[PATCH] dma-buf: add reference counting for exporter module
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Wed Aug 8 06:35:47 PDT 2012
Hi Tomasz,
Thanks for the patch.
On Wednesday 08 August 2012 12:17:41 Tomasz Stanislawski wrote:
> This patch adds reference counting on a module that exports dma-buf and
> implements its operations. This prevents the module from being unloaded
> while DMABUF file is in use.
>
> Signed-off-by: Tomasz Stanislawski <t.stanislaws at samsung.com>
> ---
> Documentation/dma-buf-sharing.txt | 3 ++-
> drivers/base/dma-buf.c | 10 +++++++++-
> drivers/gpu/drm/exynos/exynos_drm_dmabuf.c | 1 +
> drivers/gpu/drm/i915/i915_gem_dmabuf.c | 1 +
> drivers/gpu/drm/nouveau/nouveau_prime.c | 1 +
> drivers/gpu/drm/radeon/radeon_prime.c | 1 +
> drivers/staging/omapdrm/omap_gem_dmabuf.c | 1 +
> include/linux/dma-buf.h | 2 ++
> 8 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/dma-buf-sharing.txt
> b/Documentation/dma-buf-sharing.txt index ad86fb8..2613057 100644
> --- a/Documentation/dma-buf-sharing.txt
> +++ b/Documentation/dma-buf-sharing.txt
> @@ -49,7 +49,8 @@ The dma_buf buffer sharing API usage contains the
> following steps: The buffer exporter announces its wish to export a buffer.
> In this, it connects its own private buffer data, provides implementation
> for operations that can be performed on the exported dma_buf, and flags for
> the file
> - associated with this buffer.
> + associated with this buffer. The operations structure has owner field.
> + You should initialize this to THIS_MODULE in most cases.
>
> Interface:
> struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
> index c30f3e1..d14b2f5 100644
> --- a/drivers/base/dma-buf.c
> +++ b/drivers/base/dma-buf.c
> @@ -27,6 +27,7 @@
> #include <linux/dma-buf.h>
> #include <linux/anon_inodes.h>
> #include <linux/export.h>
> +#include <linux/module.h>
>
> static inline int is_dma_buf_file(struct file *);
>
> @@ -40,6 +41,7 @@ static int dma_buf_release(struct inode *inode, struct
> file *file) dmabuf = file->private_data;
>
> dmabuf->ops->release(dmabuf);
> + module_put(dmabuf->ops->owner);
> kfree(dmabuf);
> return 0;
> }
> @@ -96,6 +98,7 @@ struct dma_buf *dma_buf_export(void *priv, const struct
> dma_buf_ops *ops, struct file *file;
>
> if (WARN_ON(!priv || !ops
> + || !ops->owner
THIS_MODULE is defined as ((struct module *)0) when the driver is built-in,
this check should thus be removed.
> || !ops->map_dma_buf
> || !ops->unmap_dma_buf
> || !ops->release
>
> @@ -105,9 +108,14 @@ struct dma_buf *dma_buf_export(void *priv, const struct
> dma_buf_ops *ops, return ERR_PTR(-EINVAL);
> }
>
> + if (!try_module_get(ops->owner))
> + return ERR_PTR(-ENOENT);
> +
> dmabuf = kzalloc(sizeof(struct dma_buf), GFP_KERNEL);
> - if (dmabuf == NULL)
> + if (dmabuf == NULL) {
> + module_put(ops->owner);
> return ERR_PTR(-ENOMEM);
> + }
>
> dmabuf->priv = priv;
> dmabuf->ops = ops;
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c index 613bf8a..cf3bc6d 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_dmabuf.c
> @@ -164,6 +164,7 @@ static void exynos_gem_dmabuf_kunmap(struct dma_buf
> *dma_buf, }
>
> static struct dma_buf_ops exynos_dmabuf_ops = {
> + .owner = THIS_MODULE,
> .map_dma_buf = exynos_gem_map_dma_buf,
> .unmap_dma_buf = exynos_gem_unmap_dma_buf,
> .kmap = exynos_gem_dmabuf_kmap,
> diff --git a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> b/drivers/gpu/drm/i915/i915_gem_dmabuf.c index aa308e1..07ff03b 100644
> --- a/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> +++ b/drivers/gpu/drm/i915/i915_gem_dmabuf.c
> @@ -152,6 +152,7 @@ static int i915_gem_dmabuf_mmap(struct dma_buf *dma_buf,
> struct vm_area_struct * }
>
> static const struct dma_buf_ops i915_dmabuf_ops = {
> + .owner = THIS_MODULE,
> .map_dma_buf = i915_gem_map_dma_buf,
> .unmap_dma_buf = i915_gem_unmap_dma_buf,
> .release = i915_gem_dmabuf_release,
> diff --git a/drivers/gpu/drm/nouveau/nouveau_prime.c
> b/drivers/gpu/drm/nouveau/nouveau_prime.c index a25cf2c..8605033 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_prime.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_prime.c
> @@ -127,6 +127,7 @@ static void nouveau_gem_prime_vunmap(struct dma_buf
> *dma_buf, void *vaddr) }
>
> static const struct dma_buf_ops nouveau_dmabuf_ops = {
> + .owner = THIS_MODULE,
> .map_dma_buf = nouveau_gem_map_dma_buf,
> .unmap_dma_buf = nouveau_gem_unmap_dma_buf,
> .release = nouveau_gem_dmabuf_release,
> diff --git a/drivers/gpu/drm/radeon/radeon_prime.c
> b/drivers/gpu/drm/radeon/radeon_prime.c index 6bef46a..4061fd3 100644
> --- a/drivers/gpu/drm/radeon/radeon_prime.c
> +++ b/drivers/gpu/drm/radeon/radeon_prime.c
> @@ -127,6 +127,7 @@ static void radeon_gem_prime_vunmap(struct dma_buf
> *dma_buf, void *vaddr) mutex_unlock(&dev->struct_mutex);
> }
> const static struct dma_buf_ops radeon_dmabuf_ops = {
> + .owner = THIS_MODULE,
> .map_dma_buf = radeon_gem_map_dma_buf,
> .unmap_dma_buf = radeon_gem_unmap_dma_buf,
> .release = radeon_gem_dmabuf_release,
> diff --git a/drivers/staging/omapdrm/omap_gem_dmabuf.c
> b/drivers/staging/omapdrm/omap_gem_dmabuf.c index 42728e0..6a4dd67 100644
> --- a/drivers/staging/omapdrm/omap_gem_dmabuf.c
> +++ b/drivers/staging/omapdrm/omap_gem_dmabuf.c
> @@ -179,6 +179,7 @@ out_unlock:
> }
>
> struct dma_buf_ops omap_dmabuf_ops = {
> + .owner = THIS_MODULE,
> .map_dma_buf = omap_gem_map_dma_buf,
> .unmap_dma_buf = omap_gem_unmap_dma_buf,
> .release = omap_gem_dmabuf_release,
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index eb48f38..22953de 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -37,6 +37,7 @@ struct dma_buf_attachment;
>
> /**
> * struct dma_buf_ops - operations possible on struct dma_buf
> + * @owner: the module that implements dma_buf operations
> * @attach: [optional] allows different devices to 'attach' themselves to
> the * given buffer. It might return -EBUSY to signal that backing
> storage * is already allocated and incompatible with the requirements
> @@ -70,6 +71,7 @@ struct dma_buf_attachment;
> * @vunmap: [optional] unmaps a vmap from the buffer
> */
> struct dma_buf_ops {
> + struct module *owner;
> int (*attach)(struct dma_buf *, struct device *,
> struct dma_buf_attachment *);
--
Regards,
Laurent Pinchart
More information about the dri-devel
mailing list