mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7fd4b288ea
Each lockless action currently does its own RCU locking in ->act(). This allows using plain RCU accessor, even if the context is really RCU BH. This change drops the per action RCU lock, replace the accessors with the _bh variant, cleans up a bit the surrounding code and documents the RCU status in the relevant header. No functional nor performance change is intended. The goal of this patch is clarifying that the RCU critical section used by the tc actions extends up to the classifier's caller. v1 -> v2: - preserve rcu lock in act_bpf: it's needed by eBPF helpers, as pointed out by Daniel v3 -> v4: - fixed some typos in the commit message (JiriP) Signed-off-by: Paolo Abeni <pabeni@redhat.com> Acked-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
280 lines
7.1 KiB
C
280 lines
7.1 KiB
C
/*
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* net/sched/act_sample.c - Packet sampling tc action
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* Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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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/module.h>
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#include <linux/init.h>
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#include <linux/gfp.h>
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#include <net/net_namespace.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <linux/tc_act/tc_sample.h>
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#include <net/tc_act/tc_sample.h>
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#include <net/psample.h>
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#include <linux/if_arp.h>
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static unsigned int sample_net_id;
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static struct tc_action_ops act_sample_ops;
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static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
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[TCA_SAMPLE_PARMS] = { .len = sizeof(struct tc_sample) },
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[TCA_SAMPLE_RATE] = { .type = NLA_U32 },
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[TCA_SAMPLE_TRUNC_SIZE] = { .type = NLA_U32 },
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[TCA_SAMPLE_PSAMPLE_GROUP] = { .type = NLA_U32 },
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};
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static int tcf_sample_init(struct net *net, struct nlattr *nla,
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struct nlattr *est, struct tc_action **a, int ovr,
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int bind, bool rtnl_held,
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struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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struct nlattr *tb[TCA_SAMPLE_MAX + 1];
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struct psample_group *psample_group;
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struct tc_sample *parm;
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struct tcf_sample *s;
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bool exists = false;
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int ret, err;
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if (!nla)
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return -EINVAL;
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ret = nla_parse_nested(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL);
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if (ret < 0)
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return ret;
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if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
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!tb[TCA_SAMPLE_PSAMPLE_GROUP])
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return -EINVAL;
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parm = nla_data(tb[TCA_SAMPLE_PARMS]);
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err = tcf_idr_check_alloc(tn, &parm->index, a, bind);
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if (err < 0)
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return err;
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exists = err;
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if (exists && bind)
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return 0;
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if (!exists) {
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ret = tcf_idr_create(tn, parm->index, est, a,
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&act_sample_ops, bind, false);
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if (ret) {
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tcf_idr_cleanup(tn, parm->index);
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return ret;
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}
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ret = ACT_P_CREATED;
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} else if (!ovr) {
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tcf_idr_release(*a, bind);
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return -EEXIST;
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}
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s = to_sample(*a);
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s->tcf_action = parm->action;
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s->rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
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s->psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
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psample_group = psample_group_get(net, s->psample_group_num);
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if (!psample_group) {
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tcf_idr_release(*a, bind);
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return -ENOMEM;
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}
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RCU_INIT_POINTER(s->psample_group, psample_group);
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if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
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s->truncate = true;
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s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
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}
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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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}
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static void tcf_sample_cleanup(struct tc_action *a)
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{
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struct tcf_sample *s = to_sample(a);
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struct psample_group *psample_group;
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psample_group = rtnl_dereference(s->psample_group);
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RCU_INIT_POINTER(s->psample_group, NULL);
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if (psample_group)
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psample_group_put(psample_group);
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}
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static bool tcf_sample_dev_ok_push(struct net_device *dev)
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{
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switch (dev->type) {
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case ARPHRD_TUNNEL:
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case ARPHRD_TUNNEL6:
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case ARPHRD_SIT:
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case ARPHRD_IPGRE:
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case ARPHRD_VOID:
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case ARPHRD_NONE:
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return false;
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default:
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return true;
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}
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}
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static int tcf_sample_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_sample *s = to_sample(a);
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struct psample_group *psample_group;
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int retval;
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int size;
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int iif;
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int oif;
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tcf_lastuse_update(&s->tcf_tm);
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bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
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retval = READ_ONCE(s->tcf_action);
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psample_group = rcu_dereference_bh(s->psample_group);
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/* randomly sample packets according to rate */
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if (psample_group && (prandom_u32() % s->rate == 0)) {
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if (!skb_at_tc_ingress(skb)) {
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iif = skb->skb_iif;
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oif = skb->dev->ifindex;
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} else {
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iif = skb->dev->ifindex;
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oif = 0;
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}
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/* on ingress, the mac header gets popped, so push it back */
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if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
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skb_push(skb, skb->mac_len);
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size = s->truncate ? s->trunc_size : skb->len;
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psample_sample_packet(psample_group, skb, size, iif, oif,
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s->rate);
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if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
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skb_pull(skb, skb->mac_len);
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}
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return retval;
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}
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static int tcf_sample_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_sample *s = to_sample(a);
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struct tc_sample opt = {
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.index = s->tcf_index,
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.action = s->tcf_action,
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.refcnt = refcount_read(&s->tcf_refcnt) - ref,
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.bindcnt = atomic_read(&s->tcf_bindcnt) - bind,
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};
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struct tcf_t t;
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if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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tcf_tm_dump(&t, &s->tcf_tm);
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if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
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goto nla_put_failure;
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if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
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goto nla_put_failure;
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if (s->truncate)
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if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
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goto nla_put_failure;
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if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
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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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static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
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struct netlink_callback *cb, int type,
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const struct tc_action_ops *ops,
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struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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return tcf_generic_walker(tn, skb, cb, type, ops, extack);
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}
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static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index,
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struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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return tcf_idr_search(tn, a, index);
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}
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static int tcf_sample_delete(struct net *net, u32 index)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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return tcf_idr_delete_index(tn, index);
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}
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static struct tc_action_ops act_sample_ops = {
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.kind = "sample",
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.type = TCA_ACT_SAMPLE,
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.owner = THIS_MODULE,
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.act = tcf_sample_act,
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.dump = tcf_sample_dump,
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.init = tcf_sample_init,
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.cleanup = tcf_sample_cleanup,
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.walk = tcf_sample_walker,
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.lookup = tcf_sample_search,
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.delete = tcf_sample_delete,
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.size = sizeof(struct tcf_sample),
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};
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static __net_init int sample_init_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, sample_net_id);
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return tc_action_net_init(tn, &act_sample_ops);
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}
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static void __net_exit sample_exit_net(struct list_head *net_list)
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{
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tc_action_net_exit(net_list, sample_net_id);
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}
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static struct pernet_operations sample_net_ops = {
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.init = sample_init_net,
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.exit_batch = sample_exit_net,
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.id = &sample_net_id,
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.size = sizeof(struct tc_action_net),
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};
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static int __init sample_init_module(void)
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{
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return tcf_register_action(&act_sample_ops, &sample_net_ops);
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}
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static void __exit sample_cleanup_module(void)
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{
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tcf_unregister_action(&act_sample_ops, &sample_net_ops);
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}
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module_init(sample_init_module);
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module_exit(sample_cleanup_module);
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MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
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MODULE_DESCRIPTION("Packet sampling action");
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MODULE_LICENSE("GPL v2");
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