[PATCH v2 net-next 1/7] net: Add skb_get_hash_perturb

[Tom Herbert]

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: Tom Herbert <t...@herbertland.com>
---
 include/linux/skbuff.h    |  2 ++
 net/core/flow_dissector.c | 38 ++++++++++++++++++++++++++++++--------
 2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 66e374d..acb83e2 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -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;
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 2c35c02..b1df995 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -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.
-- 
1.8.1

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html