
arg->count++;
continue;
}
if (arg->fn(sch, i + 1, arg) < 0) {
arg->stop = 1;
break;
}
arg->count++;
}
}
static const struct Qdisc_class_ops skbprio_class_ops = {
.leaf = skbprio_leaf,
.find = skbprio_find,
.dump = skbprio_dump_class,
.dump_stats = skbprio_dump_class_stats,
.walk = skbprio_walk,
};
static struct Qdisc_ops skbprio_qdisc_ops __read_mostly = {
.cl_ops = &skbprio_class_ops,
.id = "skbprio",
.priv_size = sizeof(struct skbprio_sched_data),
.enqueue = skbprio_enqueue,
.dequeue = skbprio_dequeue,
.peek = qdisc_peek_dequeued,
.init = skbprio_init,
.reset = skbprio_reset,
.change = skbprio_change,
.dump = skbprio_dump,
.destroy = skbprio_destroy,
.owner = THIS_MODULE,
};
static int __init skbprio_module_init(void)
{
return register_qdisc(&skbprio_qdisc_ops);
}
static void __exit skbprio_module_exit(void)
{
unregister_qdisc(&skbprio_qdisc_ops);
}
module_init(skbprio_module_init)
module_exit(skbprio_module_exit)
MODULE_LICENSE("GPL");