netdev - Re: [PATCH net-next] r8169: remove not needed net

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Message-ID: <YxYrXZXfaPxL8BqX@lunn.ch>
Date:   Mon, 5 Sep 2022 19:01:17 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Francois Romieu <romieu@...zoreil.com>
Cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...emloft.net>,
        Realtek linux nic maintainers <nic_swsd@...ltek.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] r8169: remove not needed net_ratelimit() check

On Sat, Sep 03, 2022 at 05:21:35PM +0200, Francois Romieu wrote:
> Heiner Kallweit <hkallweit1@...il.com> :
> > We're not in a hot path and don't want to miss this message,
> > therefore remove the net_ratelimit() check.
> >
> > Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> 
> There had historically been some user push against excess "spam"
> messages, even when systems are able to stand a gazillion of phy
> generated messages - resources constrained systems may not - due
> to dysfunctionning hardware or externally triggered events.

Ethernet PHYs generally take 1 second to report link down. Auto neg
takes a little over 1 second to complete on link up. So i think the
worse case here is probably one message per second. Can a resource
constrained system be DoS at one message a second? If it really can, i
would suggest moving the rate limiting into the phylib helper, so all
devices are protected from this DoS vector.

       Andrew