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kref: Implement 'struct kref' using refcount_t 

Use the refcount_t 'atomic' type to implement 'struct kref', this makes kref
more robust by bringing saturation semantics.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2016-11-14 18:06:19 +01:00 committed by Ingo Molnar
parent f405df5de3
commit 10383aea2f
1 changed files with 11 additions and 18 deletions
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29
include/linux/kref.h
View File

@ -15,17 +15,14 @@
#ifndef _KREF_H_
#define _KREF_H_
#include <linux/bug.h>
#include <linux/atomic.h>
#include <linux/kernel.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/refcount.h>
struct kref {
atomic_t refcount;
refcount_t refcount;
};
#define KREF_INIT(n) { .refcount = ATOMIC_INIT(n), }
#define KREF_INIT(n) { .refcount = REFCOUNT_INIT(n), }
/**
* kref_init - initialize object.
@ -33,12 +30,12 @@ struct kref {
*/
static inline void kref_init(struct kref *kref)
{
atomic_set(&kref->refcount, 1);
refcount_set(&kref->refcount, 1);
}
static inline int kref_read(const struct kref *kref)
static inline unsigned int kref_read(const struct kref *kref)
{
return atomic_read(&kref->refcount);
return refcount_read(&kref->refcount);
}
/**
@ -47,11 +44,7 @@ static inline int kref_read(const struct kref *kref)
*/
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);
refcount_inc(&kref->refcount);
}
/**
@ -75,7 +68,7 @@ static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref)
{
WARN_ON(release == NULL);
if (atomic_dec_and_test(&kref->refcount)) {
if (refcount_dec_and_test(&kref->refcount)) {
release(kref);
return 1;
}
@ -88,7 +81,7 @@ static inline int kref_put_mutex(struct kref *kref,
{
WARN_ON(release == NULL);
if (atomic_dec_and_mutex_lock(&kref->refcount, lock)) {
if (refcount_dec_and_mutex_lock(&kref->refcount, lock)) {
release(kref);
return 1;
}
@ -101,7 +94,7 @@ static inline int kref_put_lock(struct kref *kref,
{
WARN_ON(release == NULL);
if (atomic_dec_and_lock(&kref->refcount, lock)) {
if (refcount_dec_and_lock(&kref->refcount, lock)) {
release(kref);
return 1;
}
@ -126,6 +119,6 @@ static inline int kref_put_lock(struct kref *kref,
*/
static inline int __must_check kref_get_unless_zero(struct kref *kref)
{
return atomic_add_unless(&kref->refcount, 1, 0);
return refcount_inc_not_zero(&kref->refcount);
}
#endif /* _KREF_H_ */