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

Sumit Semwal
2013-03-27T06:36:33Z

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