netdev - Re: [PATCH net-next 1/4] selftests: drv-net: try to check if port is in use

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Date: Mon, 24 Jun 2024 15:59:36 +0200
From: Przemek Kitszel <przemyslaw.kitszel@...el.com>
To: Jakub Kicinski <kuba@...nel.org>, <davem@...emloft.net>
CC: <netdev@...r.kernel.org>, <edumazet@...gle.com>, <pabeni@...hat.com>,
	<willemdebruijn.kernel@...il.com>, <ecree.xilinx@...il.com>
Subject: Re: [PATCH net-next 1/4] selftests: drv-net: try to check if port is
 in use

On 6/21/24 01:28, Jakub Kicinski wrote:
> We use random ports for communication. As Willem predicted
> this leads to occasional failures. Try to check if port is
> already in use by opening a socket and binding to that port.
> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> ---
>   tools/testing/selftests/net/lib/py/utils.py | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/selftests/net/lib/py/utils.py b/tools/testing/selftests/net/lib/py/utils.py
> index 0540ea24921d..9fa9ec720c89 100644
> --- a/tools/testing/selftests/net/lib/py/utils.py
> +++ b/tools/testing/selftests/net/lib/py/utils.py
> @@ -3,6 +3,7 @@
>   import json as _json
>   import random
>   import re
> +import socket
>   import subprocess
>   import time
>   
> @@ -81,7 +82,17 @@ import time
>       """
>       Get unprivileged port, for now just random, one day we may decide to check if used.
>       """

nit: this comment could be now updated

> -    return random.randint(10000, 65535)
> +    while True:

nit: perhaps you could limit the loop to some finite number of steps
for the case that all ports are in use :P

> +        port = random.randint(10000, 65535)
> +        try:
> +            with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
> +                s.bind(("", port))
> +            with socket.socket(socket.AF_INET6, socket.SOCK_STREAM) as s:
> +                s.bind(("", port))
> +            return port
> +        except OSError as e:
> +            if e.errno != 98:  # already in use
> +                raise
>   
>   
>   def wait_port_listen(port, proto="tcp", ns=None, host=None, sleep=0.005, deadline=5):