bpf_qdisc_fifo.c

  1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <vmlinux.h>
  4#include "bpf_experimental.h"
  5#include "bpf_qdisc_common.h"
  6
  7char _license[] SEC("license") = "GPL";
  8
  9struct skb_node {
 10	struct sk_buff __kptr * skb;
 11	struct bpf_list_node node;
 12};
 13
 14private(A) struct bpf_spin_lock q_fifo_lock;
 15private(A) struct bpf_list_head q_fifo __contains(skb_node, node);
 16
 17bool init_called;
 18
 19SEC("struct_ops/bpf_fifo_enqueue")
 20int BPF_PROG(bpf_fifo_enqueue, struct sk_buff *skb, struct Qdisc *sch,
 21	     struct bpf_sk_buff_ptr *to_free)
 22{
 23	struct skb_node *skbn;
 24	u32 pkt_len;
 25
 26	if (sch->q.qlen == sch->limit)
 27		goto drop;
 28
 29	skbn = bpf_obj_new(typeof(*skbn));
 30	if (!skbn)
 31		goto drop;
 32
 33	pkt_len = qdisc_pkt_len(skb);
 34
 35	sch->q.qlen++;
 36	skb = bpf_kptr_xchg(&skbn->skb, skb);
 37	if (skb)
 38		bpf_qdisc_skb_drop(skb, to_free);
 39
 40	bpf_spin_lock(&q_fifo_lock);
 41	bpf_list_push_back(&q_fifo, &skbn->node);
 42	bpf_spin_unlock(&q_fifo_lock);
 43
 44	sch->qstats.backlog += pkt_len;
 45	return NET_XMIT_SUCCESS;
 46drop:
 47	bpf_qdisc_skb_drop(skb, to_free);
 48	return NET_XMIT_DROP;
 49}
 50
 51SEC("struct_ops/bpf_fifo_dequeue")
 52struct sk_buff *BPF_PROG(bpf_fifo_dequeue, struct Qdisc *sch)
 53{
 54	struct bpf_list_node *node;
 55	struct sk_buff *skb = NULL;
 56	struct skb_node *skbn;
 57
 58	bpf_spin_lock(&q_fifo_lock);
 59	node = bpf_list_pop_front(&q_fifo);
 60	bpf_spin_unlock(&q_fifo_lock);
 61	if (!node)
 62		return NULL;
 63
 64	skbn = container_of(node, struct skb_node, node);
 65	skb = bpf_kptr_xchg(&skbn->skb, skb);
 66	bpf_obj_drop(skbn);
 67	if (!skb)
 68		return NULL;
 69
 70	sch->qstats.backlog -= qdisc_pkt_len(skb);
 71	bpf_qdisc_bstats_update(sch, skb);
 72	sch->q.qlen--;
 73
 74	return skb;
 75}
 76
 77SEC("struct_ops/bpf_fifo_init")
 78int BPF_PROG(bpf_fifo_init, struct Qdisc *sch, struct nlattr *opt,
 79	     struct netlink_ext_ack *extack)
 80{
 81	sch->limit = 1000;
 82	init_called = true;
 83	return 0;
 84}
 85
 86SEC("struct_ops/bpf_fifo_reset")
 87void BPF_PROG(bpf_fifo_reset, struct Qdisc *sch)
 88{
 89	struct bpf_list_node *node;
 90	struct skb_node *skbn;
 91	int i;
 92
 93	bpf_for(i, 0, sch->q.qlen) {
 94		struct sk_buff *skb = NULL;
 95
 96		bpf_spin_lock(&q_fifo_lock);
 97		node = bpf_list_pop_front(&q_fifo);
 98		bpf_spin_unlock(&q_fifo_lock);
 99
100		if (!node)
101			break;
102
103		skbn = container_of(node, struct skb_node, node);
104		skb = bpf_kptr_xchg(&skbn->skb, skb);
105		if (skb)
106			bpf_kfree_skb(skb);
107		bpf_obj_drop(skbn);
108	}
109	sch->q.qlen = 0;
110}
111
112SEC("struct_ops")
113void BPF_PROG(bpf_fifo_destroy, struct Qdisc *sch)
114{
115}
116
117SEC(".struct_ops")
118struct Qdisc_ops fifo = {
119	.enqueue   = (void *)bpf_fifo_enqueue,
120	.dequeue   = (void *)bpf_fifo_dequeue,
121	.init      = (void *)bpf_fifo_init,
122	.reset     = (void *)bpf_fifo_reset,
123	.destroy   = (void *)bpf_fifo_destroy,
124	.id        = "bpf_fifo",
125};
126