linux-kernel - Re: [PATCH v3 03/33] staging: rtl8192e: Mark unaligned memcpy()

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Message-ID: <20150513082254.GQ14154@mwanda>
Date:	Wed, 13 May 2015 11:22:54 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Mateusz Kulikowski <mateusz.kulikowski@...il.com>
Cc:	devel@...verdev.osuosl.org, gregkh@...uxfoundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 03/33] staging: rtl8192e: Mark unaligned memcpy()

On Tue, May 12, 2015 at 10:00:13PM +0200, Mateusz Kulikowski wrote:
> On 11.05.2015 10:26, Dan Carpenter wrote:
> (...)
> >>  				 */
> >>  				skb_pull(sub_skb, SNAP_SIZE);
> >> -				memcpy(skb_push(sub_skb, ETH_ALEN), prxb->src, ETH_ALEN);
> >> -				memcpy(skb_push(sub_skb, ETH_ALEN), prxb->dst, ETH_ALEN);
> >> +				memcpy(skb_push(sub_skb, ETH_ALEN), prxb->src,
> >> +				       ETH_ALEN); /* Must be unaligned */
> > 
> > 
> > Which part isn't aligned?  I think they both are.
> > 
> struct rtllib_rxb *prxb = prxbIndicateArray[j];
> 
> struct rtllib_rxb {
> 	u8 nr_subframes;
> 	struct sk_buff *subframes[MAX_SUBFRAME_COUNT == 64];
> 	u8 dst[ETH_ALEN]; // here
> 	u8 src[ETH_ALEN]; // here
> } __packed;
> 
> Either I forgot alignment / packing rules or this fields are never aligned "by design".

You must have forgotten something...  Everything after the pointer is
going to be aligned sizeof(void *).

regards,
dan carpenter

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