Date: Mon, 6 Jan 2014 10:09:20 +0100 (CET)
From: Julia Lawall <julia.lawall@lip6.fr>
To: Johannes Berg <johannes@sipsolutions.net>
cc: Julia Lawall <julia.lawall@lip6.fr>,
	Ben Greear <greearb@candelatech.com>,
	Joe Perches <joe@perches.com>,
	Henrique de Moraes Holschuh <hmh@hmh.eng.br>,
	kernel-janitors@vger.kernel.org,
	Emmanuel Grumbach <emmanuel.grumbach@intel.com>,
	Intel Linux Wireless <ilw@linux.intel.com>,
	"John W. Linville" <linville@tuxdriver.com>,
	linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/11]  use ether_addr_equal_64bits
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On Mon, 6 Jan 2014, Johannes Berg wrote:

> On Tue, 2013-12-31 at 17:40 +0100, Julia Lawall wrote:
>
> > > If nothing else, then some run-time code that calculates the offset off
> > > and asserts if it is broken in module initialization or similar might
> > > be good enough.
> >
> > Could be OK.  Something right in or after the structure declaration would
> > be nicest.
>
> I don't think you can put a BUILD_BUG_ON() into the structure
> declaration (it's code, not declarations), but I think you could just
> put
>
> BUILD_BUG_ON(sizeof(struct foo) - offsetof(struct foo, addr) < 8);
>
> with the user(s?) and that should catch the scenario I was worrying
> about?

OK, thanks.  That is what I had in mind.  But I was hoping to be able to
put it with the structure.  Perhaps there is a way to make a macro that
expands to a dummy function that contains the BUILD_BUG_ON?  But I guess
that would waste space?

I think that 8 should be 16?

julia