Hi!
On 23/06/14 21:13, ext Pantelis Antoniou wrote:
[...]
>>> I don't know of any place in the kernel accessing the value if prop->length==0
>>>
>>
>> We have a simple use case. We have an overlay which adds an interrupt controller.
>> If you look in drivers/of/irq.c, in of_irq_parse_raw():
>>
>> [...]
>> /* Now start the actual "proper" walk of the interrupt tree */
>> while (ipar != NULL) {
>> /* Now check if cursor is an interrupt-controller and if it is
>> * then we are done
>> */
>> if (of_get_property(ipar, "interrupt-controller", NULL) !=
>> NULL) {
>> pr_debug(" -> got it !\n");
>> return 0;
>> }
>> [...]
>>
>> A node is identified as an interrupt controller if it has a zero-length property
>> called "interrupt-controller" but with a non-NULL value.
>>
>> My proposed fix for this was to remove the if () condition. propn->value will be
>> allocated with kmalloc(0) which returns ZERO_SIZE_PTR which is != NULL.
>>
>
> If that's the case, the code in irq.c is wrong.
>
> interrupt-controller is a bool property; the correct call to use is of_property_read_bool()
> which returns true or false when the value is defined.
No, it's not bool... It's an existence of a void property.
> The use of of_get_property is a bug here. It is perfectly valid for a property to have a
> NULL value when length = 0.
of_find_property() would be really correct in this particular case...
--
Best regards,
Alexander Sverdlin.
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