Commit 50fb7992 authored by Tom Herbert's avatar Tom Herbert Committed by David S. Miller
Browse files

net: Add skb_get_hash_perturb 



This calls flow_disect and __skb_get_hash to procure a hash for a
packet. Input includes a key to initialize jhash. This function
does not set skb->hash.

Signed-off-by: default avatarTom Herbert <tom@herbertland.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6a211654

include/linux/skbuff.h

+2 −0
Original line number Diff line number Diff line
@@ -927,6 +927,8 @@ static inline __u32 skb_get_hash(struct sk_buff *skb) 
	return skb->hash;

}



__u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb);



static inline __u32 skb_get_hash_raw(const struct sk_buff *skb)

{

	return skb->hash;

net/core/flow_dissector.c

+30 −8
Original line number Diff line number Diff line
@@ -267,13 +267,12 @@ static __always_inline void __flow_hash_secret_init(void) 
	net_get_random_once(&hashrnd, sizeof(hashrnd));

}



static __always_inline u32 __flow_hash_3words(u32 a, u32 b, u32 c)

static __always_inline u32 __flow_hash_3words(u32 a, u32 b, u32 c, u32 keyval)

{

	__flow_hash_secret_init();

	return jhash_3words(a, b, c, hashrnd);

	return jhash_3words(a, b, c, keyval);

}



static inline u32 __flow_hash_from_keys(struct flow_keys *keys)

static inline u32 __flow_hash_from_keys(struct flow_keys *keys, u32 keyval)

{

	u32 hash;
@@ -287,7 +286,8 @@ static inline u32 __flow_hash_from_keys(struct flow_keys *keys) 


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

				  (__force u32)keys->src,

				  (__force u32)keys->ports);

				  (__force u32)keys->ports,

				  keyval);

	if (!hash)

		hash = 1;
@@ -296,10 +296,20 @@ static inline u32 __flow_hash_from_keys(struct flow_keys *keys) 


u32 flow_hash_from_keys(struct flow_keys *keys)

{

	return __flow_hash_from_keys(keys);

	__flow_hash_secret_init();

	return __flow_hash_from_keys(keys, hashrnd);

}

EXPORT_SYMBOL(flow_hash_from_keys);



static inline u32 ___skb_get_hash(const struct sk_buff *skb,

				  struct flow_keys *keys, u32 keyval)

{

	if (!skb_flow_dissect(skb, keys))

		return 0;



	return __flow_hash_from_keys(keys, keyval);

}



/*

 * __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
@@ -309,8 +319,12 @@ EXPORT_SYMBOL(flow_hash_from_keys); 
void __skb_get_hash(struct sk_buff *skb)

{

	struct flow_keys keys;

	u32 hash;



	if (!skb_flow_dissect(skb, &keys))

	__flow_hash_secret_init();



	hash = ___skb_get_hash(skb, &keys, hashrnd);

	if (!hash)

		return;



	if (keys.ports)
@@ -318,10 +332,18 @@ void __skb_get_hash(struct sk_buff *skb) 


	skb->sw_hash = 1;



	skb->hash = __flow_hash_from_keys(&keys);

	skb->hash = hash;

}

EXPORT_SYMBOL(__skb_get_hash);



__u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb)

{

	struct flow_keys keys;



	return ___skb_get_hash(skb, &keys, perturb);

}

EXPORT_SYMBOL(skb_get_hash_perturb);



/*

 * Returns a Tx hash based on the given packet descriptor a Tx queues' number

 * to be used as a distribution range.