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Commit 8f0f2223 authored by David S. Miller's avatar David S. Miller
Browse files

net: Implement simple sw TX hashing. 



It just xor hashes over IPv4/IPv6 addresses and ports of transport.

The only assumption it makes is that skb_network_header() is set
correctly.

With bug fixes from Eric Dumazet.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 51cb6db0

net/core/dev.c

+52 −0
Original line number Diff line number Diff line
@@ -121,6 +121,9 @@ 
#include <linux/ctype.h>

#include <linux/if_arp.h>

#include <linux/if_vlan.h>

#include <linux/ip.h>

#include <linux/ipv6.h>

#include <linux/in.h>



#include "net-sysfs.h"
@@ -1665,6 +1668,53 @@ int dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev, 
 *          --BLG

 */



static u16 simple_tx_hash(struct net_device *dev, struct sk_buff *skb)

{

	u32 *addr, *ports, hash, ihl;

	u8 ip_proto;

	int alen;



	switch (skb->protocol) {

	case __constant_htons(ETH_P_IP):

		ip_proto = ip_hdr(skb)->protocol;

		addr = &ip_hdr(skb)->saddr;

		ihl = ip_hdr(skb)->ihl;

		alen = 2;

		break;

	case __constant_htons(ETH_P_IPV6):

		ip_proto = ipv6_hdr(skb)->nexthdr;

		addr = &ipv6_hdr(skb)->saddr.s6_addr32[0];

		ihl = (40 >> 2);

		alen = 8;

		break;

	default:

		return 0;

	}



	ports = (u32 *) (skb_network_header(skb) + (ihl * 4));



	hash = 0;

	while (alen--)

		hash ^= *addr++;



	switch (ip_proto) {

	case IPPROTO_TCP:

	case IPPROTO_UDP:

	case IPPROTO_DCCP:

	case IPPROTO_ESP:

	case IPPROTO_AH:

	case IPPROTO_SCTP:

	case IPPROTO_UDPLITE:

		hash ^= *ports;

		break;



	default:

		break;

	}



	return hash % dev->real_num_tx_queues;

}



static struct netdev_queue *dev_pick_tx(struct net_device *dev,

					struct sk_buff *skb)

{
@@ -1672,6 +1722,8 @@ static struct netdev_queue *dev_pick_tx(struct net_device *dev, 


	if (dev->select_queue)

		queue_index = dev->select_queue(dev, skb);

	else if (dev->real_num_tx_queues > 1)

		queue_index = simple_tx_hash(dev, skb);



	skb_set_queue_mapping(skb, queue_index);

	return netdev_get_tx_queue(dev, queue_index);