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Diffstat (limited to 'Documentation/bpf/map_sk_storage.rst')
| -rw-r--r-- | Documentation/bpf/map_sk_storage.rst | 56 |
1 files changed, 30 insertions, 26 deletions
diff --git a/Documentation/bpf/map_sk_storage.rst b/Documentation/bpf/map_sk_storage.rst index 047e16c8aaa8..4e9d23ab9ecd 100644 --- a/Documentation/bpf/map_sk_storage.rst +++ b/Documentation/bpf/map_sk_storage.rst @@ -34,13 +34,12 @@ bpf_sk_storage_get() void *bpf_sk_storage_get(struct bpf_map *map, void *sk, void *value, u64 flags) -Socket-local storage can be retrieved using the ``bpf_sk_storage_get()`` -helper. The helper gets the storage from ``sk`` that is associated with ``map``. -If the ``BPF_LOCAL_STORAGE_GET_F_CREATE`` flag is used then -``bpf_sk_storage_get()`` will create the storage for ``sk`` if it does not -already exist. ``value`` can be used together with -``BPF_LOCAL_STORAGE_GET_F_CREATE`` to initialize the storage value, otherwise it -will be zero initialized. Returns a pointer to the storage on success, or +Socket-local storage for ``map`` can be retrieved from socket ``sk`` using the +``bpf_sk_storage_get()`` helper. If the ``BPF_LOCAL_STORAGE_GET_F_CREATE`` +flag is used then ``bpf_sk_storage_get()`` will create the storage for ``sk`` +if it does not already exist. ``value`` can be used together with +``BPF_LOCAL_STORAGE_GET_F_CREATE`` to initialize the storage value, otherwise +it will be zero initialized. Returns a pointer to the storage on success, or ``NULL`` in case of failure. .. note:: @@ -54,9 +53,9 @@ bpf_sk_storage_delete() long bpf_sk_storage_delete(struct bpf_map *map, void *sk) -Socket-local storage can be deleted using the ``bpf_sk_storage_delete()`` -helper. The helper deletes the storage from ``sk`` that is identified by -``map``. Returns ``0`` on success, or negative error in case of failure. +Socket-local storage for ``map`` can be deleted from socket ``sk`` using the +``bpf_sk_storage_delete()`` helper. Returns ``0`` on success, or negative +error in case of failure. User space ---------- @@ -68,16 +67,20 @@ bpf_map_update_elem() int bpf_map_update_elem(int map_fd, const void *key, const void *value, __u64 flags) -Socket-local storage for the socket identified by ``key`` belonging to -``map_fd`` can be added or updated using the ``bpf_map_update_elem()`` libbpf -function. ``key`` must be a pointer to a valid ``fd`` in the user space -program. The ``flags`` parameter can be used to control the update behaviour: +Socket-local storage for map ``map_fd`` can be added or updated locally to a +socket using the ``bpf_map_update_elem()`` libbpf function. The socket is +identified by a `socket` ``fd`` stored in the pointer ``key``. The pointer +``value`` has the data to be added or updated to the socket ``fd``. The type +and size of ``value`` should be the same as the value type of the map +definition. -- ``BPF_ANY`` will create storage for ``fd`` or update existing storage. -- ``BPF_NOEXIST`` will create storage for ``fd`` only if it did not already - exist, otherwise the call will fail with ``-EEXIST``. -- ``BPF_EXIST`` will update existing storage for ``fd`` if it already exists, - otherwise the call will fail with ``-ENOENT``. +The ``flags`` parameter can be used to control the update behaviour: + +- ``BPF_ANY`` will create storage for `socket` ``fd`` or update existing storage. +- ``BPF_NOEXIST`` will create storage for `socket` ``fd`` only if it did not + already exist, otherwise the call will fail with ``-EEXIST``. +- ``BPF_EXIST`` will update existing storage for `socket` ``fd`` if it already + exists, otherwise the call will fail with ``-ENOENT``. Returns ``0`` on success, or negative error in case of failure. @@ -88,10 +91,10 @@ bpf_map_lookup_elem() int bpf_map_lookup_elem(int map_fd, const void *key, void *value) -Socket-local storage for the socket identified by ``key`` belonging to -``map_fd`` can be retrieved using the ``bpf_map_lookup_elem()`` libbpf -function. ``key`` must be a pointer to a valid ``fd`` in the user space -program. Returns ``0`` on success, or negative error in case of failure. +Socket-local storage for map ``map_fd`` can be retrieved from a socket using +the ``bpf_map_lookup_elem()`` libbpf function. The storage is retrieved from +the socket identified by a `socket` ``fd`` stored in the pointer +``key``. Returns ``0`` on success, or negative error in case of failure. bpf_map_delete_elem() ~~~~~~~~~~~~~~~~~~~~~ @@ -100,9 +103,10 @@ bpf_map_delete_elem() int bpf_map_delete_elem(int map_fd, const void *key) -Socket-local storage for the socket identified by ``key`` belonging to -``map_fd`` can be deleted using the ``bpf_map_delete_elem()`` libbpf -function. Returns ``0`` on success, or negative error in case of failure. +Socket-local storage for map ``map_fd`` can be deleted from a socket using the +``bpf_map_delete_elem()`` libbpf function. The storage is deleted from the +socket identified by a `socket` ``fd`` stored in the pointer ``key``. Returns +``0`` on success, or negative error in case of failure. Examples ======== |