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>
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@ -15,17 +15,14 @@
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#ifndef _KREF_H_
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#define _KREF_H_
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#include <linux/bug.h>
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#include <linux/atomic.h>
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#include <linux/kernel.h>
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#include <linux/mutex.h>
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#include <linux/spinlock.h>
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#include <linux/refcount.h>
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struct kref {
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atomic_t refcount;
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refcount_t refcount;
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};
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#define KREF_INIT(n) { .refcount = ATOMIC_INIT(n), }
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#define KREF_INIT(n) { .refcount = REFCOUNT_INIT(n), }
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/**
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* kref_init - initialize object.
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@ -33,12 +30,12 @@ struct kref {
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*/
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static inline void kref_init(struct kref *kref)
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{
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atomic_set(&kref->refcount, 1);
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refcount_set(&kref->refcount, 1);
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}
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static inline int kref_read(const struct kref *kref)
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static inline unsigned int kref_read(const struct kref *kref)
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{
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return atomic_read(&kref->refcount);
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return refcount_read(&kref->refcount);
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}
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/**
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@ -47,11 +44,7 @@ static inline int kref_read(const struct kref *kref)
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*/
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static inline void kref_get(struct kref *kref)
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{
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/* If refcount was 0 before incrementing then we have a race
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* condition when this kref is freeing by some other thread right now.
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* In this case one should use kref_get_unless_zero()
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*/
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WARN_ON_ONCE(atomic_inc_return(&kref->refcount) < 2);
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refcount_inc(&kref->refcount);
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}
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/**
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@ -75,7 +68,7 @@ static inline int kref_put(struct kref *kref, void (*release)(struct kref *kref)
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{
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WARN_ON(release == NULL);
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if (atomic_dec_and_test(&kref->refcount)) {
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if (refcount_dec_and_test(&kref->refcount)) {
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release(kref);
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return 1;
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}
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@ -88,7 +81,7 @@ static inline int kref_put_mutex(struct kref *kref,
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{
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WARN_ON(release == NULL);
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if (atomic_dec_and_mutex_lock(&kref->refcount, lock)) {
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if (refcount_dec_and_mutex_lock(&kref->refcount, lock)) {
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release(kref);
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return 1;
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}
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@ -101,7 +94,7 @@ static inline int kref_put_lock(struct kref *kref,
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{
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WARN_ON(release == NULL);
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if (atomic_dec_and_lock(&kref->refcount, lock)) {
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if (refcount_dec_and_lock(&kref->refcount, lock)) {
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release(kref);
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return 1;
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}
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@ -126,6 +119,6 @@ static inline int kref_put_lock(struct kref *kref,
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*/
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static inline int __must_check kref_get_unless_zero(struct kref *kref)
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{
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return atomic_add_unless(&kref->refcount, 1, 0);
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return refcount_inc_not_zero(&kref->refcount);
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}
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#endif /* _KREF_H_ */
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