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authorPeter Zijlstra <peterz@infradead.org>2016-11-14 20:06:19 +0300
committerIngo Molnar <mingo@kernel.org>2017-02-10 11:04:19 +0300
commit10383aea2f445bce9b2a2b308def08134b438c8e (patch)
tree64fea6972561d5a8899c2da53646771e65507734 /include/linux/kref.h
parentf405df5de3170c00e5c54f8b7cf4766044a032ba (diff)
downloadlinux-10383aea2f445bce9b2a2b308def08134b438c8e.tar.xz
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>
Diffstat (limited to 'include/linux/kref.h')
-rw-r--r--include/linux/kref.h29
1 files changed, 11 insertions, 18 deletions
diff --git a/include/linux/kref.h b/include/linux/kref.h
index 9db9685fed84..f4156f88f557 100644
--- a/include/linux/kref.h
+++ b/include/linux/kref.h
@@ -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_ */