Re: [PATCH 19/26] ivtv: Convert driver to use get_user_pages_unlocked()

Andy Walls
2013-10-05T12:00:47Z

Hi Jan:

<rant>
This patch alone does not have suffcient information for me to evaluate
it. get_user_pages_unlocked() is added in another patch which I did not
receive, and which I cannot find in any list archives.

I wasted quite a bit of time looking for this additional patch:

https://git.kernel.org/cgit/linux/kernel/git/jack/linux-fs.git/commit/?h=get_user_pages&id=624fc1bfb70fb65d32d31fbd16427ad9c234653e

</rant>

If I found the correct patch for adding get_user_pages_unlocked(), then
the patch below looks fine.

Reviewed-by: Andy Walls <awalls@md.metrocast.net>
Acked-by: Andy Walls <awalls@md.metrocast.net>

Regards,
Andy

On Wed, 2013-10-02 at 16:28 +0200, Jan Kara wrote:
> CC: Andy Walls <awalls@md.metrocast.net>
> CC: linux-media@vger.kernel.org
> Signed-off-by: Jan Kara <jack@suse.cz>
> ---
> drivers/media/pci/ivtv/ivtv-udma.c | 6 ++----
> drivers/media/pci/ivtv/ivtv-yuv.c | 12 ++++++------
> 2 files changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/media/pci/ivtv/ivtv-udma.c b/drivers/media/pci/ivtv/ivtv-udma.c
> index 7338cb2d0a38..6012e5049076 100644
> --- a/drivers/media/pci/ivtv/ivtv-udma.c
> +++ b/drivers/media/pci/ivtv/ivtv-udma.c
> @@ -124,10 +124,8 @@ int ivtv_udma_setup(struct ivtv *itv, unsigned long ivtv_dest_addr,
> }
>
> /* Get user pages for DMA Xfer */
> - down_read(&current->mm->mmap_sem);
> - err = get_user_pages(current, current->mm,
> - user_dma.uaddr, user_dma.page_count, 0, 1, dma->map, NULL);
> - up_read(&current->mm->mmap_sem);
> + err = get_user_pages_unlocked(current, current->mm, user_dma.uaddr,
> + user_dma.page_count, 0, 1, dma->map);
>
> if (user_dma.page_count != err) {
> IVTV_DEBUG_WARN("failed to map user pages, returned %d instead of %d\n",
> diff --git a/drivers/media/pci/ivtv/ivtv-yuv.c b/drivers/media/pci/ivtv/ivtv-yuv.c
> index 2ad65eb29832..9365995917d8 100644
> --- a/drivers/media/pci/ivtv/ivtv-yuv.c
> +++ b/drivers/media/pci/ivtv/ivtv-yuv.c
> @@ -75,15 +75,15 @@ static int ivtv_yuv_prep_user_dma(struct ivtv *itv, struct ivtv_user_dma *dma,
> ivtv_udma_get_page_info (&uv_dma, (unsigned long)args->uv_source, 360 * uv_decode_height);
>
> /* Get user pages for DMA Xfer */
> - down_read(&current->mm->mmap_sem);
> - y_pages = get_user_pages(current, current->mm, y_dma.uaddr, y_dma.page_count, 0, 1, &dma->map[0], NULL);
> + y_pages = get_user_pages_unlocked(current, current->mm, y_dma.uaddr,
> + y_dma.page_count, 0, 1, &dma->map[0]);
> uv_pages = 0; /* silence gcc. value is set and consumed only if: */
> if (y_pages == y_dma.page_count) {
> - uv_pages = get_user_pages(current, current->mm,
> - uv_dma.uaddr, uv_dma.page_count, 0, 1,
> - &dma->map[y_pages], NULL);
> + uv_pages = get_user_pages_unlocked(current, current->mm,
> + uv_dma.uaddr,
> + uv_dma.page_count, 0, 1,
> + &dma->map[y_pages]);
> }
> - up_read(&current->mm->mmap_sem);
>
> if (y_pages != y_dma.page_count || uv_pages != uv_dma.page_count) {
> int rc = -EFAULT;