Re: [PATCH 2/2 v2] bonding: COW before overwriting the destination MAC address

Le jeudi 03 mars 2011 à 16:21 +0800, Changli Gao a écrit :

On Thu, Mar 3, 2011 at 3:55 PM, Eric Dumazet [off-list ref] wrote:

quoted

Thats minor, but using :

u16 *dest = eth_hdr(skb)->h_dest;

memcpy(dest, ptr, ETH_ALEN);

Is better because compiler knows both destination and source are at
least aligned on shorts.

On some arches, it helps to not using 6 bytes copy, but 3 shorts.

Is it still true if ptr isn't aligned on shorts? And
net_device.dev_addr is an unsigned char *pointer. Thanks.

dev_addr[] was aligned to word boundaries (because of natural structure
alignment), but the recent changes made it a char *pointer, so gcc is
not able to make this true anymore.

This could change if dev_addr was a pointer to struct netdev_hw_addr