linux-kernel - Re: [PATCH net-next 0/2] Allow disabling pause frames on panic

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Message-ID: <ad5d4ba5-bd30-429d-9c5c-86b3d6abe232@broadcom.com>
Date: Mon, 3 Nov 2025 15:34:15 -0800
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com,
 Doug Berger <opendmb@...il.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
 Stanislav Fomichev <sdf@...ichev.me>, Antoine Tenart <atenart@...nel.org>,
 Kuniyuki Iwashima <kuniyu@...gle.com>, Yajun Deng <yajun.deng@...ux.dev>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next 0/2] Allow disabling pause frames on panic

On 11/3/25 15:22, Jakub Kicinski wrote:
> On Mon,  3 Nov 2025 11:46:29 -0800 Florian Fainelli wrote:
>> This patch set allows disabling pause frame generation upon encountering
>> a kernel panic. This has proven to be helpful in lab environments where
>> devices are still being worked on, will panic for various reasons, and
>> will occasionally take down the entire Ethernet switch they are attached
>> to.
> 
> Could you explain in more detail? What does it mean that a pause frame
> takes down an Ethernet switch?

One of our devices crashed and kept on sending pause frames to its link 
partner which is an Ethernet router. Rather than continue to forward 
traffic between other LAN ports and Wi-Fi, that router just stopped 
doing that and the other devices were frozen. I don't have the exact 
model yet because this was on a different site/team but I will try to 
get that. This should obviously be treated as a router bug and its 
firmware should be updated, if there is an update available.

I have seen it happen a bunch of times at home as well with an unmanaged 
5-port TP-Link switch and a crashed laptop.
-- 
Florian