linux-kernel - Re: [PATCH 3.16.y-ckt 059/126] thermal: exynos: Fix unbalanced regulator disable on probe failure

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Message-ID: <56682B1D.9090707@samsung.com>
Date:	Wed, 9 Dec 2015 22:22:37 +0900
From:	Krzysztof Kozlowski <k.kozlowski@...sung.com>
To:	Luis Henriques <luis.henriques@...onical.com>,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	k.kozlowski.k@...il.com, Eduardo Valentin <edubezval@...il.com>
Subject: Re: [PATCH 3.16.y-ckt 059/126] thermal: exynos: Fix unbalanced
 regulator disable on probe failure

W dniu 09.12.2015 o 18:37, Luis Henriques pisze:
> 3.16.7-ckt21 -stable review patch.  If anyone has any objections, please let me know.
> 
> ------------------
> 
> From: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> 
> commit 824ead03b78403a21449cb7eb153a4344cd3b4c8 upstream.
> 
> During probe if the regulator could not be enabled, the error exit path
> would still disable it. This could lead to unbalanced counter of
> regulator enable/disable.
> 
> The patch moves code for getting and enabling the regulator from
> exynos_map_dt_data() to probe function because it is really not a part
> of getting Device Tree properties.
> 
> Acked-by: Lukasz Majewski <l.majewski@...sung.com>
> Tested-by: Lukasz Majewski <l.majewski@...sung.com>
> Reviewed-by: Alim Akhtar <alim.akhtar@...sung.com>
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@...sung.com>
> Fixes: 5f09a5cbd14a ("thermal: exynos: Disable the regulator on probe failure")
> Signed-off-by: Eduardo Valentin <edubezval@...il.com>
> [ luis: backported to 3.16: adjusted context ]
> Signed-off-by: Luis Henriques <luis.henriques@...onical.com>

This patch shouldn't be backported before 4.2. It fixes a bug introduced
in 4.2: 5f09a5cbd14a.

For kernels <4.2 this bug does not exist but fortunately the patch looks
harmless. Anyway still for <4.2 I think it shouldn't be ported.

Best regards,
Krzysztof

> ---
>  drivers/thermal/samsung/exynos_tmu.c | 33 ++++++++++++++++-----------------
>  1 file changed, 16 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/thermal/samsung/exynos_tmu.c b/drivers/thermal/samsung/exynos_tmu.c
> index efed4eedf47f..bd3ba217386e 100644
> --- a/drivers/thermal/samsung/exynos_tmu.c
> +++ b/drivers/thermal/samsung/exynos_tmu.c
> @@ -558,27 +558,10 @@ static int exynos_map_dt_data(struct platform_device *pdev)
>  	struct exynos_tmu_data *data = platform_get_drvdata(pdev);
>  	struct exynos_tmu_platform_data *pdata;
>  	struct resource res;
> -	int ret;
>  
>  	if (!data || !pdev->dev.of_node)
>  		return -ENODEV;
>  
> -	/*
> -	 * Try enabling the regulator if found
> -	 * TODO: Add regulator as an SOC feature, so that regulator enable
> -	 * is a compulsory call.
> -	 */
> -	data->regulator = devm_regulator_get(&pdev->dev, "vtmu");
> -	if (!IS_ERR(data->regulator)) {
> -		ret = regulator_enable(data->regulator);
> -		if (ret) {
> -			dev_err(&pdev->dev, "failed to enable vtmu\n");
> -			return ret;
> -		}
> -	} else {
> -		dev_info(&pdev->dev, "Regulator node (vtmu) not found\n");
> -	}
> -
>  	data->id = of_alias_get_id(pdev->dev.of_node, "tmuctrl");
>  	if (data->id < 0)
>  		data->id = 0;
> @@ -643,6 +626,22 @@ static int exynos_tmu_probe(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, data);
>  	mutex_init(&data->lock);
>  
> +	/*
> +	 * Try enabling the regulator if found
> +	 * TODO: Add regulator as an SOC feature, so that regulator enable
> +	 * is a compulsory call.
> +	 */
> +	data->regulator = devm_regulator_get(&pdev->dev, "vtmu");
> +	if (!IS_ERR(data->regulator)) {
> +		ret = regulator_enable(data->regulator);
> +		if (ret) {
> +			dev_err(&pdev->dev, "failed to enable vtmu\n");
> +			return ret;
> +		}
> +	} else {
> +		dev_info(&pdev->dev, "Regulator node (vtmu) not found\n");
> +	}
> +
>  	ret = exynos_map_dt_data(pdev);
>  	if (ret)
>  		return ret;
> --
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