Re: [PATCH 6/6] x86/xen: open code alloc_vm_area in arch_gnttab_valloc

From: boris . ostrovsky
Date: Tue Sep 22 2020 - 11:24:52 EST

On 9/22/20 10:58 AM, Christoph Hellwig wrote:
> On Mon, Sep 21, 2020 at 04:44:10PM -0400, boris.ostrovsky@xxxxxxxxxx wrote:
>> This will end up incrementing area->ptes pointer. So perhaps something like
>> pte_t **ptes = area->ptes;
>> if (apply_to_page_range(&init_mm, (unsigned long)area->area->addr,
>>                         PAGE_SIZE * nr_frames, gnttab_apply, &ptes)) {
>>        ...
> Yeah. What do you think of this version?

Oh yes, this is way better. This now can actually be read without trying to mentally unwind triple pointers. (You probably want to initialize idx to zero before calling apply_to_page_range(), I am not sure it's guaranteed to be zero).

> I think it is a little
> cleaner and matches what xenbus does. At this point it probably should
> be split into a Xen and a alloc_vm_area removal patch, though.