linux-next/net/sched/sch_prio.c
WANG Cong 143976ce99 net_sched: remove tc class reference counting
For TC classes, their ->get() and ->put() are always paired, and the
reference counting is completely useless, because:

1) For class modification and dumping paths, we already hold RTNL lock,
   so all of these ->get(),->change(),->put() are atomic.

2) For filter bindiing/unbinding, we use other reference counter than
   this one, and they should have RTNL lock too.

3) For ->qlen_notify(), it is special because it is called on ->enqueue()
   path, but we already hold qdisc tree lock there, and we hold this
   tree lock when graft or delete the class too, so it should not be gone
   or changed until we release the tree lock.

Therefore, this patch removes ->get() and ->put(), but:

1) Adds a new ->find() to find the pointer to a class by classid, no
   refcnt.

2) Move the original class destroy upon the last refcnt into ->delete(),
   right after releasing tree lock. This is fine because the class is
   already removed from hash when holding the lock.

For those who also use ->put() as ->unbind(), just rename them to reflect
this change.

Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-08-25 17:19:10 -07:00

380 lines
8.1 KiB
C

/*
* net/sched/sch_prio.c Simple 3-band priority "scheduler".
*
* 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.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
* Fixes: 19990609: J Hadi Salim <hadi@nortelnetworks.com>:
* Init -- EINVAL when opt undefined
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
struct prio_sched_data {
int bands;
struct tcf_proto __rcu *filter_list;
struct tcf_block *block;
u8 prio2band[TC_PRIO_MAX+1];
struct Qdisc *queues[TCQ_PRIO_BANDS];
};
static struct Qdisc *
prio_classify(struct sk_buff *skb, struct Qdisc *sch, int *qerr)
{
struct prio_sched_data *q = qdisc_priv(sch);
u32 band = skb->priority;
struct tcf_result res;
struct tcf_proto *fl;
int err;
*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
if (TC_H_MAJ(skb->priority) != sch->handle) {
fl = rcu_dereference_bh(q->filter_list);
err = tcf_classify(skb, fl, &res, false);
#ifdef CONFIG_NET_CLS_ACT
switch (err) {
case TC_ACT_STOLEN:
case TC_ACT_QUEUED:
case TC_ACT_TRAP:
*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
case TC_ACT_SHOT:
return NULL;
}
#endif
if (!fl || err < 0) {
if (TC_H_MAJ(band))
band = 0;
return q->queues[q->prio2band[band & TC_PRIO_MAX]];
}
band = res.classid;
}
band = TC_H_MIN(band) - 1;
if (band >= q->bands)
return q->queues[q->prio2band[0]];
return q->queues[band];
}
static int
prio_enqueue(struct sk_buff *skb, struct Qdisc *sch, struct sk_buff **to_free)
{
struct Qdisc *qdisc;
int ret;
qdisc = prio_classify(skb, sch, &ret);
#ifdef CONFIG_NET_CLS_ACT
if (qdisc == NULL) {
if (ret & __NET_XMIT_BYPASS)
qdisc_qstats_drop(sch);
kfree_skb(skb);
return ret;
}
#endif
ret = qdisc_enqueue(skb, qdisc, to_free);
if (ret == NET_XMIT_SUCCESS) {
qdisc_qstats_backlog_inc(sch, skb);
sch->q.qlen++;
return NET_XMIT_SUCCESS;
}
if (net_xmit_drop_count(ret))
qdisc_qstats_drop(sch);
return ret;
}
static struct sk_buff *prio_peek(struct Qdisc *sch)
{
struct prio_sched_data *q = qdisc_priv(sch);
int prio;
for (prio = 0; prio < q->bands; prio++) {
struct Qdisc *qdisc = q->queues[prio];
struct sk_buff *skb = qdisc->ops->peek(qdisc);
if (skb)
return skb;
}
return NULL;
}
static struct sk_buff *prio_dequeue(struct Qdisc *sch)
{
struct prio_sched_data *q = qdisc_priv(sch);
int prio;
for (prio = 0; prio < q->bands; prio++) {
struct Qdisc *qdisc = q->queues[prio];
struct sk_buff *skb = qdisc_dequeue_peeked(qdisc);
if (skb) {
qdisc_bstats_update(sch, skb);
qdisc_qstats_backlog_dec(sch, skb);
sch->q.qlen--;
return skb;
}
}
return NULL;
}
static void
prio_reset(struct Qdisc *sch)
{
int prio;
struct prio_sched_data *q = qdisc_priv(sch);
for (prio = 0; prio < q->bands; prio++)
qdisc_reset(q->queues[prio]);
sch->qstats.backlog = 0;
sch->q.qlen = 0;
}
static void
prio_destroy(struct Qdisc *sch)
{
int prio;
struct prio_sched_data *q = qdisc_priv(sch);
tcf_block_put(q->block);
for (prio = 0; prio < q->bands; prio++)
qdisc_destroy(q->queues[prio]);
}
static int prio_tune(struct Qdisc *sch, struct nlattr *opt)
{
struct prio_sched_data *q = qdisc_priv(sch);
struct Qdisc *queues[TCQ_PRIO_BANDS];
int oldbands = q->bands, i;
struct tc_prio_qopt *qopt;
if (nla_len(opt) < sizeof(*qopt))
return -EINVAL;
qopt = nla_data(opt);
if (qopt->bands > TCQ_PRIO_BANDS || qopt->bands < 2)
return -EINVAL;
for (i = 0; i <= TC_PRIO_MAX; i++) {
if (qopt->priomap[i] >= qopt->bands)
return -EINVAL;
}
/* Before commit, make sure we can allocate all new qdiscs */
for (i = oldbands; i < qopt->bands; i++) {
queues[i] = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
TC_H_MAKE(sch->handle, i + 1));
if (!queues[i]) {
while (i > oldbands)
qdisc_destroy(queues[--i]);
return -ENOMEM;
}
}
sch_tree_lock(sch);
q->bands = qopt->bands;
memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
for (i = q->bands; i < oldbands; i++) {
struct Qdisc *child = q->queues[i];
qdisc_tree_reduce_backlog(child, child->q.qlen,
child->qstats.backlog);
qdisc_destroy(child);
}
for (i = oldbands; i < q->bands; i++) {
q->queues[i] = queues[i];
if (q->queues[i] != &noop_qdisc)
qdisc_hash_add(q->queues[i], true);
}
sch_tree_unlock(sch);
return 0;
}
static int prio_init(struct Qdisc *sch, struct nlattr *opt)
{
struct prio_sched_data *q = qdisc_priv(sch);
int err;
if (!opt)
return -EINVAL;
err = tcf_block_get(&q->block, &q->filter_list);
if (err)
return err;
return prio_tune(sch, opt);
}
static int prio_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct prio_sched_data *q = qdisc_priv(sch);
unsigned char *b = skb_tail_pointer(skb);
struct tc_prio_qopt opt;
opt.bands = q->bands;
memcpy(&opt.priomap, q->prio2band, TC_PRIO_MAX + 1);
if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
goto nla_put_failure;
return skb->len;
nla_put_failure:
nlmsg_trim(skb, b);
return -1;
}
static int prio_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
struct Qdisc **old)
{
struct prio_sched_data *q = qdisc_priv(sch);
unsigned long band = arg - 1;
if (new == NULL)
new = &noop_qdisc;
*old = qdisc_replace(sch, new, &q->queues[band]);
return 0;
}
static struct Qdisc *
prio_leaf(struct Qdisc *sch, unsigned long arg)
{
struct prio_sched_data *q = qdisc_priv(sch);
unsigned long band = arg - 1;
return q->queues[band];
}
static unsigned long prio_find(struct Qdisc *sch, u32 classid)
{
struct prio_sched_data *q = qdisc_priv(sch);
unsigned long band = TC_H_MIN(classid);
if (band - 1 >= q->bands)
return 0;
return band;
}
static unsigned long prio_bind(struct Qdisc *sch, unsigned long parent, u32 classid)
{
return prio_find(sch, classid);
}
static void prio_unbind(struct Qdisc *q, unsigned long cl)
{
}
static int prio_dump_class(struct Qdisc *sch, unsigned long cl, struct sk_buff *skb,
struct tcmsg *tcm)
{
struct prio_sched_data *q = qdisc_priv(sch);
tcm->tcm_handle |= TC_H_MIN(cl);
tcm->tcm_info = q->queues[cl-1]->handle;
return 0;
}
static int prio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
struct gnet_dump *d)
{
struct prio_sched_data *q = qdisc_priv(sch);
struct Qdisc *cl_q;
cl_q = q->queues[cl - 1];
if (gnet_stats_copy_basic(qdisc_root_sleeping_running(sch),
d, NULL, &cl_q->bstats) < 0 ||
gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)
return -1;
return 0;
}
static void prio_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
struct prio_sched_data *q = qdisc_priv(sch);
int prio;
if (arg->stop)
return;
for (prio = 0; prio < q->bands; prio++) {
if (arg->count < arg->skip) {
arg->count++;
continue;
}
if (arg->fn(sch, prio + 1, arg) < 0) {
arg->stop = 1;
break;
}
arg->count++;
}
}
static struct tcf_block *prio_tcf_block(struct Qdisc *sch, unsigned long cl)
{
struct prio_sched_data *q = qdisc_priv(sch);
if (cl)
return NULL;
return q->block;
}
static const struct Qdisc_class_ops prio_class_ops = {
.graft = prio_graft,
.leaf = prio_leaf,
.find = prio_find,
.walk = prio_walk,
.tcf_block = prio_tcf_block,
.bind_tcf = prio_bind,
.unbind_tcf = prio_unbind,
.dump = prio_dump_class,
.dump_stats = prio_dump_class_stats,
};
static struct Qdisc_ops prio_qdisc_ops __read_mostly = {
.next = NULL,
.cl_ops = &prio_class_ops,
.id = "prio",
.priv_size = sizeof(struct prio_sched_data),
.enqueue = prio_enqueue,
.dequeue = prio_dequeue,
.peek = prio_peek,
.init = prio_init,
.reset = prio_reset,
.destroy = prio_destroy,
.change = prio_tune,
.dump = prio_dump,
.owner = THIS_MODULE,
};
static int __init prio_module_init(void)
{
return register_qdisc(&prio_qdisc_ops);
}
static void __exit prio_module_exit(void)
{
unregister_qdisc(&prio_qdisc_ops);
}
module_init(prio_module_init)
module_exit(prio_module_exit)
MODULE_LICENSE("GPL");