From 2f4f12e571c4e2f50f3818a3c2544929145f75dd Mon Sep 17 00:00:00 2001
From: Linus Torvalds
Date: Mon, 2 Sep 2013 11:58:20 -0700
Subject: lockref: uninline lockref helper functions

They aren't very good to inline, since they already call external
functions (the spinlock code), and we're going to create rather more
complicated versions of them that can do the reference count updates
locklessly.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 lib/lockref.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 lib/lockref.c

(limited to 'lib/lockref.c')

diff --git a/lib/lockref.c b/lib/lockref.c
new file mode 100644
index 000000000000..a9a4f4e1eff5
--- /dev/null
+++ b/lib/lockref.c
@@ -0,0 +1,69 @@
+#include <linux/export.h>
+#include <linux/lockref.h>
+
+/**
+ * lockref_get - Increments reference count unconditionally
+ * @lockcnt: pointer to lockref structure
+ *
+ * This operation is only valid if you already hold a reference
+ * to the object, so you know the count cannot be zero.
+ */
+void lockref_get(struct lockref *lockref)
+{
+	spin_lock(&lockref->lock);
+	lockref->count++;
+	spin_unlock(&lockref->lock);
+}
+EXPORT_SYMBOL(lockref_get);
+
+/**
+ * lockref_get_not_zero - Increments count unless the count is 0
+ * @lockcnt: pointer to lockref structure
+ * Return: 1 if count updated successfully or 0 if count was zero
+ */
+int lockref_get_not_zero(struct lockref *lockref)
+{
+	int retval = 0;
+
+	spin_lock(&lockref->lock);
+	if (lockref->count) {
+		lockref->count++;
+		retval = 1;
+	}
+	spin_unlock(&lockref->lock);
+	return retval;
+}
+EXPORT_SYMBOL(lockref_get_not_zero);
+
+/**
+ * lockref_get_or_lock - Increments count unless the count is 0
+ * @lockcnt: pointer to lockref structure
+ * Return: 1 if count updated successfully or 0 if count was zero
+ * and we got the lock instead.
+ */
+int lockref_get_or_lock(struct lockref *lockref)
+{
+	spin_lock(&lockref->lock);
+	if (!lockref->count)
+		return 0;
+	lockref->count++;
+	spin_unlock(&lockref->lock);
+	return 1;
+}
+EXPORT_SYMBOL(lockref_get_or_lock);
+
+/**
+ * lockref_put_or_lock - decrements count unless count <= 1 before decrement
+ * @lockcnt: pointer to lockref structure
+ * Return: 1 if count updated successfully or 0 if count <= 1 and lock taken
+ */
+int lockref_put_or_lock(struct lockref *lockref)
+{
+	spin_lock(&lockref->lock);
+	if (lockref->count <= 1)
+		return 0;
+	lockref->count--;
+	spin_unlock(&lockref->lock);
+	return 1;
+}
+EXPORT_SYMBOL(lockref_put_or_lock);
-- 
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