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authorPatrick McHardy <kaber@trash.net>2014-02-18 18:06:48 +0000
committerPablo Neira Ayuso <pablo@netfilter.org>2014-02-25 11:29:21 +0100
commit0eb5db7ad302a24fe6f0eb4bfd235357047a28db (patch)
tree70ab0a2618925c66700ed7f7e47fe70793c550b4 /include
parent3e90ebd3c920e335e155e5d3a794197897630f99 (diff)
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netfilter: nfnetlink: add rcu_dereference_protected() helpers
Add a lockdep_nfnl_is_held() function and a nfnl_dereference() macro for RCU dereferences protected by a NFNL subsystem mutex. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/netfilter/nfnetlink.h21
1 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index 28c74367e900..e955d4730625 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -44,6 +44,27 @@ int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid,
void nfnl_lock(__u8 subsys_id);
void nfnl_unlock(__u8 subsys_id);
+#ifdef CONFIG_PROVE_LOCKING
+int lockdep_nfnl_is_held(__u8 subsys_id);
+#else
+static inline int lockdep_nfnl_is_held(__u8 subsys_id)
+{
+ return 1;
+}
+#endif /* CONFIG_PROVE_LOCKING */
+
+/*
+ * nfnl_dereference - fetch RCU pointer when updates are prevented by subsys mutex
+ *
+ * @p: The pointer to read, prior to dereferencing
+ * @ss: The nfnetlink subsystem ID
+ *
+ * Return the value of the specified RCU-protected pointer, but omit
+ * both the smp_read_barrier_depends() and the ACCESS_ONCE(), because
+ * caller holds the NFNL subsystem mutex.
+ */
+#define nfnl_dereference(p, ss) \
+ rcu_dereference_protected(p, lockdep_nfnl_is_held(ss))
#define MODULE_ALIAS_NFNL_SUBSYS(subsys) \
MODULE_ALIAS("nfnetlink-subsys-" __stringify(subsys))