[PATCH net-next] ipv6 Use get_hash_from_flowi6 for rt6 hash

[PATCH net-next] ipv6 Use get_hash_from_flowi6 for rt6 hash

[Tom Herbert]

In rt6_info_hash_nhsfn replace the custom hashing over flowi6 that is
using xor with a call to common function get_hash_from_flowi6.

Signed-off-by: Tom Herbert <tom@herbertland.com>
---
 net/ipv6/route.c | 26 +-------------------------
 1 file changed, 1 insertion(+), 25 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 53617d7..111dead 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -421,31 +421,7 @@ static bool rt6_check_expired(const struct rt6_info *rt)
 static int rt6_info_hash_nhsfn(unsigned int candidate_count,
 			       const struct flowi6 *fl6)
 {
-	unsigned int val = fl6->flowi6_proto;
-
-	val ^= ipv6_addr_hash(&fl6->daddr);
-	val ^= ipv6_addr_hash(&fl6->saddr);
-
-	/* Work only if this not encapsulated */
-	switch (fl6->flowi6_proto) {
-	case IPPROTO_UDP:
-	case IPPROTO_TCP:
-	case IPPROTO_SCTP:
-		val ^= (__force u16)fl6->fl6_sport;
-		val ^= (__force u16)fl6->fl6_dport;
-		break;
-
-	case IPPROTO_ICMPV6:
-		val ^= (__force u16)fl6->fl6_icmp_type;
-		val ^= (__force u16)fl6->fl6_icmp_code;
-		break;
-	}
-	/* RFC6438 recommands to use flowlabel */
-	val ^= (__force u32)fl6->flowlabel;
-
-	/* Perhaps, we need to tune, this function? */
-	val = val ^ (val >> 7) ^ (val >> 12);
-	return val % candidate_count;
+	return get_hash_from_flowi6(fl6) % candidate_count;
 }
 
 static struct rt6_info *rt6_multipath_select(struct rt6_info *match,
-- 
2.4.6

Re: [PATCH net-next] ipv6 Use get_hash_from_flowi6 for rt6 hash

[David Miller]

From: Tom Herbert <tom@herbertland.com>
Date: Wed, 23 Sep 2015 14:13:35 -0700

> In rt6_info_hash_nhsfn replace the custom hashing over flowi6 that is
> using xor with a call to common function get_hash_from_flowi6.
> 
> Signed-off-by: Tom Herbert <tom@herbertland.com>

Applied, thanks.

Re: [PATCH net-next] ipv6 Use get_hash_from_flowi6 for rt6 hash

[David Miller]

From: David Miller <davem@davemloft.net>
Date: Wed, 23 Sep 2015 14:21:38 -0700 (PDT)

> From: Tom Herbert <tom@herbertland.com>
> Date: Wed, 23 Sep 2015 14:13:35 -0700
> 
>> In rt6_info_hash_nhsfn replace the custom hashing over flowi6 that is
>> using xor with a call to common function get_hash_from_flowi6.
>> 
>> Signed-off-by: Tom Herbert <tom@herbertland.com>
> 
> Applied, thanks.

Tom, I just so happened to look over the call paths that lead to this
function and the flowi6 ports aren't filled in much of the time.

I know your patch doesn't change things one way or the other in this
area, but I thought I'd bring it up nonetheless.

Re: [PATCH net-next] ipv6 Use get_hash_from_flowi6 for rt6 hash

[Tom Herbert]

On Wed, Sep 23, 2015 at 2:57 PM, David Miller <davem@davemloft.net> wrote:
> From: David Miller <davem@davemloft.net>
> Date: Wed, 23 Sep 2015 14:21:38 -0700 (PDT)
>
>> From: Tom Herbert <tom@herbertland.com>
>> Date: Wed, 23 Sep 2015 14:13:35 -0700
>>
>>> In rt6_info_hash_nhsfn replace the custom hashing over flowi6 that is
>>> using xor with a call to common function get_hash_from_flowi6.
>>>
>>> Signed-off-by: Tom Herbert <tom@herbertland.com>
>>
>> Applied, thanks.
>
> Tom, I just so happened to look over the call paths that lead to this
> function and the flowi6 ports aren't filled in much of the time.
>
> I know your patch doesn't change things one way or the other in this
> area, but I thought I'd bring it up nonetheless.

Yeah, I noticed  there's still a little work to do here. On input put
we should be passing in skb to use skb->hash instead of calculating
it. On ouput we should be getting hash from sk->txhash for connected
sockets.