netdev - Re: [PATCH net-next v2 1/4] selftests: drv-net: try to check if port is in use

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Date: Tue, 25 Jun 2024 08:57:00 +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>,
	<dw@...idwei.uk>, <michael.chan@...adcom.com>,
	<andrew.gospodarek@...adcom.com>
Subject: Re: [PATCH net-next v2 1/4] selftests: drv-net: try to check if port
 is in use

On 6/25/24 03:02, 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>
> ---
> v2:
>   - remove v4 check (Willem)
>   - update comment (David, Przemek)
>   - cap the iterations (Przemek)
> ---
>   tools/testing/selftests/net/lib/py/utils.py | 14 ++++++++++++--
>   1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/net/lib/py/utils.py b/tools/testing/selftests/net/lib/py/utils.py
> index 0540ea24921d..16907b51e034 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
>   
> @@ -79,9 +80,18 @@ import time
>   
>   def rand_port():
>       """
> -    Get unprivileged port, for now just random, one day we may decide to check if used.
> +    Get a random unprivileged port, try to make sure it's not already used.
>       """
> -    return random.randint(10000, 65535)
> +    for _ in range(1000):
> +        port = random.randint(10000, 65535)
> +        try:
> +            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
> +    raise Exception("Can't find any free unprivileged port")
>   
>   
>   def wait_port_listen(port, proto="tcp", ns=None, host=None, sleep=0.005, deadline=5):

Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@...el.com>