[PATCH v2 0/2] dma-buf: Add support for debugfs

[PATCH v2 0/2] dma-buf: Add support for debugfs

[Sumit Semwal]

The patch series adds a much-missed support for debugfs to dma-buf framework.

Based on the feedback received on v1 of this patch series, support is also
added to allow exporters to provide name-strings that will prove useful
while debugging.

Some more magic can be added for more advanced debugging, but we'll leave that
for the time being.

Best regards,
~Sumit.


Sumit Semwal (2):
  dma-buf: replace dma_buf_export() with dma_buf_export_named()
  dma-buf: Add debugfs support

 Documentation/dma-buf-sharing.txt |   13 ++-
 drivers/base/dma-buf.c            |  173 ++++++++++++++++++++++++++++++++++++-
 include/linux/dma-buf.h           |   16 +++-
 3 files changed, 193 insertions(+), 9 deletions(-)

-- 
1.7.10.4

[PATCH 1/2] dma-buf: replace dma_buf_export() with dma_buf_export_named()

[Sumit Semwal]

For debugging purposes, it is useful to have a name-string added
while exporting buffers. Hence, dma_buf_export() is replaced with
dma_buf_export_named(), which additionally takes 'exp_name' as a
parameter.

For backward compatibility, and for lazy exporters who don't wish to
name themselves, a #define dma_buf_export() is also made available,
which adds a __FILE__ instead of 'exp_name'.

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
  [Thanks for the idea!]
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
---
 Documentation/dma-buf-sharing.txt |   13 +++++++++++--
 drivers/base/dma-buf.c            |   11 +++++++----
 include/linux/dma-buf.h           |   11 +++++++++--
 3 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/Documentation/dma-buf-sharing.txt b/Documentation/dma-buf-sharing.txt
index 4966b1b..0b23261 100644
--- a/Documentation/dma-buf-sharing.txt
+++ b/Documentation/dma-buf-sharing.txt
@@ -52,14 +52,23 @@ The dma_buf buffer sharing API usage contains the following steps:
    associated with this buffer.
 
    Interface:
-      struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
-				     size_t size, int flags)
+      struct dma_buf *dma_buf_export_named(void *priv, struct dma_buf_ops *ops,
+				     size_t size, int flags,
+				     const char *exp_name)
 
    If this succeeds, dma_buf_export allocates a dma_buf structure, and returns a
    pointer to the same. It also associates an anonymous file with this buffer,
    so it can be exported. On failure to allocate the dma_buf object, it returns
    NULL.
 
+   'exp_name' is the name of exporter - to facilitate information while
+   debugging.
+
+   Exporting modules which do not wish to provide any specific name may use the
+   helper define 'dma_buf_export()', with the same arguments as above, but
+   without the last argument; a __FILE__ pre-processor directive will be
+   inserted in place of 'exp_name' instead.
+
 2. Userspace gets a handle to pass around to potential buffer-users
 
    Userspace entity requests for a file-descriptor (fd) which is a handle to the
diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index 2a7cb0d..d89102a 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -77,22 +77,24 @@ static inline int is_dma_buf_file(struct file *file)
 }
 
 /**
- * dma_buf_export - Creates a new dma_buf, and associates an anon file
+ * dma_buf_export_named - Creates a new dma_buf, and associates an anon file
  * with this buffer, so it can be exported.
  * Also connect the allocator specific data and ops to the buffer.
+ * Additionally, provide a name string for exporter; useful in debugging.
  *
  * @priv:	[in]	Attach private data of allocator to this buffer
  * @ops:	[in]	Attach allocator-defined dma buf ops to the new buffer.
  * @size:	[in]	Size of the buffer
  * @flags:	[in]	mode flags for the file.
+ * @exp_name:	[in]	name of the exporting module - useful for debugging.
  *
  * Returns, on success, a newly created dma_buf object, which wraps the
  * supplied private data and operations for dma_buf_ops. On either missing
  * ops, or error in allocating struct dma_buf, will return negative error.
  *
  */
-struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
-				size_t size, int flags)
+struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
+				size_t size, int flags, const char *exp_name)
 {
 	struct dma_buf *dmabuf;
 	struct file *file;
@@ -114,6 +116,7 @@ struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
 	dmabuf->priv = priv;
 	dmabuf->ops = ops;
 	dmabuf->size = size;
+	dmabuf->exp_name = exp_name;
 
 	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
 
@@ -124,7 +127,7 @@ struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
 
 	return dmabuf;
 }
-EXPORT_SYMBOL_GPL(dma_buf_export);
+EXPORT_SYMBOL_GPL(dma_buf_export_named);
 
 
 /**
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 9978b61..6f55c04 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -112,6 +112,7 @@ struct dma_buf_ops {
  * @file: file pointer used for sharing buffers across, and for refcounting.
  * @attachments: list of dma_buf_attachment that denotes all devices attached.
  * @ops: dma_buf_ops associated with this buffer object.
+ * @exp_name: name of the exporter; useful for debugging.
  * @priv: exporter specific private data for this buffer object.
  */
 struct dma_buf {
@@ -123,6 +124,7 @@ struct dma_buf {
 	struct mutex lock;
 	unsigned vmapping_counter;
 	void *vmap_ptr;
+	const char *exp_name;
 	void *priv;
 };
 
@@ -162,8 +164,13 @@ 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, const struct dma_buf_ops *ops,
-			       size_t size, int flags);
+
+struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
+			       size_t size, int flags, const char *);
+
+#define dma_buf_export(priv, ops, size, flags)	\
+	dma_buf_export_named(priv, ops, size, flags, __FILE__)
+
 int dma_buf_fd(struct dma_buf *dmabuf, int flags);
 struct dma_buf *dma_buf_get(int fd);
 void dma_buf_put(struct dma_buf *dmabuf);
-- 
1.7.10.4

Re: [PATCH 1/2] dma-buf: replace dma_buf_export() with dma_buf_export_named()

[Daniel Vetter]

On Mon, Mar 25, 2013 at 04:50:45PM +0530, Sumit Semwal wrote:
> For debugging purposes, it is useful to have a name-string added
> while exporting buffers. Hence, dma_buf_export() is replaced with
> dma_buf_export_named(), which additionally takes 'exp_name' as a
> parameter.
> 
> For backward compatibility, and for lazy exporters who don't wish to
> name themselves, a #define dma_buf_export() is also made available,
> which adds a __FILE__ instead of 'exp_name'.
> 
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>   [Thanks for the idea!]
> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  Documentation/dma-buf-sharing.txt |   13 +++++++++++--
>  drivers/base/dma-buf.c            |   11 +++++++----
>  include/linux/dma-buf.h           |   11 +++++++++--
>  3 files changed, 27 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/dma-buf-sharing.txt b/Documentation/dma-buf-sharing.txt
> index 4966b1b..0b23261 100644
> --- a/Documentation/dma-buf-sharing.txt
> +++ b/Documentation/dma-buf-sharing.txt
> @@ -52,14 +52,23 @@ The dma_buf buffer sharing API usage contains the following steps:
>     associated with this buffer.
>  
>     Interface:
> -      struct dma_buf *dma_buf_export(void *priv, struct dma_buf_ops *ops,
> -				     size_t size, int flags)
> +      struct dma_buf *dma_buf_export_named(void *priv, struct dma_buf_ops *ops,
> +				     size_t size, int flags,
> +				     const char *exp_name)
>  
>     If this succeeds, dma_buf_export allocates a dma_buf structure, and returns a
>     pointer to the same. It also associates an anonymous file with this buffer,
>     so it can be exported. On failure to allocate the dma_buf object, it returns
>     NULL.
>  
> +   'exp_name' is the name of exporter - to facilitate information while
> +   debugging.
> +
> +   Exporting modules which do not wish to provide any specific name may use the
> +   helper define 'dma_buf_export()', with the same arguments as above, but
> +   without the last argument; a __FILE__ pre-processor directive will be
> +   inserted in place of 'exp_name' instead.
> +
>  2. Userspace gets a handle to pass around to potential buffer-users
>  
>     Userspace entity requests for a file-descriptor (fd) which is a handle to the
> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
> index 2a7cb0d..d89102a 100644
> --- a/drivers/base/dma-buf.c
> +++ b/drivers/base/dma-buf.c
> @@ -77,22 +77,24 @@ static inline int is_dma_buf_file(struct file *file)
>  }
>  
>  /**
> - * dma_buf_export - Creates a new dma_buf, and associates an anon file
> + * dma_buf_export_named - Creates a new dma_buf, and associates an anon file
>   * with this buffer, so it can be exported.
>   * Also connect the allocator specific data and ops to the buffer.
> + * Additionally, provide a name string for exporter; useful in debugging.
>   *
>   * @priv:	[in]	Attach private data of allocator to this buffer
>   * @ops:	[in]	Attach allocator-defined dma buf ops to the new buffer.
>   * @size:	[in]	Size of the buffer
>   * @flags:	[in]	mode flags for the file.
> + * @exp_name:	[in]	name of the exporting module - useful for debugging.
>   *
>   * Returns, on success, a newly created dma_buf object, which wraps the
>   * supplied private data and operations for dma_buf_ops. On either missing
>   * ops, or error in allocating struct dma_buf, will return negative error.
>   *
>   */
> -struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
> -				size_t size, int flags)
> +struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
> +				size_t size, int flags, const char *exp_name)
>  {
>  	struct dma_buf *dmabuf;
>  	struct file *file;
> @@ -114,6 +116,7 @@ struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
>  	dmabuf->priv = priv;
>  	dmabuf->ops = ops;
>  	dmabuf->size = size;
> +	dmabuf->exp_name = exp_name;
>  
>  	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf, flags);
>  
> @@ -124,7 +127,7 @@ struct dma_buf *dma_buf_export(void *priv, const struct dma_buf_ops *ops,
>  
>  	return dmabuf;
>  }
> -EXPORT_SYMBOL_GPL(dma_buf_export);
> +EXPORT_SYMBOL_GPL(dma_buf_export_named);
>  
>  
>  /**
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index 9978b61..6f55c04 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -112,6 +112,7 @@ struct dma_buf_ops {
>   * @file: file pointer used for sharing buffers across, and for refcounting.
>   * @attachments: list of dma_buf_attachment that denotes all devices attached.
>   * @ops: dma_buf_ops associated with this buffer object.
> + * @exp_name: name of the exporter; useful for debugging.
>   * @priv: exporter specific private data for this buffer object.
>   */
>  struct dma_buf {
> @@ -123,6 +124,7 @@ struct dma_buf {
>  	struct mutex lock;
>  	unsigned vmapping_counter;
>  	void *vmap_ptr;
> +	const char *exp_name;
>  	void *priv;
>  };
>  
> @@ -162,8 +164,13 @@ 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, const struct dma_buf_ops *ops,
> -			       size_t size, int flags);
> +
> +struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
> +			       size_t size, int flags, const char *);
> +
> +#define dma_buf_export(priv, ops, size, flags)	\
> +	dma_buf_export_named(priv, ops, size, flags, __FILE__)
> +
>  int dma_buf_fd(struct dma_buf *dmabuf, int flags);
>  struct dma_buf *dma_buf_get(int fd);
>  void dma_buf_put(struct dma_buf *dmabuf);
> -- 
> 1.7.10.4
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch

[PATCH 2/2] dma-buf: Add debugfs support

[Sumit Semwal]

Add debugfs support to make it easier to print debug information
about the dma-buf buffers.

Cc: Dave Airlie <airlied@redhat.com>
 [minor fixes on init and warning fix]
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
---
changes since v1:
 - fixes on init and warnings as reported and corrected by Dave Airlie.
 - add locking while walking attachment list - reported by Daniel Vetter.

 drivers/base/dma-buf.c  |  162 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/dma-buf.h |    5 +-
 2 files changed, 166 insertions(+), 1 deletion(-)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index d89102a..7d867ed 100644
--- a/drivers/base/dma-buf.c
+++ b/drivers/base/dma-buf.c
@@ -27,9 +27,18 @@
 #include <linux/dma-buf.h>
 #include <linux/anon_inodes.h>
 #include <linux/export.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
 
 static inline int is_dma_buf_file(struct file *);
 
+struct dma_buf_list {
+	struct list_head head;
+	struct mutex lock;
+};
+
+static struct dma_buf_list db_list;
+
 static int dma_buf_release(struct inode *inode, struct file *file)
 {
 	struct dma_buf *dmabuf;
@@ -42,6 +51,11 @@ static int dma_buf_release(struct inode *inode, struct file *file)
 	BUG_ON(dmabuf->vmapping_counter);
 
 	dmabuf->ops->release(dmabuf);
+
+	mutex_lock(&db_list.lock);
+	list_del(&dmabuf->list_node);
+	mutex_unlock(&db_list.lock);
+
 	kfree(dmabuf);
 	return 0;
 }
@@ -125,6 +139,10 @@ struct dma_buf *dma_buf_export_named(void *priv, const struct dma_buf_ops *ops,
 	mutex_init(&dmabuf->lock);
 	INIT_LIST_HEAD(&dmabuf->attachments);
 
+	mutex_lock(&db_list.lock);
+	list_add(&dmabuf->list_node, &db_list.head);
+	mutex_unlock(&db_list.lock);
+
 	return dmabuf;
 }
 EXPORT_SYMBOL_GPL(dma_buf_export_named);
@@ -551,3 +569,147 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 	mutex_unlock(&dmabuf->lock);
 }
 EXPORT_SYMBOL_GPL(dma_buf_vunmap);
+
+static int dma_buf_init_debugfs(void);
+static void dma_buf_uninit_debugfs(void);
+
+static int __init dma_buf_init(void)
+{
+	mutex_init(&db_list.lock);
+	INIT_LIST_HEAD(&db_list.head);
+	dma_buf_init_debugfs();
+	return 0;
+}
+
+subsys_initcall(dma_buf_init);
+
+static void __exit dma_buf_deinit(void)
+{
+	dma_buf_uninit_debugfs();
+}
+
+#ifdef CONFIG_DEBUG_FS
+static int dma_buf_describe(struct seq_file *s)
+{
+	int ret;
+	struct dma_buf *buf_obj;
+	struct dma_buf_attachment *attach_obj;
+	int count = 0, attach_count;
+	size_t size = 0;
+
+	ret = mutex_lock_interruptible(&db_list.lock);
+
+	if (ret)
+		return ret;
+
+	seq_printf(s, "\nDma-buf Objects:\n");
+	seq_printf(s, "\texp_name\tsize\tflags\tmode\tcount\n");
+
+	list_for_each_entry(buf_obj, &db_list.head, list_node) {
+		ret = mutex_lock_interruptible(&buf_obj->lock);
+
+		if (ret) {
+			seq_printf(s,
+				  "\tERROR locking buffer object: skipping\n");
+			goto skip_buffer;
+		}
+
+		seq_printf(s, "\t");
+
+		seq_printf(s, "\t%s\t%08zu\t%08x\t%08x\t%08d\n",
+				buf_obj->exp_name, buf_obj->size,
+				buf_obj->file->f_flags, buf_obj->file->f_mode,
+				buf_obj->file->f_count.counter);
+
+		seq_printf(s, "\t\tAttached Devices:\n");
+		attach_count = 0;
+
+		list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
+			seq_printf(s, "\t\t");
+
+			seq_printf(s, "%s\n", attach_obj->dev->init_name);
+			attach_count++;
+		}
+
+		seq_printf(s, "\n\t\tTotal %d devices attached\n",
+				attach_count);
+
+		count++;
+		size += buf_obj->size;
+skip_buffer:
+		mutex_unlock(&buf_obj->lock);
+	}
+
+	seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
+
+	mutex_unlock(&db_list.lock);
+	return 0;
+}
+
+static int dma_buf_show(struct seq_file *s, void *unused)
+{
+	void (*func)(struct seq_file *) = s->private;
+	func(s);
+	return 0;
+}
+
+static int dma_buf_debug_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, dma_buf_show, inode->i_private);
+}
+
+static const struct file_operations dma_buf_debug_fops = {
+	.open           = dma_buf_debug_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = single_release,
+};
+
+static struct dentry *dma_buf_debugfs_dir;
+
+static int dma_buf_init_debugfs(void)
+{
+	int err = 0;
+	dma_buf_debugfs_dir = debugfs_create_dir("dma_buf", NULL);
+	if (IS_ERR(dma_buf_debugfs_dir)) {
+		err = PTR_ERR(dma_buf_debugfs_dir);
+		dma_buf_debugfs_dir = NULL;
+		return err;
+	}
+
+	err = dma_buf_debugfs_create_file("bufinfo", dma_buf_describe);
+
+	if (err)
+		pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
+
+	return err;
+}
+
+static void dma_buf_uninit_debugfs(void)
+{
+	if (dma_buf_debugfs_dir)
+		debugfs_remove_recursive(dma_buf_debugfs_dir);
+}
+
+int dma_buf_debugfs_create_file(const char *name,
+				int (*write)(struct seq_file *))
+{
+	struct dentry *d;
+
+	d = debugfs_create_file(name, S_IRUGO, dma_buf_debugfs_dir,
+			write, &dma_buf_debug_fops);
+
+	if (IS_ERR(d))
+		return PTR_ERR(d);
+
+	return 0;
+}
+#else
+static inline int dma_buf_init_debugfs(void)
+{
+	return 0;
+}
+static inline void dma_buf_uninit_debugfs(void)
+{
+}
+#endif
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 6f55c04..dfac5ed 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -113,6 +113,7 @@ struct dma_buf_ops {
  * @attachments: list of dma_buf_attachment that denotes all devices attached.
  * @ops: dma_buf_ops associated with this buffer object.
  * @exp_name: name of the exporter; useful for debugging.
+ * @list_node: node for dma_buf accounting and debugging.
  * @priv: exporter specific private data for this buffer object.
  */
 struct dma_buf {
@@ -125,6 +126,7 @@ struct dma_buf {
 	unsigned vmapping_counter;
 	void *vmap_ptr;
 	const char *exp_name;
+	struct list_head list_node;
 	void *priv;
 };
 
@@ -192,5 +194,6 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
 		 unsigned long);
 void *dma_buf_vmap(struct dma_buf *);
 void dma_buf_vunmap(struct dma_buf *, void *vaddr);
-
+int dma_buf_debugfs_create_file(const char *name,
+				int (*write)(struct seq_file *));
 #endif /* __DMA_BUF_H__ */
-- 
1.7.10.4

Re: [PATCH 2/2] dma-buf: Add debugfs support

[Laurent Pinchart]

Hi Sumit,

Thanks for the patch.

On Monday 25 March 2013 16:50:46 Sumit Semwal wrote:
> Add debugfs support to make it easier to print debug information
> about the dma-buf buffers.
> 
> Cc: Dave Airlie <airlied@redhat.com>
>  [minor fixes on init and warning fix]
> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
> ---
> changes since v1:
>  - fixes on init and warnings as reported and corrected by Dave Airlie.
>  - add locking while walking attachment list - reported by Daniel Vetter.
> 
>  drivers/base/dma-buf.c  |  162 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/dma-buf.h |    5 +-
>  2 files changed, 166 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
> index d89102a..7d867ed 100644
> --- a/drivers/base/dma-buf.c
> +++ b/drivers/base/dma-buf.c
> @@ -27,9 +27,18 @@
>  #include <linux/dma-buf.h>
>  #include <linux/anon_inodes.h>
>  #include <linux/export.h>
> +#include <linux/debugfs.h>
> +#include <linux/seq_file.h>
> 
>  static inline int is_dma_buf_file(struct file *);
> 
> +struct dma_buf_list {
> +	struct list_head head;
> +	struct mutex lock;
> +};
> +
> +static struct dma_buf_list db_list;
> +
>  static int dma_buf_release(struct inode *inode, struct file *file)
>  {
>  	struct dma_buf *dmabuf;
> @@ -42,6 +51,11 @@ static int dma_buf_release(struct inode *inode, struct
> file *file) BUG_ON(dmabuf->vmapping_counter);
> 
>  	dmabuf->ops->release(dmabuf);
> +
> +	mutex_lock(&db_list.lock);
> +	list_del(&dmabuf->list_node);
> +	mutex_unlock(&db_list.lock);
> +
>  	kfree(dmabuf);
>  	return 0;
>  }
> @@ -125,6 +139,10 @@ struct dma_buf *dma_buf_export_named(void *priv, const
> struct dma_buf_ops *ops, mutex_init(&dmabuf->lock);
>  	INIT_LIST_HEAD(&dmabuf->attachments);
> 
> +	mutex_lock(&db_list.lock);
> +	list_add(&dmabuf->list_node, &db_list.head);
> +	mutex_unlock(&db_list.lock);
> +
>  	return dmabuf;
>  }
>  EXPORT_SYMBOL_GPL(dma_buf_export_named);
> @@ -551,3 +569,147 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void
> *vaddr) mutex_unlock(&dmabuf->lock);
>  }
>  EXPORT_SYMBOL_GPL(dma_buf_vunmap);
> +
> +static int dma_buf_init_debugfs(void);
> +static void dma_buf_uninit_debugfs(void);
> +
> +static int __init dma_buf_init(void)
> +{
> +	mutex_init(&db_list.lock);
> +	INIT_LIST_HEAD(&db_list.head);
> +	dma_buf_init_debugfs();
> +	return 0;
> +}
> +
> +subsys_initcall(dma_buf_init);
> +
> +static void __exit dma_buf_deinit(void)

This function is never called.

> +{
> +	dma_buf_uninit_debugfs();
> +}

If you moved those two functions at the end of the file you could get rid of 
the forward declarations above.

> +
> +#ifdef CONFIG_DEBUG_FS
> +static int dma_buf_describe(struct seq_file *s)
> +{
> +	int ret;
> +	struct dma_buf *buf_obj;
> +	struct dma_buf_attachment *attach_obj;
> +	int count = 0, attach_count;
> +	size_t size = 0;
> +
> +	ret = mutex_lock_interruptible(&db_list.lock);
> +
> +	if (ret)
> +		return ret;
> +
> +	seq_printf(s, "\nDma-buf Objects:\n");
> +	seq_printf(s, "\texp_name\tsize\tflags\tmode\tcount\n");
> +
> +	list_for_each_entry(buf_obj, &db_list.head, list_node) {
> +		ret = mutex_lock_interruptible(&buf_obj->lock);
> +
> +		if (ret) {
> +			seq_printf(s,
> +				  "\tERROR locking buffer object: skipping\n");
> +			goto skip_buffer;
> +		}
> +
> +		seq_printf(s, "\t");
> +
> +		seq_printf(s, "\t%s\t%08zu\t%08x\t%08x\t%08d\n",
> +				buf_obj->exp_name, buf_obj->size,
> +				buf_obj->file->f_flags, buf_obj->file->f_mode,
> +				buf_obj->file->f_count.counter);
> +
> +		seq_printf(s, "\t\tAttached Devices:\n");
> +		attach_count = 0;
> +
> +		list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
> +			seq_printf(s, "\t\t");
> +
> +			seq_printf(s, "%s\n", attach_obj->dev->init_name);
> +			attach_count++;
> +		}
> +
> +		seq_printf(s, "\n\t\tTotal %d devices attached\n",
> +				attach_count);
> +
> +		count++;
> +		size += buf_obj->size;
> +skip_buffer:
> +		mutex_unlock(&buf_obj->lock);
> +	}
> +
> +	seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
> +
> +	mutex_unlock(&db_list.lock);
> +	return 0;
> +}
> +
> +static int dma_buf_show(struct seq_file *s, void *unused)
> +{
> +	void (*func)(struct seq_file *) = s->private;
> +	func(s);
> +	return 0;
> +}
> +
> +static int dma_buf_debug_open(struct inode *inode, struct file *file)
> +{
> +	return single_open(file, dma_buf_show, inode->i_private);
> +}
> +
> +static const struct file_operations dma_buf_debug_fops = {
> +	.open           = dma_buf_debug_open,
> +	.read           = seq_read,
> +	.llseek         = seq_lseek,
> +	.release        = single_release,
> +};
> +
> +static struct dentry *dma_buf_debugfs_dir;
> +
> +static int dma_buf_init_debugfs(void)
> +{
> +	int err = 0;
> +	dma_buf_debugfs_dir = debugfs_create_dir("dma_buf", NULL);
> +	if (IS_ERR(dma_buf_debugfs_dir)) {
> +		err = PTR_ERR(dma_buf_debugfs_dir);
> +		dma_buf_debugfs_dir = NULL;
> +		return err;
> +	}
> +
> +	err = dma_buf_debugfs_create_file("bufinfo", dma_buf_describe);
> +
> +	if (err)
> +		pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
> +
> +	return err;
> +}
> +
> +static void dma_buf_uninit_debugfs(void)
> +{
> +	if (dma_buf_debugfs_dir)
> +		debugfs_remove_recursive(dma_buf_debugfs_dir);
> +}
> +
> +int dma_buf_debugfs_create_file(const char *name,
> +				int (*write)(struct seq_file *))
> +{
> +	struct dentry *d;
> +
> +	d = debugfs_create_file(name, S_IRUGO, dma_buf_debugfs_dir,
> +			write, &dma_buf_debug_fops);
> +
> +	if (IS_ERR(d))
> +		return PTR_ERR(d);
> +
> +	return 0;
> +}
> +#else
> +static inline int dma_buf_init_debugfs(void)
> +{
> +	return 0;
> +}
> +static inline void dma_buf_uninit_debugfs(void)
> +{
> +}
> +#endif
> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> index 6f55c04..dfac5ed 100644
> --- a/include/linux/dma-buf.h
> +++ b/include/linux/dma-buf.h
> @@ -113,6 +113,7 @@ struct dma_buf_ops {
>   * @attachments: list of dma_buf_attachment that denotes all devices
> attached. * @ops: dma_buf_ops associated with this buffer object.
>   * @exp_name: name of the exporter; useful for debugging.
> + * @list_node: node for dma_buf accounting and debugging.
>   * @priv: exporter specific private data for this buffer object.
>   */
>  struct dma_buf {
> @@ -125,6 +126,7 @@ struct dma_buf {
>  	unsigned vmapping_counter;
>  	void *vmap_ptr;
>  	const char *exp_name;
> +	struct list_head list_node;
>  	void *priv;
>  };
> 
> @@ -192,5 +194,6 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct
> *, unsigned long);
>  void *dma_buf_vmap(struct dma_buf *);
>  void dma_buf_vunmap(struct dma_buf *, void *vaddr);
> -
> +int dma_buf_debugfs_create_file(const char *name,
> +				int (*write)(struct seq_file *));

This function is only called internally from the same file, could it be 
declared as static ?

>  #endif /* __DMA_BUF_H__ */
-- 
Regards,

Laurent Pinchart

Re: [PATCH 2/2] dma-buf: Add debugfs support

[Sumit Semwal]

Hi Laurent!

Thanks for the review:

On 27 March 2013 05:38, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hi Sumit,
>
> Thanks for the patch.
>
> On Monday 25 March 2013 16:50:46 Sumit Semwal wrote:
>> Add debugfs support to make it easier to print debug information
>> about the dma-buf buffers.
>>
>> Cc: Dave Airlie <airlied@redhat.com>
>>  [minor fixes on init and warning fix]
>> Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
>> ---
>> changes since v1:
>>  - fixes on init and warnings as reported and corrected by Dave Airlie.
>>  - add locking while walking attachment list - reported by Daniel Vetter.
>>
>>  drivers/base/dma-buf.c  |  162 ++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/dma-buf.h |    5 +-
>>  2 files changed, 166 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
>> index d89102a..7d867ed 100644
>> --- a/drivers/base/dma-buf.c
>> +++ b/drivers/base/dma-buf.c
>> @@ -27,9 +27,18 @@
>>  #include <linux/dma-buf.h>
>>  #include <linux/anon_inodes.h>
>>  #include <linux/export.h>
>> +#include <linux/debugfs.h>
>> +#include <linux/seq_file.h>
>>
>>  static inline int is_dma_buf_file(struct file *);
>>
>> +struct dma_buf_list {
>> +     struct list_head head;
>> +     struct mutex lock;
>> +};
>> +
>> +static struct dma_buf_list db_list;
>> +
>>  static int dma_buf_release(struct inode *inode, struct file *file)
>>  {
>>       struct dma_buf *dmabuf;
>> @@ -42,6 +51,11 @@ static int dma_buf_release(struct inode *inode, struct
>> file *file) BUG_ON(dmabuf->vmapping_counter);
>>
>>       dmabuf->ops->release(dmabuf);
>> +
>> +     mutex_lock(&db_list.lock);
>> +     list_del(&dmabuf->list_node);
>> +     mutex_unlock(&db_list.lock);
>> +
>>       kfree(dmabuf);
>>       return 0;
>>  }
>> @@ -125,6 +139,10 @@ struct dma_buf *dma_buf_export_named(void *priv, const
>> struct dma_buf_ops *ops, mutex_init(&dmabuf->lock);
>>       INIT_LIST_HEAD(&dmabuf->attachments);
>>
>> +     mutex_lock(&db_list.lock);
>> +     list_add(&dmabuf->list_node, &db_list.head);
>> +     mutex_unlock(&db_list.lock);
>> +
>>       return dmabuf;
>>  }
>>  EXPORT_SYMBOL_GPL(dma_buf_export_named);
>> @@ -551,3 +569,147 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void
>> *vaddr) mutex_unlock(&dmabuf->lock);
>>  }
>>  EXPORT_SYMBOL_GPL(dma_buf_vunmap);
>> +
>> +static int dma_buf_init_debugfs(void);
>> +static void dma_buf_uninit_debugfs(void);
>> +
>> +static int __init dma_buf_init(void)
>> +{
>> +     mutex_init(&db_list.lock);
>> +     INIT_LIST_HEAD(&db_list.head);
>> +     dma_buf_init_debugfs();
>> +     return 0;
>> +}
>> +
>> +subsys_initcall(dma_buf_init);
>> +
>> +static void __exit dma_buf_deinit(void)
>
> This function is never called.
>
You're right; it's missing an __exitcall() - I will add it!
>> +{
>> +     dma_buf_uninit_debugfs();
>> +}
>
> If you moved those two functions at the end of the file you could get rid of
> the forward declarations above.
>
Sure - will do that.
>> +
>> +#ifdef CONFIG_DEBUG_FS
>> +static int dma_buf_describe(struct seq_file *s)
>> +{
>> +     int ret;
>> +     struct dma_buf *buf_obj;
>> +     struct dma_buf_attachment *attach_obj;
>> +     int count = 0, attach_count;
>> +     size_t size = 0;
>> +
>> +     ret = mutex_lock_interruptible(&db_list.lock);
>> +
>> +     if (ret)
>> +             return ret;
>> +
>> +     seq_printf(s, "\nDma-buf Objects:\n");
>> +     seq_printf(s, "\texp_name\tsize\tflags\tmode\tcount\n");
>> +
>> +     list_for_each_entry(buf_obj, &db_list.head, list_node) {
>> +             ret = mutex_lock_interruptible(&buf_obj->lock);
>> +
>> +             if (ret) {
>> +                     seq_printf(s,
>> +                               "\tERROR locking buffer object: skipping\n");
>> +                     goto skip_buffer;
>> +             }
>> +
>> +             seq_printf(s, "\t");
>> +
>> +             seq_printf(s, "\t%s\t%08zu\t%08x\t%08x\t%08d\n",
>> +                             buf_obj->exp_name, buf_obj->size,
>> +                             buf_obj->file->f_flags, buf_obj->file->f_mode,
>> +                             buf_obj->file->f_count.counter);
>> +
>> +             seq_printf(s, "\t\tAttached Devices:\n");
>> +             attach_count = 0;
>> +
>> +             list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
>> +                     seq_printf(s, "\t\t");
>> +
>> +                     seq_printf(s, "%s\n", attach_obj->dev->init_name);
>> +                     attach_count++;
>> +             }
>> +
>> +             seq_printf(s, "\n\t\tTotal %d devices attached\n",
>> +                             attach_count);
>> +
>> +             count++;
>> +             size += buf_obj->size;
>> +skip_buffer:
>> +             mutex_unlock(&buf_obj->lock);
>> +     }
>> +
>> +     seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
>> +
>> +     mutex_unlock(&db_list.lock);
>> +     return 0;
>> +}
>> +
>> +static int dma_buf_show(struct seq_file *s, void *unused)
>> +{
>> +     void (*func)(struct seq_file *) = s->private;
>> +     func(s);
>> +     return 0;
>> +}
>> +
>> +static int dma_buf_debug_open(struct inode *inode, struct file *file)
>> +{
>> +     return single_open(file, dma_buf_show, inode->i_private);
>> +}
>> +
>> +static const struct file_operations dma_buf_debug_fops = {
>> +     .open           = dma_buf_debug_open,
>> +     .read           = seq_read,
>> +     .llseek         = seq_lseek,
>> +     .release        = single_release,
>> +};
>> +
>> +static struct dentry *dma_buf_debugfs_dir;
>> +
>> +static int dma_buf_init_debugfs(void)
>> +{
>> +     int err = 0;
>> +     dma_buf_debugfs_dir = debugfs_create_dir("dma_buf", NULL);
>> +     if (IS_ERR(dma_buf_debugfs_dir)) {
>> +             err = PTR_ERR(dma_buf_debugfs_dir);
>> +             dma_buf_debugfs_dir = NULL;
>> +             return err;
>> +     }
>> +
>> +     err = dma_buf_debugfs_create_file("bufinfo", dma_buf_describe);
>> +
>> +     if (err)
>> +             pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
>> +
>> +     return err;
>> +}
>> +
>> +static void dma_buf_uninit_debugfs(void)
>> +{
>> +     if (dma_buf_debugfs_dir)
>> +             debugfs_remove_recursive(dma_buf_debugfs_dir);
>> +}
>> +
>> +int dma_buf_debugfs_create_file(const char *name,
>> +                             int (*write)(struct seq_file *))
>> +{
>> +     struct dentry *d;
>> +
>> +     d = debugfs_create_file(name, S_IRUGO, dma_buf_debugfs_dir,
>> +                     write, &dma_buf_debug_fops);
>> +
>> +     if (IS_ERR(d))
>> +             return PTR_ERR(d);
>> +
>> +     return 0;
>> +}
>> +#else
>> +static inline int dma_buf_init_debugfs(void)
>> +{
>> +     return 0;
>> +}
>> +static inline void dma_buf_uninit_debugfs(void)
>> +{
>> +}
>> +#endif
>> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
>> index 6f55c04..dfac5ed 100644
>> --- a/include/linux/dma-buf.h
>> +++ b/include/linux/dma-buf.h
>> @@ -113,6 +113,7 @@ struct dma_buf_ops {
>>   * @attachments: list of dma_buf_attachment that denotes all devices
>> attached. * @ops: dma_buf_ops associated with this buffer object.
>>   * @exp_name: name of the exporter; useful for debugging.
>> + * @list_node: node for dma_buf accounting and debugging.
>>   * @priv: exporter specific private data for this buffer object.
>>   */
>>  struct dma_buf {
>> @@ -125,6 +126,7 @@ struct dma_buf {
>>       unsigned vmapping_counter;
>>       void *vmap_ptr;
>>       const char *exp_name;
>> +     struct list_head list_node;
>>       void *priv;
>>  };
>>
>> @@ -192,5 +194,6 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct
>> *, unsigned long);
>>  void *dma_buf_vmap(struct dma_buf *);
>>  void dma_buf_vunmap(struct dma_buf *, void *vaddr);
>> -
>> +int dma_buf_debugfs_create_file(const char *name,
>> +                             int (*write)(struct seq_file *));
>
> This function is only called internally from the same file, could it be
> declared as static ?
>
>>  #endif /* __DMA_BUF_H__ */
> --
> Regards,
>
> Laurent Pinchart
>

--
Thanks and regards,
Sumit Semwal