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linux-stable/net/sched/sch_dsmark.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

511 lines
12 KiB
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/* net/sched/sch_dsmark.c - Differentiated Services field marker */
/* Written 1998-2000 by Werner Almesberger, EPFL ICA */
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/bitops.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <net/dsfield.h>
#include <net/inet_ecn.h>
#include <asm/byteorder.h>
/*
* classid class marking
* ------- ----- -------
* n/a 0 n/a
* x:0 1 use entry [0]
* ... ... ...
* x:y y>0 y+1 use entry [y]
* ... ... ...
* x:indices-1 indices use entry [indices-1]
* ... ... ...
* x:y y+1 use entry [y & (indices-1)]
* ... ... ...
* 0xffff 0x10000 use entry [indices-1]
*/
#define NO_DEFAULT_INDEX (1 << 16)
struct mask_value {
u8 mask;
u8 value;
};
struct dsmark_qdisc_data {
struct Qdisc *q;
struct tcf_proto __rcu *filter_list;
struct tcf_block *block;
struct mask_value *mv;
u16 indices;
u8 set_tc_index;
u32 default_index; /* index range is 0...0xffff */
#define DSMARK_EMBEDDED_SZ 16
struct mask_value embedded[DSMARK_EMBEDDED_SZ];
};
static inline int dsmark_valid_index(struct dsmark_qdisc_data *p, u16 index)
{
return index <= p->indices && index > 0;
}
/* ------------------------- Class/flow operations ------------------------- */
static int dsmark_graft(struct Qdisc *sch, unsigned long arg,
struct Qdisc *new, struct Qdisc **old)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
pr_debug("%s(sch %p,[qdisc %p],new %p,old %p)\n",
__func__, sch, p, new, old);
if (new == NULL) {
new = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops,
sch->handle);
if (new == NULL)
new = &noop_qdisc;
}
*old = qdisc_replace(sch, new, &p->q);
return 0;
}
static struct Qdisc *dsmark_leaf(struct Qdisc *sch, unsigned long arg)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
return p->q;
}
static unsigned long dsmark_find(struct Qdisc *sch, u32 classid)
{
return TC_H_MIN(classid) + 1;
}
static unsigned long dsmark_bind_filter(struct Qdisc *sch,
unsigned long parent, u32 classid)
{
pr_debug("%s(sch %p,[qdisc %p],classid %x)\n",
__func__, sch, qdisc_priv(sch), classid);
return dsmark_find(sch, classid);
}
static void dsmark_unbind_filter(struct Qdisc *sch, unsigned long cl)
{
}
static const struct nla_policy dsmark_policy[TCA_DSMARK_MAX + 1] = {
[TCA_DSMARK_INDICES] = { .type = NLA_U16 },
[TCA_DSMARK_DEFAULT_INDEX] = { .type = NLA_U16 },
[TCA_DSMARK_SET_TC_INDEX] = { .type = NLA_FLAG },
[TCA_DSMARK_MASK] = { .type = NLA_U8 },
[TCA_DSMARK_VALUE] = { .type = NLA_U8 },
};
static int dsmark_change(struct Qdisc *sch, u32 classid, u32 parent,
struct nlattr **tca, unsigned long *arg)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
struct nlattr *opt = tca[TCA_OPTIONS];
struct nlattr *tb[TCA_DSMARK_MAX + 1];
int err = -EINVAL;
pr_debug("%s(sch %p,[qdisc %p],classid %x,parent %x), arg 0x%lx\n",
__func__, sch, p, classid, parent, *arg);
if (!dsmark_valid_index(p, *arg)) {
err = -ENOENT;
goto errout;
}
if (!opt)
goto errout;
err = nla_parse_nested(tb, TCA_DSMARK_MAX, opt, dsmark_policy, NULL);
if (err < 0)
goto errout;
if (tb[TCA_DSMARK_VALUE])
p->mv[*arg - 1].value = nla_get_u8(tb[TCA_DSMARK_VALUE]);
if (tb[TCA_DSMARK_MASK])
p->mv[*arg - 1].mask = nla_get_u8(tb[TCA_DSMARK_MASK]);
err = 0;
errout:
return err;
}
static int dsmark_delete(struct Qdisc *sch, unsigned long arg)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
if (!dsmark_valid_index(p, arg))
return -EINVAL;
p->mv[arg - 1].mask = 0xff;
p->mv[arg - 1].value = 0;
return 0;
}
static void dsmark_walk(struct Qdisc *sch, struct qdisc_walker *walker)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
int i;
pr_debug("%s(sch %p,[qdisc %p],walker %p)\n",
__func__, sch, p, walker);
if (walker->stop)
return;
for (i = 0; i < p->indices; i++) {
if (p->mv[i].mask == 0xff && !p->mv[i].value)
goto ignore;
if (walker->count >= walker->skip) {
if (walker->fn(sch, i + 1, walker) < 0) {
walker->stop = 1;
break;
}
}
ignore:
walker->count++;
}
}
static struct tcf_block *dsmark_tcf_block(struct Qdisc *sch, unsigned long cl)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
return p->block;
}
/* --------------------------- Qdisc operations ---------------------------- */
static int dsmark_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
int err;
pr_debug("%s(skb %p,sch %p,[qdisc %p])\n", __func__, skb, sch, p);
if (p->set_tc_index) {
int wlen = skb_network_offset(skb);
switch (tc_skb_protocol(skb)) {
case htons(ETH_P_IP):
wlen += sizeof(struct iphdr);
if (!pskb_may_pull(skb, wlen) ||
skb_try_make_writable(skb, wlen))
goto drop;
skb->tc_index = ipv4_get_dsfield(ip_hdr(skb))
& ~INET_ECN_MASK;
break;
case htons(ETH_P_IPV6):
wlen += sizeof(struct ipv6hdr);
if (!pskb_may_pull(skb, wlen) ||
skb_try_make_writable(skb, wlen))
goto drop;
skb->tc_index = ipv6_get_dsfield(ipv6_hdr(skb))
& ~INET_ECN_MASK;
break;
default:
skb->tc_index = 0;
break;
}
}
if (TC_H_MAJ(skb->priority) == sch->handle)
skb->tc_index = TC_H_MIN(skb->priority);
else {
struct tcf_result res;
struct tcf_proto *fl = rcu_dereference_bh(p->filter_list);
int result = tcf_classify(skb, fl, &res, false);
pr_debug("result %d class 0x%04x\n", result, res.classid);
switch (result) {
#ifdef CONFIG_NET_CLS_ACT
case TC_ACT_QUEUED:
case TC_ACT_STOLEN:
case TC_ACT_TRAP:
__qdisc_drop(skb, to_free);
return NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
case TC_ACT_SHOT:
goto drop;
#endif
case TC_ACT_OK:
skb->tc_index = TC_H_MIN(res.classid);
break;
default:
if (p->default_index != NO_DEFAULT_INDEX)
skb->tc_index = p->default_index;
break;
}
}
err = qdisc_enqueue(skb, p->q, to_free);
if (err != NET_XMIT_SUCCESS) {
if (net_xmit_drop_count(err))
qdisc_qstats_drop(sch);
return err;
}
qdisc_qstats_backlog_inc(sch, skb);
sch->q.qlen++;
return NET_XMIT_SUCCESS;
drop:
qdisc_drop(skb, sch, to_free);
return NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
}
static struct sk_buff *dsmark_dequeue(struct Qdisc *sch)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
struct sk_buff *skb;
u32 index;
pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
skb = qdisc_dequeue_peeked(p->q);
if (skb == NULL)
return NULL;
qdisc_bstats_update(sch, skb);
qdisc_qstats_backlog_dec(sch, skb);
sch->q.qlen--;
index = skb->tc_index & (p->indices - 1);
pr_debug("index %d->%d\n", skb->tc_index, index);
switch (tc_skb_protocol(skb)) {
case htons(ETH_P_IP):
ipv4_change_dsfield(ip_hdr(skb), p->mv[index].mask,
p->mv[index].value);
break;
case htons(ETH_P_IPV6):
ipv6_change_dsfield(ipv6_hdr(skb), p->mv[index].mask,
p->mv[index].value);
break;
default:
/*
* Only complain if a change was actually attempted.
* This way, we can send non-IP traffic through dsmark
* and don't need yet another qdisc as a bypass.
*/
if (p->mv[index].mask != 0xff || p->mv[index].value)
pr_warn("%s: unsupported protocol %d\n",
__func__, ntohs(tc_skb_protocol(skb)));
break;
}
return skb;
}
static struct sk_buff *dsmark_peek(struct Qdisc *sch)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
return p->q->ops->peek(p->q);
}
static int dsmark_init(struct Qdisc *sch, struct nlattr *opt)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
struct nlattr *tb[TCA_DSMARK_MAX + 1];
int err = -EINVAL;
u32 default_index = NO_DEFAULT_INDEX;
u16 indices;
int i;
pr_debug("%s(sch %p,[qdisc %p],opt %p)\n", __func__, sch, p, opt);
if (!opt)
goto errout;
err = tcf_block_get(&p->block, &p->filter_list);
if (err)
return err;
err = nla_parse_nested(tb, TCA_DSMARK_MAX, opt, dsmark_policy, NULL);
if (err < 0)
goto errout;
err = -EINVAL;
indices = nla_get_u16(tb[TCA_DSMARK_INDICES]);
if (hweight32(indices) != 1)
goto errout;
if (tb[TCA_DSMARK_DEFAULT_INDEX])
default_index = nla_get_u16(tb[TCA_DSMARK_DEFAULT_INDEX]);
if (indices <= DSMARK_EMBEDDED_SZ)
p->mv = p->embedded;
else
p->mv = kmalloc_array(indices, sizeof(*p->mv), GFP_KERNEL);
if (!p->mv) {
err = -ENOMEM;
goto errout;
}
for (i = 0; i < indices; i++) {
p->mv[i].mask = 0xff;
p->mv[i].value = 0;
}
p->indices = indices;
p->default_index = default_index;
p->set_tc_index = nla_get_flag(tb[TCA_DSMARK_SET_TC_INDEX]);
p->q = qdisc_create_dflt(sch->dev_queue, &pfifo_qdisc_ops, sch->handle);
if (p->q == NULL)
p->q = &noop_qdisc;
else
qdisc_hash_add(p->q, true);
pr_debug("%s: qdisc %p\n", __func__, p->q);
err = 0;
errout:
return err;
}
static void dsmark_reset(struct Qdisc *sch)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
qdisc_reset(p->q);
sch->qstats.backlog = 0;
sch->q.qlen = 0;
}
static void dsmark_destroy(struct Qdisc *sch)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
pr_debug("%s(sch %p,[qdisc %p])\n", __func__, sch, p);
tcf_block_put(p->block);
qdisc_destroy(p->q);
if (p->mv != p->embedded)
kfree(p->mv);
}
static int dsmark_dump_class(struct Qdisc *sch, unsigned long cl,
struct sk_buff *skb, struct tcmsg *tcm)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
struct nlattr *opts = NULL;
pr_debug("%s(sch %p,[qdisc %p],class %ld\n", __func__, sch, p, cl);
if (!dsmark_valid_index(p, cl))
return -EINVAL;
tcm->tcm_handle = TC_H_MAKE(TC_H_MAJ(sch->handle), cl - 1);
tcm->tcm_info = p->q->handle;
opts = nla_nest_start(skb, TCA_OPTIONS);
if (opts == NULL)
goto nla_put_failure;
if (nla_put_u8(skb, TCA_DSMARK_MASK, p->mv[cl - 1].mask) ||
nla_put_u8(skb, TCA_DSMARK_VALUE, p->mv[cl - 1].value))
goto nla_put_failure;
return nla_nest_end(skb, opts);
nla_put_failure:
nla_nest_cancel(skb, opts);
return -EMSGSIZE;
}
static int dsmark_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct dsmark_qdisc_data *p = qdisc_priv(sch);
struct nlattr *opts = NULL;
opts = nla_nest_start(skb, TCA_OPTIONS);
if (opts == NULL)
goto nla_put_failure;
if (nla_put_u16(skb, TCA_DSMARK_INDICES, p->indices))
goto nla_put_failure;
if (p->default_index != NO_DEFAULT_INDEX &&
nla_put_u16(skb, TCA_DSMARK_DEFAULT_INDEX, p->default_index))
goto nla_put_failure;
if (p->set_tc_index &&
nla_put_flag(skb, TCA_DSMARK_SET_TC_INDEX))
goto nla_put_failure;
return nla_nest_end(skb, opts);
nla_put_failure:
nla_nest_cancel(skb, opts);
return -EMSGSIZE;
}
static const struct Qdisc_class_ops dsmark_class_ops = {
.graft = dsmark_graft,
.leaf = dsmark_leaf,
.find = dsmark_find,
.change = dsmark_change,
.delete = dsmark_delete,
.walk = dsmark_walk,
.tcf_block = dsmark_tcf_block,
.bind_tcf = dsmark_bind_filter,
.unbind_tcf = dsmark_unbind_filter,
.dump = dsmark_dump_class,
};
static struct Qdisc_ops dsmark_qdisc_ops __read_mostly = {
.next = NULL,
.cl_ops = &dsmark_class_ops,
.id = "dsmark",
.priv_size = sizeof(struct dsmark_qdisc_data),
.enqueue = dsmark_enqueue,
.dequeue = dsmark_dequeue,
.peek = dsmark_peek,
.init = dsmark_init,
.reset = dsmark_reset,
.destroy = dsmark_destroy,
.change = NULL,
.dump = dsmark_dump,
.owner = THIS_MODULE,
};
static int __init dsmark_module_init(void)
{
return register_qdisc(&dsmark_qdisc_ops);
}
static void __exit dsmark_module_exit(void)
{
unregister_qdisc(&dsmark_qdisc_ops);
}
module_init(dsmark_module_init)
module_exit(dsmark_module_exit)
MODULE_LICENSE("GPL");
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