netdev - Re: [PATCH][NET] several cleanups and bugfixes for fec.c: don't munge MAC address from platform data

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Date:	Wed, 7 Dec 2011 09:47:38 +0100
From:	Lothar Waßmann <LW@...O-electronics.de>
To:	Shawn Guo <shawn.guo@...escale.com>
Cc:	Baruch Siach <baruch@...s.co.il>, <netdev@...r.kernel.org>,
	Shawn Guo <shawn.guo@...aro.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH][NET] several cleanups and bugfixes for fec.c: don't
 munge MAC address from platform data

Hi,

Shawn Guo writes:
> On Tue, Dec 06, 2011 at 02:44:44PM +0100, Lothar Waßmann wrote:
> > Hi,
> > 
> > Baruch Siach writes:
> > > Hi Lothar,
> > > 
> > > On Tue, Dec 06, 2011 at 11:27:13AM +0100, Lothar Waßmann wrote:
> > > > When the MAC address is supplied via platform_data it should be OK as
> > > > it is and should not be modified in case of a dual FEC setup.
> > > > Also copying the MAC from platform_data to the single 'macaddr'
> > > > variable will overwrite the MAC for the first interface in case of a
> > > > dual FEC setup.
> > > > 
> > > > Signed-off-by: Lothar Waßmann <LW@...O-electronics.de>
> > > > ---
> > > >  drivers/net/ethernet/freescale/fec.c |    2 +-
> > > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > > 
> > > > diff --git a/drivers/net/ethernet/freescale/fec.c b/drivers/net/ethernet/freescale/fec.c
> > > > index e2b5ce6..11534b9 100644
> > > > --- a/drivers/net/ethernet/freescale/fec.c
> > > > +++ b/drivers/net/ethernet/freescale/fec.c
> > > > @@ -818,7 +818,7 @@ static void __inline__ fec_get_mac(struct net_device *ndev)
> > > >  			iap = (unsigned char *)FEC_FLASHMAC;
> > > >  #else
> > > >  		if (pdata)
> > > > -			memcpy(iap, pdata->mac, ETH_ALEN);
> > > > +			iap = (unsigned char *)&pdata->mac;
> > > 
> > > Since pdata might point to __initdata struct, you must hold a copy of its 
> > > content.
> > > 
> 
> As iap will anyway be copied to ndev->dev_addr after that, it may still
> be fine to take this patch, for obviously for different reason.
> 
> > No. platform_data must be present during the life time of a driver
> > using it and thus must never be __initdata!
> > 
> Then we need to fix a lot of imx/mxc platform codes, mach-mx28evk.c
> is the one for this case.
> 
Nope. The platform_data provided there is only a template that is
copied to kmalloc'ed memory by the mxs_add...() functions.

With actual platform_data in init memory no driver built as module
would work.


Lothar Waßmann
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