Re: [PATCH net-next v4 9/9] selftests: ncdevmem: Implement devmem TCP TX

[Stanislav Fomichev <stfomichev@gmail.com>]

On 02/20, Mina Almasry wrote:
> Add support for devmem TX in ncdevmem.
> 
> This is a combination of the ncdevmem from the devmem TCP series RFCv1
> which included the TX path, and work by Stan to include the netlink API
> and refactored on top of his generic memory_provider support.
> 
> Signed-off-by: Mina Almasry <almasrymina@google.com>
> Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
> 
> ---
> 
> v4:
> - Add TX test to devmem.py (Paolo).
> 
> v3:
> - Update ncdevmem docs to run validation with RX-only and RX-with-TX.
> - Fix build warnings (Stan).
> - Make the validation expect new lines in the pattern so we can have the
>   TX path behave like netcat (Stan).
> - Change ret to errno in error() calls (Stan).
> - Handle the case where client_ip is not provided (Stan).
> - Don't assume mid is <= 2000 (Stan).
> 
> v2:
> - make errors a static variable so that we catch instances where there
>   are less than 20 errors across different buffers.
> - Fix the issue where the seed is reset to 0 instead of its starting
>   value 1.
> - Use 1000ULL instead of 1000 to guard against overflow (Willem).
> - Do not set POLLERR (Willem).
> - Update the test to use the new interface where iov_base is the
>   dmabuf_offset.
> - Update the test to send 2 iov instead of 1, so we get some test
>   coverage over sending multiple iovs at once.
> - Print the ifindex the test is using, useful for debugging issues where
>   maybe the test may fail because the ifindex of the socket is different
>   from the dmabuf binding.
> 
> ---
>  .../selftests/drivers/net/hw/devmem.py        |  28 +-
>  .../selftests/drivers/net/hw/ncdevmem.c       | 300 +++++++++++++++++-
>  2 files changed, 312 insertions(+), 16 deletions(-)
> 
> diff --git a/tools/testing/selftests/drivers/net/hw/devmem.py b/tools/testing/selftests/drivers/net/hw/devmem.py
> index 1223f0f5c10c..3d4f7fc5e63f 100755
> --- a/tools/testing/selftests/drivers/net/hw/devmem.py
> +++ b/tools/testing/selftests/drivers/net/hw/devmem.py
> @@ -1,6 +1,7 @@
>  #!/usr/bin/env python3
>  # SPDX-License-Identifier: GPL-2.0
>  
> +from os import path
>  from lib.py import ksft_run, ksft_exit
>  from lib.py import ksft_eq, KsftSkipEx
>  from lib.py import NetDrvEpEnv
> @@ -10,8 +11,7 @@ from lib.py import ksft_disruptive
>  
>  def require_devmem(cfg):
>      if not hasattr(cfg, "_devmem_probed"):
> -        port = rand_port()
> -        probe_command = f"./ncdevmem -f {cfg.ifname}"
> +        probe_command = f"{cfg.bin_local} -f {cfg.ifname}"
>          cfg._devmem_supported = cmd(probe_command, fail=False, shell=True).ret == 0
>          cfg._devmem_probed = True
>  
> @@ -25,18 +25,36 @@ def check_rx(cfg) -> None:
>      require_devmem(cfg)
>  
>      port = rand_port()
> -    listen_cmd = f"./ncdevmem -l -f {cfg.ifname} -s {cfg.v6} -p {port}"
> +    listen_cmd = f"{cfg.bin_local} -l -f {cfg.ifname} -s {cfg.v6} -p {port}"
>  
>      with bkg(listen_cmd) as socat:
>          wait_port_listen(port)
> -        cmd(f"echo -e \"hello\\nworld\"| socat -u - TCP6:[{cfg.v6}]:{port}", host=cfg.remote, shell=True)
> +        cmd(f"echo -e \"hello\\nworld\"| socat -u - TCP6:{cfg.v6}:{port},bind={cfg.remote_v6}:{port}", host=cfg.remote, shell=True)

IPv6 address need to be wrapped into [], so has to be at least:
	socat -u - TCP6:[{cfg.v6}]:{port},bind=[{cfg.remote_v6}]:{port}

But not sure why we care here about bind address here, let the kernel
figure out the routing.

Also, seems like "bkg(listen_cmd)" needs to be "bkg(listen_cmd,
exit_wait=True)", otherwise sometimes I see racy empty result.