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KFunc bpf_cgroup_ancestor

v6.2

Perform a lookup on an entry in a cgroup's ancestor array.

Definition

A cgroup returned by this kfunc which is not subsequently stored in a map, must be released by calling bpf_cgroup_release().

struct cgroup *bpf_cgroup_ancestor(struct cgroup *cgrp, int level)

Note

This kfunc returns a pointer to a refcounted object. The verifier will then ensure that the pointer to the object is eventually released using a release kfunc, or transferred to a map using a referenced kptr (by invoking bpf_kptr_xchg). If not, the verifier fails the loading of the BPF program until no lingering references remain in all possible explored states of the program.

Note

The pointer returned by the kfunc may be NULL. Hence, it forces the user to do a NULL check on the pointer returned from the kfunc before making use of it (dereferencing or passing to another helper).

Usage

Docs could be improved

This part of the docs is incomplete, contributions are very welcome

Program types

The following program types can make use of this kfunc:

Example

Docs could be improved

This part of the docs is incomplete, contributions are very welcome