mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-05 10:26:42 +07:00
3a66d7dca1
The last user is gone. Hence remove this function. Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Joern Engel <joern@logfs.org> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
139 lines
4.3 KiB
C
139 lines
4.3 KiB
C
/*
|
|
* 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>
|
|
#include <linux/mutex.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)
|
|
{
|
|
/* If refcount was 0 before incrementing then we have a race
|
|
* condition when this kref is freeing by some other thread right now.
|
|
* In this case one should use kref_get_unless_zero()
|
|
*/
|
|
WARN_ON_ONCE(atomic_inc_return(&kref->refcount) < 2);
|
|
}
|
|
|
|
/**
|
|
* 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);
|
|
}
|
|
|
|
static inline int kref_put_mutex(struct kref *kref,
|
|
void (*release)(struct kref *kref),
|
|
struct mutex *lock)
|
|
{
|
|
WARN_ON(release == NULL);
|
|
if (unlikely(!atomic_add_unless(&kref->refcount, -1, 1))) {
|
|
mutex_lock(lock);
|
|
if (unlikely(!atomic_dec_and_test(&kref->refcount))) {
|
|
mutex_unlock(lock);
|
|
return 0;
|
|
}
|
|
release(kref);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* kref_get_unless_zero - Increment refcount for object unless it is zero.
|
|
* @kref: object.
|
|
*
|
|
* Return non-zero if the increment succeeded. Otherwise return 0.
|
|
*
|
|
* This function is intended to simplify locking around refcounting for
|
|
* objects that can be looked up from a lookup structure, and which are
|
|
* removed from that lookup structure in the object destructor.
|
|
* Operations on such objects require at least a read lock around
|
|
* lookup + kref_get, and a write lock around kref_put + remove from lookup
|
|
* structure. Furthermore, RCU implementations become extremely tricky.
|
|
* With a lookup followed by a kref_get_unless_zero *with return value check*
|
|
* locking in the kref_put path can be deferred to the actual removal from
|
|
* the lookup structure and RCU lookups become trivial.
|
|
*/
|
|
static inline int __must_check kref_get_unless_zero(struct kref *kref)
|
|
{
|
|
return atomic_add_unless(&kref->refcount, 1, 0);
|
|
}
|
|
#endif /* _KREF_H_ */
|