________________________________________
From: John W. Linville [linville@xxxxxxxxxxxxx]
Sent: Wednesday, May 28, 2008 8:46 PM
To: Senthilkumar Balasubramanian
Cc: johannes@xxxxxxxxxxxxxxxx; ron.rindjunsky@xxxxxxxxx; linux-wireless@xxxxxxxxxxxxxxx; Luis Rodriguez
Subject: Re: [PATCH] mac80211: fix alignment issue with compare_ether_addr()
On Wed, May 28, 2008 at 08:20:48PM +0530, Senthil Balasubramanian wrote:
> This addresses an alignment issue with compare_ether_addr().
> The addresses passed to compare_ether_addr should be two bytes aligned.
> It may function properly in x86 platform. However may not work properly
> on IA-64 or ARM processor.
> --- a/net/mac80211/rx.c
> +++ b/net/mac80211/rx.c
> @@ -1116,7 +1116,9 @@ ieee80211_data_to_8023(struct ieee80211_rx_data *rx)
> u16 fc, hdrlen, ethertype;
> u8 *payload;
> u8 dst[ETH_ALEN];
> - u8 src[ETH_ALEN];
> + /* Should be aligned on 2 bytes for compare_ether_addr() */
> + u16 src_aligned[ETH_ALEN >> 1];
> + u8 *src = (u8 *)src_aligned;
> struct sk_buff *skb = rx->skb;
> struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
> DECLARE_MAC_BUF(mac);
Any reason you couldn't just do this?
I just thought of using the type u16 instead of attribute here. that's all. No specific reason.
@@ -1116,7 +1116,7 @@ ieee80211_data_to_8023(struct ieee80211_rx_data *rx)
u16 fc, hdrlen, ethertype;
u8 *payload;
u8 dst[ETH_ALEN];
- u8 src[ETH_ALEN];
+ u8 src[ETH_ALEN] __attribute__ ((aligned(2)));
struct sk_buff *skb = rx->skb;
struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
DECLARE_MAC_BUF(mac);
It seems to compile w/o errors on i686, and it seems more clear to me.
Will that not work?
Yes. It should also work. I will re-create the patch and send it to you. I will also include Johannes suggestion of just using __aligned macro.
John
--
John W. Linville
linville@xxxxxxxxxxxxx
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