From 0eb5db7ad302a24fe6f0eb4bfd235357047a28db Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Tue, 18 Feb 2014 18:06:48 +0000 Subject: [PATCH] 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 Signed-off-by: Pablo Neira Ayuso --- include/linux/netfilter/nfnetlink.h | 21 +++++++++++++++++++++ net/netfilter/nfnetlink.c | 8 ++++++++ 2 files changed, 29 insertions(+) diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h index 28c7436..e955d47 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)) diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c index 046aa13..e8138da 100644 --- a/net/netfilter/nfnetlink.c +++ b/net/netfilter/nfnetlink.c @@ -61,6 +61,14 @@ void nfnl_unlock(__u8 subsys_id) } EXPORT_SYMBOL_GPL(nfnl_unlock); +#ifdef CONFIG_PROVE_LOCKING +int lockdep_nfnl_is_held(u8 subsys_id) +{ + return lockdep_is_held(&table[subsys_id].mutex); +} +EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held); +#endif + int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n) { nfnl_lock(n->subsys_id); -- 2.7.4