Re: [Qemu-devel] [PATCH 2/5] exec.c: use refcnt to protect device during dispatching

[liu ping fan]

On Wed, Jul 25, 2012 at 8:27 PM, Avi Kivity <address@hidden> wrote:
> On 07/25/2012 01:58 PM, Avi Kivity wrote:
>>>      while (len > 0) {
>>>          page = addr & TARGET_PAGE_MASK;
>>>          l = (page + TARGET_PAGE_SIZE) - addr;
>>>          if (l > len)
>>>              l = len;
>>> +
>>> +        qemu_rwlock_rdlock_devtree();
>>>          section = phys_page_find(page >> TARGET_PAGE_BITS);
>>
>> Does the devtree lock also protect the data structures accessed by
>> phys_page_find()?  Seems wrong.
>
> The right way is to object_ref() in core_region_add() and object_unref()
> in core_region_del().  We're guaranteed that mr->object is alive during
> _add(), and DeviceClass::unmap() ensures that the extra ref doesn't
> block destruction.
>
OK, I see. I will try in this way.  But when
memory_region_destroy()->..->core_region_del(), should we reset the
lp.ptr to phys_section_unassigned , otherwise, if using  removed
target_phys_addr_t, we will still get the pointer to invalid
MemoryRegion?

Thanx, pingfan
> --
> error compiling committee.c: too many arguments to function
>
>