On 04/15/10 01:08, Paolo Bonzini wrote:
> On 04/14/2010 06:52 PM, Blue Swirl wrote:
>> On 4/14/10, Gerd Hoffmann<kraxel@redhat.com> wrote:
>>> +static inline void atomic_or(uint32_t *var, uint32_t add)
>>> +{
>>> + __asm__ __volatile__ ("lock; orl %1, %0" : "+m" (*var) : "r" (add)
>>> : "memory");
>>> +}
>>
>> This will break on non-x86 hosts.
>
> I'd just use __sync_fetch_and_or here.

Good idea.  I think we can zap the memory barrier and fix a small race 
while being at it, see the incremental fix below.

cheers,
   Gerd