Re: [PATCH v6 08/11] devm-helpers: Add resource managed version of debugfs directory create function

[Andy Shevchenko <andriy.shevchenko@intel.com>]

On Tue, Apr 23, 2024 at 06:20:14PM +0200, Marek Behún wrote:
> On Tue, 23 Apr 2024 19:02:21 +0300
> Andy Shevchenko <andriy.shevchenko@intel.com> wrote:
> > On Thu, Apr 18, 2024 at 02:11:13PM +0200, Marek Behún wrote:

...

> > > +static inline struct dentry *
> > > +devm_debugfs_create_dir(struct device *dev, const char *name,
> > > +			struct dentry *parent)
> > > +{
> > > +	struct dentry *dentry;
> > > +	int err;  
> > 
> > > +	dentry = debugfs_create_dir(name, parent);
> > > +	if (IS_ERR(dentry))
> > > +		return dentry;  
> > 
> > Why do we care?
> > 
> > > +	err = devm_add_action_or_reset(dev, devm_debugfs_dir_recursive_drop,
> > > +				       dentry);
> > > +	if (err < 0)
> > > +		return ERR_PTR(err);
> > > +
> > > +	return dentry;
> > > +}  
> > 
> > static inline struct dentry *
> > devm_debugfs_create_dir(struct device *dev, const char *name, struct dentry *parent)
> > {
> > 	struct dentry *dentry;
> > 	int err;
> > 
> > 	dentry = debugfs_create_dir(name, parent);
> > 
> > 	err = devm_add_action_or_reset(dev, devm_debugfs_dir_recursive_drop, dentry);
> > 	if (err)
> > 		return ERR_PTR(err);
> 
> But if the dir creation fails, there is no need to allocate devm
> destructor...

Yes, but why do we care about that?
debugfs is designed the way that we should ignore errors from it.

This discussion let me think, that probably the best solution is to add a field
to struct device_driver to handle this.

debugfs will appear only when device is completely instantiated, removed before
anything, and a lot of other benefits (see the story behind dev_groups as a
reference).

-- 
With Best Regards,
Andy Shevchenko