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docs/bpf: Reword docs for BPF_MAP_TYPE_SK_STORAGE

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Improve the grammar of the function descriptions and highlight
that the key is a socket fd.

Fixes: f3212ad5b7 ("docs/bpf: Add documentation for BPF_MAP_TYPE_SK_STORAGE")
Reported-by: Martin KaFai Lau <martin.lau@linux.dev>
Signed-off-by: Donald Hunter <donald.hunter@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20221212101600.56026-1-donald.hunter@gmail.com
This commit is contained in:
Donald Hunter 2022-12-12 10:16:00 +00:00 committed by Daniel Borkmann
parent 7ae9888d6e
commit d2b497a973
1 changed files with 30 additions and 26 deletions
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56
Documentation/bpf/map_sk_storage.rst
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@ -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
========