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Subject: Re: [PATCH v2 2/2] r8169: Avoid pointer aliasing
From:   Joe Perches <joe@perches.com>
To:     David Miller <davem@davemloft.net>, thierry.reding@gmail.com
Cc:     hkallweit1@gmail.com, andrew@lunn.ch, nic_swsd@realtek.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Date:   Tue, 05 Feb 2019 10:42:54 -0800
In-Reply-To: <20190204.192040.1074738183781998611.davem@davemloft.net>
References: <20190204164213.30727-1-thierry.reding@gmail.com>
         <20190204164213.30727-2-thierry.reding@gmail.com>
         <20190204.192040.1074738183781998611.davem@davemloft.net>
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On Mon, 2019-02-04 at 19:20 -0800, David Miller wrote:
> From: Thierry Reding <thierry.reding@gmail.com>
> Date: Mon,  4 Feb 2019 17:42:13 +0100
> 
> > @@ -7316,7 +7325,7 @@ static int rtl_get_ether_clk(struct rtl8169_private *tp)
> >  static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
> >  {
> >       const struct rtl_cfg_info *cfg = rtl_cfg_infos + ent->driver_data;
> > -     u8 mac_addr[ETH_ALEN] __aligned(4) = {};
> > +     u8 mac_addr[ETH_ALEN] = {};
> >       struct rtl8169_private *tp;
> 
> I agree with Heiner, you have to provide at least 2 byte alignment for this
> buffer due to the reasons he stated.

It's declared after a pointer so it is already is 2 byte aligned.

A lot of drivers wouldn't work otherwise.