From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: [PATCH RFC 2/2] netfilter: conntrack: replace mutex with cmpxchg Date: Wed, 2 May 2012 02:51:02 +0200 Message-ID: <20120502005102.GB14999@1984> References: <1335551333-6103-1-git-send-email-bpoirier@suse.de> <1335551333-6103-2-git-send-email-bpoirier@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, 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: Benjamin Poirier Return-path: Received: from mail.us.es ([193.147.175.20]:43036 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753398Ab2EBAvK (ORCPT ); Tue, 1 May 2012 20:51:10 -0400 Content-Disposition: inline In-Reply-To: <1335551333-6103-2-git-send-email-bpoirier@suse.de> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Fri, Apr 27, 2012 at 02:28:53PM -0400, Benjamin Poirier wrote: > This mutex protects a single pointer. You seem to be using an old Linux kernel tree. This doesn't apply. > --- > 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 > > -- > To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html