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

File Facts

System

Linux kernel

Corpus path

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

Extension

.c

Size

817 bytes

Lines

45

Domain

Support Tooling And Documentation

Bucket

tools

Inferred role

Support Tooling And Documentation: implementation source

Status

source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

• Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• linux/bpf.h
• bpf/bpf_helpers.h
• bpf/bpf_endian.h

Detected Declarations

• function redirect_ingress
• function redirect_egress
• function tc_redirect_ingress
• function tc_redirect_egress
• function tc_adjust_room

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
#include <linux/bpf.h>
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_endian.h>

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

int ifindex;
int ret;

SEC("lwt_xmit")
int redirect_ingress(struct __sk_buff *skb)
{
	ret = bpf_clone_redirect(skb, ifindex, BPF_F_INGRESS);
	return 0;
}

SEC("lwt_xmit")
int redirect_egress(struct __sk_buff *skb)
{
	ret = bpf_clone_redirect(skb, ifindex, 0);
	return 0;
}

SEC("tc")
int tc_redirect_ingress(struct __sk_buff *skb)
{
	ret = bpf_clone_redirect(skb, ifindex, BPF_F_INGRESS);
	return 0;
}

SEC("tc")
int tc_redirect_egress(struct __sk_buff *skb)
{
	ret = bpf_clone_redirect(skb, ifindex, 0);
	return 0;
}

SEC("tc")
int tc_adjust_room(struct __sk_buff *skb)
{
	ret = bpf_skb_adjust_room(skb, 4, BPF_ADJ_ROOM_NET, 0);
	return 0;
}

Annotation

• Immediate include surface: `linux/bpf.h`, `bpf/bpf_helpers.h`, `bpf/bpf_endian.h`.
• Detected declarations: `function redirect_ingress`, `function redirect_egress`, `function tc_redirect_ingress`, `function tc_redirect_egress`, `function tc_adjust_room`.
• Atlas domain: Support Tooling And Documentation / tools.
• Implementation status: source implementation candidate.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.