Re: [PATCH v2] mm: gup: fix comment of __get_user_pages()

From: David Hildenbrand
Date: Thu Oct 24 2019 - 12:10:33 EST


On 24.10.19 17:04, Liu Xiang wrote:
Fix comment of __get_user_pages() and make it more clear.

Suggested-by: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Liu Xiang <liuxiang_1999@xxxxxxx>
---

Changes in v2:
as suggested by John, rewrite the comment about return value.

mm/gup.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 8f236a3..bc6a254 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -734,11 +734,17 @@ static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_flags)
* Or NULL if the caller does not require them.
* @nonblocking: whether waiting for disk IO or mmap_sem contention
*
- * Returns number of pages pinned. This may be fewer than the number
- * requested. If nr_pages is 0 or negative, returns 0. If no pages
- * were pinned, returns -errno. Each page returned must be released
- * with a put_page() call when it is finished with. vmas will only
- * remain valid while mmap_sem is held.
+ * Returns either number of pages pinned (which may be less than the
+ * number requested), or an error. Details about the return value:
+ *
+ * -- If nr_pages is 0, returns 0.
+ * -- If nr_pages is >0, but no pages were pinned, returns -errno.
+ * -- If nr_pages is >0, and some pages were pinned, returns the number of
+ * pages pinned. Again, this may be less than nr_pages.
+ *
+ * The caller is responsible for releasing returned @pages, via put_page().
+ *
+ * @vmas are valid only as long as mmap_sem is held.
*
* Must be called with mmap_sem held. It may be released. See below.
*


Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>

--

Thanks,

David / dhildenb