I want to use lockless_dereference() from seqlock.h, which would mean
including rcupdate.h from it, however rcupdate.h already includes
seqlock.h.
Avoid this by moving lockless_dereference() into compiler.h. This is
somewhat tricky since it uses smp_read_barrier_depends() which isn't
available there, but its a CPP macro so we can get away with it.
The alternative would be moving it into asm/barrier.h, but that would
be updating each arch (I can do if people feel that is more
appropriate).
Cc: Paul McKenney <paul...@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
include/linux/compiler.h | 15 +++++++++++++++
include/linux/rcupdate.h | 15 ---------------
2 files changed, 15 insertions(+), 15 deletions(-)
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -453,6 +453,21 @@ static __always_inline void __write_once
(volatile typeof(x) *)&(x); })
#define ACCESS_ONCE(x) (*__ACCESS_ONCE(x))
+/**
+ * lockless_dereference() - safely load a pointer for later dereference
+ * @p: The pointer to load
+ *
+ * Similar to rcu_dereference(), but for situations where the pointed-to
+ * object's lifetime is managed by something other than RCU. That
+ * "something other" might be reference counting or simple immortality.
+ */
+#define lockless_dereference(p) \
+({ \
+ typeof(p) _________p1 = ACCESS_ONCE(p); \
+ smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
+ (_________p1); \
+})
+
/* Ignore/forbid kprobes attach on very low level functions marked by this
attribute: */
#ifdef CONFIG_KPROBES
# define __kprobes __attribute__((__section__(".kprobes.text")))
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -650,21 +650,6 @@ static inline void rcu_preempt_sleep_che
#define RCU_INITIALIZER(v) (typeof(*(v)) __force __rcu *)(v)
/**
- * lockless_dereference() - safely load a pointer for later dereference
- * @p: The pointer to load
- *
- * Similar to rcu_dereference(), but for situations where the pointed-to
- * object's lifetime is managed by something other than RCU. That
- * "something other" might be reference counting or simple immortality.
- */
-#define lockless_dereference(p) \
-({ \
- typeof(p) _________p1 = ACCESS_ONCE(p); \
- smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
- (_________p1); \
-})
-
-/**
* rcu_assign_pointer() - assign to RCU-protected pointer
* @p: pointer to assign to
* @v: value to assign (publish)
--
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