Subject: Re: [RFCv2 bluetooth-next 2/3] ipv6: add ipv6_addr_prefix_cpy

From: Sergei Shtylyov <sergei.shtylyov-M4DtvfQ/[email-masked]>
Date: Wed, 18 Nov 2015 16:55:02 +0300

Hello.

On 11/18/2015 1:33 AM, Alexander Aring wrote:

> This patch adds a static inline function ipv6_addr_prefix_cpy which

    I suggest not to reduce "copy".

> copies a ipv6 address prefix(argument pfx) into the ipv6 address prefix.
> The prefix len is given by plen as bits. This function mainly based on
> ipv6_addr_prefix which copies one address prefix from address into a new
> ipv6 address destination and zero all other address bits.
>
> The difference is that ipv6_addr_prefix_cpy don't get a prefix from an
> ipv6 address, it sets a prefix to an ipv6 address with keeping other
> address bits. The use case is for context based address compression
> inside 6LoWPAN IPHC header which keeping ipv6 prefixes inside a context
> table to lookup address-bits without sending them.
>
> Cc: David S. Miller <davem-fT/PcQaiUtIeIZ0/[email-masked]>
> Cc: Alexey Kuznetsov <kuznet-v/[email-masked]>
> Cc: James Morris <jmorris-gx6/[email-masked]>
> Cc: Hideaki YOSHIFUJI <[email-masked]>
> Cc: Patrick McHardy <[email-masked]>
> Signed-off-by: Alexander Aring <[email-masked]>
> ---
>   include/net/ipv6.h | 15 +++++++++++++++
>   1 file changed, 15 insertions(+)
>
> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
> index e1a10b0..9d38fc2 100644
> --- a/include/net/ipv6.h
> +++ b/include/net/ipv6.h
> @@ -382,6 +382,21 @@ static inline void ipv6_addr_prefix(struct in6_addr *pfx,
>   		pfx->s6_addr[o] = addr->s6_addr[o] & (0xff00 >> b);
>   }
>
> +static inline void ipv6_addr_prefix_cpy(struct in6_addr *addr,
> +					const struct in6_addr *pfx,
> +					int plen)
> +{
> +	/* caller must guarantee 0 <= plen <= 128 */
> +	int o = plen >> 3,
> +	    b = plen & 0x7;

    Unusual declaration style, why not just have *int* on both lines?

[...]

MBR, Sergei