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-rw-r--r--include/linux/kref.h77
1 files changed, 71 insertions, 6 deletions
diff --git a/include/linux/kref.h b/include/linux/kref.h
index d4a62ab2ee5e..abc0120b09b7 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -15,16 +15,81 @@
#ifndef _KREF_H_
#define _KREF_H_
-#include <linux/types.h>
+#include <linux/bug.h>
+#include <linux/atomic.h>
struct kref {
atomic_t refcount;
};
-void kref_init(struct kref *kref);
-void kref_get(struct kref *kref);
-int kref_put(struct kref *kref, void (*release) (struct kref *kref));
-int kref_sub(struct kref *kref, unsigned int count,
- void (*release) (struct kref *kref));
+/**
+ * kref_init - initialize object.
+ * @kref: object in question.
+ */
+static inline void kref_init(struct kref *kref)
+{
+ atomic_set(&kref->refcount, 1);
+}
+
+/**
+ * kref_get - increment refcount for object.
+ * @kref: object.
+ */
+static inline void kref_get(struct kref *kref)
+{
+ WARN_ON(!atomic_read(&kref->refcount));
+ atomic_inc(&kref->refcount);
+}
+/**
+ * kref_sub - subtract a number of refcounts for object.
+ * @kref: object.
+ * @count: Number of recounts to subtract.
+ * @release: pointer to the function that will clean up the object when the
+ * last reference to the object is released.
+ * This pointer is required, and it is not acceptable to pass kfree
+ * in as this function. If the caller does pass kfree to this
+ * function, you will be publicly mocked mercilessly by the kref
+ * maintainer, and anyone else who happens to notice it. You have
+ * been warned.
+ *
+ * Subtract @count from the refcount, and if 0, call release().
+ * Return 1 if the object was removed, otherwise return 0. Beware, if this
+ * function returns 0, you still can not count on the kref from remaining in
+ * memory. Only use the return value if you want to see if the kref is now
+ * gone, not present.
+ */
+static inline int kref_sub(struct kref *kref, unsigned int count,
+ void (*release)(struct kref *kref))
+{
+ WARN_ON(release == NULL);
+
+ if (atomic_sub_and_test((int) count, &kref->refcount)) {
+ release(kref);
+ return 1;
+ }
+ return 0;
+}
+
+/**
+ * kref_put - decrement refcount for object.
+ * @kref: object.
+ * @release: pointer to the function that will clean up the object when the
+ * last reference to the object is released.
+ * This pointer is required, and it is not acceptable to pass kfree
+ * in as this function. If the caller does pass kfree to this
+ * function, you will be publicly mocked mercilessly by the kref
+ * maintainer, and anyone else who happens to notice it. You have
+ * been warned.
+ *
+ * Decrement the refcount, and if 0, call release().
+ * Return 1 if the object was removed, otherwise return 0. Beware, if this
+ * function returns 0, you still can not count on the kref from remaining in
+ * memory. Only use the return value if you want to see if the kref is now
+ * gone, not present.
+ */
+static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
+{
+ return kref_sub(kref, 1, release);
+}
#endif /* _KREF_H_ */