[Linaro-mm-sig] Re: [PATCH 1/3] dma-buf: add flags to skip map_dma_buf() for some drivers

On 4/30/25 10:56, oushixiong1025@163.com wrote:

From: Shixiong Ou oushixiong@kylinos.cn

[WHY] Some Importer does not need to call dma_buf_map_attachment() to get the scatterlist info, especially those drivers of hardware that do not support DMA, such as the udl, the virtgpu and the ast.

[HOW] skip map_dma_buf() when dma_buf_dynamic_attach() for some drivers.

This patch is based on outdated code. Please see drm-misc-next where the mapping during attach was already dropped.

commit b72f66f22c0e39ae6684c43fead774c13db24e73 Author: Christian König christian.koenig@amd.com Date: Tue Feb 11 17:20:53 2025 +0100

dma-buf: drop caching of sg_tables

That was purely for the transition from static to dynamic dma-buf handling and can be removed again now.

Regards, Christian.

Signed-off-by: Shixiong Ou oushixiong@kylinos.cn

drivers/accel/ivpu/ivpu_gem.c | 2 +- drivers/accel/qaic/qaic_data.c | 2 +- drivers/dma-buf/dma-buf.c | 29 ++++++++++--------- drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 2 +- drivers/gpu/drm/armada/armada_gem.c | 2 +- drivers/gpu/drm/drm_prime.c | 2 +- drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 2 +- .../drm/i915/gem/selftests/i915_gem_dmabuf.c | 2 +- drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 2 +- drivers/gpu/drm/tegra/gem.c | 4 +-- drivers/gpu/drm/virtio/virtgpu_prime.c | 2 +- drivers/gpu/drm/xe/xe_dma_buf.c | 2 +- drivers/iio/industrialio-buffer.c | 2 +- drivers/infiniband/core/umem_dmabuf.c | 3 +- .../common/videobuf2/videobuf2-dma-contig.c | 2 +- .../media/common/videobuf2/videobuf2-dma-sg.c | 2 +- .../platform/nvidia/tegra-vde/dmabuf-cache.c | 2 +- drivers/misc/fastrpc.c | 2 +- drivers/usb/gadget/function/f_fs.c | 2 +- drivers/xen/gntdev-dmabuf.c | 2 +- include/linux/dma-buf.h | 5 ++-- net/core/devmem.c | 2 +- 22 files changed, 41 insertions(+), 36 deletions(-)

diff --git a/drivers/accel/ivpu/ivpu_gem.c b/drivers/accel/ivpu/ivpu_gem.c index 8741c73b92ce..5258a66ed945 100644 --- a/drivers/accel/ivpu/ivpu_gem.c +++ b/drivers/accel/ivpu/ivpu_gem.c @@ -183,7 +183,7 @@ struct drm_gem_object *ivpu_gem_prime_import(struct drm_device *dev, struct drm_gem_object *obj; int ret;

• attach = dma_buf_attach(dma_buf, attach_dev);

• attach = dma_buf_attach(dma_buf, attach_dev, false); if (IS_ERR(attach)) return ERR_CAST(attach);

diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c index 43aba57b48f0..c13c64d59143 100644 --- a/drivers/accel/qaic/qaic_data.c +++ b/drivers/accel/qaic/qaic_data.c @@ -803,7 +803,7 @@ struct drm_gem_object *qaic_gem_prime_import(struct drm_device *dev, struct dma_ obj = &bo->base; get_dma_buf(dma_buf);

• attach = dma_buf_attach(dma_buf, dev->dev);

• attach = dma_buf_attach(dma_buf, dev->dev, false); if (IS_ERR(attach)) { ret = PTR_ERR(attach); goto attach_fail;

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 5baa83b85515..dd7fe5fbf197 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -904,7 +904,7 @@ static struct sg_table *__map_dma_buf(struct dma_buf_attachment *attach, struct dma_buf_attachment * dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, const struct dma_buf_attach_ops *importer_ops,

•        void *importer_priv)
  

•        void *importer_priv, bool skip_map)
  

{ struct dma_buf_attachment *attach; int ret; @@ -941,8 +941,6 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, */ if (dma_buf_attachment_is_dynamic(attach) != dma_buf_is_dynamic(dmabuf)) {

• struct sg_table *sgt;
  

• dma_resv_lock(attach->dmabuf->resv, NULL); if (dma_buf_is_dynamic(attach->dmabuf)) { ret = dmabuf->ops->pin(attach);

@@ -950,16 +948,20 @@ dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, goto err_unlock; }

• sgt = __map_dma_buf(attach, DMA_BIDIRECTIONAL);
  

• if (!sgt)
  

• 	sgt = ERR_PTR(-ENOMEM);
  

• if (IS_ERR(sgt)) {
  

• 	ret = PTR_ERR(sgt);
  

• 	goto err_unpin;
  

• if (!skip_map) {
  

• 	struct sg_table *sgt;
  

• 	sgt = __map_dma_buf(attach, DMA_BIDIRECTIONAL);
  

• 	if (!sgt)
  

• 		sgt = ERR_PTR(-ENOMEM);
  

• 	if (IS_ERR(sgt)) {
  

• 		ret = PTR_ERR(sgt);
  

• 		goto err_unpin;
  

• 	}
  

• 	attach->sgt = sgt;
  

• 	attach->dir = DMA_BIDIRECTIONAL;
  

  } dma_resv_unlock(attach->dmabuf->resv);

• attach->sgt = sgt;
  

• attach->dir = DMA_BIDIRECTIONAL;
  

  }

return attach; @@ -989,9 +991,10 @@ EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, "DMA_BUF");

• mapping.

*/ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,

• 			  struct device *dev)
  

• 			  struct device *dev,
  

• 			  bool skip_map)
  

{

• return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);

• return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL, skip_map);

} EXPORT_SYMBOL_NS_GPL(dma_buf_attach, "DMA_BUF"); diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c index e6913fcf2c7b..26c94834e6d2 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c @@ -479,7 +479,7 @@ struct drm_gem_object *amdgpu_gem_prime_import(struct drm_device *dev, return obj; attach = dma_buf_dynamic_attach(dma_buf, dev->dev,

• 			&amdgpu_dma_buf_attach_ops, obj);
  

• 			&amdgpu_dma_buf_attach_ops, obj, false);
  

  if (IS_ERR(attach)) { drm_gem_object_put(obj); return ERR_CAST(attach);

diff --git a/drivers/gpu/drm/armada/armada_gem.c b/drivers/gpu/drm/armada/armada_gem.c index 1a1680d71486..7e1a82828b87 100644 --- a/drivers/gpu/drm/armada/armada_gem.c +++ b/drivers/gpu/drm/armada/armada_gem.c @@ -514,7 +514,7 @@ armada_gem_prime_import(struct drm_device *dev, struct dma_buf *buf) } }

• attach = dma_buf_attach(buf, dev->dev);

• attach = dma_buf_attach(buf, dev->dev, false); if (IS_ERR(attach)) return ERR_CAST(attach);

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c index bdb51c8f262e..8e70abca33b9 100644 --- a/drivers/gpu/drm/drm_prime.c +++ b/drivers/gpu/drm/drm_prime.c @@ -949,7 +949,7 @@ struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev, if (!dev->driver->gem_prime_import_sg_table) return ERR_PTR(-EINVAL);

• attach = dma_buf_attach(dma_buf, attach_dev);

• attach = dma_buf_attach(dma_buf, attach_dev, false); if (IS_ERR(attach)) return ERR_CAST(attach);

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c index 9473050ac842..6015f6beb8e6 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c @@ -305,7 +305,7 @@ struct drm_gem_object *i915_gem_prime_import(struct drm_device *dev, return ERR_PTR(-E2BIG); /* need to attach */

• attach = dma_buf_attach(dma_buf, dev->dev);

• attach = dma_buf_attach(dma_buf, dev->dev, false); if (IS_ERR(attach)) return ERR_CAST(attach);

diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c index 2fda549dd82d..1992241fdf54 100644 --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c @@ -287,7 +287,7 @@ static int igt_dmabuf_import_same_driver(struct drm_i915_private *i915, goto out_import; /* Now try a fake an importer */

• import_attach = dma_buf_attach(dmabuf, obj->base.dev->dev);

• import_attach = dma_buf_attach(dmabuf, obj->base.dev->dev, false); if (IS_ERR(import_attach)) { err = PTR_ERR(import_attach); goto out_import;

diff --git a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c index 30cf1cdc1aa3..41fb4149409e 100644 --- a/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c +++ b/drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c @@ -114,7 +114,7 @@ struct drm_gem_object *omap_gem_prime_import(struct drm_device *dev, } }

• attach = dma_buf_attach(dma_buf, dev->dev);

• attach = dma_buf_attach(dma_buf, dev->dev, false); if (IS_ERR(attach)) return ERR_CAST(attach);

diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c index ace3e5a805cf..e5527c9d10bb 100644 --- a/drivers/gpu/drm/tegra/gem.c +++ b/drivers/gpu/drm/tegra/gem.c @@ -79,7 +79,7 @@ static struct host1x_bo_mapping *tegra_bo_pin(struct device *dev, struct host1x_ if (obj->dma_buf) { struct dma_buf *buf = obj->dma_buf;

• map->attach = dma_buf_attach(buf, dev);
  

• map->attach = dma_buf_attach(buf, dev, false);
  

  if (IS_ERR(map->attach)) { err = PTR_ERR(map->attach); goto free;

@@ -470,7 +470,7 @@ static struct tegra_bo *tegra_bo_import(struct drm_device *drm, * domain, map it first to the DRM device to get an sgt. */ if (tegra->domain) {

• attach = dma_buf_attach(buf, drm->dev);
  

• attach = dma_buf_attach(buf, drm->dev, false);
  

  if (IS_ERR(attach)) { err = PTR_ERR(attach); goto free;

diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c b/drivers/gpu/drm/virtio/virtgpu_prime.c index 4de2a63ccd18..6d9d1fe342b6 100644 --- a/drivers/gpu/drm/virtio/virtgpu_prime.c +++ b/drivers/gpu/drm/virtio/virtgpu_prime.c @@ -326,7 +326,7 @@ struct drm_gem_object *virtgpu_gem_prime_import(struct drm_device *dev, drm_gem_private_object_init(dev, obj, buf->size); attach = dma_buf_dynamic_attach(buf, dev->dev,

• 			&virtgpu_dma_buf_attach_ops, obj);
  

• 			&virtgpu_dma_buf_attach_ops, obj, true);
  

  if (IS_ERR(attach)) { kfree(bo); return ERR_CAST(attach);

diff --git a/drivers/gpu/drm/xe/xe_dma_buf.c b/drivers/gpu/drm/xe/xe_dma_buf.c index f7a20264ea33..9f524b9ed425 100644 --- a/drivers/gpu/drm/xe/xe_dma_buf.c +++ b/drivers/gpu/drm/xe/xe_dma_buf.c @@ -293,7 +293,7 @@ struct drm_gem_object *xe_gem_prime_import(struct drm_device *dev, attach_ops = test->attach_ops; #endif

• attach = dma_buf_dynamic_attach(dma_buf, dev->dev, attach_ops, &bo->ttm.base);

• attach = dma_buf_dynamic_attach(dma_buf, dev->dev, attach_ops, &bo->ttm.base, false); if (IS_ERR(attach)) { obj = ERR_CAST(attach); goto out_err;

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c index a80f7cc25a27..1296af4c2f7a 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -1679,7 +1679,7 @@ static int iio_buffer_attach_dmabuf(struct iio_dev_buffer_pair *ib, goto err_free_priv; }

• attach = dma_buf_attach(dmabuf, indio_dev->dev.parent);

• attach = dma_buf_attach(dmabuf, indio_dev->dev.parent, false); if (IS_ERR(attach)) { err = PTR_ERR(attach); goto err_dmabuf_put;

diff --git a/drivers/infiniband/core/umem_dmabuf.c b/drivers/infiniband/core/umem_dmabuf.c index 0ec2e4120cc9..ed635c407cbd 100644 --- a/drivers/infiniband/core/umem_dmabuf.c +++ b/drivers/infiniband/core/umem_dmabuf.c @@ -159,7 +159,8 @@ ib_umem_dmabuf_get_with_dma_device(struct ib_device *device, dmabuf, dma_device, ops,

• 			umem_dmabuf);
  

• 			umem_dmabuf,
  

• 			false);
  

  if (IS_ERR(umem_dmabuf->attach)) { ret = ERR_CAST(umem_dmabuf->attach); goto out_free_umem;

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c index a13ec569c82f..362f5b555ce2 100644 --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c @@ -786,7 +786,7 @@ static void *vb2_dc_attach_dmabuf(struct vb2_buffer *vb, struct device *dev, buf->vb = vb; /* create attachment for the dmabuf with the user device */

• dba = dma_buf_attach(dbuf, buf->dev);

• dba = dma_buf_attach(dbuf, buf->dev, false); if (IS_ERR(dba)) { pr_err("failed to attach dmabuf\n"); kfree(buf);

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c index c6ddf2357c58..4f9a4e9783a1 100644 --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c @@ -632,7 +632,7 @@ static void *vb2_dma_sg_attach_dmabuf(struct vb2_buffer *vb, struct device *dev, buf->dev = dev; /* create attachment for the dmabuf with the user device */

• dba = dma_buf_attach(dbuf, buf->dev);

• dba = dma_buf_attach(dbuf, buf->dev, false); if (IS_ERR(dba)) { pr_err("failed to attach dmabuf\n"); kfree(buf);

diff --git a/drivers/media/platform/nvidia/tegra-vde/dmabuf-cache.c b/drivers/media/platform/nvidia/tegra-vde/dmabuf-cache.c index b34244ea14dd..d04da2d3e4da 100644 --- a/drivers/media/platform/nvidia/tegra-vde/dmabuf-cache.c +++ b/drivers/media/platform/nvidia/tegra-vde/dmabuf-cache.c @@ -95,7 +95,7 @@ int tegra_vde_dmabuf_cache_map(struct tegra_vde *vde, goto ref; }

• attachment = dma_buf_attach(dmabuf, dev);

• attachment = dma_buf_attach(dmabuf, dev, false); if (IS_ERR(attachment)) { dev_err(dev, "Failed to attach dmabuf\n"); err = PTR_ERR(attachment);

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 7b7a22c91fe4..aee6f4cbd6c6 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -778,7 +778,7 @@ static int fastrpc_map_create(struct fastrpc_user *fl, int fd, goto get_err; }

• map->attach = dma_buf_attach(map->buf, sess->dev);

• map->attach = dma_buf_attach(map->buf, sess->dev, false); if (IS_ERR(map->attach)) { dev_err(sess->dev, "Failed to attach dmabuf\n"); err = PTR_ERR(map->attach);

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 2dea9e42a0f8..51926ffdb843 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -1487,7 +1487,7 @@ static int ffs_dmabuf_attach(struct file *file, int fd) if (IS_ERR(dmabuf)) return PTR_ERR(dmabuf);

• attach = dma_buf_attach(dmabuf, gadget->dev.parent);

• attach = dma_buf_attach(dmabuf, gadget->dev.parent, false); if (IS_ERR(attach)) { err = PTR_ERR(attach); goto err_dmabuf_put;

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c index 5453d86324f6..9de191b6d1f7 100644 --- a/drivers/xen/gntdev-dmabuf.c +++ b/drivers/xen/gntdev-dmabuf.c @@ -587,7 +587,7 @@ dmabuf_imp_to_refs(struct gntdev_dmabuf_priv *priv, struct device *dev, gntdev_dmabuf->priv = priv; gntdev_dmabuf->fd = fd;

• attach = dma_buf_attach(dma_buf, dev);

• attach = dma_buf_attach(dma_buf, dev, false); if (IS_ERR(attach)) { ret = ERR_CAST(attach); goto fail_free_obj;

diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index 36216d28d8bd..1ea25089b3ba 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -598,11 +598,12 @@ dma_buf_attachment_is_dynamic(struct dma_buf_attachment *attach) } struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,

• 			  struct device *dev);
  

• 			  struct device *dev,
  

• 			  bool skip_map);
  

struct dma_buf_attachment * dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev, const struct dma_buf_attach_ops *importer_ops,

•        void *importer_priv);
  

•        void *importer_priv, bool skip_map);
  

void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach); int dma_buf_pin(struct dma_buf_attachment *attach); diff --git a/net/core/devmem.c b/net/core/devmem.c index 6e27a47d0493..8137ecff9e39 100644 --- a/net/core/devmem.c +++ b/net/core/devmem.c @@ -202,7 +202,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, unsigned int dmabuf_fd, binding->dmabuf = dmabuf;

• binding->attachment = dma_buf_attach(binding->dmabuf, dev->dev.parent);

• binding->attachment = dma_buf_attach(binding->dmabuf, dev->dev.parent, false); if (IS_ERR(binding->attachment)) { err = PTR_ERR(binding->attachment); NL_SET_ERR_MSG(extack, "Failed to bind dmabuf to device");