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authorDavid S. Miller <davem@davemloft.net>2016-07-01 16:07:50 -0400
committerDavid S. Miller <davem@davemloft.net>2016-07-01 16:07:50 -0400
commiteb70db8756717b90c01ccc765fdefc4dd969fc74 (patch)
tree80c89c33271947ab3785bcaeb66bd21a8b416c7d /include
parent08df7bc5001e7fc8bdb0a74e04ad2db5f797ed3d (diff)
downloadlinux-eb70db8756717b90c01ccc765fdefc4dd969fc74.tar.bz2
packet: Use symmetric hash for PACKET_FANOUT_HASH.
People who use PACKET_FANOUT_HASH want a symmetric hash, meaning that they want packets going in both directions on a flow to hash to the same bucket. The core kernel SKB hash became non-symmetric when the ipv6 flow label and other entities were incorporated into the standard flow hash order to increase entropy. But there are no users of PACKET_FANOUT_HASH who want an assymetric hash, they all want a symmetric one. Therefore, use the flow dissector to compute a flat symmetric hash over only the protocol, addresses and ports. This hash does not get installed into and override the normal skb hash, so this change has no effect whatsoever on the rest of the stack. Reported-by: Eric Leblond <eric@regit.org> Tested-by: Eric Leblond <eric@regit.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
-rw-r--r--include/linux/skbuff.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index ee38a4127475..24859d40acde 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -1062,6 +1062,7 @@ __skb_set_sw_hash(struct sk_buff *skb, __u32 hash, bool is_l4)
}
void __skb_get_hash(struct sk_buff *skb);
+u32 __skb_get_hash_symmetric(struct sk_buff *skb);
u32 skb_get_poff(const struct sk_buff *skb);
u32 __skb_get_poff(const struct sk_buff *skb, void *data,
const struct flow_keys *keys, int hlen);