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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /lib/kref.c
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'lib/kref.c')
-rw-r--r--lib/kref.c64
1 files changed, 64 insertions, 0 deletions
diff --git a/lib/kref.c b/lib/kref.c
new file mode 100644
index 000000000000..0d07cc31c818
--- /dev/null
+++ b/lib/kref.c
@@ -0,0 +1,64 @@
+/*
+ * kref.c - library routines for handling generic reference counted objects
+ *
+ * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
+ * Copyright (C) 2004 IBM Corp.
+ *
+ * based on lib/kobject.c which was:
+ * Copyright (C) 2002-2003 Patrick Mochel <mochel@osdl.org>
+ *
+ * This file is released under the GPLv2.
+ *
+ */
+
+#include <linux/kref.h>
+#include <linux/module.h>
+
+/**
+ * kref_init - initialize object.
+ * @kref: object in question.
+ */
+void kref_init(struct kref *kref)
+{
+ atomic_set(&kref->refcount,1);
+}
+
+/**
+ * kref_get - increment refcount for object.
+ * @kref: object.
+ */
+void kref_get(struct kref *kref)
+{
+ WARN_ON(!atomic_read(&kref->refcount));
+ atomic_inc(&kref->refcount);
+}
+
+/**
+ * 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.
+ *
+ * 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.
+ */
+int kref_put(struct kref *kref, void (*release)(struct kref *kref))
+{
+ WARN_ON(release == NULL);
+ WARN_ON(release == (void (*)(struct kref *))kfree);
+
+ if (atomic_dec_and_test(&kref->refcount)) {
+ release(kref);
+ return 1;
+ }
+ return 0;
+}
+
+EXPORT_SYMBOL(kref_init);
+EXPORT_SYMBOL(kref_get);
+EXPORT_SYMBOL(kref_put);

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