Re: [Qemu-devel] [PATCH V3 01/11] atomic: introduce atomic operations

[Avi Kivity]

On 09/13/2012 09:54 AM, liu ping fan wrote:

>>> +typedef struct Atomic {
>>> +    int counter;
>>> +} Atomic;
>>
>> Best to mark counter 'volatile'.
>>
>>> +
>>> +static inline void atomic_set(Atomic *v, int i)
>>> +{
>>> +    v->counter = i;
>>> +}
>>> +
>>> +static inline int atomic_read(Atomic *v)
>>> +{
>>> +    return v->counter;
>>> +}
>>>
>>
>> So these two operations don't get mangled by the optimizer.
>>
> Browsing linux code and reading lkml, find some similar material. But
> they have moved volatile from ->counter to function - atomic_read().
> As to atomic_read(), I think it need to prevent optimizer from
> refetching issue, but as to atomic_set(), do we need ?

I think so, to prevent reordering.


-- 
error compiling committee.c: too many arguments to function