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net: inet_add_protocol() can use cmpxchg()

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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: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2010-09-08 21:31:35 -07:00 committed by David S. Miller
parent 92e32eaee2
commit e0386005ff
2 changed files with 9 additions and 54 deletions
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31
net/ipv4/protocol.c
View File

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

32
net/ipv6/protocol.c
View File

@ -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);
int 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);
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);