linux-kernel - Re: [PATCH RESEND] drm/via: use get_user_pages

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Date:   Tue, 28 Feb 2017 10:01:10 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Lorenzo Stoakes <lstoakes@...il.com>
Cc:     Daniel Vetter <daniel@...ll.ch>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-mm@...ck.org
Subject: Re: [PATCH RESEND] drm/via: use get_user_pages_unlocked()

On Mon, Feb 27, 2017 at 09:50:08PM +0000, Lorenzo Stoakes wrote:
> Moving from get_user_pages() to get_user_pages_unlocked() simplifies the code
> and takes advantage of VM_FAULT_RETRY functionality when faulting in pages.
> 
> Signed-off-by: Lorenzo Stoakes <lstoakes@...il.com>

Queued for 4.12, thanks for the patch.
-Daniel

> ---
>  drivers/gpu/drm/via/via_dmablit.c | 10 +++-------
>  1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/via/via_dmablit.c b/drivers/gpu/drm/via/via_dmablit.c
> index 1a3ad769f8c8..98aae9809249 100644
> --- a/drivers/gpu/drm/via/via_dmablit.c
> +++ b/drivers/gpu/drm/via/via_dmablit.c
> @@ -238,13 +238,9 @@ via_lock_all_dma_pages(drm_via_sg_info_t *vsg,  drm_via_dmablit_t *xfer)
>  	vsg->pages = vzalloc(sizeof(struct page *) * vsg->num_pages);
>  	if (NULL == vsg->pages)
>  		return -ENOMEM;
> -	down_read(&current->mm->mmap_sem);
> -	ret = get_user_pages((unsigned long)xfer->mem_addr,
> -			     vsg->num_pages,
> -			     (vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0,
> -			     vsg->pages, NULL);
> -
> -	up_read(&current->mm->mmap_sem);
> +	ret = get_user_pages_unlocked((unsigned long)xfer->mem_addr,
> +			vsg->num_pages, vsg->pages,
> +			(vsg->direction == DMA_FROM_DEVICE) ? FOLL_WRITE : 0);
>  	if (ret != vsg->num_pages) {
>  		if (ret < 0)
>  			return ret;
> -- 
> 2.11.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch