Commit 66415cf8 authored by Hannes Frederic Sowa's avatar Hannes Frederic Sowa Committed by David S. Miller
Browse files

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 <>
Cc: Eric Dumazet <>
Signed-off-by: default avatarHannes Frederic Sowa <>
Signed-off-by: default avatarDavid S. Miller <>
parent f84be2bd
......@@ -184,6 +184,22 @@ bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
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)
return jhash_3words(a, b, c, hashrnd);
static __always_inline u32 __flow_hash_1word(u32 a)
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,
hash = __flow_hash_3words((__force u32)keys.dst,
(__force u32)keys.src,
(__force u32)keys.ports, hashrnd);
(__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;
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)
hash = (__force u16) skb->protocol ^
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;
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