Re: [PATCH v4 06/10] dma-buf: heaps: Add debugfs support

["Christian König" <christian.koenig@amd.com>]

On 8/7/26 17:54, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> Add a callback to struct dma_heap_ops that heap providers can implement
> to show information about the state of the heap in debugfs. A top-level
> directory named "dma_heap" is created in debugfs and individual files
> will be named after the heaps.
> 
> Reviewed-by: Maxime Ripard <mripard@kernel.org>
> Signed-off-by: Thierry Reding <treding@nvidia.com>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>  drivers/dma-buf/dma-heap.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/dma-heap.h   |  2 ++
>  2 files changed, 58 insertions(+)
> 
> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
> index 3937dd41bb0f..389cddd07c8d 100644
> --- a/drivers/dma-buf/dma-heap.c
> +++ b/drivers/dma-buf/dma-heap.c
> @@ -7,6 +7,7 @@
>   */
>  
>  #include <linux/cdev.h>
> +#include <linux/debugfs.h>
>  #include <linux/device.h>
>  #include <linux/dma-buf.h>
>  #include <linux/dma-heap.h>
> @@ -225,6 +226,46 @@ const char *dma_heap_get_name(struct dma_heap *heap)
>  }
>  EXPORT_SYMBOL_NS_GPL(dma_heap_get_name, "DMA_BUF_HEAP");
>  
> +#ifdef CONFIG_DEBUG_FS
> +static int dma_heap_debug_show(struct seq_file *s, void *unused)
> +{
> +	struct dma_heap *heap = s->private;
> +	int err = 0;
> +
> +	if (heap->ops && heap->ops->show)
> +		err = heap->ops->show(s, heap);
> +
> +	return err;
> +}
> +DEFINE_SHOW_ATTRIBUTE(dma_heap_debug);
> +
> +static struct dentry *dma_heap_debugfs_dir;
> +
> +static void dma_heap_init_debugfs(void)
> +{
> +	struct dentry *dir;
> +
> +	dir = debugfs_create_dir("dma_heap", NULL);
> +	if (IS_ERR(dir))
> +		return;
> +
> +	dma_heap_debugfs_dir = dir;
> +}
> +
> +static void dma_heap_exit_debugfs(void)
> +{
> +	debugfs_remove_recursive(dma_heap_debugfs_dir);
> +}
> +#else
> +static void dma_heap_init_debugfs(void)
> +{
> +}
> +
> +static void dma_heap_exit_debugfs(void)
> +{
> +}
> +#endif
> +
>  /**
>   * dma_heap_add - adds a heap to dmabuf heaps
>   * @exp_info: information needed to register this heap
> @@ -299,6 +340,13 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
>  
>  	/* Add heap to the list */
>  	list_add(&heap->list, &heap_list);
> +
> +#ifdef CONFIG_DEBUG_FS
> +	if (heap->ops && heap->ops->show)
> +		debugfs_create_file(heap->name, 0444, dma_heap_debugfs_dir,
> +				    heap, &dma_heap_debug_fops);
> +#endif
> +
>  	mutex_unlock(&heap_list_lock);
>  
>  	return heap;
> @@ -335,6 +383,14 @@ static int dma_heap_init(void)
>  	}
>  	dma_heap_class->devnode = dma_heap_devnode;
>  
> +	dma_heap_init_debugfs();
> +
>  	return 0;
>  }
>  subsys_initcall(dma_heap_init);
> +
> +static void __exit dma_heap_exit(void)
> +{
> +	dma_heap_exit_debugfs();
> +}
> +__exitcall(dma_heap_exit);
> diff --git a/include/linux/dma-heap.h b/include/linux/dma-heap.h
> index 648328a64b27..1c9bed1f4dde 100644
> --- a/include/linux/dma-heap.h
> +++ b/include/linux/dma-heap.h
> @@ -12,6 +12,7 @@
>  #include <linux/types.h>
>  
>  struct dma_heap;
> +struct seq_file;
>  
>  /**
>   * struct dma_heap_ops - ops to operate on a given heap
> @@ -24,6 +25,7 @@ struct dma_heap_ops {
>  				    unsigned long len,
>  				    u32 fd_flags,
>  				    u64 heap_flags);
> +	int (*show)(struct seq_file *s, struct dma_heap *heap);
>  };
>  
>  /**
>