Re: [PATCH v6 08/12] dma-buf: heaps: Add debugfs support

[Christian König]

Since AMDs mail servers blocked me from sending this out, here once more from my gmail account.

Regards,
Christian.

On 9/4/26 15:00, Christian König wrote:
> On 9/4/26 12:44, Thierry Reding wrote:
>> From: Thierry Reding <treding@xxxxxxxxxx>
>>
>> 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@xxxxxxxxxx>
>> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
> 
> One minimal nit pick below, with that taken care of Reviewed-by: Christian König <christian.koenig@xxxxxxx>.
> 
>> ---
>> Changes in v5:
>> - fix failure handling during debugfs root directory creation
>> - add more cleanup to the newly introduced dma_heap_exit()
>> ---
>>  drivers/dma-buf/dma-heap.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/dma-heap.h   |  2 ++
>>  2 files changed, 54 insertions(+)
>>
>> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
>> index 8a6c2b6e0cc6..65c80dac6500 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 +226,40 @@ 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)
>> +{
>> +	dma_heap_debugfs_dir = debugfs_create_dir("dma_heap", NULL);
>> +}
>> +
>> +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 +334,13 @@ 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 +377,16 @@ 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();
>> +	class_destroy(dma_heap_class);
>> +	unregister_chrdev_region(dma_heap_devt, NUM_HEAP_MINORS);
>> +}
>> +__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);
> 
> I found it good coding practice for objects ops pointer tables to have the object the function works with as first parameter.
> 
> Absolutely not a must have, but just looks a little bit more consistent.
> 
> Regards,
> Christian.
> 
>>  };
>>  
>>  /**
>>
>