Provide a simple API with structure and function for reference counting.
This is inspired by the linux kref.
Signed-off-by: Julien Thierry <julien.thierry@xxxxxxx>
---
include/kvm/ref_cnt.h | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 53 insertions(+)
create mode 100644 include/kvm/ref_cnt.h
diff --git a/include/kvm/ref_cnt.h b/include/kvm/ref_cnt.h
new file mode 100644
index 0000000..1c8194c
--- /dev/null
+++ b/include/kvm/ref_cnt.h
@@ -0,0 +1,53 @@
+#ifndef KVM__REF_CNT_H
+#define KVM__REF_CNT_H
+
+#include "kvm/mutex.h"
+
+#ifdef __ATOMIC_ACQUIRE
+
+#define KVM_ATOMIC_ACQUIRE __ATOMIC_ACQUIRE
+#define KVM_ATOMIC_RELEASE __ATOMIC_RELEASE
+
+#define kvm_atomic_add_fetch(ptr, val, memorder) \
+ __atomic_add_fetch((ptr), (val), (memorder))
+
+#define kvm_atomic_sub_fetch(ptr, val, memorder) \
+ __atomic_sub_fetch((ptr), (val), (memorder))
+#else
+
+#define KVM_ATOMIC_ACQUIRE 0
+#define KVM_ATOMIC_RELEASE 0
+
+#define kvm_atomic_add_fetch(ptr, val, memorder) \
+ __sync_fetch_and_add((ptr), (val))
+
+#define kvm_atomic_sub_fetch(ptr, val, memorder) \
+ __sync_fetch_and_sub((ptr), (val))
+
+#endif
+
+struct ref_cnt {
+ int cnt;
+};
+
+#define REF_CNT_INIT (struct ref_cnt) { .cnt = 1 }
+
+static inline void ref_cnt_init(struct ref_cnt *ref_cnt)
+{
+ ref_cnt->cnt = 1;
+}
+
+static inline void ref_get(struct ref_cnt *ref_cnt)
+{
+ kvm_atomic_add_fetch(&ref_cnt->cnt, 1, KVM_ATOMIC_ACQUIRE);
+
+}
+
+static inline void ref_put(struct ref_cnt *ref_cnt,
+ void (*release)(struct ref_cnt *ref_cnt))
+{
+ if (!kvm_atomic_sub_fetch(&ref_cnt->cnt, 1, KVM_ATOMIC_RELEASE))
+ release(ref_cnt);
+}
+
+#endif /* KVM__REF_CNT_H */
--
1.9.1
