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Amery HungMartin KaFai Lau
Amery Hung
authored and
Martin KaFai Lau
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selftests/bpf: Add a basic fifo qdisc test
This selftest includes a bare minimum fifo qdisc, which simply enqueues sk_buffs into the back of a bpf list and dequeues from the front of the list. Signed-off-by: Amery Hung <[email protected]> Signed-off-by: Martin KaFai Lau <[email protected]> Acked-by: Toke Høiland-Jørgensen <[email protected]> Link: https://patch.msgid.link/[email protected]
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‎tools/testing/selftests/bpf/config

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@@ -71,6 +71,7 @@ CONFIG_NET_IPGRE=y
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CONFIG_NET_IPGRE_DEMUX=y
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CONFIG_NET_IPIP=y
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CONFIG_NET_MPLS_GSO=y
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CONFIG_NET_SCH_BPF=y
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CONFIG_NET_SCH_FQ=y
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CONFIG_NET_SCH_INGRESS=y
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CONFIG_NET_SCHED=y

‎tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c

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@@ -0,0 +1,81 @@
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// SPDX-License-Identifier: GPL-2.0
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#include <linux/pkt_sched.h>
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#include <linux/rtnetlink.h>
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#include <test_progs.h>
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#include "network_helpers.h"
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#include "bpf_qdisc_fifo.skel.h"
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#define LO_IFINDEX 1
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static const unsigned int total_bytes = 10 * 1024 * 1024;
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static void do_test(char *qdisc)
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{
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DECLARE_LIBBPF_OPTS(bpf_tc_hook, hook, .ifindex = LO_IFINDEX,
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.attach_point = BPF_TC_QDISC,
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.parent = TC_H_ROOT,
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.handle = 0x8000000,
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.qdisc = qdisc);
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int srv_fd = -1, cli_fd = -1;
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int err;
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err = bpf_tc_hook_create(&hook);
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if (!ASSERT_OK(err, "attach qdisc"))
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return;
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srv_fd = start_server(AF_INET6, SOCK_STREAM, NULL, 0, 0);
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if (!ASSERT_OK_FD(srv_fd, "start server"))
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goto done;
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cli_fd = connect_to_fd(srv_fd, 0);
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if (!ASSERT_OK_FD(cli_fd, "connect to client"))
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goto done;
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err = send_recv_data(srv_fd, cli_fd, total_bytes);
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ASSERT_OK(err, "send_recv_data");
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done:
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if (srv_fd != -1)
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close(srv_fd);
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if (cli_fd != -1)
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close(cli_fd);
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bpf_tc_hook_destroy(&hook);
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}
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static void test_fifo(void)
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{
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struct bpf_qdisc_fifo *fifo_skel;
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struct bpf_link *link;
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fifo_skel = bpf_qdisc_fifo__open_and_load();
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if (!ASSERT_OK_PTR(fifo_skel, "bpf_qdisc_fifo__open_and_load"))
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return;
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link = bpf_map__attach_struct_ops(fifo_skel->maps.fifo);
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if (!ASSERT_OK_PTR(link, "bpf_map__attach_struct_ops")) {
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bpf_qdisc_fifo__destroy(fifo_skel);
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return;
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}
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do_test("bpf_fifo");
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bpf_link__destroy(link);
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bpf_qdisc_fifo__destroy(fifo_skel);
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}
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void test_bpf_qdisc(void)
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{
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struct netns_obj *netns;
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netns = netns_new("bpf_qdisc_ns", true);
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if (!ASSERT_OK_PTR(netns, "netns_new"))
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return;
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if (test__start_subtest("fifo"))
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test_fifo();
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netns_free(netns);
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}

‎tools/testing/selftests/bpf/progs/bpf_qdisc_common.h

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@@ -0,0 +1,31 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _BPF_QDISC_COMMON_H
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#define _BPF_QDISC_COMMON_H
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#define NET_XMIT_SUCCESS 0x00
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#define NET_XMIT_DROP 0x01 /* skb dropped */
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#define NET_XMIT_CN 0x02 /* congestion notification */
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#define TC_PRIO_CONTROL 7
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#define TC_PRIO_MAX 15
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#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
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u32 bpf_skb_get_hash(struct sk_buff *p) __ksym;
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void bpf_kfree_skb(struct sk_buff *p) __ksym;
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void bpf_qdisc_skb_drop(struct sk_buff *p, struct bpf_sk_buff_ptr *to_free) __ksym;
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void bpf_qdisc_watchdog_schedule(struct Qdisc *sch, u64 expire, u64 delta_ns) __ksym;
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void bpf_qdisc_bstats_update(struct Qdisc *sch, const struct sk_buff *skb) __ksym;
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static struct qdisc_skb_cb *qdisc_skb_cb(const struct sk_buff *skb)
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{
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return (struct qdisc_skb_cb *)skb->cb;
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}
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static inline unsigned int qdisc_pkt_len(const struct sk_buff *skb)
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{
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return qdisc_skb_cb(skb)->pkt_len;
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}
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#endif

‎tools/testing/selftests/bpf/progs/bpf_qdisc_fifo.c

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// SPDX-License-Identifier: GPL-2.0
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#include <vmlinux.h>
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#include "bpf_experimental.h"
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#include "bpf_qdisc_common.h"
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char _license[] SEC("license") = "GPL";
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struct skb_node {
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struct sk_buff __kptr * skb;
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struct bpf_list_node node;
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};
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private(A) struct bpf_spin_lock q_fifo_lock;
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private(A) struct bpf_list_head q_fifo __contains(skb_node, node);
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SEC("struct_ops/bpf_fifo_enqueue")
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int BPF_PROG(bpf_fifo_enqueue, struct sk_buff *skb, struct Qdisc *sch,
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struct bpf_sk_buff_ptr *to_free)
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{
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struct skb_node *skbn;
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u32 pkt_len;
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if (sch->q.qlen == sch->limit)
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goto drop;
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skbn = bpf_obj_new(typeof(*skbn));
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if (!skbn)
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goto drop;
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pkt_len = qdisc_pkt_len(skb);
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sch->q.qlen++;
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skb = bpf_kptr_xchg(&skbn->skb, skb);
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if (skb)
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bpf_qdisc_skb_drop(skb, to_free);
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bpf_spin_lock(&q_fifo_lock);
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bpf_list_push_back(&q_fifo, &skbn->node);
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bpf_spin_unlock(&q_fifo_lock);
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sch->qstats.backlog += pkt_len;
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return NET_XMIT_SUCCESS;
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drop:
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bpf_qdisc_skb_drop(skb, to_free);
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return NET_XMIT_DROP;
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}
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SEC("struct_ops/bpf_fifo_dequeue")
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struct sk_buff *BPF_PROG(bpf_fifo_dequeue, struct Qdisc *sch)
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{
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struct bpf_list_node *node;
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struct sk_buff *skb = NULL;
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struct skb_node *skbn;
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bpf_spin_lock(&q_fifo_lock);
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node = bpf_list_pop_front(&q_fifo);
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bpf_spin_unlock(&q_fifo_lock);
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if (!node)
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return NULL;
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skbn = container_of(node, struct skb_node, node);
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skb = bpf_kptr_xchg(&skbn->skb, skb);
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bpf_obj_drop(skbn);
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if (!skb)
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return NULL;
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sch->qstats.backlog -= qdisc_pkt_len(skb);
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bpf_qdisc_bstats_update(sch, skb);
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sch->q.qlen--;
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return skb;
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}
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SEC("struct_ops/bpf_fifo_init")
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int BPF_PROG(bpf_fifo_init, struct Qdisc *sch, struct nlattr *opt,
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struct netlink_ext_ack *extack)
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{
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sch->limit = 1000;
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return 0;
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}
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SEC("struct_ops/bpf_fifo_reset")
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void BPF_PROG(bpf_fifo_reset, struct Qdisc *sch)
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{
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struct bpf_list_node *node;
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struct skb_node *skbn;
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int i;
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bpf_for(i, 0, sch->q.qlen) {
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struct sk_buff *skb = NULL;
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bpf_spin_lock(&q_fifo_lock);
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node = bpf_list_pop_front(&q_fifo);
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bpf_spin_unlock(&q_fifo_lock);
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if (!node)
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break;
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skbn = container_of(node, struct skb_node, node);
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skb = bpf_kptr_xchg(&skbn->skb, skb);
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if (skb)
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bpf_kfree_skb(skb);
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bpf_obj_drop(skbn);
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}
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sch->q.qlen = 0;
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}
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SEC(".struct_ops")
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struct Qdisc_ops fifo = {
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.enqueue = (void *)bpf_fifo_enqueue,
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.dequeue = (void *)bpf_fifo_dequeue,
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.init = (void *)bpf_fifo_init,
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.reset = (void *)bpf_fifo_reset,
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.id = "bpf_fifo",
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};
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