From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Poirier Subject: [PATCH RFC 2/2] netfilter: conntrack: replace mutex with cmpxchg Date: Fri, 27 Apr 2012 14:28:53 -0400 Message-ID: <1335551333-6103-2-git-send-email-bpoirier@suse.de> References: <1335551333-6103-1-git-send-email-bpoirier@suse.de> Cc: Pablo Neira Ayuso , Patrick McHardy , "David S. Miller" , Andrew Morton , Eric Dumazet , Mike Frysinger , Arun Sharma , netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org, coreteam@netfilter.org, linux-kernel@vger.kernel.org, "Paul E. McKenney" To: netdev@vger.kernel.org Return-path: Received: from mail-gy0-f174.google.com ([209.85.160.174]:53226 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761122Ab2D0SaC (ORCPT ); Fri, 27 Apr 2012 14:30:02 -0400 In-Reply-To: <1335551333-6103-1-git-send-email-bpoirier@suse.de> Sender: netfilter-devel-owner@vger.kernel.org List-ID: This mutex protects a single pointer. --- net/netfilter/nf_conntrack_ecache.c | 38 +++++++++------------------------- 1 files changed, 10 insertions(+), 28 deletions(-) diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c index 0134009..603eb69 100644 --- a/net/netfilter/nf_conntrack_ecache.c +++ b/net/netfilter/nf_conntrack_ecache.c @@ -25,8 +25,6 @@ #include #include -static DEFINE_MUTEX(nf_ct_ecache_mutex); - /* deliver cached events and clear cache entry - must be called with locally * disabled softirqs */ void nf_ct_deliver_cached_events(struct nf_conn *ct) @@ -80,52 +78,36 @@ EXPORT_SYMBOL_GPL(nf_ct_deliver_cached_events); int nf_conntrack_register_notifier(struct net *net, struct nf_ct_event_notifier *new) { - int ret = 0; - - mutex_lock(&nf_ct_ecache_mutex); - if (net->ct.nf_conntrack_event_cb != NULL) - ret = -EBUSY; + if (cmpxchg(&net->ct.nf_conntrack_event_cb, NULL, new) != NULL) + return -EBUSY; else - net->ct.nf_conntrack_event_cb = new; - mutex_unlock(&nf_ct_ecache_mutex); - - return ret; + return 0; } EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier); void nf_conntrack_unregister_notifier(struct net *net, struct nf_ct_event_notifier *new) { - mutex_lock(&nf_ct_ecache_mutex); - BUG_ON(net->ct.nf_conntrack_event_cb != new); - net->ct.nf_conntrack_event_cb = NULL; - mutex_unlock(&nf_ct_ecache_mutex); + if (xchg(&net->ct.nf_conntrack_event_cb, NULL) != new) + BUG(); } EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier); int nf_ct_expect_register_notifier(struct net *net, struct nf_exp_event_notifier *new) { - int ret = 0; - - mutex_lock(&nf_ct_ecache_mutex); - if (net->ct.nf_expect_event_cb != NULL) - ret = -EBUSY; + if (cmpxchg(&net->ct.nf_expect_event_cb, NULL, new) != NULL) + return -EBUSY; else - net->ct.nf_expect_event_cb = new; - mutex_unlock(&nf_ct_ecache_mutex); - - return ret; + return 0; } EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier); void nf_ct_expect_unregister_notifier(struct net *net, struct nf_exp_event_notifier *new) { - mutex_lock(&nf_ct_ecache_mutex); - BUG_ON(net->ct.nf_expect_event_cb != new); - net->ct.nf_expect_event_cb = NULL; - mutex_unlock(&nf_ct_ecache_mutex); + if (xchg(&net->ct.nf_expect_event_cb, NULL) != new) + BUG(); } EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier); -- 1.7.7