netdev - Re: [RFC net-next] net: track locally triggered link loss

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Date:   Fri, 20 May 2022 14:24:47 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, linux@...linux.org.uk, olteanv@...il.com,
        hkallweit1@...il.com, f.fainelli@...il.com, saeedm@...dia.com,
        michael.chan@...adcom.com
Subject: Re: [RFC net-next] net: track locally triggered link loss

> +/**
> + * netif_carrier_local_changes_start() - enter local link reconfiguration
> + * @dev: network device
> + *
> + * Mark link as unstable due to local administrative actions. This will
> + * cause netif_carrier_off() to behave like netif_carrier_admin_off() until
> + * netif_carrier_local_changes_end() is called.
> + */
> +static inline void netif_carrier_local_changes_start(struct net_device *dev)
> +{
> +	set_bit(__LINK_STATE_NOCARRIER_LOCAL, &dev->state);
> +}
> +
> +static inline void netif_carrier_local_changes_end(struct net_device *dev)
> +{
> +	clear_bit(__LINK_STATE_NOCARRIER_LOCAL, &dev->state);
> +}
> +

Since these don't perform reference counting, maybe a WARN_ON() if the
bit is already set/not set.

>  void netif_carrier_on(struct net_device *dev);
>  void netif_carrier_off(struct net_device *dev);
> +void netif_carrier_admin_off(struct net_device *dev);
>  void netif_carrier_event(struct net_device *dev);

I need some examples of how you see this used. I can see two ways:

At the start of a reconfigure, the driver calls
netif_carrier_local_changes_start() and once it is all over and ready
to do work again, it calls netif_carrier_local_changes_end().

The driver has a few netif_carrier_off() calls changed to
netif_carrier_admin_off(). It is then unclear looking at the code
which of the calls to netif_carrier_on() match the off.

Please could you pick a few drivers, and convert them? Maybe include a
driver which makes use of phylib, which should be doing control of the
carrier based on the actual link status.

	Andrew