[PATCH RFC 2/2] netfilter: conntrack: replace mutex with cmpxchg
From: Benjamin Poirier <hidden>
Date: 2012-04-27 18:30:06
Also in:
lkml, netfilter-devel
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <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);
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1.7.7