Re: [PATCH 01/13] drm/exynos: Stop using frame_vector helpers

John Hubbard
2020-10-07T20:33:09Z

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);

>
> 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