[Xen-devel] [PATCH v3 12/41] genwqe: convert put_page() to put_user_page*()

[john.hubbard@xxxxxxxxx]

From: John Hubbard <jhubbard@xxxxxxxxxx>

For pages that were retained via get_user_pages*(), release those pages
via the new put_user_page*() routines, instead of via put_page() or
release_pages().

This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
("mm: introduce put_user_page*(), placeholder versions").

This changes the release code slightly, because each page slot in the
page_list[] array is no longer checked for NULL. However, that check
was wrong anyway, because the get_user_pages() pattern of usage here
never allowed for NULL entries within a range of pinned pages.

Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

Cc: Frank Haverkamp <haver@xxxxxxxxxxxxxxxxxx>
Cc: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
 drivers/misc/genwqe/card_utils.c | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

diff --git a/drivers/misc/genwqe/card_utils.c b/drivers/misc/genwqe/card_utils.c
index 2e1c4d2905e8..2a888f31d2c5 100644
--- a/drivers/misc/genwqe/card_utils.c
+++ b/drivers/misc/genwqe/card_utils.c
@@ -517,24 +517,13 @@ int genwqe_free_sync_sgl(struct genwqe_dev *cd, struct 
genwqe_sgl *sgl)
 /**
  * genwqe_free_user_pages() - Give pinned pages back
  *
- * Documentation of get_user_pages is in mm/gup.c:
- *
- * If the page is written to, set_page_dirty (or set_page_dirty_lock,
- * as appropriate) must be called after the page is finished with, and
- * before put_page is called.
+ * The pages may have been written to, so we call put_user_pages_dirty_lock(),
+ * rather than put_user_pages().
  */
 static int genwqe_free_user_pages(struct page **page_list,
                        unsigned int nr_pages, int dirty)
 {
-       unsigned int i;
-
-       for (i = 0; i < nr_pages; i++) {
-               if (page_list[i] != NULL) {
-                       if (dirty)
-                               set_page_dirty_lock(page_list[i]);
-                       put_page(page_list[i]);
-               }
-       }
+       put_user_pages_dirty_lock(page_list, nr_pages, dirty);
        return 0;
 }
 
-- 
2.22.0


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