![Jiri Pirko](/assets/img/avatar_default.png)
Current act_police uses rate table computed by the "tc" userspace
program, which has the following issue:
The rate table has 256 entries to map packet lengths to token (time
units). With TSO sized packets, the 256 entry granularity leads to
loss/gain of rate, making the token bucket inaccurate.
Thus, instead of relying on rate table, this patch explicitly computes
the time and accounts for packet transmission times with nanosecond
granularity.
This is a followup to 56b765b79e
("htb: improved accuracy at high rates").
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>
429 lines
10 KiB
C
429 lines
10 KiB
C
/*
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* net/sched/police.c Input police filter.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
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* J Hadi Salim (action changes)
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <net/act_api.h>
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#include <net/netlink.h>
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struct tcf_police {
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struct tcf_common common;
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int tcfp_result;
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u32 tcfp_ewma_rate;
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s64 tcfp_burst;
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u32 tcfp_mtu;
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s64 tcfp_toks;
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s64 tcfp_ptoks;
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s64 tcfp_mtu_ptoks;
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s64 tcfp_t_c;
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struct psched_ratecfg rate;
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bool rate_present;
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struct psched_ratecfg peak;
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bool peak_present;
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};
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#define to_police(pc) \
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container_of(pc, struct tcf_police, common)
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#define POL_TAB_MASK 15
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static struct tcf_common *tcf_police_ht[POL_TAB_MASK + 1];
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static u32 police_idx_gen;
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static DEFINE_RWLOCK(police_lock);
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static struct tcf_hashinfo police_hash_info = {
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.htab = tcf_police_ht,
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.hmask = POL_TAB_MASK,
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.lock = &police_lock,
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};
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/* old policer structure from before tc actions */
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struct tc_police_compat {
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u32 index;
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int action;
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u32 limit;
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u32 burst;
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u32 mtu;
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struct tc_ratespec rate;
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struct tc_ratespec peakrate;
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};
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/* Each policer is serialized by its individual spinlock */
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static int tcf_act_police_walker(struct sk_buff *skb, struct netlink_callback *cb,
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int type, struct tc_action *a)
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{
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struct tcf_common *p;
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int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;
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struct nlattr *nest;
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read_lock_bh(&police_lock);
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s_i = cb->args[0];
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for (i = 0; i < (POL_TAB_MASK + 1); i++) {
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p = tcf_police_ht[tcf_hash(i, POL_TAB_MASK)];
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for (; p; p = p->tcfc_next) {
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index++;
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if (index < s_i)
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continue;
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a->priv = p;
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a->order = index;
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nest = nla_nest_start(skb, a->order);
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if (nest == NULL)
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goto nla_put_failure;
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if (type == RTM_DELACTION)
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err = tcf_action_dump_1(skb, a, 0, 1);
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else
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err = tcf_action_dump_1(skb, a, 0, 0);
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if (err < 0) {
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index--;
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nla_nest_cancel(skb, nest);
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goto done;
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}
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nla_nest_end(skb, nest);
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n_i++;
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}
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}
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done:
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read_unlock_bh(&police_lock);
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if (n_i)
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cb->args[0] += n_i;
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return n_i;
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nla_put_failure:
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nla_nest_cancel(skb, nest);
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goto done;
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}
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static void tcf_police_destroy(struct tcf_police *p)
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{
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unsigned int h = tcf_hash(p->tcf_index, POL_TAB_MASK);
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struct tcf_common **p1p;
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for (p1p = &tcf_police_ht[h]; *p1p; p1p = &(*p1p)->tcfc_next) {
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if (*p1p == &p->common) {
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write_lock_bh(&police_lock);
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*p1p = p->tcf_next;
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write_unlock_bh(&police_lock);
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gen_kill_estimator(&p->tcf_bstats,
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&p->tcf_rate_est);
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/*
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* gen_estimator est_timer() might access p->tcf_lock
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* or bstats, wait a RCU grace period before freeing p
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*/
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kfree_rcu(p, tcf_rcu);
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return;
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}
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}
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WARN_ON(1);
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}
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static const struct nla_policy police_policy[TCA_POLICE_MAX + 1] = {
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[TCA_POLICE_RATE] = { .len = TC_RTAB_SIZE },
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[TCA_POLICE_PEAKRATE] = { .len = TC_RTAB_SIZE },
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[TCA_POLICE_AVRATE] = { .type = NLA_U32 },
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[TCA_POLICE_RESULT] = { .type = NLA_U32 },
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};
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static int tcf_act_police_locate(struct net *net, struct nlattr *nla,
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struct nlattr *est, struct tc_action *a,
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int ovr, int bind)
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{
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unsigned int h;
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int ret = 0, err;
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struct nlattr *tb[TCA_POLICE_MAX + 1];
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struct tc_police *parm;
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struct tcf_police *police;
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struct qdisc_rate_table *R_tab = NULL, *P_tab = NULL;
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int size;
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if (nla == NULL)
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return -EINVAL;
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err = nla_parse_nested(tb, TCA_POLICE_MAX, nla, police_policy);
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if (err < 0)
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return err;
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if (tb[TCA_POLICE_TBF] == NULL)
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return -EINVAL;
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size = nla_len(tb[TCA_POLICE_TBF]);
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if (size != sizeof(*parm) && size != sizeof(struct tc_police_compat))
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return -EINVAL;
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parm = nla_data(tb[TCA_POLICE_TBF]);
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if (parm->index) {
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struct tcf_common *pc;
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pc = tcf_hash_lookup(parm->index, &police_hash_info);
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if (pc != NULL) {
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a->priv = pc;
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police = to_police(pc);
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if (bind) {
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police->tcf_bindcnt += 1;
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police->tcf_refcnt += 1;
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}
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if (ovr)
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goto override;
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return ret;
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}
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}
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police = kzalloc(sizeof(*police), GFP_KERNEL);
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if (police == NULL)
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return -ENOMEM;
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ret = ACT_P_CREATED;
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police->tcf_refcnt = 1;
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spin_lock_init(&police->tcf_lock);
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if (bind)
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police->tcf_bindcnt = 1;
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override:
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if (parm->rate.rate) {
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err = -ENOMEM;
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R_tab = qdisc_get_rtab(&parm->rate, tb[TCA_POLICE_RATE]);
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if (R_tab == NULL)
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goto failure;
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if (parm->peakrate.rate) {
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P_tab = qdisc_get_rtab(&parm->peakrate,
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tb[TCA_POLICE_PEAKRATE]);
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if (P_tab == NULL)
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goto failure;
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}
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}
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spin_lock_bh(&police->tcf_lock);
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if (est) {
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err = gen_replace_estimator(&police->tcf_bstats,
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&police->tcf_rate_est,
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&police->tcf_lock, est);
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if (err)
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goto failure_unlock;
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} else if (tb[TCA_POLICE_AVRATE] &&
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(ret == ACT_P_CREATED ||
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!gen_estimator_active(&police->tcf_bstats,
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&police->tcf_rate_est))) {
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err = -EINVAL;
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goto failure_unlock;
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}
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/* No failure allowed after this point */
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police->tcfp_mtu = parm->mtu;
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if (police->tcfp_mtu == 0) {
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police->tcfp_mtu = ~0;
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if (R_tab)
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police->tcfp_mtu = 255 << R_tab->rate.cell_log;
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}
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if (R_tab) {
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police->rate_present = true;
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psched_ratecfg_precompute(&police->rate, R_tab->rate.rate);
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qdisc_put_rtab(R_tab);
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} else {
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police->rate_present = false;
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}
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if (P_tab) {
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police->peak_present = true;
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psched_ratecfg_precompute(&police->peak, P_tab->rate.rate);
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qdisc_put_rtab(P_tab);
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} else {
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police->peak_present = false;
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}
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if (tb[TCA_POLICE_RESULT])
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police->tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);
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police->tcfp_burst = PSCHED_TICKS2NS(parm->burst);
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police->tcfp_toks = police->tcfp_burst;
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if (police->peak_present) {
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police->tcfp_mtu_ptoks = (s64) psched_l2t_ns(&police->peak,
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police->tcfp_mtu);
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police->tcfp_ptoks = police->tcfp_mtu_ptoks;
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}
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police->tcf_action = parm->action;
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if (tb[TCA_POLICE_AVRATE])
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police->tcfp_ewma_rate = nla_get_u32(tb[TCA_POLICE_AVRATE]);
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spin_unlock_bh(&police->tcf_lock);
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if (ret != ACT_P_CREATED)
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return ret;
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police->tcfp_t_c = ktime_to_ns(ktime_get());
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police->tcf_index = parm->index ? parm->index :
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tcf_hash_new_index(&police_idx_gen, &police_hash_info);
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h = tcf_hash(police->tcf_index, POL_TAB_MASK);
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write_lock_bh(&police_lock);
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police->tcf_next = tcf_police_ht[h];
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tcf_police_ht[h] = &police->common;
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write_unlock_bh(&police_lock);
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a->priv = police;
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return ret;
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failure_unlock:
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spin_unlock_bh(&police->tcf_lock);
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failure:
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if (P_tab)
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qdisc_put_rtab(P_tab);
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if (R_tab)
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qdisc_put_rtab(R_tab);
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if (ret == ACT_P_CREATED)
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kfree(police);
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return err;
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}
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static int tcf_act_police_cleanup(struct tc_action *a, int bind)
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{
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struct tcf_police *p = a->priv;
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int ret = 0;
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if (p != NULL) {
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if (bind)
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p->tcf_bindcnt--;
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p->tcf_refcnt--;
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if (p->tcf_refcnt <= 0 && !p->tcf_bindcnt) {
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tcf_police_destroy(p);
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ret = 1;
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}
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}
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return ret;
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}
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static int tcf_act_police(struct sk_buff *skb, const struct tc_action *a,
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struct tcf_result *res)
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{
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struct tcf_police *police = a->priv;
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s64 now;
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s64 toks;
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s64 ptoks = 0;
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spin_lock(&police->tcf_lock);
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bstats_update(&police->tcf_bstats, skb);
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if (police->tcfp_ewma_rate &&
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police->tcf_rate_est.bps >= police->tcfp_ewma_rate) {
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police->tcf_qstats.overlimits++;
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if (police->tcf_action == TC_ACT_SHOT)
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police->tcf_qstats.drops++;
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spin_unlock(&police->tcf_lock);
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return police->tcf_action;
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}
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if (qdisc_pkt_len(skb) <= police->tcfp_mtu) {
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if (!police->rate_present) {
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spin_unlock(&police->tcf_lock);
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return police->tcfp_result;
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}
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now = ktime_to_ns(ktime_get());
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toks = min_t(s64, now - police->tcfp_t_c,
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police->tcfp_burst);
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if (police->peak_present) {
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ptoks = toks + police->tcfp_ptoks;
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if (ptoks > police->tcfp_mtu_ptoks)
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ptoks = police->tcfp_mtu_ptoks;
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ptoks -= (s64) psched_l2t_ns(&police->peak,
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qdisc_pkt_len(skb));
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}
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toks += police->tcfp_toks;
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if (toks > police->tcfp_burst)
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toks = police->tcfp_burst;
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toks -= (s64) psched_l2t_ns(&police->rate, qdisc_pkt_len(skb));
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if ((toks|ptoks) >= 0) {
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police->tcfp_t_c = now;
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police->tcfp_toks = toks;
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police->tcfp_ptoks = ptoks;
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spin_unlock(&police->tcf_lock);
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return police->tcfp_result;
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}
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}
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police->tcf_qstats.overlimits++;
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if (police->tcf_action == TC_ACT_SHOT)
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police->tcf_qstats.drops++;
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spin_unlock(&police->tcf_lock);
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return police->tcf_action;
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}
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static int
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tcf_act_police_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
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{
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unsigned char *b = skb_tail_pointer(skb);
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struct tcf_police *police = a->priv;
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struct tc_police opt = {
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.index = police->tcf_index,
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.action = police->tcf_action,
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.mtu = police->tcfp_mtu,
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.burst = PSCHED_NS2TICKS(police->tcfp_burst),
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.refcnt = police->tcf_refcnt - ref,
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.bindcnt = police->tcf_bindcnt - bind,
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};
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if (police->rate_present)
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opt.rate.rate = psched_ratecfg_getrate(&police->rate);
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if (police->peak_present)
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opt.peakrate.rate = psched_ratecfg_getrate(&police->peak);
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if (nla_put(skb, TCA_POLICE_TBF, sizeof(opt), &opt))
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goto nla_put_failure;
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if (police->tcfp_result &&
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nla_put_u32(skb, TCA_POLICE_RESULT, police->tcfp_result))
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goto nla_put_failure;
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if (police->tcfp_ewma_rate &&
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nla_put_u32(skb, TCA_POLICE_AVRATE, police->tcfp_ewma_rate))
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goto nla_put_failure;
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return skb->len;
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nla_put_failure:
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nlmsg_trim(skb, b);
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return -1;
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}
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MODULE_AUTHOR("Alexey Kuznetsov");
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MODULE_DESCRIPTION("Policing actions");
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MODULE_LICENSE("GPL");
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static struct tc_action_ops act_police_ops = {
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.kind = "police",
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.hinfo = &police_hash_info,
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.type = TCA_ID_POLICE,
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.capab = TCA_CAP_NONE,
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.owner = THIS_MODULE,
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.act = tcf_act_police,
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.dump = tcf_act_police_dump,
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.cleanup = tcf_act_police_cleanup,
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.lookup = tcf_hash_search,
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.init = tcf_act_police_locate,
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.walk = tcf_act_police_walker
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};
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static int __init
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police_init_module(void)
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{
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return tcf_register_action(&act_police_ops);
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}
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static void __exit
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police_cleanup_module(void)
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{
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tcf_unregister_action(&act_police_ops);
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}
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module_init(police_init_module);
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module_exit(police_cleanup_module);
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