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author | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
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committer | Srikant Patnaik | 2015-01-11 12:28:04 +0530 |
commit | 871480933a1c28f8a9fed4c4d34d06c439a7a422 (patch) | |
tree | 8718f573808810c2a1e8cb8fb6ac469093ca2784 /include/linux/kref.h | |
parent | 9d40ac5867b9aefe0722bc1f110b965ff294d30d (diff) | |
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Moved, renamed, and deleted files
The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.
Diffstat (limited to 'include/linux/kref.h')
-rw-r--r-- | include/linux/kref.h | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/include/linux/kref.h b/include/linux/kref.h new file mode 100644 index 00000000..9c07dceb --- /dev/null +++ b/include/linux/kref.h @@ -0,0 +1,96 @@ +/* + * kref.h - library routines for handling generic reference counted objects + * + * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> + * Copyright (C) 2004 IBM Corp. + * + * based on kobject.h which was: + * Copyright (C) 2002-2003 Patrick Mochel <mochel@osdl.org> + * Copyright (C) 2002-2003 Open Source Development Labs + * + * This file is released under the GPLv2. + * + */ + +#ifndef _KREF_H_ +#define _KREF_H_ + +#include <linux/bug.h> +#include <linux/atomic.h> +#include <linux/kernel.h> + +struct kref { + atomic_t refcount; +}; + +/** + * kref_init - initialize object. + * @kref: object in question. + */ +static inline void kref_init(struct kref *kref) +{ + atomic_set(&kref->refcount, 1); +} + +/** + * kref_get - increment refcount for object. + * @kref: object. + */ +static inline void kref_get(struct kref *kref) +{ + WARN_ON(!atomic_read(&kref->refcount)); + atomic_inc(&kref->refcount); +} + +/** + * kref_sub - subtract a number of refcounts for object. + * @kref: object. + * @count: Number of recounts to subtract. + * @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. If the caller does pass kfree to this + * function, you will be publicly mocked mercilessly by the kref + * maintainer, and anyone else who happens to notice it. You have + * been warned. + * + * Subtract @count from 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. + */ +static inline int kref_sub(struct kref *kref, unsigned int count, + void (*release)(struct kref *kref)) +{ + WARN_ON(release == NULL); + + if (atomic_sub_and_test((int) count, &kref->refcount)) { + release(kref); + return 1; + } + return 0; +} + +/** + * 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. If the caller does pass kfree to this + * function, you will be publicly mocked mercilessly by the kref + * maintainer, and anyone else who happens to notice it. You have + * been warned. + * + * 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. + */ +static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref)) +{ + return kref_sub(kref, 1, release); +} +#endif /* _KREF_H_ */ |