linux/net/sched/act_police.c
Ahmed S. Darwish 29cbcd8582 net: sched: Remove Qdisc::running sequence counter
The Qdisc::running sequence counter has two uses:

  1. Reliably reading qdisc's tc statistics while the qdisc is running
     (a seqcount read/retry loop at gnet_stats_add_basic()).

  2. As a flag, indicating whether the qdisc in question is running
     (without any retry loops).

For the first usage, the Qdisc::running sequence counter write section,
qdisc_run_begin() => qdisc_run_end(), covers a much wider area than what
is actually needed: the raw qdisc's bstats update. A u64_stats sync
point was thus introduced (in previous commits) inside the bstats
structure itself. A local u64_stats write section is then started and
stopped for the bstats updates.

Use that u64_stats sync point mechanism for the bstats read/retry loop
at gnet_stats_add_basic().

For the second qdisc->running usage, a __QDISC_STATE_RUNNING bit flag,
accessed with atomic bitops, is sufficient. Using a bit flag instead of
a sequence counter at qdisc_run_begin/end() and qdisc_is_running() leads
to the SMP barriers implicitly added through raw_read_seqcount() and
write_seqcount_begin/end() getting removed. All call sites have been
surveyed though, and no required ordering was identified.

Now that the qdisc->running sequence counter is no longer used, remove
it.

Note, using u64_stats implies no sequence counter protection for 64-bit
architectures. This can lead to the qdisc tc statistics "packets" vs.
"bytes" values getting out of sync on rare occasions. The individual
values will still be valid.

Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-10-18 12:54:41 +01:00

457 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/sched/act_police.c Input police filter
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
* J Hadi Salim (action changes)
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <net/act_api.h>
#include <net/netlink.h>
#include <net/pkt_cls.h>
#include <net/tc_act/tc_police.h>
/* Each policer is serialized by its individual spinlock */
static unsigned int police_net_id;
static struct tc_action_ops act_police_ops;
static int tcf_police_walker(struct net *net, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, police_net_id);
return tcf_generic_walker(tn, skb, cb, type, ops, extack);
}
static const struct nla_policy police_policy[TCA_POLICE_MAX + 1] = {
[TCA_POLICE_RATE] = { .len = TC_RTAB_SIZE },
[TCA_POLICE_PEAKRATE] = { .len = TC_RTAB_SIZE },
[TCA_POLICE_AVRATE] = { .type = NLA_U32 },
[TCA_POLICE_RESULT] = { .type = NLA_U32 },
[TCA_POLICE_RATE64] = { .type = NLA_U64 },
[TCA_POLICE_PEAKRATE64] = { .type = NLA_U64 },
[TCA_POLICE_PKTRATE64] = { .type = NLA_U64, .min = 1 },
[TCA_POLICE_PKTBURST64] = { .type = NLA_U64, .min = 1 },
};
static int tcf_police_init(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **a,
struct tcf_proto *tp, u32 flags,
struct netlink_ext_ack *extack)
{
int ret = 0, tcfp_result = TC_ACT_OK, err, size;
bool bind = flags & TCA_ACT_FLAGS_BIND;
struct nlattr *tb[TCA_POLICE_MAX + 1];
struct tcf_chain *goto_ch = NULL;
struct tc_police *parm;
struct tcf_police *police;
struct qdisc_rate_table *R_tab = NULL, *P_tab = NULL;
struct tc_action_net *tn = net_generic(net, police_net_id);
struct tcf_police_params *new;
bool exists = false;
u32 index;
u64 rate64, prate64;
u64 pps, ppsburst;
if (nla == NULL)
return -EINVAL;
err = nla_parse_nested_deprecated(tb, TCA_POLICE_MAX, nla,
police_policy, NULL);
if (err < 0)
return err;
if (tb[TCA_POLICE_TBF] == NULL)
return -EINVAL;
size = nla_len(tb[TCA_POLICE_TBF]);
if (size != sizeof(*parm) && size != sizeof(struct tc_police_compat))
return -EINVAL;
parm = nla_data(tb[TCA_POLICE_TBF]);
index = parm->index;
err = tcf_idr_check_alloc(tn, &index, a, bind);
if (err < 0)
return err;
exists = err;
if (exists && bind)
return 0;
if (!exists) {
ret = tcf_idr_create(tn, index, NULL, a,
&act_police_ops, bind, true, 0);
if (ret) {
tcf_idr_cleanup(tn, index);
return ret;
}
ret = ACT_P_CREATED;
spin_lock_init(&(to_police(*a)->tcfp_lock));
} else if (!(flags & TCA_ACT_FLAGS_REPLACE)) {
tcf_idr_release(*a, bind);
return -EEXIST;
}
err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
if (err < 0)
goto release_idr;
police = to_police(*a);
if (parm->rate.rate) {
err = -ENOMEM;
R_tab = qdisc_get_rtab(&parm->rate, tb[TCA_POLICE_RATE], NULL);
if (R_tab == NULL)
goto failure;
if (parm->peakrate.rate) {
P_tab = qdisc_get_rtab(&parm->peakrate,
tb[TCA_POLICE_PEAKRATE], NULL);
if (P_tab == NULL)
goto failure;
}
}
if (est) {
err = gen_replace_estimator(&police->tcf_bstats,
police->common.cpu_bstats,
&police->tcf_rate_est,
&police->tcf_lock,
false, est);
if (err)
goto failure;
} else if (tb[TCA_POLICE_AVRATE] &&
(ret == ACT_P_CREATED ||
!gen_estimator_active(&police->tcf_rate_est))) {
err = -EINVAL;
goto failure;
}
if (tb[TCA_POLICE_RESULT]) {
tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);
if (TC_ACT_EXT_CMP(tcfp_result, TC_ACT_GOTO_CHAIN)) {
NL_SET_ERR_MSG(extack,
"goto chain not allowed on fallback");
err = -EINVAL;
goto failure;
}
}
if ((tb[TCA_POLICE_PKTRATE64] && !tb[TCA_POLICE_PKTBURST64]) ||
(!tb[TCA_POLICE_PKTRATE64] && tb[TCA_POLICE_PKTBURST64])) {
NL_SET_ERR_MSG(extack,
"Both or neither packet-per-second burst and rate must be provided");
err = -EINVAL;
goto failure;
}
if (tb[TCA_POLICE_PKTRATE64] && R_tab) {
NL_SET_ERR_MSG(extack,
"packet-per-second and byte-per-second rate limits not allowed in same action");
err = -EINVAL;
goto failure;
}
new = kzalloc(sizeof(*new), GFP_KERNEL);
if (unlikely(!new)) {
err = -ENOMEM;
goto failure;
}
/* No failure allowed after this point */
new->tcfp_result = tcfp_result;
new->tcfp_mtu = parm->mtu;
if (!new->tcfp_mtu) {
new->tcfp_mtu = ~0;
if (R_tab)
new->tcfp_mtu = 255 << R_tab->rate.cell_log;
}
if (R_tab) {
new->rate_present = true;
rate64 = tb[TCA_POLICE_RATE64] ?
nla_get_u64(tb[TCA_POLICE_RATE64]) : 0;
psched_ratecfg_precompute(&new->rate, &R_tab->rate, rate64);
qdisc_put_rtab(R_tab);
} else {
new->rate_present = false;
}
if (P_tab) {
new->peak_present = true;
prate64 = tb[TCA_POLICE_PEAKRATE64] ?
nla_get_u64(tb[TCA_POLICE_PEAKRATE64]) : 0;
psched_ratecfg_precompute(&new->peak, &P_tab->rate, prate64);
qdisc_put_rtab(P_tab);
} else {
new->peak_present = false;
}
new->tcfp_burst = PSCHED_TICKS2NS(parm->burst);
if (new->peak_present)
new->tcfp_mtu_ptoks = (s64)psched_l2t_ns(&new->peak,
new->tcfp_mtu);
if (tb[TCA_POLICE_AVRATE])
new->tcfp_ewma_rate = nla_get_u32(tb[TCA_POLICE_AVRATE]);
if (tb[TCA_POLICE_PKTRATE64]) {
pps = nla_get_u64(tb[TCA_POLICE_PKTRATE64]);
ppsburst = nla_get_u64(tb[TCA_POLICE_PKTBURST64]);
new->pps_present = true;
new->tcfp_pkt_burst = PSCHED_TICKS2NS(ppsburst);
psched_ppscfg_precompute(&new->ppsrate, pps);
}
spin_lock_bh(&police->tcf_lock);
spin_lock_bh(&police->tcfp_lock);
police->tcfp_t_c = ktime_get_ns();
police->tcfp_toks = new->tcfp_burst;
if (new->peak_present)
police->tcfp_ptoks = new->tcfp_mtu_ptoks;
spin_unlock_bh(&police->tcfp_lock);
goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
new = rcu_replace_pointer(police->params,
new,
lockdep_is_held(&police->tcf_lock));
spin_unlock_bh(&police->tcf_lock);
if (goto_ch)
tcf_chain_put_by_act(goto_ch);
if (new)
kfree_rcu(new, rcu);
return ret;
failure:
qdisc_put_rtab(P_tab);
qdisc_put_rtab(R_tab);
if (goto_ch)
tcf_chain_put_by_act(goto_ch);
release_idr:
tcf_idr_release(*a, bind);
return err;
}
static int tcf_police_act(struct sk_buff *skb, const struct tc_action *a,
struct tcf_result *res)
{
struct tcf_police *police = to_police(a);
s64 now, toks, ppstoks = 0, ptoks = 0;
struct tcf_police_params *p;
int ret;
tcf_lastuse_update(&police->tcf_tm);
bstats_update(this_cpu_ptr(police->common.cpu_bstats), skb);
ret = READ_ONCE(police->tcf_action);
p = rcu_dereference_bh(police->params);
if (p->tcfp_ewma_rate) {
struct gnet_stats_rate_est64 sample;
if (!gen_estimator_read(&police->tcf_rate_est, &sample) ||
sample.bps >= p->tcfp_ewma_rate)
goto inc_overlimits;
}
if (qdisc_pkt_len(skb) <= p->tcfp_mtu) {
if (!p->rate_present && !p->pps_present) {
ret = p->tcfp_result;
goto end;
}
now = ktime_get_ns();
spin_lock_bh(&police->tcfp_lock);
toks = min_t(s64, now - police->tcfp_t_c, p->tcfp_burst);
if (p->peak_present) {
ptoks = toks + police->tcfp_ptoks;
if (ptoks > p->tcfp_mtu_ptoks)
ptoks = p->tcfp_mtu_ptoks;
ptoks -= (s64)psched_l2t_ns(&p->peak,
qdisc_pkt_len(skb));
}
if (p->rate_present) {
toks += police->tcfp_toks;
if (toks > p->tcfp_burst)
toks = p->tcfp_burst;
toks -= (s64)psched_l2t_ns(&p->rate, qdisc_pkt_len(skb));
} else if (p->pps_present) {
ppstoks = min_t(s64, now - police->tcfp_t_c, p->tcfp_pkt_burst);
ppstoks += police->tcfp_pkttoks;
if (ppstoks > p->tcfp_pkt_burst)
ppstoks = p->tcfp_pkt_burst;
ppstoks -= (s64)psched_pkt2t_ns(&p->ppsrate, 1);
}
if ((toks | ptoks | ppstoks) >= 0) {
police->tcfp_t_c = now;
police->tcfp_toks = toks;
police->tcfp_ptoks = ptoks;
police->tcfp_pkttoks = ppstoks;
spin_unlock_bh(&police->tcfp_lock);
ret = p->tcfp_result;
goto inc_drops;
}
spin_unlock_bh(&police->tcfp_lock);
}
inc_overlimits:
qstats_overlimit_inc(this_cpu_ptr(police->common.cpu_qstats));
inc_drops:
if (ret == TC_ACT_SHOT)
qstats_drop_inc(this_cpu_ptr(police->common.cpu_qstats));
end:
return ret;
}
static void tcf_police_cleanup(struct tc_action *a)
{
struct tcf_police *police = to_police(a);
struct tcf_police_params *p;
p = rcu_dereference_protected(police->params, 1);
if (p)
kfree_rcu(p, rcu);
}
static void tcf_police_stats_update(struct tc_action *a,
u64 bytes, u64 packets, u64 drops,
u64 lastuse, bool hw)
{
struct tcf_police *police = to_police(a);
struct tcf_t *tm = &police->tcf_tm;
tcf_action_update_stats(a, bytes, packets, drops, hw);
tm->lastuse = max_t(u64, tm->lastuse, lastuse);
}
static int tcf_police_dump(struct sk_buff *skb, struct tc_action *a,
int bind, int ref)
{
unsigned char *b = skb_tail_pointer(skb);
struct tcf_police *police = to_police(a);
struct tcf_police_params *p;
struct tc_police opt = {
.index = police->tcf_index,
.refcnt = refcount_read(&police->tcf_refcnt) - ref,
.bindcnt = atomic_read(&police->tcf_bindcnt) - bind,
};
struct tcf_t t;
spin_lock_bh(&police->tcf_lock);
opt.action = police->tcf_action;
p = rcu_dereference_protected(police->params,
lockdep_is_held(&police->tcf_lock));
opt.mtu = p->tcfp_mtu;
opt.burst = PSCHED_NS2TICKS(p->tcfp_burst);
if (p->rate_present) {
psched_ratecfg_getrate(&opt.rate, &p->rate);
if ((police->params->rate.rate_bytes_ps >= (1ULL << 32)) &&
nla_put_u64_64bit(skb, TCA_POLICE_RATE64,
police->params->rate.rate_bytes_ps,
TCA_POLICE_PAD))
goto nla_put_failure;
}
if (p->peak_present) {
psched_ratecfg_getrate(&opt.peakrate, &p->peak);
if ((police->params->peak.rate_bytes_ps >= (1ULL << 32)) &&
nla_put_u64_64bit(skb, TCA_POLICE_PEAKRATE64,
police->params->peak.rate_bytes_ps,
TCA_POLICE_PAD))
goto nla_put_failure;
}
if (p->pps_present) {
if (nla_put_u64_64bit(skb, TCA_POLICE_PKTRATE64,
police->params->ppsrate.rate_pkts_ps,
TCA_POLICE_PAD))
goto nla_put_failure;
if (nla_put_u64_64bit(skb, TCA_POLICE_PKTBURST64,
PSCHED_NS2TICKS(p->tcfp_pkt_burst),
TCA_POLICE_PAD))
goto nla_put_failure;
}
if (nla_put(skb, TCA_POLICE_TBF, sizeof(opt), &opt))
goto nla_put_failure;
if (p->tcfp_result &&
nla_put_u32(skb, TCA_POLICE_RESULT, p->tcfp_result))
goto nla_put_failure;
if (p->tcfp_ewma_rate &&
nla_put_u32(skb, TCA_POLICE_AVRATE, p->tcfp_ewma_rate))
goto nla_put_failure;
tcf_tm_dump(&t, &police->tcf_tm);
if (nla_put_64bit(skb, TCA_POLICE_TM, sizeof(t), &t, TCA_POLICE_PAD))
goto nla_put_failure;
spin_unlock_bh(&police->tcf_lock);
return skb->len;
nla_put_failure:
spin_unlock_bh(&police->tcf_lock);
nlmsg_trim(skb, b);
return -1;
}
static int tcf_police_search(struct net *net, struct tc_action **a, u32 index)
{
struct tc_action_net *tn = net_generic(net, police_net_id);
return tcf_idr_search(tn, a, index);
}
MODULE_AUTHOR("Alexey Kuznetsov");
MODULE_DESCRIPTION("Policing actions");
MODULE_LICENSE("GPL");
static struct tc_action_ops act_police_ops = {
.kind = "police",
.id = TCA_ID_POLICE,
.owner = THIS_MODULE,
.stats_update = tcf_police_stats_update,
.act = tcf_police_act,
.dump = tcf_police_dump,
.init = tcf_police_init,
.walk = tcf_police_walker,
.lookup = tcf_police_search,
.cleanup = tcf_police_cleanup,
.size = sizeof(struct tcf_police),
};
static __net_init int police_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, police_net_id);
return tc_action_net_init(net, tn, &act_police_ops);
}
static void __net_exit police_exit_net(struct list_head *net_list)
{
tc_action_net_exit(net_list, police_net_id);
}
static struct pernet_operations police_net_ops = {
.init = police_init_net,
.exit_batch = police_exit_net,
.id = &police_net_id,
.size = sizeof(struct tc_action_net),
};
static int __init police_init_module(void)
{
return tcf_register_action(&act_police_ops, &police_net_ops);
}
static void __exit police_cleanup_module(void)
{
tcf_unregister_action(&act_police_ops, &police_net_ops);
}
module_init(police_init_module);
module_exit(police_cleanup_module);