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net: initialize hashrnd in flow_dissector with net_get_random_once 

We also can defer the initialization of hashrnd in flow_dissector
to its first use. Since net_get_random_once is irq safe now we don't
have to audit the call paths if one of this functions get called by an
interrupt handler.

Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Hannes Frederic Sowa 2013-10-23 20:06:00 +02:00 committed by David S. Miller
parent f84be2bd96
commit 66415cf8a1
1 changed files with 21 additions and 13 deletions
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34
net/core/flow_dissector.c
View File

@ -184,6 +184,22 @@ ipv6:
EXPORT_SYMBOL(skb_flow_dissect);
static u32 hashrnd __read_mostly;
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)
{
__flow_hash_secret_init();
return jhash_3words(a, b, c, hashrnd);
}
static __always_inline u32 __flow_hash_1word(u32 a)
{
__flow_hash_secret_init();
return jhash_1word(a, hashrnd);
}
/*
* __skb_get_rxhash: calculate a flow hash based on src/dst addresses
@ -210,9 +226,9 @@ void __skb_get_rxhash(struct sk_buff *skb)
swap(keys.port16[0], keys.port16[1]);
}
hash = jhash_3words((__force u32)keys.dst,
(__force u32)keys.src,
(__force u32)keys.ports, hashrnd);
hash = __flow_hash_3words((__force u32)keys.dst,
(__force u32)keys.src,
(__force u32)keys.ports);
if (!hash)
hash = 1;
@ -248,7 +264,7 @@ u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
hash = skb->sk->sk_hash;
else
hash = (__force u16) skb->protocol;
hash = jhash_1word(hash, hashrnd);
hash = __flow_hash_1word(hash);
return (u16) (((u64) hash * qcount) >> 32) + qoffset;
}
@ -340,7 +356,7 @@ static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
else
hash = (__force u16) skb->protocol ^
skb->rxhash;
hash = jhash_1word(hash, hashrnd);
hash = __flow_hash_1word(hash);
queue_index = map->queues[
((u64)hash * map->len) >> 32];
}
@ -395,11 +411,3 @@ struct netdev_queue *netdev_pick_tx(struct net_device *dev,
skb_set_queue_mapping(skb, queue_index);
return netdev_get_tx_queue(dev, queue_index);
}
static int __init initialize_hashrnd(void)
{
get_random_bytes(&hashrnd, sizeof(hashrnd));
return 0;
}
late_initcall_sync(initialize_hashrnd);