On 12/05/2023 17.26, Larysa Zaremba wrote:
Implement functionality that enables drivers to expose VLAN tag
to XDP code.
Signed-off-by: Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
---
[...]
diff --git a/net/core/xdp.c b/net/core/xdp.c
index 41e5ca8643ec..eff21501609f 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -738,6 +738,30 @@ __bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, u32 *hash,
return -EOPNOTSUPP;
}
Remember below becomes part of main documentation on HW metadata hints:
- https://kernel.org/doc/html/latest/networking/xdp-rx-metadata.html
Hint compiling locally I use:
make SPHINXDIRS="networking" htmldocs
+/**
+ * bpf_xdp_metadata_rx_ctag - Read XDP packet inner vlan tag.
Is bpf_xdp_metadata_rx_ctag a good function name for the inner vlan tag?
Like wise below "stag".
I cannot remember if the C-tag or S-tag is the inner or outer vlan tag.
When reading BPF code that use these function names, then I would have
to ask Google for help, or find-and-read this doc.
Can we come-up with a more intuitive name, that e.g. helps when reading
the BPF-prog code?
+ * @ctx: XDP context pointer.
+ * @vlan_tag: Return value pointer.
+ *
IMHO right here, there should be a description.
E.g. for what a VLAN "tag" means. I assume a "tag" isn't the VLAN id,
but the raw VLAN tag that also contains the prio numbers etc.
It this VLAN tag expected to be in network-byte-order ?
IMHO this doc should define what is expected (and driver devel must
follow this).
+ * Returns 0 on success or ``-errno`` on error.
+ */
+__bpf_kfunc int bpf_xdp_metadata_rx_ctag(const struct xdp_md *ctx, u16 *vlan_tag)
+{
+ return -EOPNOTSUPP;
+}
+
+/**
+ * bpf_xdp_metadata_rx_stag - Read XDP packet outer vlan tag.
+ * @ctx: XDP context pointer.
+ * @vlan_tag: Return value pointer.
+ *
+ * Returns 0 on success or ``-errno`` on error.
IMHO we should provide more guidance to expected return codes, and what
they mean. IMHO driver developers must only return codes that are
described here, and if they invent a new, add it as part of their patch.
See, formatting in bpf_xdp_metadata_rx_hash and check how this gets
compiled into HTML.
+ */
+__bpf_kfunc int bpf_xdp_metadata_rx_stag(const struct xdp_md *ctx, u16 *vlan_tag)
+{
+ return -EOPNOTSUPP;
+}
+
