netdev - Re: [PATCH net-next 01/10] net: etherdevice: add address inherit helper

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Message-Id: <20130827.143501.1692335946060457637.davem@davemloft.net>
Date:	Tue, 27 Aug 2013 14:35:01 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	bjorn@...k.no
Cc:	stephen@...workplumber.org, netdev@...r.kernel.org
Subject: Re: [PATCH net-next 01/10] net: etherdevice: add address inherit
 helper

From: Bjørn Mork <bjorn@...k.no>
Date: Sat, 24 Aug 2013 00:28:55 +0200

> Stephen Hemminger <stephen@...workplumber.org> writes:
>> On Fri, 23 Aug 2013 11:35:04 +0200
>> Bjørn Mork <bjorn@...k.no> wrote:
>>
>>>  /**
>>> + * eth_hw_addr_inherit - Copy dev_addr from another net_device
>>> + * @dst: pointer to net_device to copy dev_addr to
>>> + * @src: pointer to net_device to copy dev_addr from
>>> + *
>>> + * Copy the Ethernet address from one net_device to another along with
>>> + * the addr_assign_type.
>>> + */
>>> +static inline int eth_hw_addr_inherit(struct net_device *dst,
>>> +				      struct net_device *src)
>>> +{
>>> +	if (dst->addr_len != src->addr_len)
>>> +		return -EINVAL;
>>> +
>>> +	dst->addr_assign_type = src->addr_assign_type;
>>> +	memcpy(dst->dev_addr, src->dev_addr, dst->addr_len);
>>> +	return 0;
>>> +}
>>> +
>>
>> Since all the other code in this file assumes addr_len == ETH_ALEN
>> why does this code need to handle variable addresses. Trivial but
>> then the memcpy is fixed size and can be optimized.
> 
> Didn't know that. I'll make that change in the next version.  Not that
> optimization matters much here, but consistency is always good.

You can bug check that addr_len ETH_ALEN if you want.

I realize that some drivers don't initialize it by this call point but
that is arguably a bug.
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