Re: [PATCH RFC 2/2] netfilter: conntrack: replace mutex with cmpxchg
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: 2012-05-02 00:51:12
Also in:
lkml, netfilter-devel
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.
quoted hunk ↗ jump to hunk
--- 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 <net/netfilter/nf_conntrack_core.h> #include <net/netfilter/nf_conntrack_extend.h> -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