linux-kernel - Re: [PATCH v2 net 1/2] net: phylink: add lock for serializing concurrent pl->phydev writes with resolver

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Message-ID: <20250903170437.5oqjvszb7y6v4alm@skbuf>
Date: Wed, 3 Sep 2025 20:04:37 +0300
From: Vladimir Oltean <vladimir.oltean@....com>
To: "Russell King (Oracle)" <linux@...linux.org.uk>
Cc: netdev@...r.kernel.org, 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>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 net 1/2] net: phylink: add lock for serializing
 concurrent pl->phydev writes with resolver

On Wed, Sep 03, 2025 at 04:52:09PM +0100, Russell King (Oracle) wrote:
> The reason I'm making the suggestion is for consistency. If the lock
> is there to ensure that reading pl->phydev is done safely, having one
> site where we read it and then take the lock makes it look confusing.
> I've also been thinking that it should be called pl->phydev_mutex
> (note that phylink uses _mutex for mutexes.)
> 
> To avoid it looking weird, what about this:
> 
> 	mutex_lock(&pl->phy_lock);
> 	phy = pl->phydev;
> 	if (phy) {
> 		mutex_lock(&phy->lock);
> 		mutex_lock(&pl->state_mutex);
> 		pl->phydev = NULL;
> 		pl->phy_enable_tx_lpi = false;
> 		pl->mac_tx_clk_stop = false;
> 		mutex_unlock(&pl->state_mutex);
> 		mutex_unlock(&phy->lock);
> 	}
> 	mutex_unlock(&pl->phy_lock);
> 
> 	if (phy) 
>  		flush_work(&pl->resolve);
>  
>  		phy_disconnect(phy);
>  	}

I can make these changes and repost tomorrow, after some extra testing.
Thanks for the feedback.