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Commit 5ed20a68 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

flow_dissector: Abstract out hash computation 



Move the hash computation located in __skb_get_hash to be a separate
function which takes flow_keys as input. This will allow flow hash
computation in other contexts where we only have addresses and ports.

Signed-off-by: default avatarTom Herbert <therbert@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 081a20ff

include/net/flow_keys.h

+1 −0
Original line number Diff line number Diff line
@@ -29,4 +29,5 @@ struct flow_keys { 


bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow);

__be32 skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto);

u32 flow_hash_from_keys(struct flow_keys *keys);

#endif

net/core/flow_dissector.c

+28 −16
Original line number Diff line number Diff line
@@ -202,6 +202,33 @@ static __always_inline u32 __flow_hash_1word(u32 a) 
	return jhash_1word(a, hashrnd);

}



static inline u32 __flow_hash_from_keys(struct flow_keys *keys)

{

	u32 hash;



	/* get a consistent hash (same value on both flow directions) */

	if (((__force u32)keys->dst < (__force u32)keys->src) ||

	    (((__force u32)keys->dst == (__force u32)keys->src) &&

	     ((__force u16)keys->port16[1] < (__force u16)keys->port16[0]))) {

		swap(keys->dst, keys->src);

		swap(keys->port16[0], keys->port16[1]);

	}



	hash = __flow_hash_3words((__force u32)keys->dst,

				  (__force u32)keys->src,

				  (__force u32)keys->ports);

	if (!hash)

		hash = 1;



	return hash;

}



u32 flow_hash_from_keys(struct flow_keys *keys)

{

	return __flow_hash_from_keys(keys);

}

EXPORT_SYMBOL(flow_hash_from_keys);



/*

 * __skb_get_hash: calculate a flow hash based on src/dst addresses

 * and src/dst port numbers.  Sets hash in skb to non-zero hash value
@@ -211,7 +238,6 @@ static __always_inline u32 __flow_hash_1word(u32 a) 
void __skb_get_hash(struct sk_buff *skb)

{

	struct flow_keys keys;

	u32 hash;



	if (!skb_flow_dissect(skb, &keys))

		return;
@@ -219,21 +245,7 @@ void __skb_get_hash(struct sk_buff *skb) 
	if (keys.ports)

		skb->l4_hash = 1;



	/* get a consistent hash (same value on both flow directions) */

	if (((__force u32)keys.dst < (__force u32)keys.src) ||

	    (((__force u32)keys.dst == (__force u32)keys.src) &&

	     ((__force u16)keys.port16[1] < (__force u16)keys.port16[0]))) {

		swap(keys.dst, keys.src);

		swap(keys.port16[0], keys.port16[1]);

	}



	hash = __flow_hash_3words((__force u32)keys.dst,

				  (__force u32)keys.src,

				  (__force u32)keys.ports);

	if (!hash)

		hash = 1;



	skb->hash = hash;

	skb->hash = __flow_hash_from_keys(&keys);

}

EXPORT_SYMBOL(__skb_get_hash);