Re: [PATCH net-next v3 5/5] selftests: drv-net-hw: Add a test for symmetric RSS hash

[Jakub Kicinski <kuba@kernel.org>]

On Sun, 16 Feb 2025 20:24:53 +0200 Gal Pressman wrote:
> +    # Check for symmetric xor/or-xor
> +    if input_xfrm and (input_xfrm == 1 or input_xfrm == 2):
> +        port1 = _get_rand_port(cfg.remote)
> +        port2 = _get_rand_port(cfg.remote)
> +        ksft_pr(f'Running traffic on ports: {port1 = }, {port2 = }')
> +
> +        cnts = _get_rx_cnts(cfg)
> +        GenerateTraffic(cfg, port=port1, parallel=1,
> +                        cport=port2).wait_pkts_and_stop(20000)
> +        cnts = _get_rx_cnts(cfg, prev=cnts)
> +        rxq1 = _get_active_rx_queue(cnts)
> +        ksft_pr(f'Received traffic on {rxq1 = }')
> +
> +        cnts = _get_rx_cnts(cfg)
> +        GenerateTraffic(cfg, port=port2, parallel=1,
> +                        cport=port1).wait_pkts_and_stop(20000)
> +        cnts = _get_rx_cnts(cfg, prev=cnts)
> +        rxq2 = _get_active_rx_queue(cnts)
> +        ksft_pr(f'Received traffic on {rxq2 = }')
> +
> +        ksft_eq(
> +            rxq1, rxq2, comment=f"Received traffic on different queues ({rxq1} != {rxq2}) while symmetric hash is configured")

Wouldn't it be both faster and less error prone to test this with UDP
sockets?

	sock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
	sock.connect(cfg.remove_addr_v[ipver], remote_port)
	sock.recvmsg(100)

	tgt = f"{ipver}:{cfg.addr_v[ipver]}:{local_port},sourceport={remote_port}"
	cmd("echo a | socat - UDP" + tgt, host=cfg.remote)

	cpu = sock.getsockopt(socket.SOL_SOCKET, socket.SO_INCOMING_CPU)

Run this for 10 pairs for ports, make sure we hit at least 2 CPUs,
and that the CPUs match for each pair.

Would be good to test both IPv4 and IPv6. I'm going to merge:
  https://lore.kernel.org/all/20250217194200.3011136-4-kuba@kernel.org/
it should make writing the v4 + v6 test combos easier.
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