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    SubjectRe: [PATCH 01/13] drm/exynos: Stop using frame_vector helpers
    On Wed, Oct 7, 2020 at 10:33 PM John Hubbard <jhubbard@nvidia.com> wrote:
    >
    > On 10/7/20 9:44 AM, Daniel Vetter wrote:
    > > All we need are a pages array, pin_user_pages_fast can give us that
    > > directly. Plus this avoids the entire raw pfn side of get_vaddr_frames.
    > >
    > > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
    > > Cc: Jason Gunthorpe <jgg@ziepe.ca>
    > > Cc: Inki Dae <inki.dae@samsung.com>
    > > Cc: Joonyoung Shim <jy0922.shim@samsung.com>
    > > Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
    > > Cc: Kyungmin Park <kyungmin.park@samsung.com>
    > > Cc: Kukjin Kim <kgene@kernel.org>
    > > Cc: Krzysztof Kozlowski <krzk@kernel.org>
    > > Cc: Andrew Morton <akpm@linux-foundation.org>
    > > Cc: John Hubbard <jhubbard@nvidia.com>
    > > Cc: Jérôme Glisse <jglisse@redhat.com>
    > > Cc: Jan Kara <jack@suse.cz>
    > > Cc: Dan Williams <dan.j.williams@intel.com>
    > > Cc: linux-mm@kvack.org
    > > Cc: linux-arm-kernel@lists.infradead.org
    > > Cc: linux-samsung-soc@vger.kernel.org
    > > Cc: linux-media@vger.kernel.org
    > > ---
    > > drivers/gpu/drm/exynos/Kconfig | 1 -
    > > drivers/gpu/drm/exynos/exynos_drm_g2d.c | 48 ++++++++++++-------------
    > > 2 files changed, 22 insertions(+), 27 deletions(-)
    > >
    > > diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
    > > index 6417f374b923..43257ef3c09d 100644
    > > --- a/drivers/gpu/drm/exynos/Kconfig
    > > +++ b/drivers/gpu/drm/exynos/Kconfig
    > > @@ -88,7 +88,6 @@ comment "Sub-drivers"
    > > config DRM_EXYNOS_G2D
    > > bool "G2D"
    > > depends on VIDEO_SAMSUNG_S5P_G2D=n || COMPILE_TEST
    > > - select FRAME_VECTOR
    > > help
    > > Choose this option if you want to use Exynos G2D for DRM.
    > >
    > > diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
    > > index 967a5cdc120e..c83f6faac9de 100644
    > > --- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
    > > +++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
    > > @@ -205,7 +205,8 @@ struct g2d_cmdlist_userptr {
    > > dma_addr_t dma_addr;
    > > unsigned long userptr;
    > > unsigned long size;
    > > - struct frame_vector *vec;
    > > + struct page **pages;
    > > + unsigned int npages;
    > > struct sg_table *sgt;
    > > atomic_t refcount;
    > > bool in_pool;
    > > @@ -378,7 +379,7 @@ static void g2d_userptr_put_dma_addr(struct g2d_data *g2d,
    > > bool force)
    > > {
    > > struct g2d_cmdlist_userptr *g2d_userptr = obj;
    > > - struct page **pages;
    > > + int i;
    >
    > The above line can also be deleted, see below.
    >
    > >
    > > if (!obj)
    > > return;
    > > @@ -398,15 +399,11 @@ static void g2d_userptr_put_dma_addr(struct g2d_data *g2d,
    > > dma_unmap_sgtable(to_dma_dev(g2d->drm_dev), g2d_userptr->sgt,
    > > DMA_BIDIRECTIONAL, 0);
    > >
    > > - pages = frame_vector_pages(g2d_userptr->vec);
    > > - if (!IS_ERR(pages)) {
    > > - int i;
    > > + for (i = 0; i < g2d_userptr->npages; i++)
    > > + set_page_dirty_lock(g2d_userptr->pages[i]);
    > >
    > > - for (i = 0; i < frame_vector_count(g2d_userptr->vec); i++)
    > > - set_page_dirty_lock(pages[i]);
    > > - }
    > > - put_vaddr_frames(g2d_userptr->vec);
    > > - frame_vector_destroy(g2d_userptr->vec);
    > > + unpin_user_pages(g2d_userptr->pages, g2d_userptr->npages);
    > > + kvfree(g2d_userptr->pages);
    >
    > You can avoid writing your own loop, and just simplify the whole thing down to
    > two lines:
    >
    > unpin_user_pages_dirty_lock(g2d_userptr->pages, g2d_userptr->npages,
    > true);
    > kvfree(g2d_userptr->pages);

    Oh nice, this is neat. I'll also roll it out in the habanalabs patch,
    that has the same thing. Well almost, it only uses set_page_dirty, not
    the _lock variant. But I have no idea whether that matters or not?
    -Daniel

    >
    >
    > >
    > > if (!g2d_userptr->out_of_list)
    > > list_del_init(&g2d_userptr->list);
    > > @@ -474,35 +471,34 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct g2d_data *g2d,
    > > offset = userptr & ~PAGE_MASK;
    > > end = PAGE_ALIGN(userptr + size);
    > > npages = (end - start) >> PAGE_SHIFT;
    > > - g2d_userptr->vec = frame_vector_create(npages);
    > > - if (!g2d_userptr->vec) {
    > > + g2d_userptr->pages = kvmalloc_array(npages, sizeof(*g2d_userptr->pages),
    > > + GFP_KERNEL);
    > > + if (!g2d_userptr->pages) {
    > > ret = -ENOMEM;
    > > goto err_free;
    > > }
    > >
    > > - ret = get_vaddr_frames(start, npages, FOLL_FORCE | FOLL_WRITE,
    > > - g2d_userptr->vec);
    > > + ret = pin_user_pages_fast(start, npages, FOLL_FORCE | FOLL_WRITE,
    > > + g2d_userptr->pages);
    > > if (ret != npages) {
    > > DRM_DEV_ERROR(g2d->dev,
    > > "failed to get user pages from userptr.\n");
    > > if (ret < 0)
    > > - goto err_destroy_framevec;
    > > - ret = -EFAULT;
    > > - goto err_put_framevec;
    > > - }
    > > - if (frame_vector_to_pages(g2d_userptr->vec) < 0) {
    > > + goto err_destroy_pages;
    > > + npages = ret;
    > > ret = -EFAULT;
    > > - goto err_put_framevec;
    > > + goto err_unpin_pages;
    > > }
    > > + g2d_userptr->npages = npages;
    > >
    > > sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
    > > if (!sgt) {
    > > ret = -ENOMEM;
    > > - goto err_put_framevec;
    > > + goto err_unpin_pages;
    > > }
    > >
    > > ret = sg_alloc_table_from_pages(sgt,
    > > - frame_vector_pages(g2d_userptr->vec),
    > > + g2d_userptr->pages,
    > > npages, offset, size, GFP_KERNEL);
    > > if (ret < 0) {
    > > DRM_DEV_ERROR(g2d->dev, "failed to get sgt from pages.\n");
    > > @@ -538,11 +534,11 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct g2d_data *g2d,
    > > err_free_sgt:
    > > kfree(sgt);
    > >
    > > -err_put_framevec:
    > > - put_vaddr_frames(g2d_userptr->vec);
    > > +err_unpin_pages:
    > > + unpin_user_pages(g2d_userptr->pages, npages);
    > >
    > > -err_destroy_framevec:
    > > - frame_vector_destroy(g2d_userptr->vec);
    > > +err_destroy_pages:
    > > + kvfree(g2d_userptr->pages);
    > >
    > > err_free:
    > > kfree(g2d_userptr);
    > >
    >
    > The rest all looks good, you've avoided the usual API pitfalls. :)
    >
    > thanks,
    > --
    > John Hubbard
    > NVIDIA



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

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