net/sched: act_police: don't use spinlock in the data path
use RCU instead of spinlocks, to protect concurrent read/write on act_police configuration. This reduces the effects of contention in the data path, in case multiple readers are present. Signed-off-by: Davide Caratti <dcaratti@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Davide Caratti
David S. Miller
Родитель
93be42f917
Коммит
2d550dbad8
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@ -22,8 +22,7 @@
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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 tc_action common;
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struct tcf_police_params {
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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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@ -36,6 +35,12 @@ struct tcf_police {
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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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struct rcu_head rcu;
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};
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struct tcf_police {
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struct tc_action common;
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struct tcf_police_params __rcu *params;
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};
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#define to_police(pc) ((struct tcf_police *)pc)
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@ -84,6 +89,7 @@ static int tcf_police_init(struct net *net, struct nlattr *nla,
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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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struct tc_action_net *tn = net_generic(net, police_net_id);
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struct tcf_police_params *new;
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bool exists = false;
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int size;
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@ -151,50 +157,60 @@ static int tcf_police_init(struct net *net, struct nlattr *nla,
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goto failure;
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}
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spin_lock_bh(&police->tcf_lock);
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new = kzalloc(sizeof(*new), GFP_KERNEL);
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if (unlikely(!new)) {
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err = -ENOMEM;
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goto failure;
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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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new->tcfp_mtu = parm->mtu;
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if (!new->tcfp_mtu) {
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new->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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new->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, 0);
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new->rate_present = true;
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psched_ratecfg_precompute(&new->rate, &R_tab->rate, 0);
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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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new->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, 0);
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new->peak_present = true;
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psched_ratecfg_precompute(&new->peak, &P_tab->rate, 0);
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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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new->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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new->tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);
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new->tcfp_burst = PSCHED_TICKS2NS(parm->burst);
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new->tcfp_toks = new->tcfp_burst;
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if (new->peak_present) {
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new->tcfp_mtu_ptoks = (s64)psched_l2t_ns(&new->peak,
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new->tcfp_mtu);
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new->tcfp_ptoks = new->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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new->tcfp_ewma_rate = nla_get_u32(tb[TCA_POLICE_AVRATE]);
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spin_lock_bh(&police->tcf_lock);
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new->tcfp_t_c = ktime_get_ns();
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police->tcf_action = parm->action;
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rcu_swap_protected(police->params,
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new,
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lockdep_is_held(&police->tcf_lock));
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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_get_ns();
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tcf_idr_insert(tn, *a);
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if (new)
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kfree_rcu(new, rcu);
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if (ret == ACT_P_CREATED)
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tcf_idr_insert(tn, *a);
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return ret;
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failure:
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@ -208,68 +224,77 @@ static int tcf_police_act(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 = to_police(a);
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struct tcf_police_params *p;
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s64 now, toks, ptoks = 0;
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int ret;
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tcf_lastuse_update(&police->tcf_tm);
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bstats_cpu_update(this_cpu_ptr(police->common.cpu_bstats), skb);
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spin_lock(&police->tcf_lock);
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if (police->tcfp_ewma_rate) {
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ret = READ_ONCE(police->tcf_action);
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p = rcu_dereference_bh(police->params);
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if (p->tcfp_ewma_rate) {
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struct gnet_stats_rate_est64 sample;
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if (!gen_estimator_read(&police->tcf_rate_est, &sample) ||
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sample.bps >= police->tcfp_ewma_rate) {
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ret = police->tcf_action;
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sample.bps >= p->tcfp_ewma_rate)
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goto inc_overlimits;
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}
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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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ret = police->tcfp_result;
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goto unlock;
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if (qdisc_pkt_len(skb) <= p->tcfp_mtu) {
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if (!p->rate_present) {
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ret = p->tcfp_result;
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goto end;
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}
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now = ktime_get_ns();
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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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toks = min_t(s64, now - p->tcfp_t_c, p->tcfp_burst);
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if (p->peak_present) {
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ptoks = toks + p->tcfp_ptoks;
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if (ptoks > p->tcfp_mtu_ptoks)
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ptoks = p->tcfp_mtu_ptoks;
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ptoks -= (s64)psched_l2t_ns(&p->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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toks += p->tcfp_toks;
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if (toks > p->tcfp_burst)
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toks = p->tcfp_burst;
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toks -= (s64)psched_l2t_ns(&p->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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ret = police->tcfp_result;
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p->tcfp_t_c = now;
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p->tcfp_toks = toks;
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p->tcfp_ptoks = ptoks;
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ret = p->tcfp_result;
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goto inc_drops;
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}
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}
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ret = police->tcf_action;
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inc_overlimits:
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qstats_overlimit_inc(this_cpu_ptr(police->common.cpu_qstats));
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inc_drops:
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if (ret == TC_ACT_SHOT)
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qstats_drop_inc(this_cpu_ptr(police->common.cpu_qstats));
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unlock:
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spin_unlock(&police->tcf_lock);
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end:
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return ret;
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}
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static void tcf_police_cleanup(struct tc_action *a)
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{
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struct tcf_police *police = to_police(a);
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struct tcf_police_params *p;
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p = rcu_dereference_protected(police->params, 1);
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if (p)
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kfree_rcu(p, rcu);
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}
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static int tcf_police_dump(struct sk_buff *skb, struct tc_action *a,
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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 = to_police(a);
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struct tcf_police_params *p;
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struct tc_police opt = {
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.index = police->tcf_index,
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.refcnt = refcount_read(&police->tcf_refcnt) - ref,
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@ -279,19 +304,21 @@ static int tcf_police_dump(struct sk_buff *skb, struct tc_action *a,
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spin_lock_bh(&police->tcf_lock);
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opt.action = police->tcf_action;
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opt.mtu = police->tcfp_mtu;
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opt.burst = PSCHED_NS2TICKS(police->tcfp_burst);
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if (police->rate_present)
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psched_ratecfg_getrate(&opt.rate, &police->rate);
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if (police->peak_present)
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psched_ratecfg_getrate(&opt.peakrate, &police->peak);
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p = rcu_dereference_protected(police->params,
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lockdep_is_held(&police->tcf_lock));
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opt.mtu = p->tcfp_mtu;
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opt.burst = PSCHED_NS2TICKS(p->tcfp_burst);
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if (p->rate_present)
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psched_ratecfg_getrate(&opt.rate, &p->rate);
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if (p->peak_present)
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psched_ratecfg_getrate(&opt.peakrate, &p->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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if (p->tcfp_result &&
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nla_put_u32(skb, TCA_POLICE_RESULT, p->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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if (p->tcfp_ewma_rate &&
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nla_put_u32(skb, TCA_POLICE_AVRATE, p->tcfp_ewma_rate))
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goto nla_put_failure;
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t.install = jiffies_to_clock_t(jiffies - police->tcf_tm.install);
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@ -330,6 +357,7 @@ static struct tc_action_ops act_police_ops = {
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.init = tcf_police_init,
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.walk = tcf_police_walker,
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.lookup = tcf_police_search,
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.cleanup = tcf_police_cleanup,
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.size = sizeof(struct tcf_police),
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};
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