Re: [PATCH] drm/via: use get_user_pages_unlocked()

From: Daniel Vetter
Date: Sun Feb 26 2017 - 14:48:11 EST


On Mon, Feb 20, 2017 at 06:46:54PM +0000, Lorenzo Stoakes wrote:
> On 6 January 2017 at 07:09, Lorenzo Stoakes <lstoakes@xxxxxxxxx> wrote:
> >
> > Adding Andrew, as this may be another less active corner of the corner, thanks!
>
> Hi all,
>
> Thought I'd also give this one a gentle nudge now the merge window has
> re-opened, Andrew - are you ok to pick this up? I've checked the patch
> and it still applies, for convenience the raw patch is available at
> https://marc.info/?l=linux-mm&m=147802942832515&q=raw - let me know if
> there's anything else I can do on this or if you'd prefer a re-send.

Somehow your original patch never made it to dri-devel :( The via driver
is entirely unmaintained, but if you resubmit I'll smash it into drm-misc
for 4.12. Merge window is long over already for 4.11, subsystems need to
have their stuff ready _before_ it starts.

Cheers, Daniel
>
> Best, Lorenzo
>
> > On 3 January 2017 at 20:23, Lorenzo Stoakes <lstoakes@xxxxxxxxx> wrote:
> >> Hi All,
> >>
> >> Just a gentle ping on this one :)
> >>
> >> Cheers, Lorenzo
> >>
> >> On 1 November 2016 at 19:43, Lorenzo Stoakes <lstoakes@xxxxxxxxx> 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@xxxxxxxxx>
> >>> ---
> >>> 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 1a3ad76..98aae98 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;
> >>> --
> >>> 2.10.2
> >>>
>
> --
> Lorenzo Stoakes
> https://ljs.io
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch