On 05/30/2018 02:34 AM, Oleksandr Andrushchenko wrote:
On 05/29/2018 10:10 PM, Boris Ostrovsky wrote:
On 05/25/2018 11:33 AM, Oleksandr Andrushchenko wrote:
+/**
- gnttab_dma_free_pages - free DMAable pages
- @args: arguments to the function
- */
+int gnttab_dma_free_pages(struct gnttab_dma_alloc_args *args) +{ + xen_pfn_t *frames; + size_t size; + int i, ret;
+ gnttab_pages_clear_private(args->nr_pages, args->pages);
+ frames = kcalloc(args->nr_pages, sizeof(*frames), GFP_KERNEL);
Any way you can do it without allocating memory? One possibility is to keep allocated frames from gnttab_dma_alloc_pages(). (Not sure I like that either but it's the only thing I can think of).
Yes, I was also thinking about storing the allocated frames array from gnttab_dma_alloc_pages(), but that seemed not to be clear enough as the caller of the gnttab_dma_alloc_pages will need to store those frames in some context, so we can pass them on free. But the caller doesn't really need the frames which might confuse, so I decided to make those allocations on the fly. But I can still rework that to store the frames if you insist: please let me know.
I would prefer not to allocate anything in the release path. Yes, I realize that dragging frames array around is not necessary but IMO it's better than potentially failing an allocation during a teardown. A comment in the struct definition could explain the reason for having this field.
+ if (!frames) + return -ENOMEM;
+ for (i = 0; i < args->nr_pages; i++) + frames[i] = page_to_xen_pfn(args->pages[i]);
Not xen_page_to_gfn()?
Well, according to [1] it should be : /* XENMEM_populate_physmap requires a PFN based on Xen * granularity. */ frame_list[i] = page_to_xen_pfn(page);
Ah, yes. I was looking at decrease_reservation and automatically assumed the same parameter type.
-boris