[PATCH 2/2] xen/privcmd: Convert get_user_pages*() to pin_user_pages*()

Souptick Joarder
2020-06-25T02:54:59Z

In 2019, we introduced pin_user_pages*() and now we are converting
get_user_pages*() to the new API as appropriate. [1] & [2] could
be referred for more information. This is case 5 as per document [1].

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
https://lwn.net/Articles/807108/

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Paul Durrant <xadimgnik@gmail.com>
---
Hi,

I'm compile tested this, but unable to run-time test, so any testing
help is much appriciated.

drivers/xen/privcmd.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 0da417c..eb05254 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -595,7 +595,7 @@ static int lock_pages(
if (requested > nr_pages)
return -ENOSPC;

- page_count = get_user_pages_fast(
+ page_count = pin_user_pages_fast(
(unsigned long) kbufs[i].uptr,
requested, FOLL_WRITE, pages);
if (page_count < 0) {
@@ -612,13 +612,7 @@ static int lock_pages(

static void unlock_pages(struct page *pages[], unsigned int nr_pages)
{
- unsigned int i;
-
- for (i = 0; i < nr_pages; i++) {
- if (!PageDirty(page))
- set_page_dirty_lock(page);
- put_page(pages[i]);
- }
+ unpin_user_pages_dirty_lock(pages, nr_pages, 1);
}

static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
--
1.9.1