[PATCH 1/8] flow_dissector: Abstract out hash computation
From: Tom Herbert <hidden>
Date: 2014-07-02 04:32:07
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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: Tom Herbert <redacted> --- include/net/flow_keys.h | 1 + net/core/flow_dissector.c | 44 ++++++++++++++++++++++++++++---------------- 2 files changed, 29 insertions(+), 16 deletions(-)
diff --git a/include/net/flow_keys.h b/include/net/flow_keys.h
index fbefdca..6667a05 100644
--- a/include/net/flow_keys.h
+++ b/include/net/flow_keys.h@@ -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
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index c2b53c1..2ff8cd4 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c@@ -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);
--
2.0.0.526.g5318336