Re: [Xen-devel] Xen 4.7 crash

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.06.16 at 10:53, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 02/06/16 09:47, Jan Beulich wrote:
>>>>> On 02.06.16 at 00:31, <andrew.cooper3@xxxxxxxxxx> wrote:
>>> On 01/06/2016 23:24, Julien Grall wrote:
>>>> free_xenheap_pages already tolerates NULL (even if an order != 0). Is
>>>> there any reason to not do the same for free_domheap_pages?
>>> The xenheap allocation functions deal in terms of plain virtual
>>> addresses, while the domheap functions deal in terms of struct page_info *.
>>>
>>> Overall, this means that the domheap functions have a more restricted
>>> input/output set than their xenheap variants.
>>>
>>> As there is already precedent with xenheap, making domheap tolerate NULL
>>> is probably fine, and indeed the preferred course of action.
>> I disagree, for the very reason you mention above.
> 
> Which?  Dealing with struct page_info pointer?  Its still just a
> pointer, whose value is expected to be NULL if not allocated.

Yes, but it still makes the interface not malloc()-like, other than - as
you say yourself - e.g. the xenheap one. Just look at Linux for
comparison: __free_pages() also doesn't accept NULL, while
free_pages() does. I think we should stick to that distinction.

Jan


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