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

File Facts

System

Linux kernel

Corpus path

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

Extension

.c

Size

2333 bytes

Lines

107

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.
• Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• vmlinux.h
• string.h
• stdbool.h
• bpf/bpf_helpers.h
• bpf/bpf_tracing.h
• bpf_misc.h
• errno.h

Detected Declarations

• struct elem
• function process_work
• function oncpu_hash_map
• function oncpu_array_map
• function oncpu_lru_map

Annotated Snippet

struct elem {
	char data[128];
	struct bpf_task_work tw;
};

struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__uint(map_flags, BPF_F_NO_PREALLOC);
	__uint(max_entries, 1);
	__type(key, int);
	__type(value, struct elem);
} hmap SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_ARRAY);
	__uint(max_entries, 1);
	__type(key, int);
	__type(value, struct elem);
} arrmap SEC(".maps");

struct {
	__uint(type, BPF_MAP_TYPE_LRU_HASH);
	__uint(max_entries, 1);
	__type(key, int);
	__type(value, struct elem);
} lrumap SEC(".maps");

static int process_work(struct bpf_map *map, void *key, void *value)
{
	struct elem *work = value;

	bpf_copy_from_user_str(work->data, sizeof(work->data), (const void *)user_ptr, 0);
	return 0;
}

int key = 0;

SEC("perf_event")
int oncpu_hash_map(struct pt_regs *args)
{
	struct elem empty_work = { .data = { 0 } };
	struct elem *work;
	struct task_struct *task;
	int err;

	task = bpf_get_current_task_btf();
	err = bpf_map_update_elem(&hmap, &key, &empty_work, BPF_NOEXIST);
	if (err)
		return 0;
	work = bpf_map_lookup_elem(&hmap, &key);
	if (!work)
		return 0;
	bpf_task_work_schedule_resume(task, &work->tw, &hmap, process_work);
	return 0;
}

SEC("perf_event")
int oncpu_array_map(struct pt_regs *args)
{
	struct elem *work;
	struct task_struct *task;

	task = bpf_get_current_task_btf();
	work = bpf_map_lookup_elem(&arrmap, &key);
	if (!work)
		return 0;
	bpf_task_work_schedule_signal(task, &work->tw, &arrmap, process_work);
	return 0;
}

SEC("perf_event")
int oncpu_lru_map(struct pt_regs *args)
{
	struct elem empty_work = { .data = { 0 } };
	struct elem *work;
	struct task_struct *task;
	int err;

	task = bpf_get_current_task_btf();
	work = bpf_map_lookup_elem(&lrumap, &key);
	if (work)
		return 0;
	err = bpf_map_update_elem(&lrumap, &key, &empty_work, BPF_NOEXIST);
	if (err)
		return 0;
	work = bpf_map_lookup_elem(&lrumap, &key);
	if (!work || work->data[0])
		return 0;
	bpf_task_work_schedule_resume(task, &work->tw, &lrumap, process_work);
	return 0;

Annotation

• Immediate include surface: `vmlinux.h`, `string.h`, `stdbool.h`, `bpf/bpf_helpers.h`, `bpf/bpf_tracing.h`, `bpf_misc.h`, `errno.h`.
• Detected declarations: `struct elem`, `function process_work`, `function oncpu_hash_map`, `function oncpu_array_map`, `function oncpu_lru_map`.
• Atlas domain: Support Tooling And Documentation / tools.
• Implementation status: source implementation candidate.
• This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.

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.