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From: Marek Szyprowski <m.szyprowski@samsung.com>
To: dri-devel@lists.freedesktop.org,
	iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org,
	linux-kernel@vger.kernel.org
Cc: devel@driverdev.osuosl.org, "Todd Kjos" <tkjos@android.com>,
	"Bartlomiej Zolnierkiewicz" <b.zolnierkie@samsung.com>,
	"David Airlie" <airlied@linux.ie>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Arve Hjønnevåg" <arve@android.com>,
	"Martijn Coenen" <maco@android.com>,
	"Christian Brauner" <christian@brauner.io>,
	"Joel Fernandes" <joel@joelfernandes.org>,
	"Laura Abbott" <labbott@redhat.com>,
	"Robin Murphy" <robin.murphy@arm.com>,
	"Christoph Hellwig" <hch@lst.de>,
	linux-arm-kernel@lists.infradead.org,
	"Marek Szyprowski" <m.szyprowski@samsung.com>
Subject: [PATCH v4 32/38] staging: ion: fix common struct sg_table related issues
Date: Tue, 12 May 2020 11:00:52 +0200
Message-ID: <20200512090058.14910-32-m.szyprowski@samsung.com> (raw)
In-Reply-To: <20200512090058.14910-1-m.szyprowski@samsung.com>

The Documentation/DMA-API-HOWTO.txt states that the dma_map_sg() function
returns the number of the created entries in the DMA address space.
However the subsequent calls to the dma_sync_sg_for_{device,cpu}() and
dma_unmap_sg must be called with the original number of the entries
passed to the dma_map_sg().

struct sg_table is a common structure used for describing a non-contiguous
memory buffer, used commonly in the DRM and graphics subsystems. It
consists of a scatterlist with memory pages and DMA addresses (sgl entry),
as well as the number of scatterlist entries: CPU pages (orig_nents entry)
and DMA mapped pages (nents entry).

It turned out that it was a common mistake to misuse nents and orig_nents
entries, calling DMA-mapping functions with a wrong number of entries or
ignoring the number of mapped entries returned by the dma_map_sg()
function.

To avoid such issues, lets use a common dma-mapping wrappers operating
directly on the struct sg_table objects and use scatterlist page
iterators where possible. This, almost always, hides references to the
nents and orig_nents entries, making the code robust, easier to follow
and copy/paste safe.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
For more information, see '[PATCH v4 00/38] DRM: fix struct sg_table nents
vs. orig_nents misuse' thread:
https://lore.kernel.org/dri-devel/20200512085710.14688-1-m.szyprowski@samsung.com/T/
---
 drivers/staging/android/ion/ion.c             | 25 +++++++--------
 drivers/staging/android/ion/ion_heap.c        | 44 ++++++++-------------------
 drivers/staging/android/ion/ion_system_heap.c |  2 +-
 3 files changed, 25 insertions(+), 46 deletions(-)

diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
index 38b51ea..2db041d 100644
--- a/drivers/staging/android/ion/ion.c
+++ b/drivers/staging/android/ion/ion.c
@@ -147,14 +147,14 @@ static struct sg_table *dup_sg_table(struct sg_table *table)
 	if (!new_table)
 		return ERR_PTR(-ENOMEM);
 
-	ret = sg_alloc_table(new_table, table->nents, GFP_KERNEL);
+	ret = sg_alloc_table(new_table, table->orig_nents, GFP_KERNEL);
 	if (ret) {
 		kfree(new_table);
 		return ERR_PTR(-ENOMEM);
 	}
 
 	new_sg = new_table->sgl;
-	for_each_sg(table->sgl, sg, table->nents, i) {
+	for_each_sgtable_sg(table, sg, i) {
 		memcpy(new_sg, sg, sizeof(*sg));
 		new_sg->dma_address = 0;
 		new_sg = sg_next(new_sg);
@@ -224,12 +224,13 @@ static struct sg_table *ion_map_dma_buf(struct dma_buf_attachment *attachment,
 {
 	struct ion_dma_buf_attachment *a = attachment->priv;
 	struct sg_table *table;
+	int ret;
 
 	table = a->table;
 
-	if (!dma_map_sg(attachment->dev, table->sgl, table->nents,
-			direction))
-		return ERR_PTR(-ENOMEM);
+	ret = dma_map_sgtable(attachment->dev, table, direction);
+	if (ret)
+		return ERR_PTR(ret);
 
 	return table;
 }
@@ -238,7 +239,7 @@ static void ion_unmap_dma_buf(struct dma_buf_attachment *attachment,
 			      struct sg_table *table,
 			      enum dma_data_direction direction)
 {
-	dma_unmap_sg(attachment->dev, table->sgl, table->nents, direction);
+	dma_unmap_sgtable(attachment->dev, table, direction);
 }
 
 static int ion_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
@@ -296,10 +297,8 @@ static int ion_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
 	}
 
 	mutex_lock(&buffer->lock);
-	list_for_each_entry(a, &buffer->attachments, list) {
-		dma_sync_sg_for_cpu(a->dev, a->table->sgl, a->table->nents,
-				    direction);
-	}
+	list_for_each_entry(a, &buffer->attachments, list)
+		dma_sync_sgtable_for_cpu(a->dev, a->table, direction);
 
 unlock:
 	mutex_unlock(&buffer->lock);
@@ -319,10 +318,8 @@ static int ion_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
 	}
 
 	mutex_lock(&buffer->lock);
-	list_for_each_entry(a, &buffer->attachments, list) {
-		dma_sync_sg_for_device(a->dev, a->table->sgl, a->table->nents,
-				       direction);
-	}
+	list_for_each_entry(a, &buffer->attachments, list)
+		dma_sync_sgtable_for_device(a->dev, a->table, direction);
 	mutex_unlock(&buffer->lock);
 
 	return 0;
diff --git a/drivers/staging/android/ion/ion_heap.c b/drivers/staging/android/ion/ion_heap.c
index 9c23b23..79f2794 100644
--- a/drivers/staging/android/ion/ion_heap.c
+++ b/drivers/staging/android/ion/ion_heap.c
@@ -20,8 +20,7 @@
 void *ion_heap_map_kernel(struct ion_heap *heap,
 			  struct ion_buffer *buffer)
 {
-	struct scatterlist *sg;
-	int i, j;
+	struct sg_page_iter piter;
 	void *vaddr;
 	pgprot_t pgprot;
 	struct sg_table *table = buffer->sg_table;
@@ -38,14 +37,11 @@ void *ion_heap_map_kernel(struct ion_heap *heap,
 	else
 		pgprot = pgprot_writecombine(PAGE_KERNEL);
 
-	for_each_sg(table->sgl, sg, table->nents, i) {
-		int npages_this_entry = PAGE_ALIGN(sg->length) / PAGE_SIZE;
-		struct page *page = sg_page(sg);
-
-		BUG_ON(i >= npages);
-		for (j = 0; j < npages_this_entry; j++)
-			*(tmp++) = page++;
+	for_each_sgtable_page(table, &piter, 0) {
+		BUG_ON(tmp - pages >= npages);
+		*tmp++ = sg_page_iter_page(&piter);
 	}
+
 	vaddr = vmap(pages, npages, VM_MAP, pgprot);
 	vfree(pages);
 
@@ -64,32 +60,19 @@ void ion_heap_unmap_kernel(struct ion_heap *heap,
 int ion_heap_map_user(struct ion_heap *heap, struct ion_buffer *buffer,
 		      struct vm_area_struct *vma)
 {
+	struct sg_page_iter piter;
 	struct sg_table *table = buffer->sg_table;
 	unsigned long addr = vma->vm_start;
-	unsigned long offset = vma->vm_pgoff * PAGE_SIZE;
-	struct scatterlist *sg;
-	int i;
 	int ret;
 
-	for_each_sg(table->sgl, sg, table->nents, i) {
-		struct page *page = sg_page(sg);
-		unsigned long remainder = vma->vm_end - addr;
-		unsigned long len = sg->length;
+	for_each_sgtable_page(table, &piter, vma->vm_pgoff) {
+		struct page *page = sg_page_iter_page(&piter);
 
-		if (offset >= sg->length) {
-			offset -= sg->length;
-			continue;
-		} else if (offset) {
-			page += offset / PAGE_SIZE;
-			len = sg->length - offset;
-			offset = 0;
-		}
-		len = min(len, remainder);
-		ret = remap_pfn_range(vma, addr, page_to_pfn(page), len,
+		ret = remap_pfn_range(vma, addr, page_to_pfn(page), PAGE_SIZE,
 				      vma->vm_page_prot);
 		if (ret)
 			return ret;
-		addr += len;
+		addr += PAGE_SIZE;
 		if (addr >= vma->vm_end)
 			return 0;
 	}
@@ -109,15 +92,14 @@ static int ion_heap_clear_pages(struct page **pages, int num, pgprot_t pgprot)
 	return 0;
 }
 
-static int ion_heap_sglist_zero(struct scatterlist *sgl, unsigned int nents,
-				pgprot_t pgprot)
+static int ion_heap_sglist_zero(struct sg_table *sgt, pgprot_t pgprot)
 {
 	int p = 0;
 	int ret = 0;
 	struct sg_page_iter piter;
 	struct page *pages[32];
 
-	for_each_sg_page(sgl, &piter, nents, 0) {
+	for_each_sgtable_page(sgt, &piter, 0) {
 		pages[p++] = sg_page_iter_page(&piter);
 		if (p == ARRAY_SIZE(pages)) {
 			ret = ion_heap_clear_pages(pages, p, pgprot);
@@ -142,7 +124,7 @@ int ion_heap_buffer_zero(struct ion_buffer *buffer)
 	else
 		pgprot = pgprot_writecombine(PAGE_KERNEL);
 
-	return ion_heap_sglist_zero(table->sgl, table->nents, pgprot);
+	return ion_heap_sglist_zero(table, pgprot);
 }
 
 void ion_heap_freelist_add(struct ion_heap *heap, struct ion_buffer *buffer)
diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index b83a1d1..eac0632 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -162,7 +162,7 @@ static void ion_system_heap_free(struct ion_buffer *buffer)
 	if (!(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE))
 		ion_heap_buffer_zero(buffer);
 
-	for_each_sg(table->sgl, sg, table->nents, i)
+	for_each_sgtable_sg(table, sg, i)
 		free_buffer_page(sys_heap, buffer, sg_page(sg));
 	sg_free_table(table);
 	kfree(table);
-- 
1.9.1

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  parent reply index

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20200512085722eucas1p2fbaab30e49c9ddadc64b27db856e5921@eucas1p2.samsung.com>
2020-05-12  8:57 ` [PATCH v4 00/38] DRM: fix struct sg_table nents vs. orig_nents misuse Marek Szyprowski
     [not found]   ` <CGME20200512090107eucas1p13a38ce5ce4c15cd0033acaea7b26c9b0@eucas1p1.samsung.com>
2020-05-12  9:00     ` [PATCH v4 01/38] dma-mapping: add generic helpers for mapping sgtable objects Marek Szyprowski
     [not found]       ` <CGME20200512090108eucas1p10a3571be3f60265daea3b3f1469b5e82@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 02/38] scatterlist: add generic wrappers for iterating over " Marek Szyprowski
2020-05-13 13:24           ` Robin Murphy
     [not found]       ` <CGME20200512090108eucas1p2168167ab5e1de09df0d5def83f64dbfe@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 03/38] iommu: add generic helper for mapping " Marek Szyprowski
2020-05-13  9:03           ` Joerg Roedel
2020-05-13 13:27           ` Robin Murphy
     [not found]       ` <CGME20200512090109eucas1p285ca10dceb29f43aae1c40814e2dec8d@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 04/38] drm: prime: add common helper to check scatterlist contiguity Marek Szyprowski
     [not found]       ` <CGME20200512090110eucas1p1fdf69509f401e425c45e958430a99b65@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 05/38] drm: prime: use sgtable iterators in drm_prime_sg_to_page_addr_arrays() Marek Szyprowski
     [not found]       ` <CGME20200512090110eucas1p1b8de7671df480c071718c96f8ebdbc42@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 06/38] drm: core: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090111eucas1p2fd703addaa7975c16a1ea2d7807cc6a6@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 07/38] drm: amdgpu: " Marek Szyprowski
     [not found]       ` <CGME20200512090111eucas1p29897737c262b467437d0775204129105@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 08/38] drm: armada: " Marek Szyprowski
     [not found]       ` <CGME20200512090112eucas1p225de9f54f7fd54346043fc8c31e7ea2d@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 09/38] drm: etnaviv: " Marek Szyprowski
     [not found]       ` <CGME20200512090112eucas1p280707473d14730b8d3054fe9b0781a05@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 10/38] drm: exynos: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200512090113eucas1p254a8b23dd0ee63411df200f66d193203@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 11/38] drm: exynos: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090114eucas1p1917c16e0312cfb191f327e6dad2f7808@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 12/38] drm: i915: " Marek Szyprowski
     [not found]       ` <CGME20200512090114eucas1p1bc4ab112b490205283e7d2f82a9713ee@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 13/38] drm: lima: " Marek Szyprowski
     [not found]       ` <CGME20200512090115eucas1p25e71b29fa935e53e4c04f9b3789a09fc@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 14/38] drm: mediatek: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200512090116eucas1p2089d6eb7aa6bad4d2cbc2875c175873f@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 15/38] drm: mediatek: use common helper for extracting pages array Marek Szyprowski
     [not found]       ` <CGME20200512090116eucas1p24662e01574c0700cfe6d474280bb8df5@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 16/38] drm: msm: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090117eucas1p1acf4ddfe65242d28eee247ab2ca21454@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 17/38] drm: omapdrm: use common helper for extracting pages array Marek Szyprowski
     [not found]       ` <CGME20200512090117eucas1p1179ea62b61b45fae70630e66e434ffb3@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 18/38] drm: omapdrm: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090118eucas1p19ed5cf76c6e1e3f3bcaaefaeff7cf333@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 19/38] drm: panfrost: " Marek Szyprowski
     [not found]       ` <CGME20200512090119eucas1p2c0db485fddf17f15135f8e69e46fc097@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 20/38] drm: radeon: " Marek Szyprowski
     [not found]       ` <CGME20200512090119eucas1p2b3e1a858d8893f8d209d5c19fcbab941@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 21/38] drm: rockchip: use common helper for a scatterlist contiguity check Marek Szyprowski
     [not found]       ` <CGME20200512090120eucas1p28cc382480b2e3298b59fb6bf5ffde80b@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 22/38] drm: rockchip: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090120eucas1p18ae5489153837bbf5b8baa5089234c40@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 23/38] drm: tegra: " Marek Szyprowski
     [not found]       ` <CGME20200512090121eucas1p2f20e300f70ff54da15fe49cc6690f608@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 24/38] drm: v3d: " Marek Szyprowski
     [not found]       ` <CGME20200512090122eucas1p10cc3f42cb0452a8a279fcc8702e50a7a@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 25/38] drm: virtio: " Marek Szyprowski
     [not found]       ` <CGME20200512090122eucas1p155db33deb51b4bbc34c0a012e4a7361d@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 26/38] drm: vmwgfx: " Marek Szyprowski
     [not found]       ` <CGME20200512090123eucas1p268736ef6e202c23e8be77c56873f415f@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 27/38] xen: gntdev: " Marek Szyprowski
     [not found]       ` <CGME20200512090123eucas1p25758ba07ba913e5a3eeca13c7f386fdb@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 28/38] drm: host1x: " Marek Szyprowski
     [not found]       ` <CGME20200512090124eucas1p1f96fac067834c139fe1095a63b4dc2f0@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 29/38] drm: rcar-du: " Marek Szyprowski
     [not found]       ` <CGME20200512090124eucas1p20509113bdbdd1070d8265aa1af80e64a@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 30/38] dmabuf: " Marek Szyprowski
     [not found]       ` <CGME20200512090125eucas1p1f9eae024a33e92bf1468f2af4e5a1b0a@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 31/38] staging: ion: remove dead code Marek Szyprowski
     [not found]       ` <CGME20200512090126eucas1p1ad8d5dfd09fce31d9a18691a76e9fa75@eucas1p1.samsung.com>
2020-05-12  9:00         ` Marek Szyprowski [this message]
     [not found]       ` <CGME20200512090127eucas1p19889d83b1c750dcdc869323e8d1946a3@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 33/38] staging: tegra-vde: fix common struct sg_table related issues Marek Szyprowski
     [not found]       ` <CGME20200512090128eucas1p2cf31bfdca3b096585ba9f2741ef08ce0@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 34/38] misc: fastrpc: " Marek Szyprowski
     [not found]       ` <CGME20200512090128eucas1p11ee8a5e72ca37dc6b3e8a07ea094bab6@eucas1p1.samsung.com>
2020-05-12  9:00         ` [PATCH v4 35/38] rapidio: " Marek Szyprowski
     [not found]       ` <CGME20200512090129eucas1p2e67c8a9adafb202970a59c3412cd887a@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 36/38] samples: vfio-mdev/mbochs: " Marek Szyprowski
     [not found]       ` <CGME20200512090129eucas1p24fa7e83acb8cde494f71ca5694279401@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 37/38] media: pci: fix common ALSA DMA-mapping related codes Marek Szyprowski
     [not found]       ` <CGME20200512090130eucas1p2eb86c5d34be56bbc81032bc0b6927d1e@eucas1p2.samsung.com>
2020-05-12  9:00         ` [PATCH v4 38/38] videobuf2: use sgtable-based scatterlist wrappers Marek Szyprowski
2020-05-12 17:52           ` Ruhl, Michael J
2020-05-12 20:33             ` Marek Szyprowski
2020-05-13 12:01               ` Ruhl, Michael J
     [not found]       ` <20200512121808.GA20393@lst.de>
2020-05-12 13:00         ` [PATCH v4 01/38] dma-mapping: add generic helpers for mapping sgtable objects Marek Szyprowski
     [not found]           ` <20200512130936.GA24428@lst.de>
2020-05-12 13:19             ` Marek Szyprowski
2020-05-13 13:23       ` Robin Murphy

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  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

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dri-devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/dri-devel/0 dri-devel/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 dri-devel dri-devel/ https://lore.kernel.org/dri-devel \
		dri-devel@lists.freedesktop.org
	public-inbox-index dri-devel

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.freedesktop.lists.dri-devel


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git