diff mbox

dma-buf: add reference counting for exporter module

Message ID 50223CC5.9060007@samsung.com
State New
Headers show

Commit Message

Tomasz Stanislawski Aug. 8, 2012, 10:17 a.m. UTC
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@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(-)

Comments

Laurent Pinchart Aug. 8, 2012, 1:35 p.m. UTC | #1
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@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 *);
Tomasz Stanislawski Aug. 8, 2012, 1:53 p.m. UTC | #2
Hi Laurent,

On 08/08/2012 03:35 PM, Laurent Pinchart wrote:
> 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@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(-)
>>
[snip]

>> @@ -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

Thank you for spotting this.
I didn'y know that try_get_module returned true is module was NULL.

BTW. Is it worth to add ".owner = THIS_MODULE," to all dma_buf
exporters in this patch?

Regards,
Tomasz Stanislawski

> 
> 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
>>
Daniel Vetter Aug. 8, 2012, 2:06 p.m. UTC | #3
On Wed, Aug 08, 2012 at 03:53:10PM +0200, Tomasz Stanislawski wrote:
> Hi Laurent,
> 
> On 08/08/2012 03:35 PM, Laurent Pinchart wrote:
> > 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@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(-)
> >>
> [snip]
> 
> >> @@ -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
> 
> Thank you for spotting this.
> I didn'y know that try_get_module returned true is module was NULL.
> 
> BTW. Is it worth to add ".owner = THIS_MODULE," to all dma_buf
> exporters in this patch?

Yeah, I think that makes sense. Otherwise it might get lost somewhere,
i.e. you can smash my Ack on this.
-Daniel
Sumit Semwal Aug. 9, 2012, 5:32 a.m. UTC | #4
Hi Tomasz,

On 8 August 2012 19:36, Daniel Vetter <daniel@ffwll.ch> wrote:
> On Wed, Aug 08, 2012 at 03:53:10PM +0200, Tomasz Stanislawski wrote:
>> Hi Laurent,
>>
>> On 08/08/2012 03:35 PM, Laurent Pinchart wrote:
>> > Hi Tomasz,
>> >
>> > Thanks for the patch.
Thanks for the patch; may I ask you to split it into 2 patches (1
dma-buf and 1 drm) and submit? That ways, either Dave or I can take
the patches for either pull request.
With that, please feel free to add my Acked-by as well.
>> >
>> > 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@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(-)
>> >>
>> [snip]
>>
>> >> @@ -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
>>
>> Thank you for spotting this.
>> I didn'y know that try_get_module returned true is module was NULL.
>>
>> BTW. Is it worth to add ".owner = THIS_MODULE," to all dma_buf
>> exporters in this patch?
>
> Yeah, I think that makes sense. Otherwise it might get lost somewhere,
> i.e. you can smash my Ack on this.
> -Daniel
> --
> Daniel Vetter
> Mail: daniel@ffwll.ch
> Mobile: +41 (0)79 365 57 48
diff mbox

Patch

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
 			  || !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 *);