linux-kernel - Re: [PATCH net-next v7 0/5] netconsole: support automatic target recovery

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Message-ID: <v44skio47zulg6jok5wq7w2ylw4abk7dxtjarlgnuz7hukvbts@7clzpd7cqc5u>
Date: Thu, 27 Nov 2025 23:07:02 +0000
From: Andre Carvalho <asantostc@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: Breno Leitao <leitao@...ian.org>, 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>, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next v7 0/5] netconsole: support automatic target
 recovery

Hi Jakub!

On Wed, Nov 26, 2025 at 05:36:46PM -0800, Jakub Kicinski wrote:
> Netpoll does not seem to handle DOWN events, so I'm guessing your
> primary use case is that the device had a HW fault and netdev was
> recreated after device reset?

Correct, this is the intended use case for this series. Handling cases where
the device was unregistered and then brought back up.

> Should we not be listening for the REGISTER event then? On boot
> we force UP the device if we find it, theoretically there may
> be a case where user space is not configured to UP the device,
> and then we'd never resume the target?

This is indeed a limitation on the current implementation. Based on
your feedback, I'm working on a new version of this series handling REGISTER
instead of UP and ensuring we force UP the device.
This will make it consistent with the boot behavior you described.

Based on my tests, I can't force the device UP while handling the REGISTER event.
I believe this is due to dev_open attempting to lock the device which is already held.
For this reason, I'm resorting to defering this to a workqueue, similar to my approach 
on v1 [1] (but correctly handling target_list lock).

Let me know if this approach makes sense or if I'm missing something.

Thanks for the review!

[1] https://lore.kernel.org/all/20250909-netcons-retrigger-v1-4-3aea904926cf@gmail.com
-- 
Andre Carvalho