netdev - Re: [PATCH net-next 1/2] ethernet: use eth_hw_addr_set() for dev->addr

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Message-ID: <20211004155642.369db0ab@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Mon, 4 Oct 2021 15:56:42 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH net-next 1/2] ethernet: use eth_hw_addr_set() for
 dev->addr_len cases

On Tue, 5 Oct 2021 00:18:45 +0200 Andrew Lunn wrote:
> On Mon, Oct 04, 2021 at 09:05:21AM -0700, Jakub Kicinski wrote:
> > Convert all Ethernet drivers from memcpy(... dev->addr_len)
> > to eth_hw_addr_set():
> > 
> >   @@
> >   expression dev, np;
> >   @@
> >   - memcpy(dev->dev_addr, np, dev->addr_len)
> >   + eth_hw_addr_set(dev, np)  
> 
> eth_hw_addr_set() uses ether_addr_copy(), which says:
> 
> Please note: dst & src must both be aligned to u16.
> 
> memcpy() does not have this restriction. If the source is something
> funky, like an EEPROM, it could be oddly aligned.
> 
> If you are going to do this, i think the assumption needs removing, a
> test added for unaligned addresses and fall back to memcpy().

Thanks for pointing that out, I'll queue up a fix.

At the end of the conversion eth_hw_addr_set() calls dev_addr_set()
which is a memcpy() but I created the former first hence the wrong
ordering.