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

Sumit Semwal
2013-03-25T11:21:33Z

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