linux/samples/bpf/xdpsock_kern.c

// SPDX-License-Identifier: GPL-2.0
#define KBUILD_MODNAME "foo"
#include <uapi/linux/bpf.h>
#include "bpf_helpers.h"

#include "xdpsock.h"

struct bpf_map_def SEC("maps") qidconf_map = {
	.type		= BPF_MAP_TYPE_ARRAY,
	.key_size	= sizeof(int),
	.value_size	= sizeof(int),
	.max_entries	= 1,
};

struct bpf_map_def SEC("maps") xsks_map = {
	.type = BPF_MAP_TYPE_XSKMAP,
	.key_size = sizeof(int),
	.value_size = sizeof(int),
	.max_entries = MAX_SOCKS,
};

struct bpf_map_def SEC("maps") rr_map = {
	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
	.key_size = sizeof(int),
	.value_size = sizeof(unsigned int),
	.max_entries = 1,
};

SEC("xdp_sock")
int xdp_sock_prog(struct xdp_md *ctx)
{
	int *qidconf, key = 0, idx;
	unsigned int *rr;

	qidconf = bpf_map_lookup_elem(&qidconf_map, &key);
	if (!qidconf)
		return XDP_ABORTED;

	if (*qidconf != ctx->rx_queue_index)
		return XDP_PASS;

#if RR_LB /* NB! RR_LB is configured in xdpsock.h */
	rr = bpf_map_lookup_elem(&rr_map, &key);
	if (!rr)
		return XDP_ABORTED;

	*rr = (*rr + 1) & (MAX_SOCKS - 1);
	idx = *rr;
#else
	idx = 0;
#endif

	return bpf_redirect_map(&xsks_map, idx, 0);
}

char _license[] SEC("license") = "GPL";