1 #ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H 2 #define _TOOLS_LINUX_ASM_X86_ATOMIC_H 3 4 #include <linux/compiler.h> 5 #include <linux/types.h> 6 #include "rmwcc.h" 7 8 #define LOCK_PREFIX "\n\tlock; " 9 10 #include <asm/cmpxchg.h> 11 12 /* 13 * Atomic operations that C can't guarantee us. Useful for 14 * resource counting etc.. 15 */ 16 17 #define ATOMIC_INIT(i) { (i) } 18 19 /** 20 * atomic_read - read atomic variable 21 * @v: pointer of type atomic_t 22 * 23 * Atomically reads the value of @v. 24 */ 25 static inline int atomic_read(const atomic_t *v) 26 { 27 return ACCESS_ONCE((v)->counter); 28 } 29 30 /** 31 * atomic_set - set atomic variable 32 * @v: pointer of type atomic_t 33 * @i: required value 34 * 35 * Atomically sets the value of @v to @i. 36 */ 37 static inline void atomic_set(atomic_t *v, int i) 38 { 39 v->counter = i; 40 } 41 42 /** 43 * atomic_inc - increment atomic variable 44 * @v: pointer of type atomic_t 45 * 46 * Atomically increments @v by 1. 47 */ 48 static inline void atomic_inc(atomic_t *v) 49 { 50 asm volatile(LOCK_PREFIX "incl %0" 51 : "+m" (v->counter)); 52 } 53 54 /** 55 * atomic_dec_and_test - decrement and test 56 * @v: pointer of type atomic_t 57 * 58 * Atomically decrements @v by 1 and 59 * returns true if the result is 0, or false for all other 60 * cases. 61 */ 62 static inline int atomic_dec_and_test(atomic_t *v) 63 { 64 GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e"); 65 } 66 67 static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new) 68 { 69 return cmpxchg(&v->counter, old, new); 70 } 71 72 #endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */ 73