Re: [Qemu-devel] [patch v5 6/8] memory: make mmio dispatch able to be out of biglock

[Avi Kivity]

On 10/30/2012 09:06 AM, liu ping fan wrote:
>>>      while (len > 0) {
>>>          page = addr & TARGET_PAGE_MASK;
>>>          l = (page + TARGET_PAGE_SIZE) - addr;
>>>          if (l > len)
>>>              l = len;
>>> -        section = phys_page_find(d, page >> TARGET_PAGE_BITS);
>>> +
>>> +        if (as->lock) {
>>> +            qemu_mutex_lock(as->lock);
>>> +            safe_ref = memory_region_section_lookup_ref(d, page, &obj_mrs);
>>> +            qemu_mutex_unlock(as->lock);
>>> +            if (!safe_ref) {
>>> +                qemu_mutex_lock_iothread();
>>> +                qemu_mutex_lock(as->lock);
>>> +                /* when 2nd try, mem map can change, need to judge it 
>>> again */
>>> +                safe_ref = memory_region_section_lookup_ref(d, page, 
>>> &obj_mrs);
>>> +                qemu_mutex_unlock(as->lock);
>>> +                if (safe_ref) {
>>> +                    qemu_mutex_unlock_iothread();
>>> +                }
>>> +            }
>>> +        } else {
>>> +            /* Caller hold the big lock */
>>> +            memory_region_section_lookup_ref(d, page, &obj_mrs);
>>
>> It's not a property of the address space, it's a property of the caller.
>>
> Sorry, what is your meaning?

Whether the caller holds the big lock or not is not known by the address
space.  It is only known by the caller itself.


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