linux-kernel - Re: [PATCH] pinctrl: renesas: rzg2l: Fix double unlock in rzg2l_dt_subnode_to

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Date: Fri, 12 Jan 2024 10:55:40 +0200
From: claudiu beznea <claudiu.beznea@...on.dev>
To: Dan Carpenter <dan.carpenter@...aro.org>,
 Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Cc: Geert Uytterhoeven <geert+renesas@...der.be>,
 Linus Walleij <linus.walleij@...aro.org>, linux-renesas-soc@...r.kernel.org,
 linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
 kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] pinctrl: renesas: rzg2l: Fix double unlock in
 rzg2l_dt_subnode_to_map()

Hi, Dan,

Thanks for your patch!

On 10.01.2024 20:41, Dan Carpenter wrote:
> If rzg2l_map_add_config() fails then the error handling calls
> mutex_unlock(&pctrl->mutex) but we're not holding that mutex.  Move
> the unlocks to before the gotos to avoid this situation.
> 
> Fixes: d3aaa7203a17 ("pinctrl: renesas: rzg2l: Add pin configuration support for pinmux groups")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
> (Not tested).

I've tested it on RZ/G3S SoC and all is good.

However, I think, to keep the locking scheme unchanged and simpler (FMPOV),
commit d3aaa7203a17 ("pinctrl: renesas: rzg2l: Add pin configuration
support for pinmux groups") should have been call rzg2l_map_add_config()
just before the mutex is locked. That would be the following diff:

--- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
+++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
@@ -447,6 +447,16 @@ static int rzg2l_dt_subnode_to_map(struct pinctrl_dev
*pctldev,
 		name = np->name;
 	}

+	if (num_configs) {
+		ret = rzg2l_map_add_config(&maps[idx], name,
+					   PIN_MAP_TYPE_CONFIGS_GROUP,
+					   configs, num_configs);
+		if (ret < 0)
+			goto done;
+
+		idx++;
+	}
+
 	mutex_lock(&pctrl->mutex);

 	/* Register a single pin group listing all the pins we read from DT */
@@ -474,16 +484,6 @@ static int rzg2l_dt_subnode_to_map(struct pinctrl_dev
*pctldev,
 	maps[idx].data.mux.function = name;
 	idx++;

-	if (num_configs) {
-		ret = rzg2l_map_add_config(&maps[idx], name,
-					   PIN_MAP_TYPE_CONFIGS_GROUP,
-					   configs, num_configs);
-		if (ret < 0)
-			goto remove_group;
-
-		idx++;
-	}
-
 	dev_dbg(pctrl->dev, "Parsed %pOF with %d pins\n", np, num_pinmux);
 	ret = 0;
 	goto done;

Would you mind doing it like this?

Please, let me know if you want me to handle it.

Thank you,
Claudiu Beznea

> 
>  drivers/pinctrl/renesas/pinctrl-rzg2l.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pinctrl/renesas/pinctrl-rzg2l.c b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> index 80fb5011c7bb..8bbfb0530538 100644
> --- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> +++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> @@ -453,7 +453,8 @@ static int rzg2l_dt_subnode_to_map(struct pinctrl_dev *pctldev,
>  	gsel = pinctrl_generic_add_group(pctldev, name, pins, num_pinmux, NULL);
>  	if (gsel < 0) {
>  		ret = gsel;
> -		goto unlock;
> +		mutex_unlock(&pctrl->mutex);
> +		goto done;
>  	}
>  
>  	/*
> @@ -464,6 +465,7 @@ static int rzg2l_dt_subnode_to_map(struct pinctrl_dev *pctldev,
>  	fsel = pinmux_generic_add_function(pctldev, name, pin_fn, 1, psel_val);
>  	if (fsel < 0) {
>  		ret = fsel;
> +		mutex_unlock(&pctrl->mutex);
>  		goto remove_group;
>  	}
>  
> @@ -490,8 +492,6 @@ static int rzg2l_dt_subnode_to_map(struct pinctrl_dev *pctldev,
>  
>  remove_group:
>  	pinctrl_generic_remove_group(pctldev, gsel);
> -unlock:
> -	mutex_unlock(&pctrl->mutex);
>  done:
>  	*index = idx;
>  	kfree(configs);