[alsa-devel] [PATCH 02/28] ASoC: soc-core: set component->debugfs_root NULL

[Pierre-Louis Bossart]

On 8/6/19 11:22 AM, Mark Brown wrote:
> On Tue, Aug 06, 2019 at 09:49:20AM -0500, Pierre-Louis Bossart wrote:
>>>    {
>>> +	if (!component->debugfs_root)
>>> +		return;
> 
>> that test is redundant, it's safe to call debugfs_remove_recursive() without
>> checking the argument (done internally).
> 
> It's not completely redundant...
> 
>>>    	debugfs_remove_recursive(component->debugfs_root);
>>> +	component->debugfs_root = NULL;
>>>    }
> 
> ...with this, the two in combination add protection against a double
> free.  Not 100% sure it's worth it but I queued the patch since I
> couldn't strongly convince myself it's a bad idea.

I was only referring to the first test, which will be duplicated. see below.
The second part is just fine.

/**
  * debugfs_remove_recursive - recursively removes a directory
  * @dentry: a pointer to a the dentry of the directory to be removed. 
If this
  *          parameter is NULL or an error value, nothing will be done.
  *
  * This function recursively removes a directory tree in debugfs that
  * was previously created with a call to another debugfs function
  * (like debugfs_create_file() or variants thereof.)
  *
  * This function is required to be called in order for the file to be
  * removed, no automatic cleanup of files will happen when a module is
  * removed, you are responsible here.
  */
void debugfs_remove_recursive(struct dentry *dentry)
{
	struct dentry *child, *parent;

	if (IS_ERR_OR_NULL(dentry))
		return;