RE: [PATCH v3 3/3] xen/privcmd: Convert get_user_pages*() to pin_user_pages*()

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----Original Message-----
> From: Souptick Joarder <jrdr.linux@xxxxxxxxx>
> Sent: 12 July 2020 04:40
> To: boris.ostrovsky@xxxxxxxxxx; jgross@xxxxxxxx; sstabellini@xxxxxxxxxx
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Souptick 
> Joarder
> <jrdr.linux@xxxxxxxxx>; John Hubbard <jhubbard@xxxxxxxxxx>; Paul Durrant 
> <xadimgnik@xxxxxxxxx>
> Subject: [PATCH v3 3/3] xen/privcmd: Convert get_user_pages*() to 
> pin_user_pages*()
> 
> 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@xxxxxxxxx>
> Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
> Cc: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Cc: Paul Durrant <xadimgnik@xxxxxxxxx>

Reviewed-by: Paul Durrant <paul@xxxxxxx>

> ---
>  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 079d35b..63abe6c 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -593,7 +593,7 @@ 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)
> @@ -609,13 +609,7 @@ 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(pages[i]))
> -                     set_page_dirty_lock(pages[i]);
> -             put_page(pages[i]);
> -     }
> +     unpin_user_pages_dirty_lock(pages, nr_pages, true);
>  }
> 
>  static long privcmd_ioctl_dm_op(struct file *file, void __user *udata)
> --
> 1.9.1