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authorEric Dumazet <eric.dumazet@gmail.com>2010-09-09 08:31:35 +0400
committerDavid S. Miller <davem@davemloft.net>2010-09-09 08:31:35 +0400
commite0386005ff2a729998735e10769d99e1acbc2dd1 (patch)
treec04134571b728581d9692fb16dffcdd38d52dbda
parent92e32eaee288ee2e838fe76680cbaeaea25643c6 (diff)
downloadlinux-e0386005ff2a729998735e10769d99e1acbc2dd1.tar.xz
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: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/protocol.c31
-rw-r--r--net/ipv6/protocol.c32
2 files changed, 9 insertions, 54 deletions
diff --git a/net/ipv4/protocol.c b/net/ipv4/protocol.c
index f2d297351405..65699c24411c 100644
--- a/net/ipv4/protocol.c
+++ b/net/ipv4/protocol.c
@@ -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();
diff --git a/net/ipv6/protocol.c b/net/ipv6/protocol.c
index 1fa3468f0f32..9bb936ae2452 100644
--- a/net/ipv6/protocol.c
+++ b/net/ipv6/protocol.c
@@ -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);