On 11/8/22 9:48 AM, mtahhan@xxxxxxxxxx wrote:
From: Maryam Tahhan <mtahhan@xxxxxxxxxx>
Add documentation for BPF_MAP_TYPE_DEVMAP and
BPF_MAP_TYPE_DEVMAP_HASH including kernel version
introduced, usage and examples.
Add documentation that describes XDP_REDIRECT.
Signed-off-by: Maryam Tahhan <mtahhan@xxxxxxxxxx>
LGTM with a couple of nits below.
Acked-by: Yonghong Song <yhs@xxxxxx>
---
Documentation/bpf/index.rst | 1 +
Documentation/bpf/map_devmap.rst | 221 +++++++++++++++++++++++++++++++
Documentation/bpf/redirect.rst | 81 +++++++++++
net/core/filter.c | 8 +-
4 files changed, 309 insertions(+), 2 deletions(-)
create mode 100644 Documentation/bpf/map_devmap.rst
create mode 100644 Documentation/bpf/redirect.rst
diff --git a/Documentation/bpf/index.rst b/Documentation/bpf/index.rst
index 1b50de1983ee..1088d44634d6 100644
--- a/Documentation/bpf/index.rst
+++ b/Documentation/bpf/index.rst
@@ -29,6 +29,7 @@ that goes into great technical depth about the BPF Architecture.
clang-notes
linux-notes
other
+ redirect
.. only:: subproject and html
[...]
+
+User space
+----------
+
+The following code snippet shows how to update a devmap called ``tx_port``.
+
+.. code-block:: c
+
+ int update_devmap(int ifindex, int redirect_ifindex)
+ {
+ int ret = -1;
There is no need to initialize the value to -1, the below is 'ret = ...'.
+
+ ret = bpf_map_update_elem(bpf_map__fd(tx_port), &ifindex, &redirect_ifindex, 0);
+ if (ret < 0) {
+ fprintf(stderr, "Failed to update devmap_ value: %s\n",
+ strerror(errno));
+ }
+
+ return ret;
+ }
+
+The following code snippet shows how to update a hash_devmap called ``forward_map``.
+
+.. code-block:: c
+
+ int update_devmap(int ifindex, int redirect_ifindex)
+ {
+ struct bpf_devmap_val devmap_val = { .ifindex = redirect_ifindex };
+ int ret = -1;
same here, no need to have '-1'.
+
+ ret = bpf_map_update_elem(bpf_map__fd(forward_map), &ifindex, &devmap_val, 0);
+ if (ret < 0) {
+ fprintf(stderr, "Failed to update devmap_ value: %s\n",
+ strerror(errno));
+ }
+ return ret;
+ }
+
[...]
