Re: [PATCH] usbnet: smsc95xx: simplify tx_fixup code

[David Miller]

From: Ben Dooks <ben.dooks@xxxxxxxxxxxxxxx>
Date: Tue,  2 Oct 2018 17:56:02 +0100

> -	memcpy(skb->data, &tx_cmd_a, 4);
> +	ptr = skb_push(skb, 8);
> +	tx_cmd_a = cpu_to_le32(tx_cmd_a);
> +	tx_cmd_b = cpu_to_le32(tx_cmd_b);
> +	memcpy(ptr, &tx_cmd_a, 4);
> +	memcpy(ptr+4, &tx_cmd_b, 4);

Even a memcpy() through a void pointer does not guarantee that gcc will
not emit word sized loads and stores.

You must use the get_unaligned()/put_unaligned() facilities to do this
properly.

I also agree that making a proper type and structure instead of using
a void pointer would be better.