[PATCH v3 3/6] genetlink: Add rcu_dereference_genl and genl_dereference.

[Jesse Gross <jesse-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>]

This adds rcu_dereference_genl and genl_dereference, which are genl
variants of the RTNL functions to enforce proper locking with lockdep
and sparse.

Signed-off-by: Jesse Gross <jesse-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>
---
v3: Unchanged.
v2: New patch.
---
 include/linux/genetlink.h |   21 +++++++++++++++++++++
 1 files changed, 21 insertions(+), 0 deletions(-)

diff --git a/include/linux/genetlink.h b/include/linux/genetlink.h
index 59311ad..73c28de 100644
--- a/include/linux/genetlink.h
+++ b/include/linux/genetlink.h
@@ -89,6 +89,27 @@ extern void genl_unlock(void);
 extern int lockdep_genl_is_held(void);
 #endif
 
+/**
+ * rcu_dereference_genl - rcu_dereference with debug checking
+ * @p: The pointer to read, prior to dereferencing
+ *
+ * Do an rcu_dereference(p), but check caller either holds rcu_read_lock()
+ * or genl mutex. Note : Please prefer genl_dereference() or rcu_dereference()
+ */
+#define rcu_dereference_genl(p)					\
+	rcu_dereference_check(p, lockdep_genl_is_held())
+
+/**
+ * genl_dereference - fetch RCU pointer when updates are prevented by genl mutex
+ * @p: The pointer to read, prior to dereferencing
+ *
+ * Return the value of the specified RCU-protected pointer, but omit
+ * both the smp_read_barrier_depends() and the ACCESS_ONCE(), because
+ * caller holds genl mutex.
+ */
+#define genl_dereference(p)					\
+	rcu_dereference_protected(p, lockdep_genl_is_held())
+
 #endif /* __KERNEL__ */
 
 #endif	/* __LINUX_GENERIC_NETLINK_H */
-- 
1.7.5.4