1/* SPDX-License-Identifier: GPL-2.0 */ 2#ifndef __TOOLS_ASM_GENERIC_ATOMIC_H 3#define __TOOLS_ASM_GENERIC_ATOMIC_H 4 5#include <linux/compiler.h> 6#include <linux/types.h> 7#include <linux/bitops.h> 8 9/* 10 * Atomic operations that C can't guarantee us. Useful for 11 * resource counting etc.. 12 * 13 * Excerpts obtained from the Linux kernel sources. 14 */ 15 16#define ATOMIC_INIT(i) { (i) } 17 18/** 19 * atomic_read - read atomic variable 20 * @v: pointer of type atomic_t 21 * 22 * Atomically reads the value of @v. 23 */ 24static inline int atomic_read(const atomic_t *v) 25{ 26 return READ_ONCE((v)->counter); 27} 28 29/** 30 * atomic_set - set atomic variable 31 * @v: pointer of type atomic_t 32 * @i: required value 33 * 34 * Atomically sets the value of @v to @i. 35 */ 36static inline void atomic_set(atomic_t *v, int i) 37{ 38 v->counter = i; 39} 40 41/** 42 * atomic_inc - increment atomic variable 43 * @v: pointer of type atomic_t 44 * 45 * Atomically increments @v by 1. 46 */ 47static inline void atomic_inc(atomic_t *v) 48{ 49 __sync_add_and_fetch(&v->counter, 1); 50} 51 52/** 53 * atomic_dec_and_test - decrement and test 54 * @v: pointer of type atomic_t 55 * 56 * Atomically decrements @v by 1 and 57 * returns true if the result is 0, or false for all other 58 * cases. 59 */ 60static inline int atomic_dec_and_test(atomic_t *v) 61{ 62 return __sync_sub_and_fetch(&v->counter, 1) == 0; 63} 64 65#define cmpxchg(ptr, oldval, newval) \ 66 __sync_val_compare_and_swap(ptr, oldval, newval) 67 68static inline int atomic_cmpxchg(atomic_t *v, int oldval, int newval) 69{ 70 return cmpxchg(&(v)->counter, oldval, newval); 71} 72 73static inline int test_and_set_bit(long nr, unsigned long *addr) 74{ 75 unsigned long mask = BIT_MASK(nr); 76 long old; 77 78 addr += BIT_WORD(nr); 79 80 old = __sync_fetch_and_or(addr, mask); 81 return !!(old & mask); 82} 83 84static inline int test_and_clear_bit(long nr, unsigned long *addr) 85{ 86 unsigned long mask = BIT_MASK(nr); 87 long old; 88 89 addr += BIT_WORD(nr); 90 91 old = __sync_fetch_and_and(addr, ~mask); 92 return !!(old & mask); 93} 94 95#endif /* __TOOLS_ASM_GENERIC_ATOMIC_H */ 96