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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /lib/kref.c | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
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!
Diffstat (limited to 'lib/kref.c')
-rw-r--r-- | lib/kref.c | 64 |
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); |