netdev - Re: [PATCH net] net: phylink: ensure PHY momentary link-fails are handled

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Message-ID: <ZzRDDbecGLMiRP0m@pengutronix.de>
Date: Wed, 13 Nov 2024 07:11:25 +0100
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: "Russell King (Oracle)" <rmk+kernel@...linux.org.uk>
Cc: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	netdev@...r.kernel.org
Subject: Re: [PATCH net] net: phylink: ensure PHY momentary link-fails are
 handled

On Tue, Nov 12, 2024 at 04:20:00PM +0000, Russell King (Oracle) wrote:
> Normally, phylib won't notify changes in quick succession. However, as
> a result of commit 3e43b903da04 ("net: phy: Immediately call
> adjust_link if only tx_lpi_enabled changes") this is no longer true -
> it is now possible that phy_link_down() and phy_link_up() will both
> complete before phylink's resolver has run, which means it'll miss that
> pl->phy_state.link momentarily became false.
> 
> Rename "mac_link_dropped" to be more generic "link_failed" since it will
> cover more than the MAC/PCS end of the link failing, and arrange to set
> this in phylink_phy_change() if we notice that the PHY reports that the
> link is down.
> 
> This will ensure that we capture an EEE reconfiguration event.
> 
> Fixes: 3e43b903da04 ("net: phy: Immediately call adjust_link if only tx_lpi_enabled changes")
> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>

Reviewed-by: Oleksij Rempel <o.rempel@...gutronix.de>

Thank you!

> ---
>  drivers/net/phy/phylink.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
> index 4309317de3d1..3e9957b6aa14 100644
> --- a/drivers/net/phy/phylink.c
> +++ b/drivers/net/phy/phylink.c
> @@ -78,7 +78,7 @@ struct phylink {
>  	unsigned int pcs_neg_mode;
>  	unsigned int pcs_state;
>  
> -	bool mac_link_dropped;
> +	bool link_failed;
>  	bool using_mac_select_pcs;
>  
>  	struct sfp_bus *sfp_bus;
> @@ -1475,9 +1475,9 @@ static void phylink_resolve(struct work_struct *w)
>  		cur_link_state = pl->old_link_state;
>  
>  	if (pl->phylink_disable_state) {
> -		pl->mac_link_dropped = false;
> +		pl->link_failed = false;
>  		link_state.link = false;
> -	} else if (pl->mac_link_dropped) {
> +	} else if (pl->link_failed) {
>  		link_state.link = false;
>  		retrigger = true;
>  	} else {
> @@ -1572,7 +1572,7 @@ static void phylink_resolve(struct work_struct *w)
>  			phylink_link_up(pl, link_state);
>  	}
>  	if (!link_state.link && retrigger) {
> -		pl->mac_link_dropped = false;
> +		pl->link_failed = false;
>  		queue_work(system_power_efficient_wq, &pl->resolve);
>  	}
>  	mutex_unlock(&pl->state_mutex);
> @@ -1835,6 +1835,8 @@ static void phylink_phy_change(struct phy_device *phydev, bool up)
>  		pl->phy_state.pause |= MLO_PAUSE_RX;
>  	pl->phy_state.interface = phydev->interface;
>  	pl->phy_state.link = up;
> +	if (!up)
> +		pl->link_failed = true;
>  	mutex_unlock(&pl->state_mutex);
>  
>  	phylink_run_resolve(pl);
> @@ -2158,7 +2160,7 @@ EXPORT_SYMBOL_GPL(phylink_disconnect_phy);
>  static void phylink_link_changed(struct phylink *pl, bool up, const char *what)
>  {
>  	if (!up)
> -		pl->mac_link_dropped = true;
> +		pl->link_failed = true;
>  	phylink_run_resolve(pl);
>  	phylink_dbg(pl, "%s link %s\n", what, up ? "up" : "down");
>  }
> @@ -2792,7 +2794,7 @@ int phylink_ethtool_set_pauseparam(struct phylink *pl,
>  	 * link will cycle.
>  	 */
>  	if (manual_changed) {
> -		pl->mac_link_dropped = true;
> +		pl->link_failed = true;
>  		phylink_run_resolve(pl);
>  	}
>  
> -- 
> 2.30.2
> 
> 

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