[PATCH v3 0/2] dma-buf: Add support for debugfs

[PATCH v3 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.

---
changes since v2: (based on review comments from Laurent Pinchart)
 - reordered functions to avoid forward declaration
 - added __exitcall for dma_buf_deinit()

changes since v1:
 - added patch to replace dma_buf_export() with dma_buf_export_named(), per
    suggestion from Daniel Vetter.
 - fixes on init and warnings as reported and corrected by Dave Airlie.
 - added locking while walking attachment list - reported by Daniel Vetter.

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            |  170 ++++++++++++++++++++++++++++++++++++-
 include/linux/dma-buf.h           |   16 +++-
 3 files changed, 190 insertions(+), 9 deletions(-)

-- 
1.7.10.4

[PATCH v3 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!]
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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

[PATCH v3 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 v2: (based on review comments from Laurent Pinchart)
 - reordered functions to avoid forward declaration
 - added __exitcall for dma_buf_deinit()

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  |  159 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/dma-buf.h |    5 +-
 2 files changed, 163 insertions(+), 1 deletion(-)

diff --git a/drivers/base/dma-buf.c b/drivers/base/dma-buf.c
index d89102a..466476f 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 +569,144 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, void *vaddr)
 	mutex_unlock(&dmabuf->lock);
 }
 EXPORT_SYMBOL_GPL(dma_buf_vunmap);
+
+#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
+
+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();
+}
+__exitcall(dma_buf_deinit);
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 v3 0/2] dma-buf: Add support for debugfs

[Sumit Semwal]

Hi All,


On 4 April 2013 11:58, Sumit Semwal <sumit.semwal@linaro.org> wrote:
> 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.

Since there're no more comments, I'll add this to my for-next, to
queue it up for 3.10.

Best regards,
~Sumit.
>
> Some more magic can be added for more advanced debugging, but we'll leave that
> for the time being.
>
> Best regards,
> ~Sumit.
>
> ---
> changes since v2: (based on review comments from Laurent Pinchart)
>  - reordered functions to avoid forward declaration
>  - added __exitcall for dma_buf_deinit()
>
> changes since v1:
>  - added patch to replace dma_buf_export() with dma_buf_export_named(), per
>     suggestion from Daniel Vetter.
>  - fixes on init and warnings as reported and corrected by Dave Airlie.
>  - added locking while walking attachment list - reported by Daniel Vetter.
>
> 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            |  170 ++++++++++++++++++++++++++++++++++++-
>  include/linux/dma-buf.h           |   16 +++-
>  3 files changed, 190 insertions(+), 9 deletions(-)
>
> --
> 1.7.10.4
>



--
Thanks and regards,

Sumit Semwal

Linaro Kernel Engineer - Graphics working group

Linaro.org │ Open source software for ARM SoCs

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