linux-kernel - Re: [PATCH net-next 0/4] (no cover subject)

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Message-ID: <20251210130538.38374707@kernel.org>
Date: Wed, 10 Dec 2025 13:05:38 +0900
From: Jakub Kicinski <kuba@...nel.org>
To: Breno Leitao <leitao@...ian.org>
Cc: Petr Mladek <pmladek@...e.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet
 <edumazet@...gle.com>, Paolo Abeni <pabeni@...hat.com>, Shuah Khan
 <shuah@...nel.org>, Simon Horman <horms@...nel.org>, Jonathan Corbet
 <corbet@....net>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-kselftest@...r.kernel.org, linux-doc@...r.kernel.org,
 gustavold@...il.com, asantostc@...il.com, calvin@...nvd.org,
 kernel-team@...a.com, davej@...emonkey.org.uk
Subject: Re: [PATCH net-next 0/4] (no cover subject)

On Tue, 9 Dec 2025 09:46:51 -0800 Breno Leitao wrote:
> > I think I was alluding that another option (not saying that it's the
> > best but IIUC your requirements it'd be the best fit)):
> > 
> > 5) Add a keepalive configfs knob, if set to a non-zero value netconsole
> > will send an empty (?) message at given interval
> > 
> >   Pros:
> >    - truly does not require a user binary to run periodically, netcons
> >      would set a timer in the kernel
> >   Cons:
> >    - does not provide the arbitrary "console bypass" message
> >      functionality  
> 
> This is a good idea if we change it slightly. What about a "ping"
> configfs item that send sit when I touch it?
> 
> Something as:
> 
> 	# echo 1 > /sys/kernel/configs/<target>/ping
>
> And it would ping the host with a predefined "ping" message, and nothing
> else.
> 
> That would work, for my current problem, honestly.
> 
> One drawback compared to a more flexible "send_msg" is that I don't have
> complete flexibility on the message format. Thus, if I want to pass
> extra information such as a Nonce, timestamp, host state, interface
> name, health state, it will not be possible, which is fine for now,
> given I am NOT planning to use it at this stage.

If you still want to tickle it from user space periodically, I guess
send_msg is more flexible. I think the main advantage of keepalive
would be to remove the need for periodic userspace work.