[PATCH 4.9 097/102] locking/atomic, kref: Add kref_read()

[Greg Kroah-Hartman]

From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>

commit 2c935bc57221cc2edc787c72ea0e2d30cdcd3d5e upstream.

Since we need to change the implementation, stop exposing internals.

Provide kref_read() to read the current reference count; typically
used for debug messages.

Kills two anti-patterns:

	atomic_read(&kref->refcount)
	kref->refcount.counter

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
[only add kref_read() to kref.h for stable backports - gregkh]
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 include/linux/kref.h |    5 +++++
 1 file changed, 5 insertions(+)

--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -33,6 +33,11 @@ static inline void kref_init(struct kref
 	atomic_set(&kref->refcount, 1);
 }
 
+static inline int kref_read(const struct kref *kref)
+{
+	return atomic_read(&kref->refcount);
+}
+
 /**
  * kref_get - increment refcount for object.
  * @kref: object.