Re: [PATCH 9/9] drm/exynos: Convert g2d_userptr_get_dma_addr() to use get_vaddr_frames()

From: Jan Kara <jack@suse.cz>
To: Inki Dae <inki.dae@samsung.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>, Jan Kara <jack@suse.com>,
	linux-media@vger.kernel.org,
	Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
	linux-samsung-soc@vger.kernel.org, linux-mm@kvack.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Jan Kara <jack@suse.cz>,
	Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH 9/9] drm/exynos: Convert g2d_userptr_get_dma_addr() to use get_vaddr_frames()
Date: Mon, 20 Jul 2015 10:03:35 +0200	[thread overview]
Message-ID: <20150720080335.GB3131@quack.suse.cz> (raw)
In-Reply-To: <55A9C484.2090707@samsung.com>

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On Sat 18-07-15 12:14:12, Inki Dae wrote:
> On 2015년 07월 17일 19:31, Hans Verkuil wrote:
> > On 07/17/2015 12:29 PM, Inki Dae wrote:
> >> On 2015년 07월 17일 19:20, Hans Verkuil wrote:
> >>> On 07/13/2015 04:55 PM, Jan Kara wrote:
> >>>> From: Jan Kara <jack@suse.cz>
> >>>>
> >>>> Convert g2d_userptr_get_dma_addr() to pin pages using get_vaddr_frames().
> >>>> This removes the knowledge about vmas and mmap_sem locking from exynos
> >>>> driver. Also it fixes a problem that the function has been mapping user
> >>>> provided address without holding mmap_sem.
> >>>
> >>> I'd like to see an Ack from one of the exynos drm driver maintainers before
> >>> I merge this.
> >>>
> >>> Inki, Marek?
> >>
> >> I already gave Ack but it seems that Jan missed it while updating.
> >>
> >> Anyway,
> >> Acked-by: Inki Dae <inki.dae@samsung.com>
> > 
> > Thanks!
> 
> Oops, sorry. This patch would incur a build warning. Below is my comment.
> 
> >>>> @@ -456,65 +455,38 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
> >>>>  		return ERR_PTR(-ENOMEM);
> >>>>  
> >>>>  	atomic_set(&g2d_userptr->refcount, 1);
> >>>> +	g2d_userptr->size = size;
> >>>>  
> >>>>  	start = userptr & PAGE_MASK;
> >>>>  	offset = userptr & ~PAGE_MASK;
> >>>>  	end = PAGE_ALIGN(userptr + size);
> >>>>  	npages = (end - start) >> PAGE_SHIFT;
> >>>> -	g2d_userptr->npages = npages;
> >>>> -
> >>>> -	pages = drm_calloc_large(npages, sizeof(struct page *));
> >>>> -	if (!pages) {
> >>>> -		DRM_ERROR("failed to allocate pages.\n");
> >>>> -		ret = -ENOMEM;
> >>>> +	g2d_userptr->vec = frame_vector_create(npages);
> >>>> +	if (!g2d_userptr->vec)
> 
> You would need ret = -EFAULT here. And below is a patch posted already,
> 	http://www.spinics.net/lists/dri-devel/msg85321.html

The error should IMHO be -ENOMEM because frame_vector_create() fails only
if we fail to allocate the structure. Attached is the updated version of
the patch. Hans, can you please pick this one?
 
> ps. please, ignore the codes related to build error in the patch.
> 
> With the change, Acked-by: Inki Dae <inki.dae@samsung.com>

Thanks and sorry for making so many stupid mistakes in the Exynos driver.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

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>From e1ce3781eb0a3ffe045055f4145bc60ee7b2a6b5 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Wed, 4 Dec 2013 14:41:22 +0100
Subject: [PATCH 9/9] drm/exynos: Convert g2d_userptr_get_dma_addr() to use
 get_vaddr_frames()

Convert g2d_userptr_get_dma_addr() to pin pages using get_vaddr_frames().
This removes the knowledge about vmas and mmap_sem locking from exynos
driver. Also it fixes a problem that the function has been mapping user
provided address without holding mmap_sem.

Acked-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 drivers/gpu/drm/exynos/Kconfig          |  1 +
 drivers/gpu/drm/exynos/exynos_drm_g2d.c | 89 ++++++++++--------------------
 drivers/gpu/drm/exynos/exynos_drm_gem.c | 97 ---------------------------------
 3 files changed, 30 insertions(+), 157 deletions(-)

diff --git a/drivers/gpu/drm/exynos/Kconfig b/drivers/gpu/drm/exynos/Kconfig
index 43003c4ad80b..b364562dc6c1 100644
--- a/drivers/gpu/drm/exynos/Kconfig
+++ b/drivers/gpu/drm/exynos/Kconfig
@@ -77,6 +77,7 @@ config DRM_EXYNOS_VIDI
 config DRM_EXYNOS_G2D
 	bool "Exynos DRM G2D"
 	depends on DRM_EXYNOS && !VIDEO_SAMSUNG_S5P_G2D
+	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 81a250830808..7584834a53c9 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -190,10 +190,8 @@ struct g2d_cmdlist_userptr {
 	dma_addr_t		dma_addr;
 	unsigned long		userptr;
 	unsigned long		size;
-	struct page		**pages;
-	unsigned int		npages;
+	struct frame_vector	*vec;
 	struct sg_table		*sgt;
-	struct vm_area_struct	*vma;
 	atomic_t		refcount;
 	bool			in_pool;
 	bool			out_of_list;
@@ -363,6 +361,7 @@ static void g2d_userptr_put_dma_addr(struct drm_device *drm_dev,
 {
 	struct g2d_cmdlist_userptr *g2d_userptr =
 					(struct g2d_cmdlist_userptr *)obj;
+	struct page **pages;
 
 	if (!obj)
 		return;
@@ -382,19 +381,21 @@ out:
 	exynos_gem_unmap_sgt_from_dma(drm_dev, g2d_userptr->sgt,
 					DMA_BIDIRECTIONAL);
 
-	exynos_gem_put_pages_to_userptr(g2d_userptr->pages,
-					g2d_userptr->npages,
-					g2d_userptr->vma);
+	pages = frame_vector_pages(g2d_userptr->vec);
+	if (!IS_ERR(pages)) {
+		int i;
 
-	exynos_gem_put_vma(g2d_userptr->vma);
+		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);
 
 	if (!g2d_userptr->out_of_list)
 		list_del_init(&g2d_userptr->list);
 
 	sg_free_table(g2d_userptr->sgt);
 	kfree(g2d_userptr->sgt);
-
-	drm_free_large(g2d_userptr->pages);
 	kfree(g2d_userptr);
 }
 
@@ -408,9 +409,7 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
 	struct exynos_drm_g2d_private *g2d_priv = file_priv->g2d_priv;
 	struct g2d_cmdlist_userptr *g2d_userptr;
 	struct g2d_data *g2d;
-	struct page **pages;
 	struct sg_table	*sgt;
-	struct vm_area_struct *vma;
 	unsigned long start, end;
 	unsigned int npages, offset;
 	int ret;
@@ -456,65 +455,40 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct drm_device *drm_dev,
 		return ERR_PTR(-ENOMEM);
 
 	atomic_set(&g2d_userptr->refcount, 1);
+	g2d_userptr->size = size;
 
 	start = userptr & PAGE_MASK;
 	offset = userptr & ~PAGE_MASK;
 	end = PAGE_ALIGN(userptr + size);
 	npages = (end - start) >> PAGE_SHIFT;
-	g2d_userptr->npages = npages;
-
-	pages = drm_calloc_large(npages, sizeof(struct page *));
-	if (!pages) {
-		DRM_ERROR("failed to allocate pages.\n");
+	g2d_userptr->vec = frame_vector_create(npages);
+	if (!g2d_userptr->vec) {
 		ret = -ENOMEM;
 		goto err_free;
 	}
 
-	down_read(&current->mm->mmap_sem);
-	vma = find_vma(current->mm, userptr);
-	if (!vma) {
-		up_read(&current->mm->mmap_sem);
-		DRM_ERROR("failed to get vm region.\n");
+	ret = get_vaddr_frames(start, npages, true, true, g2d_userptr->vec);
+	if (ret != npages) {
+		DRM_ERROR("failed to get user pages from userptr.\n");
+		if (ret < 0)
+			goto err_destroy_framevec;
 		ret = -EFAULT;
-		goto err_free_pages;
+		goto err_put_framevec;
 	}
-
-	if (vma->vm_end < userptr + size) {
-		up_read(&current->mm->mmap_sem);
-		DRM_ERROR("vma is too small.\n");
+	if (frame_vector_to_pages(g2d_userptr->vec) < 0) {
 		ret = -EFAULT;
-		goto err_free_pages;
-	}
-
-	g2d_userptr->vma = exynos_gem_get_vma(vma);
-	if (!g2d_userptr->vma) {
-		up_read(&current->mm->mmap_sem);
-		DRM_ERROR("failed to copy vma.\n");
-		ret = -ENOMEM;
-		goto err_free_pages;
-	}
-
-	g2d_userptr->size = size;
-
-	ret = exynos_gem_get_pages_from_userptr(start & PAGE_MASK,
-						npages, pages, vma);
-	if (ret < 0) {
-		up_read(&current->mm->mmap_sem);
-		DRM_ERROR("failed to get user pages from userptr.\n");
-		goto err_put_vma;
+		goto err_put_framevec;
 	}
 
-	up_read(&current->mm->mmap_sem);
-	g2d_userptr->pages = pages;
-
 	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
 	if (!sgt) {
 		ret = -ENOMEM;
-		goto err_free_userptr;
+		goto err_put_framevec;
 	}
 
-	ret = sg_alloc_table_from_pages(sgt, pages, npages, offset,
-					size, GFP_KERNEL);
+	ret = sg_alloc_table_from_pages(sgt,
+					frame_vector_pages(g2d_userptr->vec),
+					npages, offset, size, GFP_KERNEL);
 	if (ret < 0) {
 		DRM_ERROR("failed to get sgt from pages.\n");
 		goto err_free_sgt;
@@ -549,16 +523,11 @@ err_sg_free_table:
 err_free_sgt:
 	kfree(sgt);
 
-err_free_userptr:
-	exynos_gem_put_pages_to_userptr(g2d_userptr->pages,
-					g2d_userptr->npages,
-					g2d_userptr->vma);
-
-err_put_vma:
-	exynos_gem_put_vma(g2d_userptr->vma);
+err_put_framevec:
+	put_vaddr_frames(g2d_userptr->vec);
 
-err_free_pages:
-	drm_free_large(pages);
+err_destroy_framevec:
+	frame_vector_destroy(g2d_userptr->vec);
 
 err_free:
 	kfree(g2d_userptr);
diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 0d5b9698d384..47068ae44ced 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -378,103 +378,6 @@ int exynos_drm_gem_get_ioctl(struct drm_device *dev, void *data,
 	return 0;
 }
 
-struct vm_area_struct *exynos_gem_get_vma(struct vm_area_struct *vma)
-{
-	struct vm_area_struct *vma_copy;
-
-	vma_copy = kmalloc(sizeof(*vma_copy), GFP_KERNEL);
-	if (!vma_copy)
-		return NULL;
-
-	if (vma->vm_ops && vma->vm_ops->open)
-		vma->vm_ops->open(vma);
-
-	if (vma->vm_file)
-		get_file(vma->vm_file);
-
-	memcpy(vma_copy, vma, sizeof(*vma));
-
-	vma_copy->vm_mm = NULL;
-	vma_copy->vm_next = NULL;
-	vma_copy->vm_prev = NULL;
-
-	return vma_copy;
-}
-
-void exynos_gem_put_vma(struct vm_area_struct *vma)
-{
-	if (!vma)
-		return;
-
-	if (vma->vm_ops && vma->vm_ops->close)
-		vma->vm_ops->close(vma);
-
-	if (vma->vm_file)
-		fput(vma->vm_file);
-
-	kfree(vma);
-}
-
-int exynos_gem_get_pages_from_userptr(unsigned long start,
-						unsigned int npages,
-						struct page **pages,
-						struct vm_area_struct *vma)
-{
-	int get_npages;
-
-	/* the memory region mmaped with VM_PFNMAP. */
-	if (vma_is_io(vma)) {
-		unsigned int i;
-
-		for (i = 0; i < npages; ++i, start += PAGE_SIZE) {
-			unsigned long pfn;
-			int ret = follow_pfn(vma, start, &pfn);
-			if (ret)
-				return ret;
-
-			pages[i] = pfn_to_page(pfn);
-		}
-
-		if (i != npages) {
-			DRM_ERROR("failed to get user_pages.\n");
-			return -EINVAL;
-		}
-
-		return 0;
-	}
-
-	get_npages = get_user_pages(current, current->mm, start,
-					npages, 1, 1, pages, NULL);
-	get_npages = max(get_npages, 0);
-	if (get_npages != npages) {
-		DRM_ERROR("failed to get user_pages.\n");
-		while (get_npages)
-			put_page(pages[--get_npages]);
-		return -EFAULT;
-	}
-
-	return 0;
-}
-
-void exynos_gem_put_pages_to_userptr(struct page **pages,
-					unsigned int npages,
-					struct vm_area_struct *vma)
-{
-	if (!vma_is_io(vma)) {
-		unsigned int i;
-
-		for (i = 0; i < npages; i++) {
-			set_page_dirty_lock(pages[i]);
-
-			/*
-			 * undo the reference we took when populating
-			 * the table.
-			 */
-			put_page(pages[i]);
-		}
-	}
-}
-
 int exynos_gem_map_sgt_with_dma(struct drm_device *drm_dev,
 				struct sg_table *sgt,
 				enum dma_data_direction dir)
-- 
2.1.4

