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 static inline __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r) 57 { 58 return atomic_add_unless(&r->refs, i, 0); 59 } 60 61 static inline void refcount_add(unsigned int i, refcount_t *r) 62 { 63 atomic_add(i, &r->refs); 64 } 65 66 static inline __must_check bool refcount_inc_not_zero(refcount_t *r) 67 { 68 return atomic_add_unless(&r->refs, 1, 0); 69 } 70 71 static inline void refcount_inc(refcount_t *r) 72 { 73 atomic_inc(&r->refs); 74 } 75 76 static inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r) 77 { 78 return atomic_sub_and_test(i, &r->refs); 79 } 80 81 static inline __must_check bool refcount_dec_and_test(refcount_t *r) 82 { 83 return atomic_dec_and_test(&r->refs); 84 } 85 86 static inline void refcount_dec(refcount_t *r) 87 { 88 atomic_dec(&r->refs); 89 } 90 #endif /* CONFIG_REFCOUNT_FULL */ 91 92 extern __must_check bool refcount_dec_if_one(refcount_t *r); 93 extern __must_check bool refcount_dec_not_one(refcount_t *r); 94 extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock); 95 extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock); 96 97 #endif /* _LINUX_REFCOUNT_H */ 98