Re: [PATCH net-next 10/11] selftests: drv-net: add primary_rx_redirect support to NetDrvContEnv

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Hardcoded little-endian byte order for BPF global variable map update breaks the test on big-endian architectures.
--

commit 33211f25ad75b60103232678a2183e101cf2a050
Author: Bobby Eshleman <bobbyeshleman@meta.com>

selftests: drv-net: add primary_rx_redirect support to NetDrvContEnv

When sending from a namespace that has access to a netkit device with a
leased queue, the nk primary in the host namespace needs to redirect its
RX to the physical device. This patch adds that redirection bpf program
and teaches the harness to install it.

> diff --git a/tools/testing/selftests/drivers/net/lib/py/env.py b/tools/testing/selftests/drivers/net/lib/py/env.py
> --- a/tools/testing/selftests/drivers/net/lib/py/env.py
> +++ b/tools/testing/selftests/drivers/net/lib/py/env.py

[ ... ]

> @@ -505,3 +520,31 @@ class NetDrvContEnv(NetDrvEpEnv):
> +    def _attach_primary_rx_redirect_bpf(self):

[ ... ]

> +        bss_map_id = self._find_bss_map_id(redirect_prog_id)
> +        phys_ifindex_bytes = self.ifindex.to_bytes(4, byteorder='little')

Will this cause the selftest to fail on big-endian architectures like s390x?

The test script hardcodes byteorder='little' when serializing the physical
interface index to write to the BPF .bss map. However, the BPF program runs in
native byte order and will read the little-endian map bytes as a byte-reversed
32-bit integer on big-endian architectures.

This would result in an incorrect interface index being passed to
bpf_redirect_neigh(), causing it to fail silently.

> +        value_hex = ' '.join(f'{b:02x}' for b in phys_ifindex_bytes)
> +        bpftool(f"map update id {bss_map_id} key hex 00 00 00 00 value hex {value_hex}")

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260428-tcp-dm-netkit-v1-0-719280eba4d2@meta.com?part=10