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netfilter: nfnetlink: add rcu_dereference_protected() helpers

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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>
This commit is contained in:
Patrick McHardy 2014-02-18 18:06:48 +00:00 committed by Pablo Neira Ayuso
parent 3e90ebd3c9
commit 0eb5db7ad3
2 changed files with 29 additions and 0 deletions
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21
include/linux/netfilter/nfnetlink.h
View file

@ -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))

8
net/netfilter/nfnetlink.c
View file

@ -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);