netdev - Re: net/eth/ibmveth: Fixup retrieval of MAC address

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Message-ID: <1367598632.2756.3.camel@bwh-desktop.uk.solarflarecom.com>
Date:	Fri, 3 May 2013 17:30:32 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
CC:	<netdev@...r.kernel.org>, David Miller <davem@...emloft.net>,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
	David Gibson <dwg@....ibm.com>
Subject: Re: net/eth/ibmveth: Fixup retrieval of MAC address

On Thu, 2013-05-02 at 11:35 +1000, Benjamin Herrenschmidt wrote:
> Some ancient pHyp versions used to create a 8 bytes local-mac-address
> property in the device-tree instead of a 6 bytes one for veth.
> 
> The Linux driver code to deal with that is an insane hack which also
> happens to break with some choices of MAC addresses in qemu by testing
> for a bit in the address rather than just looking at the size of the
> property.
> 
> Sanitize this by doing the latter instead.
[...]
> @@ -1334,11 +1334,19 @@ static int ibmveth_probe(struct vio_dev *dev, const struct vio_device_id *id)
>  		dev->unit_address);
>  
>  	mac_addr_p = (unsigned char *)vio_get_attribute(dev, VETH_MAC_ADDR,
> -							NULL);
> +							&mac_len);
>  	if (!mac_addr_p) {
>  		dev_err(&dev->dev, "Can't find VETH_MAC_ADDR attribute\n");
>  		return -EINVAL;
>  	}
> +	/* Workaround for old/broken pHyp */
> +	if (mac_len == 8)
> +		mac_addr_p += 2;
> +	if (mac_len != 6) {

Missing 'else' before the second if?

> +		dev_err(&dev->dev, "VETH_MAC_ADDR attribute wrong len %d\n",
> +			mac_len);
> +		return -EINVAL;
> +	}
[...]

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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