On 2/5/21 2:46 AM, Joao Martins wrote:
...>> If instead you keep npages constant like it naturally wants to be, you could
just do a "(*ntails)++" in the loop, to take care of *ntails.
I didn't do it as such as I would need to deref @ntails per iteration, so
it felt more efficient to do as above. On a second thought, I could alternatively do the
following below, thoughts?
diff --git a/mm/gup.c b/mm/gup.c
index d68bcb482b11..8defe4f670d5 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -215,6 +215,32 @@ void unpin_user_page(struct page *page)
}
EXPORT_SYMBOL(unpin_user_page);
+static inline void compound_next(unsigned long i, unsigned long npages,
+ struct page **list, struct page **head,
+ unsigned int *ntails)
+{
+ struct page *page;
+ unsigned int nr;
+
+ if (i >= npages)
+ return;
+
+ page = compound_head(list[i]);
+ for (nr = i + 1; nr < npages; nr++) {
+ if (compound_head(list[nr]) != page)
+ break;
+ }
+
+ *head = page;
+ *ntails = nr - i;
+}
+
Yes, this is cleaner and quite a bit easier to verify that it is correct.
However, given that the patch is correct and works as-is, the above is really just
an optional idea, so please feel free to add:
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Thanks!
Hopefully I can retain that if the snippet above is preferred?
Joao
Yes. Still looks good.
thanks,
--
John Hubbard
NVIDIA
