Reference count

include/types/refcount.h View source View on GitHub

Functions

refcount_init

void refcount_init(refcount_t *rc, uint32_t val)

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refcount_inc

bool refcount_inc(refcount_t *rc)

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refcount_inc_not_zero

bool refcount_inc_not_zero(refcount_t *rc)

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refcount_read

uint32_t refcount_read(refcount_t *rc)

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refcount_dec_and_test

bool refcount_dec_and_test(refcount_t *rc)

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refcount_put_not_last

void refcount_put_not_last(refcount_t *rc)

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drop a reference that is known not to be the last one

Macros

REFCOUNT_GENERATE_GETREF_FOR_STRUCT_WITH_FAILURE_COND

#define REFCOUNT_GENERATE_GETREF_FOR_STRUCT_WITH_FAILURE_COND( \ __struct, __refcount_member, __failure_member, __failure_state)

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generate a _getref function for a structure type, given a refcount member name and a failure condition. if the failure condition (e.g. object being cleaned up) is met, then the _getref will return false. will panic if refcount drops to zero before we get a chance to decrement it.

Expansion

#define REFCOUNT_GENERATE_GETREF_FOR_STRUCT_WITH_FAILURE_COND( \
    __struct, __refcount_member, __failure_member, __failure_state) \
    static inline bool __struct##_getref(struct __struct *obj) { \
        uint32_t old; \
        while (true) { \
            old = atomic_load_acq(&obj->__refcount_member); \
 \
            /* panic if refcount is zero (possible UAF) */

REFCOUNT_ASSERT_ZERO

#define REFCOUNT_ASSERT_ZERO(rc)

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Expansion

#define REFCOUNT_ASSERT_ZERO(rc) (enforce(atomic_load(&rc) == 0))