linux-kernel - Re: [PATCH 01/21] pinctrl: ti: iodelay: Use scope based of_node

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Date: Wed, 1 May 2024 16:32:40 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
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	Peng Fan <peng.fan@....com>
Subject: Re: [PATCH 01/21] pinctrl: ti: iodelay: Use scope based
 of_node_put() cleanups

On Wed, May 01, 2024 at 08:55:59PM +0800, Peng Fan (OSS) wrote:
> @@ -879,16 +874,12 @@ static int ti_iodelay_probe(struct platform_device *pdev)
>  	ret = pinctrl_register_and_init(&iod->desc, dev, iod, &iod->pctl);
>  	if (ret) {
>  		dev_err(dev, "Failed to register pinctrl\n");
> -		goto exit_out;
> +		return ret;
>  	}
>  
>  	platform_set_drvdata(pdev, iod);
>  
>  	return pinctrl_enable(iod->pctl);
> -
> -exit_out:
> -	of_node_put(np);
> -	return ret;
>  }

This will call of_node_put() on the success path so it's a behavior
change.  The original code is buggy, it's supposed to call of_node_put()
on the success path here or in ti_iodelay_remove().

If it's supposed to call of_node_put() here, then fine, this is bugfix
but if it's supposed to call it in ti_iodelay_remove() then we need to
save the pointer somewhere using no_free_ptr().  Probably saving ->np
is the safest choice?

The original code is already a little bit buggy because it doesn't
check for pinctrl_enable() errors and cleanup.


diff --git a/drivers/pinctrl/ti/pinctrl-ti-iodelay.c b/drivers/pinctrl/ti/pinctrl-ti-iodelay.c
index 040f2c46a868..f40a1476e4ff 100644
--- a/drivers/pinctrl/ti/pinctrl-ti-iodelay.c
+++ b/drivers/pinctrl/ti/pinctrl-ti-iodelay.c
@@ -156,6 +156,7 @@ struct ti_iodelay_device {
 
 	const struct ti_iodelay_reg_data *reg_data;
 	struct ti_iodelay_reg_values reg_init_conf_values;
+	struct device_node *np;
 };
 
 /**
@@ -884,7 +885,12 @@ static int ti_iodelay_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, iod);
 
-	return pinctrl_enable(iod->pctl);
+	ret = pinctrl_enable(iod->pctl);
+	if (ret)
+		goto exit_out;
+
+	iod->np = no_free_ptr(np);
+	return 0;
 
 exit_out:
 	of_node_put(np);
@@ -903,6 +909,7 @@ static void ti_iodelay_remove(struct platform_device *pdev)
 		pinctrl_unregister(iod->pctl);
 
 	ti_iodelay_pinconf_deinit_dev(iod);
+	of_node_put(iod->np);
 
 	/* Expect other allocations to be freed by devm */
 }