On Wed, May 28, 2008 at 8:33 PM, Senthilkumar Balasubramanian <Senthilkumar.Balasubramanian@xxxxxxxxxxx> wrote: > > ________________________________________ > From: Tomas Winkler [tomasw@xxxxxxxxx] > Sent: Wednesday, May 28, 2008 10:37 PM > To: Senthilkumar Balasubramanian > Cc: John W. Linville; 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 7:50 PM, Senthilkumar Balasubramanian > <Senthilkumar.Balasubramanian@xxxxxxxxxxx> wrote: >> ________________________________________ >> 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. >> > Can we split the two issues in seperate patches. It's better for tracking. > > They are not two different issues. All of them addresses the same alignment issue only. Initially I thought of using u16 to get it aligned on 2 byte and then I started using the attribute stuff as in page_group_addr[] and others required initializations for the u8 array. > I mean reordering buffer allocation and alignment are not the same issues. Thanks Tomas -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
