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Revision 528ba4ef855bd184b7d68e3fa596b420fb4fa86a authored by Linus Torvalds on 31 October 2006, 03:31:20 UTC, committed by Linus Torvalds on 31 October 2006, 03:31:20 UTC 
Merge branch 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus
 
* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus:
  [MIPS] MIPS doesn't need compat_sys_getdents.
  [MIPS] JMR3927: Fixup another victim of the irq pt_regs cleanup.
  [MIPS] EMMA 2 / Markeins: struct resource takes physical addresses.
  [MIPS] EMMA 2 / Markeins: Convert to name struct resource initialization.
  [MIPS] EMMA 2 / Markeins: Formitting fixes split from actual address fixes.
  [MIPS] EMMA 2 / Markeins: Fix build wreckage due to genirq wreckage.
  [MIPS] Ocelot G: Fix build error and numerous warnings.
  [MIPS] Fix return value of TXX9 SPI interrupt handler
  [MIPS] Au1000: Fix warning about unused variable.
  [MIPS] Wire up getcpu(2) and epoll_wait(2) syscalls.
  [MIPS] Make SB1 cache flushes not to use on_each_cpu
  [MIPS] Fix warning about unused definition in c-sb1.c
  [MIPS] SMTC: Make 8 the default number of processors.
  [MIPS] Oprofile: Fix MIPSxx counter number detection.
  [MIPS] Au1xx0 code sets incorrect mips_hpt_frequency
  [MIPS] Oprofile: fix on non-VSMP / non-SMTC SMP configurations.
2 parent s df6c0cd + 21e9ac7
Raw File
kref.c 
/*
 * 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 current count is one, we are the last user and can release object
	 * right now, avoiding an atomic operation on 'refcount'
	 */
	if ((atomic_read(&kref->refcount) == 1) ||
	    (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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