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Commit e0386005 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: inet_add_protocol() can use cmpxchg() 



Use cmpxchg() to get rid of spinlocks in inet_add_protocol() and
friends.

inet_protos[] & inet6_protos[] are moved to read_mostly section

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 92e32eae

net/ipv4/protocol.c

+5 −26
Original line number Diff line number Diff line
@@ -28,8 +28,7 @@ 
#include <linux/spinlock.h>

#include <net/protocol.h>



const struct net_protocol *inet_protos[MAX_INET_PROTOS] ____cacheline_aligned_in_smp;

static DEFINE_SPINLOCK(inet_proto_lock);

const struct net_protocol *inet_protos[MAX_INET_PROTOS] __read_mostly;



/*

 *	Add a protocol handler to the hash tables
@@ -37,20 +36,9 @@ static DEFINE_SPINLOCK(inet_proto_lock); 


int inet_add_protocol(const struct net_protocol *prot, unsigned char protocol)

{

	int hash, ret;

	int hash = protocol & (MAX_INET_PROTOS - 1);



	hash = protocol & (MAX_INET_PROTOS - 1);



	spin_lock_bh(&inet_proto_lock);

	if (inet_protos[hash]) {

		ret = -1;

	} else {

		inet_protos[hash] = prot;

		ret = 0;

	}

	spin_unlock_bh(&inet_proto_lock);



	return ret;

	return !cmpxchg(&inet_protos[hash], NULL, prot) ? 0 : -1;

}

EXPORT_SYMBOL(inet_add_protocol);
@@ -60,18 +48,9 @@ EXPORT_SYMBOL(inet_add_protocol); 


int inet_del_protocol(const struct net_protocol *prot, unsigned char protocol)

{

	int hash, ret;



	hash = protocol & (MAX_INET_PROTOS - 1);

	int ret, hash = protocol & (MAX_INET_PROTOS - 1);



	spin_lock_bh(&inet_proto_lock);

	if (inet_protos[hash] == prot) {

		inet_protos[hash] = NULL;

		ret = 0;

	} else {

		ret = -1;

	}

	spin_unlock_bh(&inet_proto_lock);

	ret = (cmpxchg(&inet_protos[hash], prot, NULL) == prot) ? 0 : -1;



	synchronize_net();

net/ipv6/protocol.c

+4 −28
Original line number Diff line number Diff line
@@ -25,28 +25,14 @@ 
#include <linux/spinlock.h>

#include <net/protocol.h>



const struct inet6_protocol *inet6_protos[MAX_INET_PROTOS];

static DEFINE_SPINLOCK(inet6_proto_lock);



const struct inet6_protocol *inet6_protos[MAX_INET_PROTOS] __read_mostly;



int inet6_add_protocol(const struct inet6_protocol *prot, unsigned char protocol)

{

	int ret, hash = protocol & (MAX_INET_PROTOS - 1);



	spin_lock_bh(&inet6_proto_lock);



	if (inet6_protos[hash]) {

		ret = -1;

	} else {

		inet6_protos[hash] = prot;

		ret = 0;

	}



	spin_unlock_bh(&inet6_proto_lock);

	int hash = protocol & (MAX_INET_PROTOS - 1);



	return ret;

	return !cmpxchg(&inet6_protos[hash], NULL, prot) ? 0 : -1;

}



EXPORT_SYMBOL(inet6_add_protocol);



/*
@@ -57,20 +43,10 @@ int inet6_del_protocol(const struct inet6_protocol *prot, unsigned char protocol 
{

	int ret, hash = protocol & (MAX_INET_PROTOS - 1);



	spin_lock_bh(&inet6_proto_lock);



	if (inet6_protos[hash] != prot) {

		ret = -1;

	} else {

		inet6_protos[hash] = NULL;

		ret = 0;

	}



	spin_unlock_bh(&inet6_proto_lock);

	ret = (cmpxchg(&inet6_protos[hash], prot, NULL) == prot) ? 0 : -1;



	synchronize_net();



	return ret;

}



EXPORT_SYMBOL(inet6_del_protocol);