Re: [PATCH net v2 2/2] selftests/net: psp: test bidirectional data transfer

["Daniel Zahka" <daniel.zahka@gmail.com>]

On Fri Oct 30, 2026 at 12:31 AM EDT, Wei Wang wrote:
> _data_basic_send() and _data_basic_send_netkit_psp_assoc() currently
> only verify unidirectional data transmission from the test socket to
> psp_responder. As a result, they do not exercise the receive path for
> PSP-encrypted TCP data segments arriving at the test socket (such as
> packets redirected across a netkit interface associated via dev-assoc,
> which relies on SKB_EXT_PSP surviving packet scrubbing).
>
> Use the existing "data echo" command in psp_responder to verify that the
> test socket can also receive PSP-encrypted data from the peer in both
> _data_basic_send() and _data_basic_send_netkit_psp_assoc().
>
> Signed-off-by: Wei Wang <weiwan@google.com>
> ---
>  tools/testing/selftests/drivers/net/psp.py | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/tools/testing/selftests/drivers/net/psp.py b/tools/testing/selftests/drivers/net/psp.py
> index 473500901879..e507951b440b 100755
> --- a/tools/testing/selftests/drivers/net/psp.py
> +++ b/tools/testing/selftests/drivers/net/psp.py
> @@ -120,6 +120,12 @@ def _check_data_rx(cfg, exp_len):
>      ksft_eq(read_len, exp_len)
>  
>  
> +def _check_data_echo(cfg, s):
> +    _send_with_ack(cfg, b'data echo\0')
> +    s.settimeout(1.0)

I'm not a huge fan of setting the blocking timeout here. If we are going
to set a timeout it should be when the socket is created. Otherwise this
function has an unexpected side-effect. Another option is to use non
blocking reads with timeout like:

def _recv_careful(s, target, timeout=2):
    """Read exactly target bytes, tolerating short reads"""
    data = b''
    end = time.monotonic() + timeout
    while time.monotonic() < end:
        try:
            data += s.recv(target - len(data), socket.MSG_DONTWAIT)
            if len(data) == target:
                return data
        except BlockingIOError:
            time.sleep(0.001)
    raise KsftFailEx(f"short read, got {len(data)} of {target} bytes")


def _req_echo(cfg, s):
    """Ask the peer to echo, and check the reply arrives intact"""
    _send_with_ack(cfg, b'data echo\0')
    ksft_eq(_recv_careful(s, 5), b'echo\0')

> +    ksft_eq(s.recv(5), b'echo\0')
> +
> +
>  def _check_data_outq(s, exp_len, force_wait=False):
>      outq = 0
>      for _ in range(10):
> @@ -478,6 +484,7 @@ def _data_basic_send(cfg, version, ipver):
>  
>      data_len = _send_careful(cfg, s, 100)
>      _check_data_rx(cfg, data_len)
> +    _check_data_echo(cfg, s)
>      _close_psp_conn(cfg, s)
>  
>  
> @@ -726,6 +733,7 @@ def _data_basic_send_netkit_psp_assoc(cfg, version, ipver):
>  
>          data_len = _send_careful(cfg, sock, 100)
>          _check_data_rx(cfg, data_len)
> +        _check_data_echo(cfg, sock)
>          _close_psp_conn(cfg, sock)
>  
>  

I'm ok with the approach overall. The coverage is sufficient for the
purposes of the series.