[PATCH tip/core/rcu 04/14] rcu: Add a gcc-style structure initializer for RCU pointers

Paul E. McKenney
2012-06-15T20:13:40Z

From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>

RCU_INIT_POINTER() returns a value that is never used, and which should
be abolished due to terminal ugliness:

q = RCU_INIT_POINTER(global_p, p);

However, there are two uses that cannot be handled by a do-while
formulation because they do gcc-style initialization:

RCU_INIT_POINTER(.real_cred, &init_cred),
RCU_INIT_POINTER(.cred, &init_cred),

This usage is clever, but not necessarily the nicest approach. This
commit therefore creates an INIT_RCU_POINTER() macro that is specifically
designed for gcc-style initialization.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
include/linux/rcupdate.h | 8 ++++++++
1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 26d1a47..eb92c21 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -906,6 +906,14 @@ static inline notrace void rcu_read_unlock_sched_notrace(void)
#define RCU_INIT_POINTER(p, v) \
p = (typeof(*v) __force __rcu *)(v)

+/**
+ * INIT_RCU_POINTER() - statically initialize an RCU protected pointer
+ *
+ * GCC-style initialization for an RCU-protected pointer in a structure field.
+ */
+#define INIT_RCU_POINTER(p, v) \
+ .p = (typeof(*v) __force __rcu *)(v)
+
static __always_inline bool __is_kfree_rcu_offset(unsigned long offset)
{
return offset < 4096;
--
1.7.8