Subject: Re: [PATCH net-next v2 7/7] net: ethernet: fs_enet: phylink conversion

From: Jakub Kicinski <[email-masked]>
Date: Mon, 2 Sep 2024 18:55:43 -0700

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;