1 #ifndef _LINUX_REFCOUNT_H 2 #define _LINUX_REFCOUNT_H 3 4 #include <linux/atomic.h> 5 #include <linux/mutex.h> 6 #include <linux/spinlock.h> 7 #include <linux/kernel.h> 8 9 /** 10 * refcount_t - variant of atomic_t specialized for reference counts 11 * @refs: atomic_t counter field 12 * 13 * The counter saturates at UINT_MAX and will not move once 14 * there. This avoids wrapping the counter and causing 'spurious' 15 * use-after-free bugs. 16 */ 17 typedef struct refcount_struct { 18 atomic_t refs; 19 } refcount_t; 20 21 #define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), } 22 23 /** 24 * refcount_set - set a refcount's value 25 * @r: the refcount 26 * @n: value to which the refcount will be set 27 */ 28 static inline void refcount_set(refcount_t *r, unsigned int n) 29 { 30 atomic_set(&r->refs, n); 31 } 32 33 /** 34 * refcount_read - get a refcount's value 35 * @r: the refcount 36 * 37 * Return: the refcount's value 38 */ 39 static inline unsigned int refcount_read(const refcount_t *r) 40 { 41 return atomic_read(&r->refs); 42 } 43 44 #ifdef CONFIG_REFCOUNT_FULL 45 extern __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r); 46 extern void refcount_add(unsigned int i, refcount_t *r); 47 48 extern __must_check bool refcount_inc_not_zero(refcount_t *r); 49 extern void refcount_inc(refcount_t *r); 50 51 extern __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r); 52 53 extern __must_check bool refcount_dec_and_test(refcount_t *r); 54 extern void refcount_dec(refcount_t *r); 55 #else 56 # ifdef CONFIG_ARCH_HAS_REFCOUNT 57 # include <asm/refcount.h> 58 # else 59 static inline __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r) 60 { 61 return atomic_add_unless(&r->refs, i, 0); 62 } 63 64 static inline void refcount_add(unsigned int i, refcount_t *r) 65 { 66 atomic_add(i, &r->refs); 67 } 68 69 static inline __must_check bool refcount_inc_not_zero(refcount_t *r) 70 { 71 return atomic_add_unless(&r->refs, 1, 0); 72 } 73 74 static inline void refcount_inc(refcount_t *r) 75 { 76 atomic_inc(&r->refs); 77 } 78 79 static inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r) 80 { 81 return atomic_sub_and_test(i, &r->refs); 82 } 83 84 static inline __must_check bool refcount_dec_and_test(refcount_t *r) 85 { 86 return atomic_dec_and_test(&r->refs); 87 } 88 89 static inline void refcount_dec(refcount_t *r) 90 { 91 atomic_dec(&r->refs); 92 } 93 # endif /* !CONFIG_ARCH_HAS_REFCOUNT */ 94 #endif /* CONFIG_REFCOUNT_FULL */ 95 96 extern __must_check bool refcount_dec_if_one(refcount_t *r); 97 extern __must_check bool refcount_dec_not_one(refcount_t *r); 98 extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock); 99 extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock); 100 101 #endif /* _LINUX_REFCOUNT_H */ 102