Re: [PATCH] power: reset: at91-reset: free resources on exit path

[Nicolas Ferre]

On 01/04/2021 at 16:42, Claudiu Beznea - M18063 wrote:
> > > +unmap:
> > > +    iounmap(reset->rstc_base);
> > > +    for (idx = 0; idx < ARRAY_SIZE(reset->ramc_base); idx++)
> > > +        iounmap(reset->ramc_base[idx]);
> > But if we keep this loop, I have the feeling that some kind of
> > "of_node_put()" is needed as well.
> No! In the loop:
>
> for_each_matching_node_and_match(np, at91_ramc_of_match, &match) {
> 	reset->ramc_lpr = (u32)match->data;
> 	reset->ramc_base[idx] = of_iomap(np, 0);
> 	if (!reset->ramc_base[idx]) {
> 		dev_err(&pdev->dev, "Could not map ram controller address\n");
> 		of_node_put(np);
> 		ret = -ENODEV;
> 		goto unmap;
> 	}
> 	idx++;
> }
>
> the of_node_put() is needed only if the loop is interrupted as the macro:
> for_each_matching_node_and_match() is defined as follows:
>
> #define for_each_matching_node_and_match(dn, matches, match) \
> 	for (dn = of_find_matching_node_and_match(NULL, matches, match); \
> 	     dn; dn = of_find_matching_node_and_match(dn, matches, match))
>
> and of_find_matching_node_and_match() will return a np with refcount
> incremented but at the next loop step the of_find_matching_node_and_match()
> will be called with the same np pointer and the np refcount will be
> decremented.
>
> struct device_node *of_find_matching_node_and_match(
> 		struct device_node *from,
> 		const struct of_device_id *matches,
> 		const struct of_device_id **match)
> {
> 	// ...
> 	of_node_put(from);
> 	// ...
> }

Oh yes you're right Claudiu, I overlooked this one. Thanks for the 
in-depth explanation.

Best regards,
  Nicolas

--
Nicolas Ferre