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

From: Paul Durrant <xadimgnik@gmail.com>
To: "'Souptick Joarder'" <jrdr.linux@gmail.com>,
	<boris.ostrovsky@oracle.com>, <jgross@suse.com>,
	<sstabellini@kernel.org>
Cc: <xen-devel@lists.xenproject.org>, <linux-kernel@vger.kernel.org>,
	"'John Hubbard'" <jhubbard@nvidia.com>,
	"'Paul Durrant'" <xadimgnik@gmail.com>
Subject: RE: [PATCH v3 3/3] xen/privcmd: Convert get_user_pages*() to pin_user_pages*()
Date: Mon, 13 Jul 2020 09:10:38 +0100	[thread overview]
Message-ID: <003a01d658ed$1858e220$490aa660$@xen.org> (raw)
In-Reply-To: <1594525195-28345-4-git-send-email-jrdr.linux@gmail.com>

> -----Original Message-----
> From: Souptick Joarder <jrdr.linux@gmail.com>
> Sent: 12 July 2020 04:40
> To: boris.ostrovsky@oracle.com; jgross@suse.com; sstabellini@kernel.org
> Cc: xen-devel@lists.xenproject.org; linux-kernel@vger.kernel.org; Souptick Joarder
> <jrdr.linux@gmail.com>; John Hubbard <jhubbard@nvidia.com>; Paul Durrant <xadimgnik@gmail.com>
> 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@gmail.com>
> Reviewed-by: Juergen Gross <jgross@suse.com>
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Paul Durrant <xadimgnik@gmail.com>

Reviewed-by: Paul Durrant <paul@xen.org>

> ---
>  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