netdev - Re: [PATCH net-next v3 3/4] net: macb: Add ARP support to WOL

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Message-ID: <901ec7a8-7460-492e-8f50-6d339a987020@lunn.ch>
Date: Thu, 6 Jun 2024 03:59:45 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Vineeth Karumanchi <vineeth.karumanchi@....com>
Cc: nicolas.ferre@...rochip.com, claudiu.beznea@...on.dev,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
	linux@...linux.org.uk, vadim.fedorenko@...ux.dev,
	netdev@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, git@....com
Subject: Re: [PATCH net-next v3 3/4] net: macb: Add ARP support to WOL

> @@ -3278,13 +3280,11 @@ static void macb_get_wol(struct net_device *netdev, struct ethtool_wolinfo *wol)
>  {
>  	struct macb *bp = netdev_priv(netdev);
>  
> -	if (bp->wol & MACB_WOL_HAS_MAGIC_PACKET) {
> -		phylink_ethtool_get_wol(bp->phylink, wol);
> -		wol->supported |= WAKE_MAGIC;
> -
> -		if (bp->wol & MACB_WOL_ENABLED)
> -			wol->wolopts |= WAKE_MAGIC;
> -	}
> +	phylink_ethtool_get_wol(bp->phylink, wol);

So you ask the PHY what it supports, and what it currently has
enabled.

> +	wol->supported |= (bp->wol & MACB_WOL_HAS_MAGIC_PACKET) ? WAKE_MAGIC : 0;
> +	wol->supported |= (bp->wol & MACB_WOL_HAS_ARP_PACKET) ? WAKE_ARP : 0;

You mask in what the MAC supports.

> +	/* Pass wolopts to ethtool */
> +	wol->wolopts = bp->wolopts;

And then you overwrite what the PHY is currently doing with
bp->wolopts.

Now, if we look at what macb_set_wol does:

> @@ -3300,11 +3300,10 @@ static int macb_set_wol(struct net_device *netdev, struct ethtool_wolinfo *wol)
>  	if (!ret || ret != -EOPNOTSUPP)
>  		return ret;
>

We are a little bit short of context here. This is checking the return
value of:

	ret = phylink_ethtool_set_wol(bp->phylink, wol);

So if there is no error, or an error which is not EOPNOTSUPP, it
returns here. So if the PHY supports WAKE_MAGIC and/or WAKE_ARP, there
is nothing for the MAC to do. Importantly, the code below which sets
bp->wolopts is not reached.

So your get_wol looks wrong.

> -	if (!(bp->wol & MACB_WOL_HAS_MAGIC_PACKET) ||
> -	    (wol->wolopts & ~WAKE_MAGIC))
> -		return -EOPNOTSUPP;
> +	bp->wolopts = (wol->wolopts & WAKE_MAGIC) ? WAKE_MAGIC : 0;
> +	bp->wolopts |= (wol->wolopts & WAKE_ARP) ? WAKE_ARP : 0;
>  
> -	if (wol->wolopts & WAKE_MAGIC)
> +	if (bp->wolopts)
>  		bp->wol |= MACB_WOL_ENABLED;
>  	else
>  		bp->wol &= ~MACB_WOL_ENABLED;
> @@ -5085,10 +5084,8 @@ static int macb_probe(struct platform_device *pdev)
>  	else
>  		bp->max_tx_length = GEM_MAX_TX_LEN;
>  

> @@ -5257,6 +5255,12 @@ static int __maybe_unused macb_suspend(struct device *dev)
>  		return 0;
>  
>  	if (bp->wol & MACB_WOL_ENABLED) {
> +		/* Check for IP address in WOL ARP mode */
> +		ifa = rcu_dereference(__in_dev_get_rcu(bp->dev)->ifa_list);
> +		if ((bp->wolopts & WAKE_ARP) && !ifa) {
> +			netdev_err(netdev, "IP address not assigned\n");
> +			return -EOPNOTSUPP;
> +		}

I don't know suspend too well. Is returning an error enough abort the
suspend?

	Andrew