linux-kernel - Re: [PATCH net-next v2 7/7] net: ethernet: fs

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Message-ID: <20240902185543.48d91e87@kernel.org>
Date: Mon, 2 Sep 2024 18:55:43 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Maxime Chevallier <maxime.chevallier@...tlin.com>
Cc: davem@...emloft.net, Pantelis Antoniou <pantelis.antoniou@...il.com>,
 Andrew Lunn <andrew@...n.ch>, Eric Dumazet <edumazet@...gle.com>, Paolo
 Abeni <pabeni@...hat.com>, Russell King <linux@...linux.org.uk>, Christophe
 Leroy <christophe.leroy@...roup.eu>, Florian Fainelli
 <f.fainelli@...il.com>, Heiner Kallweit <hkallweit1@...il.com>,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 thomas.petazzoni@...tlin.com, Herve Codina <herve.codina@...tlin.com>,
 Simon Horman <horms@...nel.org>, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH net-next v2 7/7] net: ethernet: fs_enet: phylink
 conversion

On Thu, 29 Aug 2024 18:15:30 +0200 Maxime Chevallier wrote:
> @@ -582,15 +591,12 @@ static void fs_timeout_work(struct work_struct *work)
>  
>  	dev->stats.tx_errors++;
>  
> -	spin_lock_irqsave(&fep->lock, flags);
> -
> -	if (dev->flags & IFF_UP) {
> -		phy_stop(dev->phydev);
> -		(*fep->ops->stop)(dev);
> -		(*fep->ops->restart)(dev);
> -	}
> +	rtnl_lock();

so we take rtnl_lock here..

> +	phylink_stop(fep->phylink);
> +	phylink_start(fep->phylink);
> +	rtnl_unlock();
>  
> -	phy_start(dev->phydev);
> +	spin_lock_irqsave(&fep->lock, flags);
>  	wake = fep->tx_free >= MAX_SKB_FRAGS &&
>  	       !(CBDR_SC(fep->cur_tx) & BD_ENET_TX_READY);
>  	spin_unlock_irqrestore(&fep->lock, flags);

> @@ -717,19 +686,18 @@ static int fs_enet_close(struct net_device *dev)
>  	unsigned long flags;
>  
>  	netif_stop_queue(dev);
> -	netif_carrier_off(dev);
>  	napi_disable(&fep->napi);
>  	cancel_work_sync(&fep->timeout_work);

..and cancel_work_sync() under rtnl_lock here?

IDK if removing the the "dev->flags & IFF_UP" check counts as
meaningfully making it worse, but we're going in the wrong direction.
The _sync() has to go, and the timeout work needs to check if device
has been closed under rtnl_lock ?


> -	phy_stop(dev->phydev);
> +	phylink_stop(fep->phylink);
>  
>  	spin_lock_irqsave(&fep->lock, flags);
>  	spin_lock(&fep->tx_lock);
>  	(*fep->ops->stop)(dev);
>  	spin_unlock(&fep->tx_lock);
>  	spin_unlock_irqrestore(&fep->lock, flags);
> +	phylink_disconnect_phy(fep->phylink);
>  
>  	/* release any irqs */
> -	phy_disconnect(dev->phydev);
>  	free_irq(fep->interrupt, dev);
>  
>  	return 0;