diff mbox series

[v6,04/36] drm: amdgpu: fix common struct sg_table related issues

Message ID 20200618153956.29558-5-m.szyprowski@samsung.com (mailing list archive)
State New, archived
Headers show
Series DRM: fix struct sg_table nents vs. orig_nents misuse | expand

Commit Message

Marek Szyprowski June 18, 2020, 3:39 p.m. UTC 
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>
Reviewed-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c  | 6 +++---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c      | 9 +++------
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 8 ++++----
 3 files changed, 10 insertions(+), 13 deletions(-)

Comments

kernel test robot June 18, 2020, 9:32 p.m. UTC | #1 
Hi Marek,

I love your patch! Perhaps something to improve:

[auto build test WARNING on next-20200618]
[also build test WARNING on v5.8-rc1]
[cannot apply to linuxtv-media/master staging/staging-testing drm-exynos/exynos-drm-next drm-intel/for-linux-next linus/master v5.8-rc1 v5.7 v5.7-rc7]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use  as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Marek-Szyprowski/DRM-fix-struct-sg_table-nents-vs-orig_nents-misuse/20200619-000417
base:    ce2cc8efd7a40cbd17841add878cb691d0ce0bba
config: alpha-allyesconfig (attached as .config)
compiler: alpha-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=alpha 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>, old ones prefixed by <<):

In file included from include/linux/dma-mapping.h:11,
from drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:25:
drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c: In function 'amdgpu_vram_mgr_alloc_sgt':
include/linux/scatterlist.h:158:17: error: '*sgt' is a pointer; did you mean to use '->'?
158 |  for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
|                 ^~
include/linux/scatterlist.h:152:22: note: in definition of macro 'for_each_sg'
152 |  for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
|                      ^~~~~~
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:480:2: note: in expansion of macro 'for_each_sgtable_sg'
480 |  for_each_sgtable_sg(*sgt, sg, i)
|  ^~~~~~~~~~~~~~~~~~~
include/linux/scatterlist.h:158:31: error: '*sgt' is a pointer; did you mean to use '->'?
158 |  for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
|                               ^~
include/linux/scatterlist.h:152:38: note: in definition of macro 'for_each_sg'
152 |  for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
|                                      ^~
>> drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:480:2: note: in expansion of macro 'for_each_sgtable_sg'
480 |  for_each_sgtable_sg(*sgt, sg, i)
|  ^~~~~~~~~~~~~~~~~~~
include/linux/scatterlist.h:158:17: error: '*sgt' is a pointer; did you mean to use '->'?
158 |  for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
|                 ^~
include/linux/scatterlist.h:152:22: note: in definition of macro 'for_each_sg'
152 |  for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
|                      ^~~~~~
drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:484:2: note: in expansion of macro 'for_each_sgtable_sg'
484 |  for_each_sgtable_sg(*sgt, sg, i) {
|  ^~~~~~~~~~~~~~~~~~~
include/linux/scatterlist.h:158:31: error: '*sgt' is a pointer; did you mean to use '->'?
158 |  for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
|                               ^~
include/linux/scatterlist.h:152:38: note: in definition of macro 'for_each_sg'
152 |  for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
|                                      ^~
drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:484:2: note: in expansion of macro 'for_each_sgtable_sg'
484 |  for_each_sgtable_sg(*sgt, sg, i) {
|  ^~~~~~~~~~~~~~~~~~~
include/linux/scatterlist.h:158:17: error: '*sgt' is a pointer; did you mean to use '->'?
158 |  for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
|                 ^~
include/linux/scatterlist.h:152:22: note: in definition of macro 'for_each_sg'
152 |  for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
|                      ^~~~~~
drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:504:2: note: in expansion of macro 'for_each_sgtable_sg'
504 |  for_each_sgtable_sg(*sgt, sg, i) {
|  ^~~~~~~~~~~~~~~~~~~
include/linux/scatterlist.h:158:31: error: '*sgt' is a pointer; did you mean to use '->'?
158 |  for_each_sg(sgt->sgl, sg, sgt->orig_nents, i)
|                               ^~
include/linux/scatterlist.h:152:38: note: in definition of macro 'for_each_sg'
152 |  for (__i = 0, sg = (sglist); __i < (nr); __i++, sg = sg_next(sg))
|                                      ^~
drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:504:2: note: in expansion of macro 'for_each_sgtable_sg'
504 |  for_each_sgtable_sg(*sgt, sg, i) {
|  ^~~~~~~~~~~~~~~~~~~
In file included from drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:26:
At top level:
drivers/gpu/drm/amd/amdgpu/amdgpu.h:190:18: warning: 'sched_policy' defined but not used [-Wunused-const-variable=]
190 | static const int sched_policy = KFD_SCHED_POLICY_HWS;
|                  ^~~~~~~~~~~~
In file included from drivers/gpu/drm/amd/amdgpu/../display/dc/dc_types.h:33,
from drivers/gpu/drm/amd/amdgpu/../display/dc/dm_services_types.h:30,
from drivers/gpu/drm/amd/amdgpu/../include/dm_pp_interface.h:26,
from drivers/gpu/drm/amd/amdgpu/amdgpu.h:65,
from drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c:26:
drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h:76:32: warning: 'dc_fixpt_ln2_div_2' defined but not used [-Wunused-const-variable=]
76 | static const struct fixed31_32 dc_fixpt_ln2_div_2 = { 1488522236LL };
|                                ^~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h:75:32: warning: 'dc_fixpt_ln2' defined but not used [-Wunused-const-variable=]
75 | static const struct fixed31_32 dc_fixpt_ln2 = { 2977044471LL };
|                                ^~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h:74:32: warning: 'dc_fixpt_e' defined but not used [-Wunused-const-variable=]
74 | static const struct fixed31_32 dc_fixpt_e = { 11674931555LL };
|                                ^~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h:73:32: warning: 'dc_fixpt_two_pi' defined but not used [-Wunused-const-variable=]
73 | static const struct fixed31_32 dc_fixpt_two_pi = { 26986075409LL };
|                                ^~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h:72:32: warning: 'dc_fixpt_pi' defined but not used [-Wunused-const-variable=]
72 | static const struct fixed31_32 dc_fixpt_pi = { 13493037705LL };
|                                ^~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../display/include/fixed31_32.h:67:32: warning: 'dc_fixpt_zero' defined but not used [-Wunused-const-variable=]
67 | static const struct fixed31_32 dc_fixpt_zero = { 0 };
|                                ^~~~~~~~~~~~~

vim +/for_each_sgtable_sg +480 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c

   444	
   445	/**
   446	 * amdgpu_vram_mgr_alloc_sgt - allocate and fill a sg table
   447	 *
   448	 * @adev: amdgpu device pointer
   449	 * @mem: TTM memory object
   450	 * @dev: the other device
   451	 * @dir: dma direction
   452	 * @sgt: resulting sg table
   453	 *
   454	 * Allocate and fill a sg table from a VRAM allocation.
   455	 */
   456	int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
   457				      struct ttm_mem_reg *mem,
   458				      struct device *dev,
   459				      enum dma_data_direction dir,
   460				      struct sg_table **sgt)
   461	{
   462		struct drm_mm_node *node;
   463		struct scatterlist *sg;
   464		int num_entries = 0;
   465		unsigned int pages;
   466		int i, r;
   467	
   468		*sgt = kmalloc(sizeof(*sg), GFP_KERNEL);
   469		if (!*sgt)
   470			return -ENOMEM;
   471	
   472		for (pages = mem->num_pages, node = mem->mm_node;
   473		     pages; pages -= node->size, ++node)
   474			++num_entries;
   475	
   476		r = sg_alloc_table(*sgt, num_entries, GFP_KERNEL);
   477		if (r)
   478			goto error_free;
   479	
 > 480		for_each_sgtable_sg(*sgt, sg, i)
   481			sg->length = 0;
   482	
   483		node = mem->mm_node;
   484		for_each_sgtable_sg(*sgt, sg, i) {
   485			phys_addr_t phys = (node->start << PAGE_SHIFT) +
   486				adev->gmc.aper_base;
   487			size_t size = node->size << PAGE_SHIFT;
   488			dma_addr_t addr;
   489	
   490			++node;
   491			addr = dma_map_resource(dev, phys, size, dir,
   492						DMA_ATTR_SKIP_CPU_SYNC);
   493			r = dma_mapping_error(dev, addr);
   494			if (r)
   495				goto error_unmap;
   496	
   497			sg_set_page(sg, NULL, size, 0);
   498			sg_dma_address(sg) = addr;
   499			sg_dma_len(sg) = size;
   500		}
   501		return 0;
   502	
   503	error_unmap:
   504		for_each_sgtable_sg(*sgt, sg, i) {
   505			if (!sg->length)
   506				continue;
   507	
   508			dma_unmap_resource(dev, sg->dma_address,
   509					   sg->length, dir,
   510					   DMA_ATTR_SKIP_CPU_SYNC);
   511		}
   512		sg_free_table(*sgt);
   513	
   514	error_free:
   515		kfree(*sgt);
   516		return r;
   517	}
   518	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
index 43d8ed7dbd00..519ce4427fce 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
@@ -307,8 +307,8 @@  static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach,
 		if (IS_ERR(sgt))
 			return sgt;
 
-		if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
-				      DMA_ATTR_SKIP_CPU_SYNC))
+		if (dma_map_sgtable(attach->dev, sgt, dir,
+				    DMA_ATTR_SKIP_CPU_SYNC))
 			goto error_free;
 		break;
 
@@ -349,7 +349,7 @@  static void amdgpu_dma_buf_unmap(struct dma_buf_attachment *attach,
 	struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
 
 	if (sgt->sgl->page_link) {
-		dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+		dma_unmap_sgtable(attach->dev, sgt, dir, 0);
 		sg_free_table(sgt);
 		kfree(sgt);
 	} else {
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 5129a996e941..97fb73e5a6ae 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1025,7 +1025,6 @@  static int amdgpu_ttm_tt_pin_userptr(struct ttm_tt *ttm)
 {
 	struct amdgpu_device *adev = amdgpu_ttm_adev(ttm->bdev);
 	struct amdgpu_ttm_tt *gtt = (void *)ttm;
-	unsigned nents;
 	int r;
 
 	int write = !(gtt->userflags & AMDGPU_GEM_USERPTR_READONLY);
@@ -1040,9 +1039,8 @@  static int amdgpu_ttm_tt_pin_userptr(struct ttm_tt *ttm)
 		goto release_sg;
 
 	/* Map SG to device */
-	r = -ENOMEM;
-	nents = dma_map_sg(adev->dev, ttm->sg->sgl, ttm->sg->nents, direction);
-	if (nents == 0)
+	r = dma_map_sgtable(adev->dev, ttm->sg, direction, 0);
+	if (r)
 		goto release_sg;
 
 	/* convert SG to linear array of pages and dma addresses */
@@ -1073,8 +1071,7 @@  static void amdgpu_ttm_tt_unpin_userptr(struct ttm_tt *ttm)
 		return;
 
 	/* unmap the pages mapped to the device */
-	dma_unmap_sg(adev->dev, ttm->sg->sgl, ttm->sg->nents, direction);
-
+	dma_unmap_sgtable(adev->dev, ttm->sg, direction, 0);
 	sg_free_table(ttm->sg);
 
 #if IS_ENABLED(CONFIG_DRM_AMDGPU_USERPTR)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index d399e5893170..75495a7898b9 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -477,11 +477,11 @@  int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
 	if (r)
 		goto error_free;
 
-	for_each_sg((*sgt)->sgl, sg, num_entries, i)
+	for_each_sgtable_sg(*sgt, sg, i)
 		sg->length = 0;
 
 	node = mem->mm_node;
-	for_each_sg((*sgt)->sgl, sg, num_entries, i) {
+	for_each_sgtable_sg(*sgt, sg, i) {
 		phys_addr_t phys = (node->start << PAGE_SHIFT) +
 			adev->gmc.aper_base;
 		size_t size = node->size << PAGE_SHIFT;
@@ -501,7 +501,7 @@  int amdgpu_vram_mgr_alloc_sgt(struct amdgpu_device *adev,
 	return 0;
 
 error_unmap:
-	for_each_sg((*sgt)->sgl, sg, num_entries, i) {
+	for_each_sgtable_sg(*sgt, sg, i) {
 		if (!sg->length)
 			continue;
 
@@ -532,7 +532,7 @@  void amdgpu_vram_mgr_free_sgt(struct amdgpu_device *adev,
 	struct scatterlist *sg;
 	int i;
 
-	for_each_sg(sgt->sgl, sg, sgt->nents, i)
+	for_each_sgtable_sg(sgt, sg, i)
 		dma_unmap_resource(dev, sg->dma_address,
 				   sg->length, dir,
 				   DMA_ATTR_SKIP_CPU_SYNC);