Re: [PATCH v4 01/13] notifier: add device-managed registration APIs

[Andy Shevchenko]

On Mon, Aug 10, 2026 at 12:11:40PM +0300, Andy Shevchenko wrote:
> On Mon, Aug 10, 2026 at 06:37:25AM +0200, Uwe Kleine-König wrote:
> > On Sun, Jul 26, 2026 at 10:17:27AM +0000, Eliav Farber wrote:

...

> > > +{
> > > +	struct atomic_notifier_chain_devres *dr;
> > > +	int ret;
> > > +
> > > +	dr = devres_alloc(devm_atomic_notifier_chain_unregister,
> > > +			  sizeof(*dr), GFP_KERNEL);
> > > +	if (!dr)
> > > +		return -ENOMEM;
> > > +
> > > +	ret = atomic_notifier_chain_register(nh, n);
> > > +	if (ret) {
> > > +		devres_free(dr);
> > > +		return ret;
> > > +	}
> > > +
> > > +	dr->nh = nh;
> > > +	dr->nb = n;
> > > +	devres_add(dev, dr);
> > > +
> > > +	return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(devm_atomic_notifier_chain_register);
> > 
> > IMHO devm_atomic_notifier_chain_register() should look as follows:
> > 
> > 	ret = atomic_notifier_chain_register(nh, n);
> > 	if (ret)
> > 		return ret;
> > 
> > 	return devm_add_action_or_reset(dev, devm_atomic_notifier_chain_unregister, dr)
> > 
> > which is much easier and includes less details from the inner workings
> > of devm. Same for the blocking variant.
> 
> Won't work. We need more than one parameter and hence the whole devres_alloc().
> Please, look closer to the code.

And just answering ahead, no, devm_kmalloc() is not good bandaid as it makes code
not anyhow better to read and have a downside of memory fragmentation.

-- 
With Best Regards,
Andy Shevchenko