From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-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! --- lib/kref.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 lib/kref.c (limited to 'lib/kref.c') diff --git a/lib/kref.c b/lib/kref.c new file mode 100644 index 00000000000..0d07cc31c81 --- /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 + * Copyright (C) 2004 IBM Corp. + * + * based on lib/kobject.c which was: + * Copyright (C) 2002-2003 Patrick Mochel + * + * This file is released under the GPLv2. + * + */ + +#include +#include + +/** + * 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); -- cgit v1.2.3