mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-24 13:13:57 +08:00
ecf7ace9a8
Makes it possible to optimize batched multiple unrefs. Initial user will be drivers/gpu/ttm which accumulates unrefs to be processed outside of atomic code. Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com> Signed-off-by: Dave Airlie <airlied@redhat.com>
98 lines
2.6 KiB
C
98 lines
2.6 KiB
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>
|
|
#include <linux/slab.h>
|
|
|
|
/**
|
|
* kref_init - initialize object.
|
|
* @kref: object in question.
|
|
*/
|
|
void kref_init(struct kref *kref)
|
|
{
|
|
atomic_set(&kref->refcount, 1);
|
|
smp_mb();
|
|
}
|
|
|
|
/**
|
|
* kref_get - increment refcount for object.
|
|
* @kref: object.
|
|
*/
|
|
void kref_get(struct kref *kref)
|
|
{
|
|
WARN_ON(!atomic_read(&kref->refcount));
|
|
atomic_inc(&kref->refcount);
|
|
smp_mb__after_atomic_inc();
|
|
}
|
|
|
|
/**
|
|
* 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;
|
|
}
|
|
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* 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.
|
|
*/
|
|
int kref_sub(struct kref *kref, unsigned int count,
|
|
void (*release)(struct kref *kref))
|
|
{
|
|
WARN_ON(release == NULL);
|
|
WARN_ON(release == (void (*)(struct kref *))kfree);
|
|
|
|
if (atomic_sub_and_test((int) count, &kref->refcount)) {
|
|
release(kref);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
EXPORT_SYMBOL(kref_init);
|
|
EXPORT_SYMBOL(kref_get);
|
|
EXPORT_SYMBOL(kref_put);
|
|
EXPORT_SYMBOL(kref_sub);
|