From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net-next-2.6] net: inet_add_protocol() can use cmpxchg() Date: Thu, 09 Sep 2010 00:56:16 +0200 Message-ID: <1283986576.2428.21.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev To: David Miller Return-path: Received: from mail-fx0-f46.google.com ([209.85.161.46]:40255 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755835Ab0IHW4V (ORCPT ); Wed, 8 Sep 2010 18:56:21 -0400 Received: by fxm16 with SMTP id 16so528884fxm.19 for ; Wed, 08 Sep 2010 15:56:20 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: 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 --- net/ipv4/protocol.c | 31 +++++-------------------------- net/ipv6/protocol.c | 32 ++++---------------------------- 2 files changed, 9 insertions(+), 54 deletions(-) diff --git a/net/ipv4/protocol.c b/net/ipv4/protocol.c index f2d2973..65699c2 100644 --- a/net/ipv4/protocol.c +++ b/net/ipv4/protocol.c @@ -28,8 +28,7 @@ #include #include -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 1fa3468..9bb936a 100644 --- a/net/ipv6/protocol.c +++ b/net/ipv6/protocol.c @@ -25,28 +25,14 @@ #include #include -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);