1 files changed, 180 insertions, 0 deletions
diff --git a/c_src/include/linux/percpu-refcount.h b/c_src/include/linux/percpu-refcount.h
new file mode 100644
index 00000000..06550564
--- /dev/null
+++ b/c_src/include/linux/percpu-refcount.h
@@ -0,0 +1,180 @@
+#ifndef __TOOLS_LINUX_PERCPU_REFCOUNT_H
+#define __TOOLS_LINUX_PERCPU_REFCOUNT_H
+
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/percpu.h>
+
+struct percpu_ref;
+typedef void (percpu_ref_func_t)(struct percpu_ref *);
+
+/* flags set in the lower bits of percpu_ref->percpu_count_ptr */
+enum {
+	__PERCPU_REF_ATOMIC	= 1LU << 0,	/* operating in atomic mode */
+	__PERCPU_REF_DEAD	= 1LU << 1,	/* (being) killed */
+	__PERCPU_REF_ATOMIC_DEAD = __PERCPU_REF_ATOMIC | __PERCPU_REF_DEAD,
+
+	__PERCPU_REF_FLAG_BITS	= 2,
+};
+
+/* @flags for percpu_ref_init() */
+enum {
+	PERCPU_REF_INIT_ATOMIC	= 1 << 0,
+
+	/*
+	 * Start dead w/ ref == 0 in atomic mode.  Must be revived with
+	 * percpu_ref_reinit() before used.  Implies INIT_ATOMIC.
+	 */
+	PERCPU_REF_INIT_DEAD	= 1 << 1,
+};
+
+struct percpu_ref {
+	atomic_long_t		count;
+	percpu_ref_func_t	*release;
+	percpu_ref_func_t	*confirm_switch;
+};
+
+static inline void percpu_ref_exit(struct percpu_ref *ref) {}
+
+static inline int __must_check percpu_ref_init(struct percpu_ref *ref,
+				 percpu_ref_func_t *release, unsigned int flags,
+				 gfp_t gfp)
+{
+	unsigned long start_count = 0;
+
+	if (!(flags & PERCPU_REF_INIT_DEAD))
+		start_count++;
+
+	atomic_long_set(&ref->count, start_count);
+
+	ref->release = release;
+	return 0;
+}
+
+/**
+ * percpu_ref_get_many - increment a percpu refcount
+ * @ref: percpu_ref to get
+ * @nr: number of references to get
+ *
+ * Analogous to atomic_long_add().
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+static inline void percpu_ref_get_many(struct percpu_ref *ref, unsigned long nr)
+{
+	atomic_long_add(nr, &ref->count);
+}
+
+/**
+ * percpu_ref_get - increment a percpu refcount
+ * @ref: percpu_ref to get
+ *
+ * Analagous to atomic_long_inc().
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+static inline void percpu_ref_get(struct percpu_ref *ref)
+{
+	percpu_ref_get_many(ref, 1);
+}
+
+/**
+ * percpu_ref_tryget - try to increment a percpu refcount
+ * @ref: percpu_ref to try-get
+ *
+ * Increment a percpu refcount unless its count already reached zero.
+ * Returns %true on success; %false on failure.
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+static inline bool percpu_ref_tryget(struct percpu_ref *ref)
+{
+	return atomic_long_inc_not_zero(&ref->count);
+}
+
+/**
+ * percpu_ref_tryget_live - try to increment a live percpu refcount
+ * @ref: percpu_ref to try-get
+ *
+ * Increment a percpu refcount unless it has already been killed.  Returns
+ * %true on success; %false on failure.
+ *
+ * Completion of percpu_ref_kill() in itself doesn't guarantee that this
+ * function will fail.  For such guarantee, percpu_ref_kill_and_confirm()
+ * should be used.  After the confirm_kill callback is invoked, it's
+ * guaranteed that no new reference will be given out by
+ * percpu_ref_tryget_live().
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+static inline bool percpu_ref_tryget_live(struct percpu_ref *ref)
+{
+	return atomic_long_inc_not_zero(&ref->count);
+}
+
+/**
+ * percpu_ref_put_many - decrement a percpu refcount
+ * @ref: percpu_ref to put
+ * @nr: number of references to put
+ *
+ * Decrement the refcount, and if 0, call the release function (which was passed
+ * to percpu_ref_init())
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+static inline void percpu_ref_put_many(struct percpu_ref *ref, unsigned long nr)
+{
+	if (unlikely(atomic_long_sub_and_test(nr, &ref->count)))
+		ref->release(ref);
+}
+
+/**
+ * percpu_ref_put - decrement a percpu refcount
+ * @ref: percpu_ref to put
+ *
+ * Decrement the refcount, and if 0, call the release function (which was passed
+ * to percpu_ref_init())
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+static inline void percpu_ref_put(struct percpu_ref *ref)
+{
+	percpu_ref_put_many(ref, 1);
+}
+
+static inline void percpu_ref_reinit(struct percpu_ref *ref)
+{
+	percpu_ref_get(ref);
+}
+
+/**
+ * percpu_ref_kill - drop the initial ref
+ * @ref: percpu_ref to kill
+ *
+ * Must be used to drop the initial ref on a percpu refcount; must be called
+ * precisely once before shutdown.
+ */
+static inline void percpu_ref_kill(struct percpu_ref *ref)
+{
+	percpu_ref_put(ref);
+}
+
+/**
+ * percpu_ref_is_zero - test whether a percpu refcount reached zero
+ * @ref: percpu_ref to test
+ *
+ * Returns %true if @ref reached zero.
+ *
+ * This function is safe to call as long as @ref is between init and exit.
+ */
+static inline bool percpu_ref_is_zero(struct percpu_ref *ref)
+{
+	return !atomic_long_read(&ref->count);
+}
+
+static inline bool percpu_ref_is_dying(struct percpu_ref *ref)
+{
+	return percpu_ref_is_zero(ref);
+}
+
+#endif /* __TOOLS_LINUX_PERCPU_REFCOUNT_H */