Skip to content

Helper function bpf_cgrp_storage_get

v6.2

Definition

Copyright (c) 2015 The Libbpf Authors. All rights reserved.

Get a bpf_local_storage from the cgroup.

Logically, it could be thought of as getting the value from a map with cgroup as the key. From this perspective, the usage is not much different from bpf_map_lookup_elem(map, &cgroup) except this helper enforces the key must be a cgroup struct and the map must also be a BPF_MAP_TYPE_CGRP_STORAGE.

In reality, the local-storage value is embedded directly inside of the cgroup object itself, rather than being located in the BPF_MAP_TYPE_CGRP_STORAGE map. When the local-storage value is queried for some map on a cgroup object, the kernel will perform an O(n) iteration over all of the live local-storage values for that cgroup object until the local-storage value for the map is found.

An optional flags (BPF_LOCAL_STORAGE_GET_F_CREATE) can be used such that a new bpf_local_storage will be created if one does not exist. value can be used together with BPF_LOCAL_STORAGE_GET_F_CREATE to specify the initial value of a bpf_local_storage. If value is NULL, the new bpf_local_storage will be zero initialized.

Returns

A bpf_local_storage pointer is returned on success.

NULL if not found or there was an error in adding a new bpf_local_storage.

static void *(* const bpf_cgrp_storage_get)(void *map, struct cgroup *cgroup, void *value, __u64 flags) = (void *) 210;

Usage

Docs could be improved

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

Program types

This helper call can be used in the following program types:

Example

Docs could be improved

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