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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 <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f84be2bd

net/core/flow_dissector.c

+21 −13
Original line number Diff line number Diff line
@@ -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,

	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;

	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);