4af679cd7c
These are tiny functions, there's no point in having them out-of-line. Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/n/tip-8eccvi2ur2fzgi00xdjlbf5z@git.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
101 lines
2.7 KiB
C
101 lines
2.7 KiB
C
/*
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* kref.h - library routines for handling generic reference counted objects
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*
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* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
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* Copyright (C) 2004 IBM Corp.
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*
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* based on kobject.h which was:
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* Copyright (C) 2002-2003 Patrick Mochel <mochel@osdl.org>
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* Copyright (C) 2002-2003 Open Source Development Labs
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*
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* This file is released under the GPLv2.
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*
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*/
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#ifndef _KREF_H_
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#define _KREF_H_
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#include <linux/types.h>
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#include <linux/slab.h>
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struct kref {
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atomic_t refcount;
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};
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/**
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* kref_init - initialize object.
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* @kref: object in question.
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*/
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static inline void kref_init(struct kref *kref)
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{
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atomic_set(&kref->refcount, 1);
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smp_mb();
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}
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/**
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* kref_get - increment refcount for object.
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* @kref: object.
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*/
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static inline void kref_get(struct kref *kref)
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{
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WARN_ON(!atomic_read(&kref->refcount));
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atomic_inc(&kref->refcount);
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smp_mb__after_atomic_inc();
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}
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/**
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* kref_put - decrement refcount for object.
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* @kref: object.
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* @release: pointer to the function that will clean up the object when the
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* last reference to the object is released.
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* This pointer is required, and it is not acceptable to pass kfree
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* in as this function.
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*
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* Decrement the refcount, and if 0, call release().
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* Return 1 if the object was removed, otherwise return 0. Beware, if this
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* function returns 0, you still can not count on the kref from remaining in
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* memory. Only use the return value if you want to see if the kref is now
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* gone, not present.
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*/
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static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref))
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{
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WARN_ON(release == NULL);
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WARN_ON(release == (void (*)(struct kref *))kfree);
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if (atomic_dec_and_test(&kref->refcount)) {
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release(kref);
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return 1;
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}
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return 0;
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}
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/**
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* kref_sub - subtract a number of refcounts for object.
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* @kref: object.
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* @count: Number of recounts to subtract.
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* @release: pointer to the function that will clean up the object when the
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* last reference to the object is released.
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* This pointer is required, and it is not acceptable to pass kfree
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* in as this function.
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*
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* Subtract @count from the refcount, and if 0, call release().
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* Return 1 if the object was removed, otherwise return 0. Beware, if this
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* function returns 0, you still can not count on the kref from remaining in
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* memory. Only use the return value if you want to see if the kref is now
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* gone, not present.
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*/
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static inline int kref_sub(struct kref *kref, unsigned int count,
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void (*release)(struct kref *kref))
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{
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WARN_ON(release == NULL);
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WARN_ON(release == (void (*)(struct kref *))kfree);
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if (atomic_sub_and_test((int) count, &kref->refcount)) {
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release(kref);
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return 1;
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}
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return 0;
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}
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#endif /* _KREF_H_ */
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