Re: [Qemu-devel] [PATCH] qom: Make object_child_foreach safe for objects removal

[Andreas Färber]

Am 14.07.2014 15:12, schrieb Alexey Kardashevskiy:
> On 07/14/2014 06:14 PM, Paolo Bonzini wrote:
>> Il 13/07/2014 16:41, Alexey Kardashevskiy ha scritto:
>>> Current object_child_foreach() uses QTAILQ_FOREACH() to walk
>>> through children and that makes children removal from the callback
>>> impossible.
>>>
>>> This makes object_child_foreach() use QTAILQ_FOREACH_SAFE().
>>>
>>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
>>> ---
>>>
>>> The problem I am trying to solve is:
>>> there is a PHB with multiple DMA windows a.k.a. sPAPRTCETable's which are
>>> QOM children of PHB. One of RTAS functions is "reset" which is supposed to
>>> remove all windows (now just one) except the default one.
>>>
>>> I could call QTAILQ_FOREACH_SAFE in sPAPR PHB code but
>>> object_property_is_child()
>>> is static and we probably do not want to make it public.
>>>
>>>
>>> ---
>>>  qom/object.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/qom/object.c b/qom/object.c
>>> index 0e8267b..4a814dc 100644
>>> --- a/qom/object.c
>>> +++ b/qom/object.c
>>> @@ -678,10 +678,10 @@ void object_class_foreach(void (*fn)(ObjectClass
>>> *klass, void *opaque),
>>>  int object_child_foreach(Object *obj, int (*fn)(Object *child, void
>>> *opaque),
>>>                           void *opaque)
>>>  {
>>> -    ObjectProperty *prop;
>>> +    ObjectProperty *prop, *next;
>>>      int ret = 0;
>>>
>>> -    QTAILQ_FOREACH(prop, &obj->properties, node) {
>>> +    QTAILQ_FOREACH_SAFE(prop, &obj->properties, node, next) {
>>>          if (object_property_is_child(prop)) {
>>>              ret = fn(prop->opaque, opaque);
>>>              if (ret != 0) {
>>>
>>
>> The patch is certainly okay, do you need it in 2.1?
> 
> 
> Nope, I will need it for dynamic DMA windows (VFIO, PPC) which are not for
> 2.1 for sure.

Thanks, applied to qom-next so that it doesn't get forgotten.
https://github.com/afaerber/qemu-cpu/commits/qom-next

Andreas

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