Re: [PATCH net-next] ipv6: add ipv6_addr_hash() helper

[Joe Perches <joe@perches.com>]

On Wed, 2012-07-18 at 14:08 +0200, Eric Dumazet wrote:
> Introduce ipv6_addr_hash() helper doing a XOR on all bits
> of an IPv6 address, with an optimized x86_64 version.
[]
> diff --git a/include/net/ipv6.h b/include/net/ipv6.h
[]
> @@ -419,6 +419,19 @@ static inline bool ipv6_addr_any(const struct in6_addr *a)
>  #endif
>  }
>  
> +static inline u32 ipv6_addr_hash(const struct in6_addr *a)
> +{
> +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && BITS_PER_LONG == 64
> +	const unsigned long *ul = (const unsigned long *)a;
> +	unsigned long x = ul[0] ^ ul[1];
> +
> +	return x ^ (x >> 32);

Thanks Eric.

Perhaps this would be better with an explicit rather
than implicit cast.