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

File Facts

System

Linux kernel

Corpus path

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

Extension

.h

Size

1882 bytes

Lines

80

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.
• Uses kernel synchronization; read lock ordering, sleepability, and interrupt context assumptions before translating.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• errno.h
• vmlinux.h
• bpf/bpf_helpers.h
• bpf/bpf_tracing.h

Detected Declarations

• struct __cgrps_kfunc_map_value
• function cgrps_kfunc_map_insert

Annotated Snippet

struct __cgrps_kfunc_map_value {
	struct cgroup __kptr * cgrp;
};

struct {
	__uint(type, BPF_MAP_TYPE_HASH);
	__type(key, int);
	__type(value, struct __cgrps_kfunc_map_value);
	__uint(max_entries, 1);
} __cgrps_kfunc_map SEC(".maps");

struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
void bpf_cgroup_release(struct cgroup *p) __ksym;
struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level) __ksym;
struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
void bpf_rcu_read_lock(void) __ksym;
void bpf_rcu_read_unlock(void) __ksym;

static inline struct __cgrps_kfunc_map_value *cgrps_kfunc_map_value_lookup(struct cgroup *cgrp)
{
	s32 id;
	long status;

	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
	if (status)
		return NULL;

	return bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
}

static inline int cgrps_kfunc_map_insert(struct cgroup *cgrp)
{
	struct __cgrps_kfunc_map_value local, *v;
	long status;
	struct cgroup *acquired, *old;
	s32 id;

	status = bpf_probe_read_kernel(&id, sizeof(id), &cgrp->self.id);
	if (status)
		return status;

	local.cgrp = NULL;
	status = bpf_map_update_elem(&__cgrps_kfunc_map, &id, &local, BPF_NOEXIST);
	if (status)
		return status;

	v = bpf_map_lookup_elem(&__cgrps_kfunc_map, &id);
	if (!v) {
		bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
		return -ENOENT;
	}

	acquired = bpf_cgroup_acquire(cgrp);
	if (!acquired) {
		bpf_map_delete_elem(&__cgrps_kfunc_map, &id);
		return -ENOENT;
	}

	old = bpf_kptr_xchg(&v->cgrp, acquired);
	if (old) {
		bpf_cgroup_release(old);
		return -EEXIST;
	}

	return 0;
}

#endif /* _CGRP_KFUNC_COMMON_H */

Annotation

• Immediate include surface: `errno.h`, `vmlinux.h`, `bpf/bpf_helpers.h`, `bpf/bpf_tracing.h`.
• Detected declarations: `struct __cgrps_kfunc_map_value`, `function cgrps_kfunc_map_insert`.
• Atlas domain: Support Tooling And Documentation / tools.
• Implementation status: source implementation candidate.
• Synchronization appears in or near this file; preserve lock ordering, sleepability, and interrupt-context constraints.

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.