Implement FETCH-OP atomic primitives, these are very similar to the existing OP-RETURN primitives we already have, except they return the value of the atomic variable _before_ modification. This is especially useful for irreversible operations -- such as bitops (because it becomes impossible to reconstruct the state prior to modification). Signed-off-by: Peter Zijlstra (Intel) --- arch/avr32/include/asm/atomic.h | 56 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 51 insertions(+), 5 deletions(-) --- a/arch/avr32/include/asm/atomic.h +++ b/arch/avr32/include/asm/atomic.h @@ -41,21 +41,51 @@ static inline int __atomic_##op##_return return result; \ } +#define ATOMIC_FETCH_OP(op, asm_op, asm_con) \ +static inline int __atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + int result, val; \ + \ + asm volatile( \ + "/* atomic_fetch_" #op " */\n" \ + "1: ssrf 5\n" \ + " ld.w %0, %3\n" \ + " mov %1, %0\n" \ + " " #asm_op " %1, %4\n" \ + " stcond %2, %1\n" \ + " brne 1b" \ + : "=&r" (result), "=&r" (val), "=o" (v->counter) \ + : "m" (v->counter), #asm_con (i) \ + : "cc"); \ + \ + return result; \ +} + ATOMIC_OP_RETURN(sub, sub, rKs21) ATOMIC_OP_RETURN(add, add, r) +ATOMIC_FETCH_OP (sub, sub, rKs21) +ATOMIC_FETCH_OP (add, add, r) -#define ATOMIC_OP(op, asm_op) \ +#define atomic_fetch_or atomic_fetch_or + +#define ATOMIC_OPS(op, asm_op) \ ATOMIC_OP_RETURN(op, asm_op, r) \ static inline void atomic_##op(int i, atomic_t *v) \ { \ (void)__atomic_##op##_return(i, v); \ +} \ +ATOMIC_FETCH_OP(op, asm_op, r) \ +static inline int atomic_fetch_##op(int i, atomic_t *v) \ +{ \ + return __atomic_fetch_##op(i, v); \ } -ATOMIC_OP(and, and) -ATOMIC_OP(or, or) -ATOMIC_OP(xor, eor) +ATOMIC_OPS(and, and) +ATOMIC_OPS(or, or) +ATOMIC_OPS(xor, eor) -#undef ATOMIC_OP +#undef ATOMIC_OPS +#undef ATOMIC_FETCH_OP #undef ATOMIC_OP_RETURN /* @@ -87,6 +117,14 @@ static inline int atomic_add_return(int return __atomic_add_return(i, v); } +static inline int atomic_fetch_add(int i, atomic_t *v) +{ + if (IS_21BIT_CONST(i)) + return __atomic_fetch_sub(-i, v); + + return __atomic_fetch_add(i, v); +} + /* * atomic_sub_return - subtract the atomic variable * @i: integer value to subtract @@ -102,6 +140,14 @@ static inline int atomic_sub_return(int return __atomic_add_return(-i, v); } +static inline int atomic_fetch_sub(int i, atomic_t *v) +{ + if (IS_21BIT_CONST(i)) + return __atomic_fetch_sub(i, v); + + return __atomic_fetch_add(-i, v); +} + /* * __atomic_add_unless - add unless the number is a given value * @v: pointer of type atomic_t