Commit 40384999 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv4: change inet_addr_hash() 



Use net_hash_mix(net) instead of hash_ptr(net, 8), and use
hash_32() instead of using a serie of XOR

Define IN4_ADDR_HSIZE_SHIFT for clarity

__ip_dev_find() can perform the net_eq() call only if ifa_local
matches the key, to avoid unneeded dereferences.

remove inline attributes

# size net/ipv4/devinet.o.before net/ipv4/devinet.o
   text	   data	    bss	    dec	    hex	filename
  17471	   2545	   2048	  22064	   5630	net/ipv4/devinet.o.before
  17335	   2545	   2048	  21928	   55a8	net/ipv4/devinet.o

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 47061bc4

net/ipv4/devinet.c

+18 −21
Original line number Diff line number Diff line
@@ -94,25 +94,22 @@ static const struct nla_policy ifa_ipv4_policy[IFA_MAX+1] = { 
	[IFA_LABEL]     	= { .type = NLA_STRING, .len = IFNAMSIZ - 1 },

};



/* inet_addr_hash's shifting is dependent upon this IN4_ADDR_HSIZE

 * value.  So if you change this define, make appropriate changes to

 * inet_addr_hash as well.

 */

#define IN4_ADDR_HSIZE	256

#define IN4_ADDR_HSIZE_SHIFT	8

#define IN4_ADDR_HSIZE		(1U << IN4_ADDR_HSIZE_SHIFT)



static struct hlist_head inet_addr_lst[IN4_ADDR_HSIZE];

static DEFINE_SPINLOCK(inet_addr_hash_lock);



static inline unsigned int inet_addr_hash(struct net *net, __be32 addr)

static u32 inet_addr_hash(struct net *net, __be32 addr)

{

	u32 val = (__force u32) addr ^ hash_ptr(net, 8);

	u32 val = (__force u32) addr ^ net_hash_mix(net);



	return ((val ^ (val >> 8) ^ (val >> 16) ^ (val >> 24)) &

		(IN4_ADDR_HSIZE - 1));

	return hash_32(val, IN4_ADDR_HSIZE_SHIFT);

}



static void inet_hash_insert(struct net *net, struct in_ifaddr *ifa)

{

	unsigned int hash = inet_addr_hash(net, ifa->ifa_local);

	u32 hash = inet_addr_hash(net, ifa->ifa_local);



	spin_lock(&inet_addr_hash_lock);

	hlist_add_head_rcu(&ifa->hash, &inet_addr_lst[hash]);
@@ -136,18 +133,18 @@ static void inet_hash_remove(struct in_ifaddr *ifa) 
 */

struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref)

{

	unsigned int hash = inet_addr_hash(net, addr);

	u32 hash = inet_addr_hash(net, addr);

	struct net_device *result = NULL;

	struct in_ifaddr *ifa;

	struct hlist_node *node;



	rcu_read_lock();

	hlist_for_each_entry_rcu(ifa, node, &inet_addr_lst[hash], hash) {

		if (ifa->ifa_local == addr) {

			struct net_device *dev = ifa->ifa_dev->dev;



			if (!net_eq(dev_net(dev), net))

				continue;

		if (ifa->ifa_local == addr) {

			result = dev;

			break;

		}
@@ -182,10 +179,10 @@ static void inet_del_ifa(struct in_device *in_dev, struct in_ifaddr **ifap, 
static void devinet_sysctl_register(struct in_device *idev);

static void devinet_sysctl_unregister(struct in_device *idev);

#else

static inline void devinet_sysctl_register(struct in_device *idev)

static void devinet_sysctl_register(struct in_device *idev)

{

}

static inline void devinet_sysctl_unregister(struct in_device *idev)

static void devinet_sysctl_unregister(struct in_device *idev)

{

}

#endif
@@ -205,7 +202,7 @@ static void inet_rcu_free_ifa(struct rcu_head *head) 
	kfree(ifa);

}



static inline void inet_free_ifa(struct in_ifaddr *ifa)

static void inet_free_ifa(struct in_ifaddr *ifa)

{

	call_rcu(&ifa->rcu_head, inet_rcu_free_ifa);

}
@@ -659,7 +656,7 @@ static int inet_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg 
 *	Determine a default network mask, based on the IP address.

 */



static inline int inet_abc_len(__be32 addr)

static int inet_abc_len(__be32 addr)

{

	int rc = -1;	/* Something else, probably a multicast. */
@@ -1124,7 +1121,7 @@ skip: 
	}

}



static inline bool inetdev_valid_mtu(unsigned int mtu)

static bool inetdev_valid_mtu(unsigned int mtu)

{

	return mtu >= 68;

}
@@ -1239,7 +1236,7 @@ static struct notifier_block ip_netdev_notifier = { 
	.notifier_call = inetdev_event,

};



static inline size_t inet_nlmsg_size(void)

static size_t inet_nlmsg_size(void)

{

	return NLMSG_ALIGN(sizeof(struct ifaddrmsg))

	       + nla_total_size(4) /* IFA_ADDRESS */

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