[PATCH 0/4] Miscellaneous dma-buf patches

[PATCH 0/4] Miscellaneous dma-buf patches

[Laurent Pinchart]

Hi Sumit,

Here are 4 dma-buf patches that fix small issues.

Laurent Pinchart (4):
  dma-buf: Constify ops argument to dma_buf_export()
  dma-buf: Remove unneeded sanity checks
  dma-buf: Return error instead of using a goto statement when possible
  dma-buf: Move code out of mutex-protected section in dma_buf_attach()

 drivers/base/dma-buf.c  |   26 +++++++++++---------------
 include/linux/dma-buf.h |    8 ++++----
 2 files changed, 15 insertions(+), 19 deletions(-)

-- 
Regards,

Laurent Pinchart

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[PATCH 1/4] dma-buf: Constify ops argument to dma_buf_export()

[Laurent Pinchart]

This allows drivers to make the dma buf operations structure constant.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/base/dma-buf.c  |    2 +-
 include/linux/dma-buf.h |    8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index e38ad24..965833ac 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -71,7 +71,7 @@ static inline int is_dma_buf_file(struct file *file)
  * ops, or error in allocating struct dma_buf, will return negative error.
  *
  */
-struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
+struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
 				size_t size, int flags)
 {
 	struct dma_buf *dmabuf;
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index f8ac076..86f6241 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -114,8 +114,8 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 							struct device *dev);
 void dma_buf_detach(struct dma_buf *dmabuf,
 				struct dma_buf_attachment *dmabuf_attach);
-struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
-			size_t size, int flags);
+struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
+			       size_t size, int flags);
 int dma_buf_fd(struct dma_buf *dmabuf);
 struct dma_buf *dma_buf_get(int fd);
 void dma_buf_put(struct dma_buf *dmabuf);
@@ -138,8 +138,8 @@ static inline void dma_buf_detach(struct dma_buf *dmabuf,
 }
 
 static inline struct dma_buf *dma_buf_export(void *priv,
-						struct dma_buf_ops *ops,
-						size_t size, int flags)
+					     const struct dma_buf_ops *ops,
+					     size_t size, int flags)
 {
 	return ERR_PTR(-ENODEV);
 }
-- 
1.7.3.4

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[PATCH 2/4] dma-buf: Remove unneeded sanity checks

[Laurent Pinchart]

ops, ops->map_dma_buf and ops->unmap_dma_buf are guaranteed to be
non-NULL by a check in dma_buf_export(). Remove NULL checks on those
variables in the other API functions.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/base/dma-buf.c |   15 ++++++---------
 1 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 965833ac..198edd8 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -185,7 +185,7 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 	struct dma_buf_attachment *attach;
 	int ret;
 
-	if (WARN_ON(!dmabuf || !dev || !dmabuf->ops))
+	if (WARN_ON(!dmabuf || !dev))
 		return ERR_PTR(-EINVAL);
 
 	attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
@@ -224,7 +224,7 @@ EXPORT_SYMBOL_GPL(dma_buf_attach);
  */
 void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
 {
-	if (WARN_ON(!dmabuf || !attach || !dmabuf->ops))
+	if (WARN_ON(!dmabuf || !attach))
 		return;
 
 	mutex_lock(&dmabuf->lock);
@@ -255,12 +255,11 @@ struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
 
 	might_sleep();
 
-	if (WARN_ON(!attach || !attach->dmabuf || !attach->dmabuf->ops))
+	if (WARN_ON(!attach || !attach->dmabuf))
 		return ERR_PTR(-EINVAL);
 
 	mutex_lock(&attach->dmabuf->lock);
-	if (attach->dmabuf->ops->map_dma_buf)
-		sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
+	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
 	mutex_unlock(&attach->dmabuf->lock);
 
 	return sg_table;
@@ -278,13 +277,11 @@ EXPORT_SYMBOL_GPL(dma_buf_map_attachment);
 void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
 				struct sg_table *sg_table)
 {
-	if (WARN_ON(!attach || !attach->dmabuf || !sg_table
-			    || !attach->dmabuf->ops))
+	if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
 		return;
 
 	mutex_lock(&attach->dmabuf->lock);
-	if (attach->dmabuf->ops->unmap_dma_buf)
-		attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
+	attach->dmabuf->ops->unmap_dma_buf(attach, sg_table);
 	mutex_unlock(&attach->dmabuf->lock);
 
 }
-- 
1.7.3.4

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[PATCH 3/4] dma-buf: Return error instead of using a goto statement when possible

[Laurent Pinchart]

Remove an error label in dma_buf_attach() that just returns an error
code.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/base/dma-buf.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 198edd8..97450a5 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -190,7 +190,7 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 
 	attach = kzalloc(sizeof(struct dma_buf_attachment), GFP_KERNEL);
 	if (attach == NULL)
-		goto err_alloc;
+		return ERR_PTR(-ENOMEM);
 
 	mutex_lock(&dmabuf->lock);
 
@@ -206,8 +206,6 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 	mutex_unlock(&dmabuf->lock);
 	return attach;
 
-err_alloc:
-	return ERR_PTR(-ENOMEM);
 err_attach:
 	kfree(attach);
 	mutex_unlock(&dmabuf->lock);
-- 
1.7.3.4

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[PATCH 4/4] dma-buf: Move code out of mutex-protected section in dma_buf_attach()

[Laurent Pinchart]

Some fields can be set without mutex protection. Initialize them before
locking the mutex.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/base/dma-buf.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 97450a5..8afe2dd 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -192,10 +192,11 @@ struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 	if (attach == NULL)
 		return ERR_PTR(-ENOMEM);
 
-	mutex_lock(&dmabuf->lock);
-
 	attach->dev = dev;
 	attach->dmabuf = dmabuf;
+
+	mutex_lock(&dmabuf->lock);
+
 	if (dmabuf->ops->attach) {
 		ret = dmabuf->ops->attach(dmabuf, dev, attach);
 		if (ret)
-- 
1.7.3.4

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Re: [Linaro-mm-sig] [PATCH 1/4] dma-buf: Constify ops argument to dma_buf_export()

[Daniel Vetter]

On Thu, Jan 26, 2012 at 12:27:22PM +0100, Laurent Pinchart wrote:
> This allows drivers to make the dma buf operations structure constant.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Re: [Linaro-mm-sig] [PATCH 2/4] dma-buf: Remove unneeded sanity checks

[Daniel Vetter]

On Thu, Jan 26, 2012 at 12:27:23PM +0100, Laurent Pinchart wrote:
> ops, ops->map_dma_buf and ops->unmap_dma_buf are guaranteed to be
> non-NULL by a check in dma_buf_export(). Remove NULL checks on those
> variables in the other API functions.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
-- 
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Re: [Linaro-mm-sig] [PATCH 3/4] dma-buf: Return error instead of using a goto statement when possible

[Daniel Vetter]

On Thu, Jan 26, 2012 at 12:27:24PM +0100, Laurent Pinchart wrote:
> Remove an error label in dma_buf_attach() that just returns an error
> code.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
-- 
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Re: [Linaro-mm-sig] [PATCH 4/4] dma-buf: Move code out of mutex-protected section in dma_buf_attach()

[Daniel Vetter]

On Thu, Jan 26, 2012 at 12:27:25PM +0100, Laurent Pinchart wrote:
> Some fields can be set without mutex protection. Initialize them before
> locking the mutex.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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Re: [Linaro-mm-sig] [PATCH 4/4] dma-buf: Move code out of mutex-protected section in dma_buf_attach()

[Chris Wilson]

On Thu, 26 Jan 2012 12:27:25 +0100, Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote:
> Some fields can be set without mutex protection. Initialize them before
> locking the mutex.

struct mutex lock is described as

 /* mutex to serialize list manipulation and other ops */

maybe now is a good time to be a little more descriptive in what that
mutex is meant to protect and sprinkle enforcement throughout the code
as a means of documentation.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

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Re: [Linaro-mm-sig] [PATCH 4/4] dma-buf: Move code out of mutex-protected section in dma_buf_attach()

[Daniel Vetter]

On Thu, Jan 26, 2012 at 12:11:57PM +0000, Chris Wilson wrote:
> On Thu, 26 Jan 2012 12:27:25 +0100, Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote:
> > Some fields can be set without mutex protection. Initialize them before
> > locking the mutex.
> 
> struct mutex lock is described as
> 
>  /* mutex to serialize list manipulation and other ops */
> 
> maybe now is a good time to be a little more descriptive in what that
> mutex is meant to protect and sprinkle enforcement throughout the code
> as a means of documentation.

As, sore spot there. I think the current locking scheme is rather much
still in flux. I think we need to pull out callbacks to the exporter out
from the dma_buf mutex because otherwise we won't be able to avoid
deadlocks.

I think we'll need to wait for 1-2 exporters to show up in upstream until
we can clarify this. But it is very much on my list.
-Daniel
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Mobile: +41 (0)79 365 57 48

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Re: [PATCH 0/4] Miscellaneous dma-buf patches

[Sumit Semwal]

On 26 January 2012 16:57, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hi Sumit,
Hi Laurent,
>
> Here are 4 dma-buf patches that fix small issues.
Thanks; merged to 'dev' branch on
git://git.linaro.org/people/sumitsemwal/linux-3.x.git.
>
> Laurent Pinchart (4):
>  dma-buf: Constify ops argument to dma_buf_export()
>  dma-buf: Remove unneeded sanity checks
>  dma-buf: Return error instead of using a goto statement when possible
>  dma-buf: Move code out of mutex-protected section in dma_buf_attach()
>
>  drivers/base/dma-buf.c  |   26 +++++++++++---------------
>  include/linux/dma-buf.h |    8 ++++----
>  2 files changed, 15 insertions(+), 19 deletions(-)
>
> --
> Regards,
>
> Laurent Pinchart
Best regards,
~Sumit.

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Re: [PATCH 0/4] Miscellaneous dma-buf patches

[Laurent Pinchart]

Hi Sumit,

On Friday 27 January 2012 10:49:24 Sumit Semwal wrote:
> On 26 January 2012 16:57, Laurent Pinchart wrote:
> > Hi Sumit,
> 
> Hi Laurent,
> 
> > Here are 4 dma-buf patches that fix small issues.
> 
> Thanks; merged to 'dev' branch on
> git://git.linaro.org/people/sumitsemwal/linux-3.x.git.

Thank you. It would be even nicer if you could push them to mainline at some 
point :-)

> > Laurent Pinchart (4):
> >  dma-buf: Constify ops argument to dma_buf_export()
> >  dma-buf: Remove unneeded sanity checks
> >  dma-buf: Return error instead of using a goto statement when possible
> >  dma-buf: Move code out of mutex-protected section in dma_buf_attach()
> > 
> >  drivers/base/dma-buf.c  |   26 +++++++++++---------------
> >  include/linux/dma-buf.h |    8 ++++----
> >  2 files changed, 15 insertions(+), 19 deletions(-)

-- 
Regards,

Laurent Pinchart

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Re: [PATCH 0/4] Miscellaneous dma-buf patches

[Sumit Semwal]

On 21 March 2012 16:50, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hi Sumit,
>
> On Friday 27 January 2012 10:49:24 Sumit Semwal wrote:
>> On 26 January 2012 16:57, Laurent Pinchart wrote:
>> > Hi Sumit,
>>
>> Hi Laurent,
>>
>> > Here are 4 dma-buf patches that fix small issues.
>>
>> Thanks; merged to 'dev' branch on
>> git://git.linaro.org/people/sumitsemwal/linux-3.x.git.
>
> Thank you. It would be even nicer if you could push them to mainline at some
> point :-)
>
:) - Laurent, this set is already part of for-next, and will be part
of my pull request to Linus.

best regards,
~Sumit.
<snip>
>
> --
> Regards,
>
> Laurent Pinchart
>

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